WorldWideScience

Sample records for sar attributed scattering

  1. Polarimetric scattering and SAR information retrieval

    CERN Document Server

    Jin, Ya-Qiu

    2013-01-01

    Taking an innovative look at Synthetic Aperture Radar (SAR), this practical reference fully covers new developments in SAR and its various methodologies and enables readers to interpret SAR imagery An essential reference on polarimetric Synthetic Aperture Radar (SAR), this book uses scattering theory and radiative transfer theory as a basis for its treatment of topics. It is organized to include theoretical scattering models and SAR data analysis techniques, and presents cutting-edge research on theoretical modelling of terrain surface. The book includes quantitative app

  2. InSAR Forensics: Tracing InSAR Scatterers in High Resolution Optical Image

    Science.gov (United States)

    Wang, Yuanyuan; Zhu, XiaoXiang

    2015-05-01

    This paper presents a step towards a better interpretation of the scattering mechanism of different objects and their deformation histories in SAR interferometry (InSAR). The proposed technique traces individual SAR scatterer in high resolution optical images where their geometries, materials, and other properties can be better analyzed and classified. And hence scatterers of a same object can be analyzed in group, which brings us to a new level of InSAR deformation monitoring.

  3. Permanent scatterer InSAR processing: Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Dehls, John F. [Geological Survey of Norway, Trondheim (Norway)

    2006-04-15

    It has been speculated that slow, aseismic movement may be occurring along some of the fracture zones crosscutting the Forsmark area. The purpose of this study is to determine if it is possible to measure such movement using dInSAR. Differential SAR Interferometry (DInSAR) is a technique that compares the phases of multiple radar images of an area to measure surface change. The method has the potential to detect millimetric surface deformation along the sensor - target line-of-sight. Differences in phase between two images are easily viewed by combining, or interfering, the two phase-images. In the resulting image, the waves will either reinforce or cancel one another, depending upon the relative phases. The resulting image is called an interferogram and contains concentric bands of colour, or fringes, that are related to topography and/or surface deformation. New algorithms use many images acquired over a long time period to determine the movement history of individual objects, referred to as permanent scatterers. In the current project, standard PSInSAR processing was performed on 40 ERS-1 and ERS-2 scenes. The total area processed is approximately 1,500 km{sup 2}. Slightly less than 20,000 permanent scatterers were identified.The highest densities were obtained along the coast and on the islands, where natural outcrops are more abundant. Two main classes of objects act as permanent scatterers in this area. The first are natural reflectors, such as rocks. The second are man-made reflectors, such as parts of buildings. Numerous local movements were found in the study area, relating to building subsidence, or compaction of anthropogenic fill. The dataset was divided into three groups for analysis, based upon the location of regional lineaments provided by SKB. Both statistical and geostatistical techniques were used. The median velocity of the three blocks did not differ by more than 0.2 mm/yr. This is not considered significant, given the possible magnitude of

  4. Interferometric SAR Persistent Scatterer Analysis of Mayon volcano, Albay, Philippines

    Science.gov (United States)

    Bato, M. P.; Lagmay, A. A.; Paguican, E. R.

    2011-12-01

    Persistent Scatterer Interferometry (PSInSAR) is a new method of interferometric processing that overcomes the limitations of conventional Synthetic Aperture Radar differential interferometry (DInSAR) and is capable of detecting millimeter scale ground displacements. PSInSAR eliminate anomalies due to atmospheric delays and temporal and geometric decorrelation eminent in tropical regions by exploiting the temporal and spatial characteristics of radar interferometric signatures derived from time-coherent point-wise targets. In this study, PSInSAR conducted in Mayon Volcano, Albay Province, Bicol, Philippines, reveal tectonic deformation passing underneath the volcano. Using 47 combined ERS and ENVISAT ascending and descending imageries, differential movement between the northern horst and graben on which Mayon volcano lies, is as much as 2.5 cm/year in terms of the line-of-sight (LOS) change in the radar signal. The northern horst moves in the northwest direction whereas the graben moves mostly downward. PSInSAR results when coupled with morphological interpretation suggest left-lateral oblique-slip movement of the northern bounding fault of the Oas graben. The PSInSAR results are validated with dGPS measurements. This work presents the functionality of PSInSAR in a humid tropical environment and highlights the probable landslide hazards associated with an oversteepened volcano that may have been further deformed by tectonic activity.

  5. Sample Extraction Bsaed on Helix Scattering for Polarimetric SAR Calibratio

    Science.gov (United States)

    Chang, Y.; Yang, J.; Li, P.; Zhao, L.; Shi, L.

    2017-09-01

    Polarimetric calibration (PolCAL) of Synthetic Aperture Radar (SAR) images is a significant preprocessing for further applications. Since the reflection symmetry property of distributed objects can provide stable constraints for PolCAL. It is reasonable to extract these reference samples before calibration. The helix scattering generally appears in complex urban area and disappears for a natural scatterer, making it a good measure to extract distributed objects. In this paper, a novel technique that extracts reflecting symmetry samples is proposed by using helix scattering. The helix scattering information is calculated by Yamaguchi four-component decomposition algorithm. An adaptive threshold selection algorithm based on generalized Gaussian distribution is also utilized to scale the helix scattering components automatically, getting rid of the problem of various numerical range. The extracting results will be taken as PolCAL reference samples and the Quegan method are utilized to calibrate these PolSAR images. A C-band airborne PolSAR data was taken as examples to evaluate its ability in improving calibration precision. Traditional method i.e. extracting samples with span power was also evaluated as contrast experiment. The results showed that the samples extracting method based on helix scattering can improve the Polcal precision preferably.

  6. On the application of SAR interferometry to geomorphological studies: estimation of landform attributes and mass movements

    Science.gov (United States)

    Catani, Filippo; Farina, Paolo; Moretti, Sandro; Nico, Giovanni; Strozzi, Tazio

    2005-03-01

    This paper presents two examples of application of Synthetic Aperture Radar (SAR) interferometry (InSAR) to typical geomorphological problems. The principles of InSAR are introduced, taking care to clarify the limits and the potential of this technique for geomorphological studies. The application of InSAR to the quantification of landform attributes such as the slope and to the estimation of landform variations is investigated. Two case studies are presented. A first case study focuses on the problem of measuring landform attributes by interferometric SAR data. The interferometric result is compared with the corresponding one obtained by a Digital Elevation Model (DEM). In the second case study, the use of InSAR for the estimation of landform variations caused by a landslide is detailed.

  7. Scattering Mechanism Extraction by a Modified Cloude-Pottier Decomposition for Dual Polarization SAR

    Directory of Open Access Journals (Sweden)

    Kefeng Ji

    2015-06-01

    Full Text Available Dual polarization is a typical operational mode of polarimetric synthetic aperture radar (SAR. However, few studies have considered the scattering mechanism extraction of dual-polarization SARs. A modified Cloude-Pottier decomposition is proposed to investigate the performance of the scattering mechanism extraction of dual-polarization SARs. It is theoretically demonstrated that only HH-VV SAR can discriminate the three canonical scattering mechanisms from an isotropic surface, horizontal dipole, and isotropic dihedral. Various experiments are conducted using 21 scenes from real datasets acquired by AIRSAR, Convair-580 SAR, EMISAR, E-SAR, Pi-SAR, and RADARSAT-2. Division of the dual-polarization H-α plane is experimentally obtained. The lack of cross-polarization induces the diffusion of scattering mechanisms and their overlap in the HH-VV H-α plane. However, the performance of HH-VV SAR for extracting scattering mechanisms is acceptable. Thus, HH-VV SAR is a suitable alternative to full-polarization SAR in certain cases. Meanwhile, the extraction performance of the other two dual-polarization SARs is badly degraded due to the lack of co-polarization. Therefore, HH-HV and HV-VV SARs cannot effectively extract the scattering mechanisms in the H-α plane.

  8. Synthetic aperture radar imaging based on attributed scatter model using sparse recovery techniques

    Institute of Scientific and Technical Information of China (English)

    苏伍各; 王宏强; 阳召成

    2014-01-01

    The sparse recovery algorithms formulate synthetic aperture radar (SAR) imaging problem in terms of sparse representation (SR) of a small number of strong scatters’ positions among a much large number of potential scatters’ positions, and provide an effective approach to improve the SAR image resolution. Based on the attributed scatter center model, several experiments were performed with different practical considerations to evaluate the performance of five representative SR techniques, namely, sparse Bayesian learning (SBL), fast Bayesian matching pursuit (FBMP), smoothed l0 norm method (SL0), sparse reconstruction by separable approximation (SpaRSA), fast iterative shrinkage-thresholding algorithm (FISTA), and the parameter settings in five SR algorithms were discussed. In different situations, the performances of these algorithms were also discussed. Through the comparison of MSE and failure rate in each algorithm simulation, FBMP and SpaRSA are found suitable for dealing with problems in the SAR imaging based on attributed scattering center model. Although the SBL is time-consuming, it always get better performance when related to failure rate and high SNR.

  9. Delta-K Wideband SAR Interferometry for DEM Generation and Persistent Scatterers Using TeraSAR-X

    Science.gov (United States)

    Brcic, Ramon; Eineder, Michael; Bamler, Richard; Steinbrecher, Ulrich; Schulze, Daniel; Metzig, Robert; Papathanassiou, Konstantinos; Nagler, Thomas; Mueller, Florian; Suess, Martin

    2010-03-01

    Wideband SAR systems such as TerraSAR-X allow estimation of the absolute interferometric phase without resorting to error prone phase unwrapping. This is achieved through the delta-k technique that exploits frequency diversity within the range bandwidth to simulate a SAR system with a much longer carrier wavelength. This benefits all interferometric applications including DEM generation and land surface motion determination. Here we present the results of an ESA study (21318/07/NL/HE) into using delta-k absolute phase estimation for DEM generation and PSI (Persistent Scatterer Interferometry). Using TerraSAR- X data, examples from a delta-k DEM generation system are shown which avoid the errors induced by conventional phase unwrapping. For PSI, the possibilities of absolute phase estimation for a single PS are explored in theory and examples where wideband estimation is compared to conventional PSI processing for a stack of acquisitions over Paris.

  10. Analysis on Vertical Scattering Signatures in Forestry with PolInSAR

    Science.gov (United States)

    Guo, Shenglong; Li, Yang; Zhang, Jingjing; Hong, Wen

    2014-11-01

    We apply accurate topographic phase to the Freeman-Durden decomposition for polarimetric SAR interferometry (PolInSAR) data. The cross correlation matrix obtained from PolInSAR observations can be decomposed into three scattering mechanisms matrices accounting for the odd-bounce, double-bounce and volume scattering. We estimate the phase based on the Random volume over Ground (RVoG) model, and as the initial input parameter of the numerical method which is used to solve the parameters of decomposition. In addition, the modified volume scattering model introduced by Y. Yamaguchi is applied to the PolInSAR target decomposition in forest areas rather than the pure random volume scattering as proposed by Freeman-Durden to make best fit to the actual measured data. This method can accurately retrieve the magnitude associated with each mechanism and their vertical location along the vertical dimension. We test the algorithms with L- and P- band simulated data.

  11. Three-Component Power Decomposition for Polarimetric SAR Data Based on Adaptive Volume Scatter Modeling

    Directory of Open Access Journals (Sweden)

    Sang-Eun Park

    2012-05-01

    Full Text Available In this paper, the three-component power decomposition for polarimetric SAR (PolSAR data with an adaptive volume scattering model is proposed. The volume scattering model is assumed to be reflection-symmetric but parameterized. For each image pixel, the decomposition first starts with determining the adaptive parameter based on matrix similarity metric. Then, a respective scattering power component is retrieved with the established procedure. It has been shown that the proposed method leads to complete elimination of negative powers as the result of the adaptive volume scattering model. Experiments with the PolSAR data from both the NASA/JPL (National Aeronautics and Space Administration/Jet Propulsion Laboratory Airborne SAR (AIRSAR and the JAXA (Japan Aerospace Exploration Agency ALOS-PALSAR also demonstrate that the proposed method not only obtains similar/better results in vegetated areas as compared to the existing Freeman-Durden decomposition but helps to improve discrimination of the urban regions.

  12. SAR Automatic Target Recognition Based on Numerical Scattering Simulation and Model-based Matching

    Directory of Open Access Journals (Sweden)

    Zhou Yu

    2015-12-01

    Full Text Available This study proposes a model-based Synthetic Aperture Radar (SAR automatic target recognition algorithm. Scattering is computed offline using the laboratory-developed Bidirectional Analytic Ray Tracing software and the same system parameter settings as the Moving and Stationary Target Acquisition and Recognition (MSTAR datasets. SAR images are then created by simulated electromagnetic scattering data. Shape features are extracted from the measured and simulated images, and then, matches are searched. The algorithm is verified using three types of targets from MSTAR data and simulated SAR images, and it is shown that the proposed approach is fast and easy to implement with high accuracy.

  13. A dense medium electromagnetic scattering model for the InSAR correlation of snow

    Science.gov (United States)

    Lei, Yang; Siqueira, Paul; Treuhaft, Robert

    2016-05-01

    Snow characteristics, such as snow water equivalent (SWE) and snow grain size, are important characteristics for the monitoring of the global hydrological cycle and as indicators of climate change. This paper derives an interferometric synthetic aperture radar (InSAR) scattering model for dense media, such as snow, which takes into account multiple scattering effects through the Quasi-Crystalline Approximation. The result of this derivation is a simplified version of the InSAR correlation model derived for relating the InSAR correlation measurements to the snowpack characteristics of grain size, volume fraction, and layer depth as well as those aspects of the volume-ground interaction that affects the interferometric observation (i.e., the surface topography and the ratio of ground-to-volume scattering). Based on the model, the sensitivity of the InSAR correlation measurements to the snow characteristics is explored by simulation. Through this process, it is shown that Ka-band InSAR phase has a good sensitivity to snow grain size and volume fraction, while for lower frequency signals (Ku-band to L-band), the InSAR correlation magnitude and phase have a sensitivity to snow depth. Since the formulation depends, in part, on the pair distribution function, three functional forms of the pair distribution function are implemented and their effects on InSAR phase measurements compared. The InSAR scattering model described in this paper is intended to be an observational prototype for future Ka-band and L-band InSAR missions, such as NASA's Surface Water and Ocean Topography and NASA-ISRO Synthetic Aperture Radar missions, planned for launch in the 2020-2021 time frame. This formulation also enables further investigation of the InSAR-based snow retrieval approaches.

  14. Exploiting azimuthal variance of scatterers for multiple-look SAR recognition

    Science.gov (United States)

    Bhanu, Bir; Jones, Grinnell, III

    2002-08-01

    The focus of this paper is optimizing the recognition of vehicles in Synthetic Aperture Radar (SAR) imagery using multiple SAR recognizers at different look angles. The variance of SAR scattering center locations with target azimuth leads to recognition system results at different azimuths that are independent, even for small azimuth deltas. Extensive experimental recognition results are presented in terms of receiver operating characteristic (ROC) curves to show the effects of multiple look angles on recognition performance for MSTAR vehicle targets with configuration variants, articulation, and occlusion.

  15. Model Simulation and Eigen-Analysis for Polarimetric Scattering from Tree Canopy in SAR Imagery

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, a theoretical model of multi-level, non-spherical scatterers is develotped for fully polarimetric scattering from tree canopy in SAR imaging at C band. The amplitude functions of non-spherical particles with randomly spatial orientation are derived by the generalized Rayleigh Gans (GRG) approximation. The non-diagonal extinction matrix and the Mueller matrix solution are constructed. Numerical solutions of polarimetric scattering of four Stokes parametersfrom random, non-spherical scatterers are obtained. To physically identify polarimetric scattering of the Mueller matrix solution, the coherency matrix and its eigen-analysis are discussed. Functional dependence of the coherency matrix and entropy upon various parameters are obtained. As an application, the analysis of AirSAR images at P, L, C bands is discussed.

  16. Deorientation of PolSAR coherency matrix for volume scattering retrieval

    Science.gov (United States)

    Kumar, Shashi; Garg, R. D.; Kushwaha, S. P. S.

    2016-05-01

    Polarimetric SAR data has proven its potential to extract scattering information for different features appearing in single resolution cell. Several decomposition modelling approaches have been developed to retrieve scattering information from PolSAR data. During scattering power decomposition based on physical scattering models it becomes very difficult to distinguish volume scattering as a result from randomly oriented vegetation from scattering nature of oblique structures which are responsible for double-bounce and volume scattering , because both are decomposed in same scattering mechanism. The polarization orientation angle (POA) of an electromagnetic wave is one of the most important character which gets changed due to scattering from geometrical structure of topographic slopes, oriented urban area and randomly oriented features like vegetation cover. The shift in POA affects the polarimetric radar signatures. So, for accurate estimation of scattering nature of feature compensation in polarization orientation shift becomes an essential procedure. The prime objective of this work was to investigate the effect of shift in POA in scattering information retrieval and to explore the effect of deorientation on regression between field-estimated aboveground biomass (AGB) and volume scattering. For this study Dudhwa National Park, U.P., India was selected as study area and fully polarimetric ALOS PALSAR data was used to retrieve scattering information from the forest area of Dudhwa National Park. Field data for DBH and tree height was collect for AGB estimation using stratified random sampling. AGB was estimated for 170 plots for different locations of the forest area. Yamaguchi four component decomposition modelling approach was utilized to retrieve surface, double-bounce, helix and volume scattering information. Shift in polarization orientation angle was estimated and deorientation of coherency matrix for compensation of POA shift was performed. Effect of

  17. Time-domain compressive dictionary of attributed scattering center model for sparse representation

    Institute of Scientific and Technical Information of China (English)

    ZHONG Jin-rong; WEN Gong-jian

    2016-01-01

    Parameter estimation of the attributed scattering center (ASC) model is significant for automatic target recognition (ATR). Sparse representation based parameter estimation methods have developed rapidly. Construction of the separable dictionary is a key issue for sparse representation technology. A compressive time-domain dictionary (TD) for ASC model is presented. Two-dimensional frequency domain responses of the ASC are produced and transformed into the time domain. Then these time domain responses are cutoff and stacked into vectors. These vectored time-domain responses are amalgamated to form the TD. Compared with the traditional frequency-domain dictionary (FD), the TD is a matrix that is quite spare and can markedly reduce the data size of the dictionary. Based on the basic TD construction method, we present four extended TD construction methods, which are available for different applications. In the experiments, the performance of the TD, including the basic model and the extended models, has been firstly analyzed in comparison with the FD. Secondly, an example of parameter estimation from SAR synthetic aperture radar (SAR) measurements of a target collected in an anechoic room is exhibited. Finally, a sparse image reconstruction example is from two apart apertures. Experimental results demonstrate the effectiveness and efficiency of the proposed TD.

  18. Permanent Scatterer InSAR Analysis and Validation in the Gulf of Corinth

    Directory of Open Access Journals (Sweden)

    Charalabos Kontoes

    2009-01-01

    Full Text Available The Permanent Scatterers Interferometric SAR technique (PSInSAR is a method that accurately estimates the near vertical terrain deformation rates, of the order of ~1 mm year-1, overcoming the physical and technical restrictions of classic InSAR. In this paper the method is strengthened by creating a robust processing chain, incorporating PSInSAR analysis together with algorithmic adaptations for Permanent Scatterer Candidates (PSCs and Permanent Scatterers (PSs selection. The processing chain, called PerSePHONE, was applied and validated in the geophysically active area of the Gulf of Corinth. The analysis indicated a clear subsidence trend in the north-eastern part of the gulf, with the maximum deformation of ~2.5 mm year-1 occurring in the region north of the Gulf of Alkyonides. The validity of the results was assessed against geophysical/geological and geodetic studies conducted in the area, which include continuous seismic profiling data and GPS height measurements. All these observations converge to the same deformation pattern as the one derived by the PSInSAR technique.

  19. Phase History Decomposition for efficient Scatterer Classification in SAR Imagery

    Science.gov (United States)

    2011-09-15

    Force Research Laboratory, Wright-Patterson AFB , OH, 2009. [125] Rau, R., JH McClellan , L. Technol, and G. Nuremberg. “Analytic models and...Institute of Technology, Wright-Patterson AFB , OH, 2009. [5] Bajcsy, P. and A.R. Chaudhuri. “Benefits of high resolution SAR for ATR of targets in...AFRL strategic tech- nology development. Technical report, Air Force Research Laboratory, Wright- Patterson AFB , OH, 2008. [20] Cameron, W.L. and L.K

  20. Monitoring subsidence rates along road network by persistent scatterer SAR interferometry with high-resolution TerraSAR-X imagery

    Institute of Scientific and Technical Information of China (English)

    Bing Yu; Guoxiang Liu; Rui Zhang; Hongguo Jia; Tao Li; Xiaowen Wang; Keren Dai; Deying Ma

    2013-01-01

    Ground subsidence is one of the key factors damaging transportation facilities, e.g., road networks consisting of highways and railways. In this paper, we propose to apply the persistent scatterer synthetic aperture radar interferometry (PS-InSAR) approach that uses high-resolution TerraSAR-X (TSX) imagery to extract the regional scale subsidence rates (i.e., average annual sub-sidence in mm/year) along road networks. The primary procedures involve interferometric pair selection, interfer-ogram generation, persistent scatterer (PS) detection, PS networking, phase parameterization, and subsidence rate estimation. The Xiqing District in southwest Tianjin (China) is selected as the study area. This district contains one railway line and several highway lines. A total of 15 TSX images covering this area between April 2009 and June 2010 are utilized to obtain the subsidence rates by using the PS-InSAR (PSI) approach. The subsidence rates derived from PSI range from -68.7 to -1.3 mm/year. These findings show a significantly uneven subsidence pattern along the road network. Comparison between the PSI-derived subsidence rates and the leveling data obtained along the highways shows that the mean and standard deviation (SD) of the discrepancies between the two types of subsidence rates are 0.1 and ±3.2 mm/year, respec-tively. The results indicate that the high-resolution TSX PSI is capable of providing comprehensive and detailed subsidence information regarding road networks with millimeter-level accuracy. Further inspections under geo-logical conditions and land-use categories in the study area indicate that the observed subsidence is highly related to aquifer compression due to groundwater pumping. There-fore, measures should be taken to mitigate groundwater extraction for the study area.

  1. Characterization of Vegetation and Soil Scattering Mechanisms across Different Biomes using P-band SAR Polarimetry

    CERN Document Server

    Alemohammad, Seyed Hamed; Jagdhuber, Thomas; Moghaddam, Mahta; Entekhabi, Dara

    2016-01-01

    A quantitative analysis of vegetation and soil scattering mechanisms retrieved from the observations of an airborne P-band Synthetic Aperture Radar (SAR) instrument across nine different biomes in North America is presented. The understanding of scattering mechanisms from the surface in the presence of different vegetation densities is necessary for the interpretation of P-band SAR observations and for the design of retrieval algorithms. Observations used here are part of the NASA Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission, and data have been collected between 2013 and 2015. A data-driven phase calibration technique is used to correct the phase information in the polarimetric observations. A hybrid (model- and eigen- based) three component decomposition algorithm is developed to separate the contributions of surface, double-bounce and vegetation scattering. The decomposition makes no prior assumptions about vegetation structure and is analytically tractable. Applying the retr...

  2. Multi-Temporal InSAR Analysis of Wenjiagou Landslide using Distributed Scatterers

    Science.gov (United States)

    Wang, Chao; Zhang, Zhengjia; Zhang, Hong; Tang, Yixian

    2015-05-01

    This paper presents a multi-temporal InSAR method to monitor landslide movement at wenjiagou using Distributed Scatterers (DS). In this study, TDX and TSX bistatic SAR data are processed to obtain high precision DEM of the pose-landslide. DSs are efficiently identified using classified information and statistical characteristics. A series of Radarsat-2 HH polarization images collected in Wenjiagou from 2014.6 to 2014.9 are used to generate the deformation of the giant landslide. The experimental results show that there are obvious ground movement detected in the depositing area of the landslide during the observation.

  3. Long term monitoring of urban subsidence by Permanent Scatterer DInSAR

    Institute of Scientific and Technical Information of China (English)

    TANG Yixian; ZHANG Hong; WANG Chao

    2007-01-01

    When using differential SAR interferometry (DInSAR) to monitor the surface deformation over a long time scale, it is often strongly affected by the spatial and temporal decorrelations and atmospheric dishomogeneities. The recently developed Permanent Scatterers (PS) technique proposed by Fertti et al. can overcome these difficulties by interpreting time-series of interferometric phase only at coherent point scatterers. In this study, we apply this PS technique using 25 ERS-1/2 scenes from 1992 to 2000 to monitor the subsidence in Suzhou. By using the linear deformation model, the deformation map in Suzhou urban area over the eight years is obtained. And the calculated results are in good agreement with the measurements of leveling.

  4. Sandbank and Oyster Farm Monitoring with Multi-Temporal Polarimetric SAR Data Using Four-Component Scattering Power Decomposition

    OpenAIRE

    Cheng, Tzu-Yu; Yamaguchi, Yoshio; Chen, Kun-Shan; Lee, Jong-Sen; Cui, Yi

    2013-01-01

    In this paper, a multi-temporal analysis of polarimetric synthetic aperture radar (Pol-SAR) data over the sandbank and oyster farm area is presented. Specifically, a four-component scattering model, being able to identify single bounce, double bounce, volume, and helix scattering power contributions, has been employed to retrieve information. Decomposition results of a time series RADARSAT Pol-SAR images acquired over the western Taiwan coast indicate that the coastal tide level plays a key r...

  5. Grouping of Persistent Scatterers in high-resolution SAR data of urban scenes

    Science.gov (United States)

    Schunert, Alexander; Soergel, Uwe

    2012-09-01

    Persistent Scatterer Interferometry (PSI) is a technique to simultaneously estimate surface deformation and 3D structure from stacks of SAR images. It was proposed first about one decade ago to monitor preferably urban areas, where in general the highest numbers of PS are found. At that time no high-resolution satellite SAR data were available. Instead, for example, stacks of ERS imagery were used providing ground range resolution of about 25 m. In data of such kind only the strongest PS can be detected, which are usually caused by corner reflectors built by orthogonal building and road planes of considerable size, whereas smaller structures causing weaker ones signal are averaged by clutter or mutually interfere with others in the same resolution cell. Thus, if any, only a few or even just one single PS are found per building. The advent of a new senor generation of systems like TerraSAR-X and COSMO-Skymed in 2007 led to a significant improvement of spatial resolution of about one order of magnitude. This comes along with a dramatic rise of PS density: In some cases tens to hundreds are detected at large buildings, which offers the possibility to monitor even individual urban objects. In addition, especially at building façades the distribution of those PS is often quite regular. A reason for that is the usually rectilinear arrangement of façade structures inducing PS like windows or balconies. Those patterns contain a lot of information about the objects under investigation, which is mostly ignored in current PSI processing schemes. For example, consider a regular structure of windows on a certain façade of a multi-story building. Assuming the same kind of structure generates one single PS at each window, the phase centers of all scatterers caused by windows of each floor share the same height. This means, we may benefit from such kind of redundancy, for instance, to improve the height estimate by averaging over PS having the same elevation. In this work, we

  6. Comparison of Laser and Stereo Optical, SAR and InSAR Point Clouds from Air- and Space-Borne Sources in the Retrieval of Forest Inventory Attributes

    Directory of Open Access Journals (Sweden)

    Xiaowei Yu

    2015-11-01

    Full Text Available It is anticipated that many of the future forest mapping applications will be based on three-dimensional (3D point clouds. A comparison study was conducted to verify the explanatory power and information contents of several 3D remote sensing data sources on the retrieval of above ground biomass (AGB, stem volume (VOL, basal area (G, basal-area weighted mean diameter (Dg and Lorey’s mean height (Hg at the plot level, utilizing the following data: synthetic aperture radar (SAR Interferometry, SAR radargrammetry, satellite-imagery having stereo viewing capability, airborne laser scanning (ALS with various densities (0.8–6 pulses/m2 and aerial stereo imagery. Laser scanning is generally known as the primary source providing a 3D point cloud. However, photogrammetric, radargrammetric and interferometric techniques can be used to produce 3D point clouds from space- and air-borne stereo images. Such an image-based point cloud could be utilized in a similar manner as ALS providing that accurate digital terrain model is available. In this study, the performance of these data sources for providing point cloud data was evaluated with 91 sample plots that were established in Evo, southern Finland within a boreal forest zone and surveyed in 2014 for this comparison. The prediction models were built using random forests technique with features derived from each data sources as independent variables and field measurements of forest attributes as response variable. The relative root mean square errors (RMSEs varied in the ranges of 4.6% (0.97 m–13.4% (2.83 m for Hg, 11.7% (3.0 cm–20.6% (5.3 cm for Dg, 14.8% (4.0 m2/ha–25.8% (6.9 m2/ha for G, 15.9% (43.0 m3/ha–31.2% (84.2 m3/ha for VOL and 14.3% (19.2 Mg/ha–27.5% (37.0 Mg/ha for AGB, respectively, depending on the data used. Results indicate that ALS data achieved the most accurate estimates for all forest inventory attributes. For image-based 3D data, high-altitude aerial images and WorldView-2

  7. Subsidence monitoring in coal area using time-series InSAR combining persistent scatterers and distributed scatterers

    Science.gov (United States)

    Zhang, Zhengjia; Wang, Chao; Tang, Yixian; Fu, Qiaoyan; Zhang, Hong

    2015-07-01

    In coal mining areas, ground subsidence persistently happens, which produces serious environmental issues and affects the development of cities. To monitor the ground deformation due to coal mining, a modified time-series InSAR technique combining persistent scatterers (PSs) and distributed scatterers (DSs) is presented in this paper. In particular, DSs are efficiently identified using classified information and statistical characteristics. Furthermore, a two-scale network is introduced into traditional PSI to deal with PSs and DSs in a multi-layer framework by taking the advantage of the robust of PSs and the widely distribution of DSs. The proposed method is performed to investigate the subsidence of Huainan City, Anhui province (China), during 2012-2013 using 14 scenes of Radarsat-2 images. Experimental results show that the proposed method can ease the estimation complexity and significantly increase the spatial density of measurement points, which can provide more detailed deformation information. Result shows that there are obvious subsidence areas detected in the test site with subsidence velocity larger than 5 cm/year. The proposed method brings practical applications for non-urban area deformation monitoring.

  8. Tutorial on Fourier space coverage for scattering experiments, with application to SAR

    Science.gov (United States)

    Deming, Ross W.

    2010-04-01

    The Fourier Diffraction Theorem relates the data measured during electromagnetic, optical, or acoustic scattering experiments to the spatial Fourier transform of the object under test. The theorem is well-known, but since it is based on integral equations and complicated mathematical expansions, the typical derivation may be difficult for the non-specialist. In this paper, the theorem is derived and presented using simple geometry, plus undergraduatelevel physics and mathematics. For practitioners of synthetic aperture radar (SAR) imaging, the theorem is important to understand because it leads to a simple geometric and graphical understanding of image resolution and sampling requirements, and how they are affected by radar system parameters and experimental geometry. Also, the theorem can be used as a starting point for imaging algorithms and motion compensation methods. Several examples are given in this paper for realistic scenarios.

  9. Single-Network Wide-Area Persistent Scatterer Interferometry: Algorithms with Application to Sentinel-1 InSAR Data

    Science.gov (United States)

    Goel, K.; Shau, R.; Adam, N.

    2015-12-01

    Advanced InSAR techniques, for example, Persistent Scatterer Interferometry (PSI), allow long term deformation time series analysis with millimeter accuracy. ESA's Sentinel-1 SAR mission employs the TOPS mode as the standard mode for acquiring InSAR data. It provides a continuous and large coverage at conventional resolution. The idea is to have a wide-area PSI for mapping countries and continents. Although PSI has been successfully demonstrated and validated in the past for various applications, there are some limitations for processing a large-scale dataset. First, PSI is most effective in urban areas which have a large number of stable scatterers. For large-scale PSI, even non-urban areas need to be processed; and this requires robust algorithms for scatterer selection, network construction and inversion, and atmospheric phase removal. Second, the computational load can be very high, due to which, the processing is usually divided into overlapping blocks and merged later. This can however lead to spatial error propagation. This paper presents algorithms which have been developed for a robust PSI reference network estimation, while mitigating error propagation. Instead of dividing the scene into overlapping blocks, a single network (i.e. arcs connecting the scatterers) is created for the full scene. The relative deformation and residual DEM are estimated for the arcs using the LAMBDA estimator. The relative measurements of the network are finally integrated via least-squares inversion. Here, the sparsity of the system of linear equations is exploited to deal with big data (e.g. 10,000,000 arcs for 500,000 scatterers is a typical configuration for Sentinel-1). A QR or LU parallelizable solver is used for fast inversion. Also, variances of the estimates are calculated using a selected parallel inversion method based on LDL decomposition. Demonstration of the algorithms for large-scale deformation monitoring is provided using available Sentinel-1 data for Germany.

  10. Deformation Mapping for Coal Mining Using Time-Series InSAR Combining Persistent Scatterer and Distributed Scatterer in Huainan City, China

    Science.gov (United States)

    Zhang, Zhengjia; Tang, Yixian; Wang, Chao; Zhang, Hong

    2015-05-01

    A modified time-series InSAR technique combing Persistent Scatterers and Distributed scatterers is applied to obtain the deformation information at coal mining areas in Huainan city. In order to select DSs, a selecting strategy combining both classified information and statistical characteristics is used. To control error propagation and improve computational efficiency, a region growing-based strategy is applied to extract the deformation rate at DSs. A series of Radarsat-2 HH polarization images collected in Huainan over a period of approximately two years are processed to verify the effectiveness of the proposed method. The experimental results show that zones with obvious subsidence are detected in coal mining areas with a maximum deformation rate larger than 10.7 cm/year during the observation period.

  11. Classifying sets of attributed scattering centers using a hash coded database

    Science.gov (United States)

    Dungan, Kerry E.; Potter, Lee C.

    2010-04-01

    We present a fast, scalable method to simultaneously register and classify vehicles in circular synthetic aperture radar imagery. The method is robust to clutter, occlusions, and partial matches. Images are represented as a set of attributed scattering centers that are mapped to local sets, which are invariant to rigid transformations. Similarity between local sets is measured using a method called pyramid match hashing, which applies a pyramid match kernel to compare sets and a Hamming distance to compare hash codes generated from those sets. By preprocessing a database into a Hamming space, we are able to quickly find the nearest neighbor of a query among a large number of records. To demonstrate the algorithm, we simulated X-band scattering from ten civilian vehicles placed throughout a large scene, varying elevation angles in the 35 to 59 degree range. We achieved better than 98 percent classification performance. We also classified seven vehicles in a 2006 public release data collection with 100% success.

  12. Analysis of the double bounce scattering mechanism of buildings in VHR SAR data

    Science.gov (United States)

    Brunner, D.; Bruzzone, L.; Ferro, A.; Fortuny, J.; Lemoine, G.

    2008-10-01

    This paper presents a detailed experimental study on the behavior of the backscattering of buildings in very high resolution (VHR) synthetic aperture radar (SAR) images under varying conditions. The double bounce effect caused by the corner reflector between the front wall of the buildign and its surrounding ground area is an important characterist of the building in VHR SAR. Therefore, we focus on the analysis of the relation between the double bounce effect and the aspect angle of the building. The study is carried out in three phases: i)development of a laboratory experimental setup on a scaled building model under well-controlled conditions with a variety of viewing configurations; ii) validation of the results obtained from the laboratyr measurements with real VHR airborne SAR data; iii) comparison of the above mentioned results with the simulations obtained by two theoretical models derived from electromagnetic theory. The laboratory experiments were carried out at the European Microwave Signature Lab (EMSL) at the Joint Research Centre (JRC) of the European Commission (EC), whie the real airborne SAR images wer acquired by the RAMSES sensor and were processed in order to obtain simulations of COSMO-SkyMed satellite images. The analyses showed that the strength of the double bounce drops rapidly in the low aspect angle range, while it decreases moderately for larter angles.

  13. Estimating forest variables from fusion of SAR and TM data and analytical scattering and reflectance models

    Science.gov (United States)

    Dungan, J.; Moghaddam, M.

    2001-01-01

    A method for simultaneous integration of synthetic aperture radar (SAR) and optical remote sensing data in an estimation algorithm is presented which results in estimates of foliage mass over a larger range of values and more accurately than would be possible with either data type alone.

  14. Doppler Spectrum-Based NRCS Estimation Method for Low-Scattering Areas in Ocean SAR Images

    Directory of Open Access Journals (Sweden)

    Hui Meng

    2017-02-01

    Full Text Available The image intensities of low-backscattering areas in synthetic aperture radar (SAR images are often seriously contaminated by the system noise floor and azimuthal ambiguity signal from adjacent high-backscattering areas. Hence, the image intensity of low-backscattering areas does not correctly reflect the backscattering intensity, which causes confusion in subsequent image processing or interpretation. In this paper, a method is proposed to estimate the normalized radar cross-section (NRCS of low-backscattering area by utilizing the differences between noise, azimuthal ambiguity, and signal in the Doppler frequency domain of single-look SAR images; the aim is to eliminate the effect of system noise and azimuthal ambiguity. Analysis shows that, for a spaceborne SAR with a noise equivalent sigma zero (NESZ of −25 dB and a single-look pixel of 8 m × 5 m, the NRCS-estimation precision of this method can reach −38 dB at a resolution of 96 m × 100 m. Three examples are given to validate the advantages of this method in estimating the low NRCS and the filtering of the azimuthal ambiguity.

  15. SARS Basics

    Science.gov (United States)

    ... and Resources Related Links Clinician Registry Travelers' Health SARS Basics Fact Sheet Language: English Español (Spanish) Format: ... 3 pages] SARS [3 pages] SARS [3 pages] SARS? Severe acute respiratory syndrome (SARS) is a viral ...

  16. Feature Extraction Using Attributed Scattering Center Models for Model-Based Automatic Target Recognition (ATR)

    Science.gov (United States)

    2005-10-01

    radar cross section (RCS), which is a measure of a target’s reflectivity. Assuming a specific imaging scene, we predict the SNR through the RCS of the...the effective length Lk of the scattering primitive. Many scattering geometries, such as dihedrals , corner reflectors , and cylinders, are...and M. T. Tuley. Radar Cross Section . Artech House, Boston, 1993. [4] E. R. Keydel, S. W. Lee and J. T. Moore. MSTAR extended operating conditions: a

  17. Estimation of rice grain yield from dual-polarization Radarsat-2 SAR data by integrating a rice canopy scattering model and a genetic algorithm

    Science.gov (United States)

    Zhang, Yuan; Yang, Bin; Liu, Xiaohui; Wang, Cuizhen

    2017-05-01

    Fast and accurate estimation of rice yield plays a role in forecasting rice productivity for ensuring regional or national food security. Microwave synthetic aperture radar (SAR) data has been proved to have a great potential for rice monitoring and parameters retrieval. In this study, a rice canopy scattering model (RCSM) was revised and then was applied to simulate the backscatter of rice canopy. The combination of RCSM and genetic algorithm (GA) was proposed for retrieving two important rice parameters relating to grain yield, ear length and ear number density, from a C-band, dual-polarization (HH and HV) Radarsat-2 SAR data. The stability of retrieved results of GA inversion was also evaluated by changing various parameter configurations. Results show that RCSM can effectively simulate backscattering coefficients of rice canopy at HH and HV mode with an error of operational yield estimation.

  18. Detection and Monitoring of Surface Motions in Active Open Pit Iron Mine in the Amazon Region, Using Persistent Scatterer Interferometry with TerraSAR-X Satellite Data

    Directory of Open Access Journals (Sweden)

    Marcos E. Hartwig

    2013-09-01

    Full Text Available Persistent Scatterer interferometry (PSI represents a powerful tool for the detection and monitoring of tiny surface deformations in vast areas, allowing a better understanding of its triggering mechanisms, planning of mitigation measures, as well as to find better solutions for social and environmental issues. However, there is no record hitherto of its use in active open pit mine in tropical rainforest environment. In this paper we evaluate the use of the PSI technique for the detection and monitoring of mine slope deformations in the N4W iron mine and its surroundings, Pará State, Northern Brazil. The PSI processing was performed with 18 ascending SAR scenes of the TerraSAR-X satellite acquired in the dry season of 2012. The results showed a significant number of widely distributed persistent scatterers. It was observed that most of the study area was stable during the time span. Nevertheless, high deformation rates (312 mm/year were mapped over the mine waste piles, but do not offer any hazard, since they are expected displacements of meters in magnitude for these manmade land structures. Additionally, it was mapped tiny deformation rates in both the east and west flanks of pits 1 and 2. The main underlying reasons can be assigned to the accommodation phenomena of very poor rock masses, to the local geometric variations of the slope cuts, to the geological contact between ironstones and the country rocks, to the exploitation activities, as well as to the major geological structures. This study showed the applicability of the PSI technique using TerraSAR-X scenes in active open pit mines in tropical moist environment. However, the PSI technique is not capable in providing real-time warnings, and faces limitations due to SAR viewing geometry. In this sense, we strongly recommend the use of radar scenes acquired in both ascending and descending orbits, which would also provide a more complete understanding of the deformation patterns.

  19. Noninvasive Qualitative and Quantitative Assessment of Spoilage Attributes of Chilled Pork Using Hyperspectral Scattering Technique.

    Science.gov (United States)

    Zhang, Leilei; Peng, Yankun

    2016-08-01

    The objective of this research was to develop a rapid noninvasive method for quantitative and qualitative determination of chilled pork spoilage. Microbiological, physicochemical, and organoleptic characteristics such as the total viable count (TVC), Pseudomonas spp., total volatile basic-nitrogen (TVB-N), pH value, and color parameter L* were determined to appraise pork quality. The hyperspectral scattering characteristics from 54 meat samples were fitted by four-parameter modified Gompertz function accurately. Support vector machines (SVM) was applied to establish quantitative prediction model between scattering fitting parameters and reference values. In addition, partial least squares discriminant analysis (PLS-DA) and Bayesian analysis were utilized as supervised and unsupervised techniques for the qualitative identification of meat spoilage. All stored chilled meat samples were classified into three grades: "fresh," "semi-fresh," and "spoiled." Bayesian classification model was superior to PLS-DA with overall classification accuracy of 92.86%. The results demonstrated that hyperspectral scattering technique combined with SVM and Bayesian possessed a powerful capability for meat spoilage assessment rapidly and noninvasively. © The Author(s) 2016.

  20. Bistatic SAR: Imagery & Image Products.

    Energy Technology Data Exchange (ETDEWEB)

    Yocky, David A.; Wahl, Daniel E.; Jakowatz, Charles V,

    2014-10-01

    While typical SAR imaging employs a co-located (monostatic) RADAR transmitter and receiver, bistatic SAR imaging separates the transmitter and receiver locations. The transmitter and receiver geometry determines if the scattered signal is back scatter, forward scatter, or side scatter. The monostatic SAR image is backscatter. Therefore, depending on the transmitter/receiver collection geometry, the captured imagery may be quite different that that sensed at the monostatic SAR. This document presents imagery and image products formed from captured signals during the validation stage of the bistatic SAR research. Image quality and image characteristics are discussed first. Then image products such as two-color multi-view (2CMV) and coherent change detection (CCD) are presented.

  1. SAR: Stroke Authorship Recognition

    KAUST Repository

    Shaheen, Sara

    2015-10-15

    Are simple strokes unique to the artist or designer who renders them? If so, can this idea be used to identify authorship or to classify artistic drawings? Also, could training methods be devised to develop particular styles? To answer these questions, we propose the Stroke Authorship Recognition (SAR) approach, a novel method that distinguishes the authorship of 2D digitized drawings. SAR converts a drawing into a histogram of stroke attributes that is discriminative of authorship. We provide extensive classification experiments on a large variety of data sets, which validate SAR\\'s ability to distinguish unique authorship of artists and designers. We also demonstrate the usefulness of SAR in several applications including the detection of fraudulent sketches, the training and monitoring of artists in learning a particular new style and the first quantitative way to measure the quality of automatic sketch synthesis tools. © 2015 The Eurographics Association and John Wiley & Sons Ltd.

  2. Estimation of Moisture Content of Forest Canopy and Floor from SAR Data Part I: Volume Scattering Case

    Science.gov (United States)

    Moghaddam, M.; Saatchi, S.

    1996-01-01

    To understand and predict the functioning of forest biomes, their interaction with the atmosphere, and their growth rates, the knowledge of moisture content of their canopy and the floor soil is essential. The synthetic aperture radar on airborne and spaceborne platforms has proven to be a flexible tool for measuring electromagnetic back- scattering properties of vegetation related to their moisture content.

  3. Extent and distribution of aseismic slip on the Ismetpaşa segment of the North Anatolian Fault (Turkey) from Persistent Scatterer InSAR

    KAUST Repository

    Cetin, Esra

    2014-07-01

    We use the Persistent Scatterer InSAR (PSI) technique with elastic dislocation models and geology along the creeping section of the North Anatolian Fault (NAF) at Ismetpaşa, to map and deduce the velocity field and the aseismic slip distribution. Revealing the spatiotemporal nature of the creep helped us associate the creep with potential lithological controls, hence providing a new perspective to better understand the underlying causes and mechanisms. The PSI analysis of Envisat ASAR images between 2003 and 2010 reveals a clear picture of surface creep along the fault and a new interseismic velocity field transitioning gradually between the creeping and the locked fault sections. The creep rate is found to fluctuate along a 100 km long section of the fault in a manner similar to that along the Hayward fault, reaching a maximum of ∼20±2 mm/yr, close to the far field plate velocity (∼25±1.5 mm/yr). At Ismetpaşa, it is in the range of 8±2 mm/yr, consistent with the previous geodetic observations. The creeping section appears to extend 30 km further east than those previously reported. Modeling of the PSI data reveals a heterogeneous creep distribution at depth with two main patches confined mostly to the uppermost 5 km portion of the seismogenic crust, releasing annually 6.2 × 1016 Nm (Mw=5.1) geodetic moment. Our analysis combined with previous studies suggests that creep might have commenced as postseismic deformation following the 1944 earthquake and has evolved to stable fault creep with time. There is a correlation between aseismic surface creep and the geology along the fault as it is in major part associated to rocks with low frictional strength such as the andesitic-basaltic, limestone, and serpentine bodies within the fault zone. © 2014. American Geophysical Union. All Rights Reserved.

  4. Updated progress in theories and applications of spaceborne SAR interferometry

    Science.gov (United States)

    Chen, Yan-Ling; Huang, Cheng; Ding, Xiao-Li; Li, Zhi-Wei

    2006-12-01

    InSAR (Interferometric Synthetic Aperture Radar) and D-InSAR (Differential InSAR) are rapidly developed new technologies of space geodesy during the late 20th century, and now obviously become hot research topics in the field of microwave remote sensing. Compared with the other sensors, InSAR possesses many incomparable advantages such as the capability to work at all-time and under all weather, very high spatial resolution and strong penetrability through the ground surface. This paper introduces general status of SAR, InSAR, D-InSAR technology, and the principles of InSAR and D-InSAR. New theories and the potential problems of (D-)InSAR technology are largely discussed, including multi-baseline interferometry, Pol-InSAR technique, the correction of atmospheric effects, permanent Scatterers method, the synthesization technique between InSAR and GPS, LIDAR etc., and the InSAR parallel algorithm. Then the new applications of InSAR and D-InSAR are described in detail including 3D topographic mapping, deformation monitoring (including surface subsidence, landside monitoring and ITRF's foundation and maintenance, etc.), thematic mapping (including agriculture and forestry, oceanic surveying and flood monitoring, etc.) and meteorology etc.. Finally, the prospect and future trends in InSAR development are summarized.

  5. Computerized ionospheric tomography based on geosynchronous SAR

    Science.gov (United States)

    Hu, Cheng; Tian, Ye; Dong, Xichao; Wang, Rui; Long, Teng

    2017-02-01

    Computerized ionospheric tomography (CIT) based on spaceborne synthetic aperture radar (SAR) is an emerging technique to construct the three-dimensional (3-D) image of ionosphere. The current studies are all based on the Low Earth Orbit synthetic aperture radar (LEO SAR) which is limited by long repeat period and small coverage. In this paper, a novel ionospheric 3-D CIT technique based on geosynchronous SAR (GEO SAR) is put forward. First, several influences of complex atmospheric environment on GEO SAR focusing are detailedly analyzed, including background ionosphere and multiple scattering effects (induced by turbulent ionosphere), tropospheric effects, and random noises. Then the corresponding GEO SAR signal model is constructed with consideration of the temporal-variant background ionosphere within the GEO SAR long integration time (typically 100 s to 1000 s level). Concurrently, an accurate total electron content (TEC) retrieval method based on GEO SAR data is put forward through subband division in range and subaperture division in azimuth, obtaining variant TEC value with respect to the azimuth time. The processing steps of GEO SAR CIT are given and discussed. Owing to the short repeat period and large coverage area, GEO SAR CIT has potentials of covering the specific space continuously and completely and resultantly has excellent real-time performance. Finally, the TEC retrieval and GEO SAR CIT construction are performed by employing a numerical study based on the meteorological data. The feasibility and correctness of the proposed methods are verified.

  6. (abstract) Using an Inversion Algorithm to Retrieve Parameters and Monitor Changes over Forested Areas from SAR Data

    Science.gov (United States)

    Moghaddam, Mahta

    1995-01-01

    In this work, the application of an inversion algorithm based on a nonlinear opimization technique to retrieve forest parameters from multifrequency polarimetric SAR data is discussed. The approach discussed here allows for retrieving and monitoring changes in forest parameters in a quantative and systematic fashion using SAR data. The parameters to be inverted directly from the data are the electromagnetic scattering properties of the forest components such as their dielectric constants and size characteristics. Once these are known, attributes such as canopy moisture content can be obtained, which are useful in the ecosystem models.

  7. SAR Raw Data Generation for Complex Airport Scenes

    Directory of Open Access Journals (Sweden)

    Jia Li

    2014-10-01

    Full Text Available The method of generating the SAR raw data of complex airport scenes is studied in this paper. A formulation of the SAR raw signal model of airport scenes is given. Via generating the echoes from the background, aircrafts and buildings, respectively, the SAR raw data of the unified SAR imaging geometry is obtained from their vector additions. The multipath scattering and the shadowing between the background and different ground covers of standing airplanes and buildings are analyzed. Based on the scattering characteristics, coupling scattering models and SAR raw data models of different targets are given, respectively. A procedure is given to generate the SAR raw data of airport scenes. The SAR images from the simulated raw data demonstrate the validity of the proposed method.

  8. SAR Polarimetry

    Science.gov (United States)

    vanZyl, Jakob J.

    2012-01-01

    Radar Scattering includes: Surface Characteristics, Geometric Properties, Dielectric Properties, Rough Surface Scattering, Geometrical Optics and Small Perturbation Method Solutions, Integral Equation Method, Magellan Image of Pancake Domes on Venus, Dickinson Impact Crater on Venus (Magellan), Lakes on Titan (Cassini Radar, Longitudinal Dunes on Titan (Cassini Radar), Rough Surface Scattering: Effect of Dielectric Constant, Vegetation Scattering, Effect of Soil Moisture. Polarimetric Radar includes: Principles of Polarimetry: Field Descriptions, Wave Polarizations: Geometrical Representations, Definition of Ellipse Orientation Angles, Scatter as Polarization Transformer, Scattering Matrix, Coordinate Systems, Scattering Matrix, Covariance Matrix, Pauli Basis and Coherency Matrix, Polarization Synthesis, Polarimeter Implementation.

  9. SAR Polarimetry

    Science.gov (United States)

    vanZyl, Jakob J.

    2012-01-01

    Radar Scattering includes: Surface Characteristics, Geometric Properties, Dielectric Properties, Rough Surface Scattering, Geometrical Optics and Small Perturbation Method Solutions, Integral Equation Method, Magellan Image of Pancake Domes on Venus, Dickinson Impact Crater on Venus (Magellan), Lakes on Titan (Cassini Radar, Longitudinal Dunes on Titan (Cassini Radar), Rough Surface Scattering: Effect of Dielectric Constant, Vegetation Scattering, Effect of Soil Moisture. Polarimetric Radar includes: Principles of Polarimetry: Field Descriptions, Wave Polarizations: Geometrical Representations, Definition of Ellipse Orientation Angles, Scatter as Polarization Transformer, Scattering Matrix, Coordinate Systems, Scattering Matrix, Covariance Matrix, Pauli Basis and Coherency Matrix, Polarization Synthesis, Polarimeter Implementation.

  10. Polarization Filtering of SAR Data

    Science.gov (United States)

    Dubois, Pascale C.; Van Zyl, Jakob J.

    1991-01-01

    Theoretical analysis of polarization filtering of synthetic-aperture-radar (SAR) returns provide hybrid method applied to either (1) maximize signal-to-noise ratio of return from given target or (2) enhance contrast between targets of two different types (that have different polarization properties). Method valid for both point and extended targets and for both monostatic and bistatic radars as well as SAR. Polarization information in return signals provides more complete description of radar-scattering properties of targets and used to obtain additional information about targets for use in classifying them, discriminating between them, or enhancing features of radar images.

  11. Seismic scattering attribute for sedimentary classification of nearshore marine quarries for a major beach nourishment project: Case study of Adriatic coastline, Regione Abruzzo (Italy)

    Science.gov (United States)

    Orlando, Luciana; Contini, Paolo; De Girolamo, Paolo

    2017-06-01

    Of fundamental importance for any major beach nourishment project using marine quarries is a correct sedimentary classification. The main purpose of such a classification is to identify sand with the appropriate features for beach nourishment. This task is more onerous when quarry sediments are heterogeneous and mixed with silt. This is typical of nearshore marine quarries. The presence of excess silt compromises the use of marine quarries because of the water turbidity that may be induced in the nourished beaches, especially when the beaches are protected by defense structures. Here we discuss the use of scattering amplitude of seismic data, acquired with a pinger source (2-10 kHz), to detect and classify the unconsolidated sediment of a marine quarry. A robust correlation was found between this seismic attribute and the silt content in the sediment. The scattering amplitude was numerically calculated from the seismic data and used to map slices of silt content at different depths. The results have been validated with sedimentary analysis of vibra- and rotary cores, and by the dredged material used for the beach nourishment. The marine quarry produced about 1.200.000 m3 of sand used to nourish eight different beach sites along the Adriatic coasts of the Regione Abruzzo (Italy). The large-scale sedimentary assessment of the area was based on seismic boomer data and the evaluation of the volume of dredged sediments on multibeam data surveyed before and after the exploitation of the quarry. The study shows that this approach is effective in sites with high lateral and vertical variations in the percentage of sand in the sediments.

  12. Land Subsidence Monitoring Using PS-InSAR Technique for L-Band SAR Data

    Science.gov (United States)

    Thapa, S.; Chatterjee, R. S.; Singh, K. B.; Kumar, D.

    2016-10-01

    Differential SAR-Interferometry (D-InSAR) is one of the potential source to measure land surface motion induced due to underground coal mining. However, this technique has many limitation such as atmospheric in homogeneities, spatial de-correlation, and temporal decorrelation. Persistent Scatterer Interferometry synthetic aperture radar (PS-InSAR) belongs to a family of time series InSAR technique, which utilizes the properties of some of the stable natural and anthropogenic targets which remain coherent over long time period. In this study PS-InSAR technique has been used to monitor land subsidence over selected location of Jharia Coal field which has been correlated with the ground levelling measurement. This time series deformation observed using PS InSAR helped us to understand the nature of the ground surface deformation due to underground mining activity.

  13. Terrain Measurement with SAR/InSAR

    Science.gov (United States)

    Li, Deren; Liao, Mingsheng; Balz, Timo; Zhang, Lu; Yang, Tianliang

    2016-08-01

    Terrain measurement and surface motion estimation are the most important applications for commercial and scientific SAR missions. In Dragon-3, we worked on these applications, especially regarding DEM generation, surface motion estimation with SAR time- series for urban subsidence monitoring and landslide motion estimation, as well as developing tomographic SAR processing methods in urban areas.

  14. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...

  15. TomoSAR Platform: The New Irstea Service as Demand for SAR, Interferometry, Polarimetry and Tomography

    Science.gov (United States)

    Ho Tong Minh, Dinh; Ngo, Yen-Nhi; Baghdadi, Nicolas; Maurel, Pierre

    2016-08-01

    Developing and improving methods to monitor both natural and non-natural environments such as forest and urban in space and time is a timely challenge. To overcome this challenge, we created a software platform - TomoSAR. The kernel of this platform supports the entire processing from SAR, Interferometry, Polarimetry, to Tomography (so called TomoSAR). The objective of this paper is to introduce this platform about its design architecture and its capacity. We showed four examples to highlight the TomoSAR platform capacities. First, the useful of the interferometric coherence of TOPS Sentinel-1 for land cover classification was highlighted. Second, a TOPS Sentinel-1 differential interferogram in a complex scenario volcano was successfully produced. Third, a TOPS Persistent Scatterers Interferometry analysis for estimating subsidence in Ho Chi Minh City area was demonstrated. Finally, the capability of processing and modelling of 3D P-band tomography in volume forest scattering were reported.

  16. Landslide Inventory and Monitoring Using Sentinel-1 SAR Imagery

    Science.gov (United States)

    Monserrat, Oriol; Crosetto, Michele; Devanthery, Nuria; Cuevas-Gonzalez, Maria; Barra, Anna; Crippa, Bruno

    2016-08-01

    An important application of differential SAR interferometry (DInSAR) and Persistent Scatterer Interferometry is landslide detection and monitoring. Several studies have been published, which make use of the entire spectrum of SAR data types available in the last 25 years. This paper describes a procedure to update landslide inventory maps using Sentinel-1 data. The paper briefly discusses the main advantages of the Sentinel-1 SAR data. Then it describes the data analysis procedure used to update landslide inventory maps using interferometric data and a number of additional information layers. The effectiveness of the procedure is illustrated by the results of a study area located in the Molise region, in Southern Italy.

  17. Infrastructure monitoring with spaceborne SAR sensors

    CERN Document Server

    ANGHEL, ANDREI; CACOVEANU, REMUS

    2017-01-01

    This book presents a novel non-intrusive infrastructure monitoring technique based on the detection and tracking of scattering centers in spaceborne SAR images. The methodology essentially consists of refocusing each available SAR image on an imposed 3D point cloud associated to the envisaged infrastructure element and identifying the reliable scatterers to be monitored by means of four dimensional (4D) tomography. The methodology described in this book provides a new perspective on infrastructure monitoring with spaceborne SAR images, is based on a standalone processing chain, and brings innovative technical aspects relative to conventional approaches. The book is intended primarily for professionals and researchers working in the area of critical infrastructure monitoring by radar remote sensing.

  18. MULTI-TEMPORAL SAR INTERFEROMETRY FOR LANDSLIDE MONITORING

    Directory of Open Access Journals (Sweden)

    R. Dwivedi

    2016-06-01

    Full Text Available In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS and Small Baseline (SB methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS based PS-InSAR and the Small Baselines Subset (SBAS techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.

  19. Multi-Temporal SAR Interferometry for Landslide Monitoring

    Science.gov (United States)

    Dwivedi, R.; Narayan, A. B.; Tiwari, A.; Dikshit, O.; Singh, A. K.

    2016-06-01

    In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS) and Small Baseline (SB) methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS) based PS-InSAR and the Small Baselines Subset (SBAS) techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS) mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS) velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.

  20. Spaceborne Polarimetric SAR Interferometry: Performance Analysis and Mission Concepts

    Directory of Open Access Journals (Sweden)

    Cloude Shane R

    2005-01-01

    Full Text Available We investigate multichannel imaging radar systems employing coherent combinations of polarimetry and interferometry (Pol-InSAR. Such systems are well suited for the extraction of bio- and geophysical parameters by evaluating the combined scattering from surfaces and volumes. This combination leads to several important differences between the design of Pol-InSAR sensors and conventional single polarisation SAR interferometers. We first highlight these differences and then investigate the Pol-InSAR performance of two proposed spaceborne SAR systems (ALOS/PalSAR and TerraSAR-L operating in repeat-pass mode. For this, we introduce the novel concept of a phase tube which enables (1 a quantitative assessment of the Pol-InSAR performance, (2 a comparison between different sensor configurations, and (3 an optimization of the instrument settings for different Pol-InSAR applications. The phase tube may hence serve as an interface between system engineers and application-oriented scientists. The performance analysis reveals major limitations for even moderate levels of temporal decorrelation. Such deteriorations may be avoided in single-pass sensor configurations and we demonstrate the potential benefits from the use of future bi- and multistatic SAR interferometers.

  1. Evaluation of Polarimetric SAR Decomposition for Classifying Wetland Vegetation Types

    Directory of Open Access Journals (Sweden)

    Sang-Hoon Hong

    2015-07-01

    Full Text Available The Florida Everglades is the largest subtropical wetland system in the United States and, as with subtropical and tropical wetlands elsewhere, has been threatened by severe environmental stresses. It is very important to monitor such wetlands to inform management on the status of these fragile ecosystems. This study aims to examine the applicability of TerraSAR-X quadruple polarimetric (quad-pol synthetic aperture radar (PolSAR data for classifying wetland vegetation in the Everglades. We processed quad-pol data using the Hong & Wdowinski four-component decomposition, which accounts for double bounce scattering in the cross-polarization signal. The calculated decomposition images consist of four scattering mechanisms (single, co- and cross-pol double, and volume scattering. We applied an object-oriented image analysis approach to classify vegetation types with the decomposition results. We also used a high-resolution multispectral optical RapidEye image to compare statistics and classification results with Synthetic Aperture Radar (SAR observations. The calculated classification accuracy was higher than 85%, suggesting that the TerraSAR-X quad-pol SAR signal had a high potential for distinguishing different vegetation types. Scattering components from SAR acquisition were particularly advantageous for classifying mangroves along tidal channels. We conclude that the typical scattering behaviors from model-based decomposition are useful for discriminating among different wetland vegetation types.

  2. Deployment and design of bi-directional corner reflectors for op-timal ground motion monitoring using InSAR

    NARCIS (Netherlands)

    Caro Cuenca, M.; Dheenathayalan, P.; Rossum, W.L. van; Hoogeboom, P.

    2014-01-01

    SAR interferometry (InSAR) requires coherent radar reflections to measure ground displacements. Howev-er, natural coherent reflectors are not always available due to changes in the scattering properties of the ground, e.g., growing vegetation. Furthermore, the opportunistic nature of InSAR measureme

  3. A Global Optimal Coherence Method for Multi-baseline InSAR Elevation Inversion

    Directory of Open Access Journals (Sweden)

    HUA Fenfen

    2015-11-01

    Full Text Available A global optimal coherence method for elevation inversion from multi-baseline polarimetric InSAR data is proposed. The multi-baseline polarimetric InSAR data used in experiments were obtained by Chinese X-SAR system and Germany's E-SAR system. Through combining several full polarimetric InSAR images, the proposed method constructs the multi-baseline polarimetric InSAR coherency matrix, and solves the optimal interferograms under global optimal coherence criterion. The optimal interferograms generated by global optimal coherence method were used to calculate the elevation of target with multi-baseline InSAR elevation inversion method. The proposed method reduces the influence of different scattering centers effectively using multi-baseline InSAR, which improves the accuracy and reliability of the interferometric phase and eventually improves the accuracy of DEM. The results verify the validity of the proposed method.

  4. Monitoring Building Deformation with InSAR: Experiments and Validation.

    Science.gov (United States)

    Yang, Kui; Yan, Li; Huang, Guoman; Chen, Chu; Wu, Zhengpeng

    2016-12-20

    Synthetic Aperture Radar Interferometry (InSAR) techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS) regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE) indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated.

  5. INVENTORY OF IRRIGATED RICE ECOSYSTEM USING POLARIMETRIC SAR DATA

    Directory of Open Access Journals (Sweden)

    P. Srikanth

    2012-08-01

    Full Text Available An attempt has been made in the current study to assess the potential of polarimetric SAR data for inventory of kharif rice and the major competing crop like cotton. In the process, physical process of the scattering mechanisms occurring in rice and cotton crops at different phonological stages was studied through the use of temporal Radarsat 2 Fine quadpol SAR data. The temporal dynamics of the volume, double and odd bounce, entropy, anisotropy, alpha parameters and polarimertic signatures, classification through isodata clustering and Wishart techniques were assessed. The Wishart (H-a classification showed higher overall as well as rice and cotton crop accuracies compared to the isodata clustering from Freeman 3-component decomposition. The classification of temporal SAR data sets independently showed that the rice crop forecasting can be advanced with the use of appropriate single date polarimetric SAR data rather than using temporal SAR amplitude data sets with the single polarization in irrigated rice ecosystems

  6. Health Communication during SARS

    Science.gov (United States)

    Navin, Ava W.; Steele, Stefanie F.; Weld, Leisa H.; Kozarsky, Phyllis E.

    2004-01-01

    During the severe acute respiratory syndrome (SARS) outbreak, electronic media made it possible to disseminate prevention messages rapidly. The Centers for Disease Control and Prevention’s Travelers’ Health Web site was frequently visited in the first half of 2003; more than 2.6 million visits were made to travel alerts, advisories, and other SARS-related documents. PMID:15030717

  7. SARS Pathogenesis: Host Factors

    NARCIS (Netherlands)

    A. de Lang (Anna)

    2012-01-01

    textabstractWhile it is hypothesized that Sever Acute Respiratory Syndrome (SARS) in humans is caused by a disproportional immune response illustrated by inappropriate induction of inflammatory cytokines, the exact nature of the host response to SARS coronavirus (CoV) infection causing severe

  8. Representations of SARS in the British newspapers.

    Science.gov (United States)

    Washer, Peter

    2004-12-01

    In the Spring of 2003, there was a huge interest in the global news media following the emergence of a new infectious disease: severe acute respiratory syndrome (SARS). This study examines how this novel disease threat was depicted in the UK newspapers, using social representations theory and in particular existing work on social representations of HIV/AIDS and Ebola to analyse the meanings of the epidemic. It investigates the way that SARS was presented as a dangerous threat to the UK public, whilst almost immediately the threat was said to be 'contained' using the mechanism of 'othering': SARS was said to be unlikely to personally affect the UK reader because the Chinese were so different to 'us'; so 'other'. In this sense, the SARS scare, despite the remarkable speed with which it was played out in the modern global news media, resonates with the meanings attributed to other epidemics of infectious diseases throughout history. Yet this study also highlights a number of differences in the social representations of SARS compared with earlier epidemics. In particular, this study examines the phenomena of 'emerging and re-emerging infectious diseases' over the past 30 or so years and suggests that these have impacted on the faith once widely held that Western biomedicine could 'conquer' infectious disease.

  9. Full polarization scattering characteristics of sea fractal surface

    Institute of Scientific and Technical Information of China (English)

    Xie Tao; He Yijun; Nan Chengfeng

    2006-01-01

    In the conventional single polarization SAR system, only the scattering information of HH polarization or VV polarization can be obtained. Only co-polarizaion scattering cases are considered and cross-polarizaiton (HV and VH polarization) scattering cases are neglected. Therefore, much important information must be lost. Research on full polarization SAR system is an important approach to extract more useful information from SAR imaging. In this paper, the authors derived the full polarization scattering coefficients of 2-D sea fractal surface and simulated the radar cross section (RCS) of different polarizations. They also gave the exact theoretical explanations of the fully polarization scattering characteristics of sea fractal surface, and confirmed that the depolarization can be neglected. The result is the basis of the full SAR system design and SAR imaging.

  10. ANALYSIS OF MULTIPATH PIXELS IN SAR IMAGES

    Directory of Open Access Journals (Sweden)

    J. W. Zhao

    2016-06-01

    Full Text Available As the received radar signal is the sum of signal contributions overlaid in one single pixel regardless of the travel path, the multipath effect should be seriously tackled as the multiple bounce returns are added to direct scatter echoes which leads to ghost scatters. Most of the existing solution towards the multipath is to recover the signal propagation path. To facilitate the signal propagation simulation process, plenty of aspects such as sensor parameters, the geometry of the objects (shape, location, orientation, mutual position between adjacent buildings and the physical parameters of the surface (roughness, correlation length, permittivitywhich determine the strength of radar signal backscattered to the SAR sensor should be given in previous. However, it's not practical to obtain the highly detailed object model in unfamiliar area by field survey as it's a laborious work and time-consuming. In this paper, SAR imaging simulation based on RaySAR is conducted at first aiming at basic understanding of multipath effects and for further comparison. Besides of the pre-imaging simulation, the product of the after-imaging, which refers to radar images is also taken into consideration. Both Cosmo-SkyMed ascending and descending SAR images of Lupu Bridge in Shanghai are used for the experiment. As a result, the reflectivity map and signal distribution map of different bounce level are simulated and validated by 3D real model. The statistic indexes such as the phase stability, mean amplitude, amplitude dispersion, coherence and mean-sigma ratio in case of layover are analyzed with combination of the RaySAR output.

  11. BioSAR Airborne Biomass Sensing System

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R.L.; Johnson, P.

    2007-05-24

    This CRADA was developed to enable ORNL to assist American Electronics, Inc. test a new technology--BioSAR. BioSAR is a an airborne, low frequency (80-120 MHz {approx} FM radio frequencies) synthetic aperture radar (SAR) technology which was designed and built for NASA by ZAI-Amelex under Patrick Johnson's direction. At these frequencies, leaves and small branches are nearly transparent and the majority of the energy reflected from the forest and returned to the radar is from the tree trunks. By measuring the magnitude of the back scatter, the volume of the tree trunk and therefore the biomass of the trunks can be inferred. The instrument was successfully tested on tropical rain forests in Panama. Patrick Johnson, with American Electronics, Inc received a Phase II SBIR grant from DOE Office of Climate Change to further test and refine the instrument. Mr Johnson sought ORNL expertise in measuring forest biomass in order for him to further validate his instrument. ORNL provided ground truth measurements of forest biomass at three locations--the Oak Ridge Reservation, Weyerhaeuser Co. commercial pine plantations in North Carolina, and American Energy and Power (AEP) Co. hardwood forests in southern Ohio, and facilitated flights over these forests. After Mr. Johnson processed the signal data from BioSAR instrument, the processed data were given to ORNL and we attempted to derive empirical relationships between the radar signals and the ground truth forest biomass measurements using standard statistical techniques. We were unsuccessful in deriving such relationships. Shortly before the CRADA ended, Mr Johnson discovered that FM signal from local radio station broadcasts had interfered with the back scatter measurements such that the bulk of the signal received by the BioSAR instrument was not backscatter from the radar but rather was local radio station signals.

  12. ONERA airborne SAR facilities

    Energy Technology Data Exchange (ETDEWEB)

    Boutry, J.M. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), Chatillon (France)

    1996-11-01

    ONERA has developed and operates the RAMSES experimental SAR on board a TRANSALL C160 aircraft. This system has been designed in order to analyze the effect of various parameters, such as frequency, polarization, incidence, resolution,... in the field of air-to-ground radar applications. These applications include SAR imaging for ground radar applications. These applications include SAR imaging for various purposes such as map-matching for navigation update, battlefield surveillance, reconnaissance, treaty applications... It consists of several radar sections operating over a wide range of frequency bands (L, S, C, X, Ku, Ka, W). 7 figs., 3 tabs.

  13. Geocoding of AIRSAR/TOPSAR SAR Data

    Science.gov (United States)

    Holecz, Francesco; Lou, Yun-Ling; vanZyl, Jakob

    1996-01-01

    It has been demonstrated and recognized that radar interferometry is a promising method for the determination of digital elevation information and terrain slope from Synthetic Aperture Radar (SAR) data. An important application of Interferometric SAR (InSAR) data in areas with topographic variations is that the derived elevation and slope can be directly used for the absolute radiometric calibration of the amplitude SAR data as well as for scattering mechanisms analysis. On the other hand polarimetric SAR data has long been recognized as permitting a more complete inference of natural surfaces than a single channel radar system. In fact, imaging polarimetry provides the measurement of the amplitude and relative phase of all transmit and receive polarizations. On board the NASA DC-8 aircraft, NASA/JPL operates the multifrequency (P, L and C bands) multipolarimetric radar AIRSAR. The TOPSAR, a special mode of the AIRSAR system, is able to collect single-pass interferometric C- and/or L-band VV polarized data. A possible configuration of the AIRSAR/TOPSAR system is to acquire single-pass interferometric data at C-band VV polarization and polarimetric radar data at the two other lower frequencies. The advantage of this system configuration is to get digital topography information at the same time the radar data is collected. The digital elevation information can therefore be used to correctly calibrate the SAR data. This step is directly included in the new AIRSAR Integrated Processor. This processor uses a modification of the full motion compensation algorithm described by Madsen et al. (1993). However, the Digital Elevation Model (DEM) with the additional products such as local incidence angle map, and the SAR data are in a geometry which is not convenient, since especially DEMs must be referred to a specific cartographic reference system. Furthermore, geocoding of SAR data is important for multisensor and/or multitemporal purposes. In this paper, a procedure to

  14. Advances in space-borne SAR interferometry and its application to ground deformation monitoring

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-guo; BIAN Zheng-fu

    2011-01-01

    The development of Differential Synthetic Aperture Radar Interferometry (D-InSAR), in terms of its evolution from classic to advanced forms, such as Least-Squares approach, Permanent Scatterer Interferometry, Small Baseline Subset, and Coherent Pixel Technique, is reviewed, describing concisely the main principles of each method and highlighting the difference and relationship between them. Applications of InSAR technology in China were then introduced, together with the obstacles to overcome and feasible strategies, such as integrating MERIS/MODIS data to compensate for the atmospheric effect and GPS, and multi-platform SAR data to make InSAR technique practical and operational under various conditions. The latest developments were then analyzed along with high-quality SAR data, available thanks to the newly launched high-tech satellites, TerraSAR-X, and Cosmo Sky-med, and conclusions were drawn about the main limitations of the technique.

  15. Simulation of SAR backscatter for forest vegetation

    Science.gov (United States)

    Prajapati, Richa; Kumar, Shashi; Agrawal, Shefali

    2016-05-01

    Synthetic Aperture Radar (SAR) is one of the most recent imaging technology to study the forest parameters. The invincible characteristics of microwave acquisition in cloudy regions and night imaging makes it a powerful tool to study dense forest regions. A coherent combination of radar polarimetry and interferometry (PolInSAR) enhances the accuracy of retrieved biophysical parameters. This paper attempts to address the issue of estimation of forest structural information caused due to instability of radar platforms through simulation of SAR image. The Terai Central Forest region situated at Haldwani area in Uttarakhand state of India was chosen as the study area. The system characteristics of PolInSAR dataset of Radarsat-2 SAR sensor was used for simulation process. Geometric and system specifications like platform altitude, center frequency, mean incidence angle, azimuth and range resolution were taken from metadata. From the field data it was observed that average tree height and forest stand density were 25 m and 300 stems/ha respectively. The obtained simulated results were compared with the sensor acquired master and slave intensity images. It was analyzed that for co-polarized horizontal component (HH), the mean values of simulated and real master image had a difference of 0.3645 with standard deviation of 0.63. Cross-polarized (HV) channel showed better results with mean difference of 0.06 and standard deviation of 0.1 while co-polarized vertical component (VV) did not show similar values. In case of HV polarization, mean variation between simulated and real slave images was found to be the least. Since cross-polarized channel is more sensitive to vegetation feature therefore better simulated results were obtained for this channel. Further the simulated images were processed using PolInSAR inversion modelling approach using three different techniques DEM differencing, Coherence Amplitude Inversion and Random Volume over Ground Inversion. DEM differencing

  16. Born approximation, scattering, and algorithm

    Science.gov (United States)

    Martinez, Alex; Hu, Mengqi; Gu, Haicheng; Qiao, Zhijun

    2015-05-01

    In the past few decades, there were many imaging algorithms designed in the case of the absence of multiple scattering. Recently, we discussed an algorithm for removing high order scattering components from collected data. This paper is a continuation of our previous work. First, we investigate the current state of multiple scattering in SAR. Then, we revise our method and test it. Given an estimate of our target reflectivity, we compute the multi scattering effects in the target region for various frequencies. Furthermore, we propagate this energy through free space towards our antenna, and remove it from the collected data.

  17. Adaptive Three-component Decomposition Approach for Polarimetric SAR Data

    Directory of Open Access Journals (Sweden)

    CAI Yongjun

    2016-09-01

    Full Text Available In this paper, the problems such as negative power and scattering mechanism ambiguity in original polarimetric SAR three-component decomposition are introduced, and the remaining flaws in its improved approaches are in depth analyzed. Based on these, an adaptive three-component decomposition is proposed, and more generalized scattering models are used. Because in one pixel there may exist two odd or double bounce scattering targets with different orientation angels, the proposed method firstly considers this situation, so that the surface and double bounce scattering can be preserved more sufficiently. And then the alpha parameter is used to identify the dominant scattering except for the volume scattering. Lastly, an optimization measure to the pixels with negative power is proposed, which significantly decreases the negative power pixels count, so the decomposition will be more accurate and more valid. The results show great improvements in real scattering characteristics extraction and the flaws in model based decomposition approaches can be better resolved.

  18. Crop Classification by Polarimetric SAR

    DEFF Research Database (Denmark)

    Skriver, Henning; Svendsen, Morten Thougaard; Nielsen, Flemming;

    1999-01-01

    Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric L- and C-band SAR (EMISAR) during a number of missions at the Danish agricultural test site Foulum during 1995. The data are used to study the classification potential of polarimetric SAR data using...

  19. Improved SMB speckle filtering of polarimetric SAR data with synergistic use of orientation angle compensation and spatial majority rule

    Institute of Scientific and Technical Information of China (English)

    柳林; 江利明; 李洪忠

    2016-01-01

    The scattering-model-based (SMB) speckle filtering for polarimetric SAR (PolSAR) data is reasonably effective in preserving dominant scattering mechanisms. However, the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties. In addition, a relatively weak speckle reduction particularly in distributed media was reported in the related literatures. In this work, an improved SMB filtering strategy is proposed considering the aforementioned deficiencies. First, the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition. In addition, an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction. We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band PolSAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR (AIRSAR) system.

  20. SARS: just another viral acronym?

    Science.gov (United States)

    Broxmeyer, L

    2003-08-01

    Recent observations and experimental evidence have purported that a virus causes SARS, but such viruses have been isolated in only less than half of SARS patients in some studies and virologist Vincent Plummer of Winnipeg's National Microbiology Laboratory found that indeed 1 in 5 perfectly healthy Canadians with a history of recent travel to Asia had the virus. Therefore SARS microbiologic origins remain unclear. Outbreaks of multi-drug resistant (MDR) tuberculosis and the atypical mycobacteria simulate SARS on clinical, radiologic, epidemiologic, and diagnostic laboratory grounds and it is only logical then to include them in the differential to find a definitive cause and cure for SARS.

  1. Sparse SAR imaging based on L1/2 regularization

    Institute of Scientific and Technical Information of China (English)

    ZENG JinShan; FANG Jian; XU ZongBen

    2012-01-01

    In this paper,a novel method for synthetic aperture radar (SAR) imaging is proposed.The approach is based on L1/2 regularization to reconstruct the scattering field,which optimizes a quadratic error term of the SAR observation process subject to the interested scene sparsity. Compared to the conventional SAR imaging technique,the new method implements SAR imaging effectively at much lower sampling rate than the Nyquist rate,and produces high-quality images with reduced sidelobes and increased resolution. Also,over the prevalent greedy pursuit and L1 regularization based SAR imaging methods,there are remarkable performance improvements of the new method.On one hand,the new method significantly reduces the number of measurements needed for reconstruction,as supported by a phase transition diagram study.On the other hand,the new method is more robust to the observation noise.These fundamental properties of the new method are supported and demonstrated both by simulations and real SAR data experiments.

  2. Effect of polarization orientation angle shift on X-band TDM SAR COSSC product of TerraSAR-X and TanDEM-X

    Science.gov (United States)

    Gupta, Asmita; Kumar, Shashi; Pandey, Uttara

    2016-05-01

    Polarization orientation angle (POA) shift in the backscattered SAR wave induced, due to irregularity of the target surface. Polarimetric signatures of the backscatter SAR wave gets affected by the POA shift, causes error in the decomposition modelling as shift in POA makes coherency matrix asymmetric. POA shift compensation is very necessary to avoid misinterpretation of decomposition modelling results. POA shift effect has been observed using coherency matrix and decomposition model results. This study is conducted over Dudhwa National Park in the state of Uttar Pradesh, using high resolution, TDM SAR COSSC Product of TerraSAR-X and TanDEM-X in Bistatic mode. Present study mainly focused on the comparative analysis of resultant scattering component of decomposition model before and after POA shift compensation. Shift in POA is investigated using circular polarization technique. Yamaguchi four component decomposition model is used to express total backscatter information in terms of volume, double bounce, surface and helix scattering. Volume scattering is overestimated however double bounce and surface scattering is under estimated in decomposition model due to POA shift present in the backscatter SAR wave. Different scattering mechanisms resulted after POA compensation were analyzed using 100 random points taken from forest structure. The results obtained by TerraSAR-X and TanDEM-X shows an overall increase in double bounce scattering and decrease in volume scattering component after POA shift compensation. It is observed that there is negligible effect of POA shift on surface scattering. POA shift compensation necessarily required to improve the accuracy of decomposition models used in the forest parameter retrieval applications.

  3. Bats and SARS

    Centers for Disease Control (CDC) Podcasts

    2006-11-08

    Bats are a natural reservoir for emerging viruses, among them henipaviruses and rabies virus variants. Dr. Nina Marano, Chief, Geographic Medicine and Health Promotion Branch, Division of Global Migration and Quarantine, CDC, explains connection between horseshoe bats and SARS coronavirus transmission.  Created: 11/8/2006 by Emerging Infectious Diseases.   Date Released: 11/17/2006.

  4. Multichannel FMCW SAR

    NARCIS (Netherlands)

    Rossum, W.L. van; Otten, M.P.G.; Dorp, Ph. van

    2012-01-01

    A light weight SAR, suitable for use on short range tactical UAV, has been designed and built. The system consists of a fully digital receive array, and a very compact active transmit antenna. The approximate weight of the complete system is 6 kg, with power consumption below 75 W, depending on the

  5. Bistatic SAR: Proof of Concept.

    Energy Technology Data Exchange (ETDEWEB)

    Yocky, David A.; Doren, Neall E.; Bacon, Terry A.; Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V,; Delaplain, Gilbert G.; Dubbert, Dale F.; Tise, Bertice L.; White, Kyle R.

    2014-10-01

    Typical synthetic aperture RADAR (SAR) imaging employs a co-located RADAR transmitter and receiver. Bistatic SAR imaging separates the transmitter and receiver locations. A bistatic SAR configuration allows for the transmitter and receiver(s) to be in a variety of geometric alignments. Sandia National Laboratories (SNL) / New Mexico proposed the deployment of a ground-based RADAR receiver. This RADAR receiver was coupled with the capability of digitizing and recording the signal collected. SNL proposed the possibility of creating an image of targets the illuminating SAR observes. This document describes the developed hardware, software, bistatic SAR configuration, and its deployment to test the concept of a ground-based bistatic SAR. In the proof-of-concept experiments herein, the RADAR transmitter will be a commercial SAR satellite and the RADAR receiver will be deployed at ground level, observing and capturing RADAR ground/targets illuminated by the satellite system.

  6. Understanding SARS with Wolfram Approach

    Institute of Scientific and Technical Information of China (English)

    Da-WeiLI; Yu-XiPAN; YunDUAN; Zhen-DeHUNG; Ming-QingXU; LinHE

    2004-01-01

    Stepping acquired immunodeficiency syndrome (AIDS), severe acute respiratory syndrome (SARS) as another type of disease has been threatening mankind since late last year. Many scientists worldwide are making great efforts to study the etiology of this disease with different approaches. 13 species of SARS virus have been sequenced. However, most people still largely rely on the traditional methods with some disadvantages. In this work, we used Wolfram approach to study the relationship among SARS viruses and between SARS viruses and other types of viruses, the effect of variations on the whole genome and the advantages in the analysis of SARS based on this novel approach. As a result, the similarities between SARS viruses and other coronaviruses are not really higher than those between SARS viruses and non-coronaviruses.

  7. Capability of geometric features to classify ships in SAR imagery

    Science.gov (United States)

    Lang, Haitao; Wu, Siwen; Lai, Quan; Ma, Li

    2016-10-01

    Ship classification in synthetic aperture radar (SAR) imagery has become a new hotspot in remote sensing community for its valuable potential in many maritime applications. Several kinds of ship features, such as geometric features, polarimetric features, and scattering features have been widely applied on ship classification tasks. Compared with polarimetric features and scattering features, which are subject to SAR parameters (e.g., sensor type, incidence angle, polarization, etc.) and environment factors (e.g., sea state, wind, wave, current, etc.), geometric features are relatively independent of SAR and environment factors, and easy to be extracted stably from SAR imagery. In this paper, the capability of geometric features to classify ships in SAR imagery with various resolution has been investigated. Firstly, the relationship between the geometric feature extraction accuracy and the SAR imagery resolution is analyzed. It shows that the minimum bounding rectangle (MBR) of ship can be extracted exactly in terms of absolute precision by the proposed automatic ship-sea segmentation method. Next, six simple but effective geometric features are extracted to build a ship representation for the subsequent classification task. These six geometric features are composed of length (f1), width (f2), area (f3), perimeter (f4), elongatedness (f5) and compactness (f6). Among them, two basic features, length (f1) and width (f2), are directly extracted based on the MBR of ship, the other four are derived from those two basic features. The capability of the utilized geometric features to classify ships are validated on two data set with different image resolutions. The results show that the performance of ship classification solely by geometric features is close to that obtained by the state-of-the-art methods, which obtained by a combination of multiple kinds of features, including scattering features and geometric features after a complex feature selection process.

  8. Beyond PSInSAR: the SQUEESAR Approach

    Science.gov (United States)

    Ferretti, A.; Novali, F.; Fumagalli, A.; Prati, C.; Rocca, F.; Rucci, A.

    2009-12-01

    After a decade since the first results on ERS data, Permanent Scatterer (PS) InSAR has become an operational technology for detecting and monitoring slow surface deformation phenomena such as subsidence and uplift, landslides, seismic fault creeping, volcanic inflation, etc. Processing procedures have been continuously updated, but the core of the algorithm has not been changed significantly. As well known, in PSInSAR, the main target is the identification of individual pixels that exhibit a “PS behavior”, i.e. they are only slightly affected by both temporal and geometrical decorrelation. Typically, these scatterers correspond to man-made objects, but PS have been identified also in non-urban areas, where exposed rocks or outcrops can indeed create good radar benchmarks and enable high-quality displacement measurements. Contrary to interferogram stacking techniques, PS analyses are carried out on a pixel-by-pixel basis, with no filtering of the interferograms, in order to preserve phase values from possible incoherent clutter surrounding good radar targets. In fact, any filtering process implies a spatial smoothing of the data that could compromise - rather than improve - phase coherence, at least for isolated PS. Although the PS approach usually allows one to retrieve high quality deformation measurements on a sparse grid of good radar targets, in some datasets it is quite evident how the number of pixels where some information can be extracted could be significantly increased by relaxing the hypothesis on target coherence and searching for pixels where the coherence level is high enough at least in some interferograms of the data-stack, not necessarily all. The idea of computing a “coherence matrix” for each pixel of the area of interest have been already proposed in previous papers, together with a statistical estimation of some physical parameters of interest (e.g. the average displacement rate) based on the covariance matrix. In past publications

  9. Missile-Borne SAR Raw Signal Simulation for Maneuvering Target

    Directory of Open Access Journals (Sweden)

    Weijie Xia

    2016-01-01

    Full Text Available SAR raw signal simulation under the case of maneuver and high-speed has been a challenging and urgent work recently. In this paper, a new method based on one-dimensional fast Fourier transform (1DFFT algorithm is presented for raw signal simulation of maneuvering target for missile-borne SAR. Firstly, SAR time-domain raw signal model is given and an effective Range Frequency Azimuth Time (RFAT algorithm based on 1DFFT is derived. In this algorithm, the “Stop and Go” (SaG model is adopted and the wide radar scattering characteristic of target is taken into account. Furthermore, the “Inner Pulse Motion” (IPM model is employed to deal with high-speed case. This new RFAT method can handle the maneuvering cases, high-speed cases, and bistatic radar cases, which are all possible in the missile-borne SAR. Besides, this raw signal simulation adopts the electromagnetic scattering calculation so that we do not need a scattering rate distribution map as the simulation input. Thus, the multiple electromagnetic reflections can be considered. Simulation examples prove the effectiveness of our method.

  10. UAVSAR and TerraSAR-X Based InSAR Detection of Localized Subsidence in the New Orleans Area

    Science.gov (United States)

    Blom, R. G.; An, K.; Jones, C. E.; Latini, D.

    2014-12-01

    Vulnerability of the US Gulf coast to inundation has received increased attention since hurricanes Katrina and Rita. Compounding effects of sea level rise, wetland loss, and regional and local subsidence makes flood protection a difficult challenge, and particularly for the New Orleans area. Key to flood protection is precise knowledge of elevations and elevation changes. Analysis of historical and continuing geodetic measurements show surprising complexity, including locations subsiding more rapidly than considered during planning of hurricane protection and coastal restoration projects. Combining traditional, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations can provide geographically dense constraints on surface deformation. The Gulf Coast environment is challenging for InSAR techniques, especially with systems not designed for interferometry. We use two InSAR capable systems, the L- band (24 cm wavelength) airborne JPL/NASA UAVSAR, and the DLR/EADS Astrium spaceborne TerraSAR X-band (3 cm wavelength), and compare results. First, we are applying pair-wise InSAR to the longer wavelength UAVSAR data to detect localized elevation changes potentially impacting flood protection infrastructure from 2009 - 2014. We focus on areas on and near flood protection infrastructure to identify changes indicative of subsidence, structural deformation, and/or seepage. The Spaceborne TerraSAR X-band SAR system has relatively frequent observations, and dense persistent scatterers in urban areas, enabling measurement of very small displacements. We compare L-band UAVSAR results with permanent scatterer (PS-InSAR) and Short Baseline Subsets (SBAS) interferometric analyses of a stack composed by 28 TerraSAR X-band images acquired over the same period. Thus we can evaluate results from the different radar frequencies and analyses techniques. Preliminary results indicate subsidence features potentially of a variety of causes, including ground water

  11. Bistatic sAR data processing algorithms

    CERN Document Server

    Qiu, Xiaolan; Hu, Donghui

    2013-01-01

    Synthetic Aperture Radar (SAR) is critical for remote sensing. It works day and night, in good weather or bad. Bistatic SAR is a new kind of SAR system, where the transmitter and receiver are placed on two separate platforms. Bistatic SAR is one of the most important trends in SAR development, as the technology renders SAR more flexible and safer when used in military environments. Imaging is one of the most difficult and important aspects of bistatic SAR data processing. Although traditional SAR signal processing is fully developed, bistatic SAR has a more complex system structure, so sign

  12. SAR++: A Multi-Channel Scalable and Reconfigurable SAR System

    DEFF Research Database (Denmark)

    Høeg, Flemming; Christensen, Erik Lintz

    2002-01-01

    SAR++ is a technology program aiming at developing know-how and technology needed to design the next generation civilian SAR systems. Technology has reached a state, which allows major parts of the digital subsystem to be built using custom-off-the-shelf (COTS) components. A design goal is to des......SAR++ is a technology program aiming at developing know-how and technology needed to design the next generation civilian SAR systems. Technology has reached a state, which allows major parts of the digital subsystem to be built using custom-off-the-shelf (COTS) components. A design goal...... is to design a modular, scalable and reconfigurable SAR system using such components, in order to ensure maximum flexibility for the users of the actual system and for future system updates. Having these aspects in mind the SAR++ system is presented with focus on the digital subsystem architecture...... and the analog to digital interface....

  13. Bistatic Polarimetric SAR Decomposition in Terms of Roll-Invariant Parameters

    Science.gov (United States)

    Bombrun, Lionel

    2011-03-01

    This paper introduces a new bistatic Polarimetric SAR decomposition in terms of roll-invariant parameters. The proposed decomposition is an extension of the Target Scattering Vector Model to the bistatic case, where the cross-polarization terms of the scattering matrix are not necessary equal.

  14. Bistatic Polarimetric SAR Decomposition in Terms of Roll-Invariant Parameters

    OpenAIRE

    Bombrun, Lionel

    2011-01-01

    International audience; This paper introduces a new bistatic Polarimetric SAR decomposition in terms of roll-invariant parameters. The proposed decomposition is an extension of the Target Scattering Vector Model to the bistatic case, where the cross-polarization terms of the scattering matrix are not necessary equal.

  15. THz-SAR Vibrating Target Imaging via the Bayesian Method

    Directory of Open Access Journals (Sweden)

    Bin Deng

    2017-01-01

    Full Text Available Target vibration bears important information for target recognition, and terahertz, due to significant micro-Doppler effects, has strong advantages for remotely sensing vibrations. In this paper, the imaging characteristics of vibrating targets with THz-SAR are at first analyzed. An improved algorithm based on an excellent Bayesian approach, that is, the expansion-compression variance-component (ExCoV method, has been proposed for reconstructing scattering coefficients of vibrating targets, which provides more robust and efficient initialization and overcomes the deficiencies of sidelobes as well as artifacts arising from the traditional correlation method. A real vibration measurement experiment of idle cars was performed to validate the range model. Simulated SAR data of vibrating targets and a tank model in a real background in 220 GHz show good performance at low SNR. Rapidly evolving high-power terahertz devices will offer viable THz-SAR application at a distance of several kilometers.

  16. An Improved Shape Contexts Based Ship Classification in SAR Images

    Directory of Open Access Journals (Sweden)

    Ji-Wei Zhu

    2017-02-01

    Full Text Available In synthetic aperture radar (SAR imagery, relating to maritime surveillance studies, the ship has always been the main focus of study. In this letter, a method of ship classification in SAR images is proposed to enhance classification accuracy. In the proposed method, to fully exploit the distinguishing characters of the ship targets, both topology and intensity of the scattering points of the ship are considered. The results of testing the proposed method on a data set of three types of ships, collected via a space-borne SAR sensor designed by the Institute of Electronics, Chinese Academy of Sciences (IECAS, establish that the proposed method is superior to several existing methods, including the original shape contexts method, traditional invariant moments and the recent approach.

  17. Novel Polarimetric SAR Interferometry Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...

  18. Wetland InSAR

    Science.gov (United States)

    Wdowinski, S.; Kim, S.; Amelung, F.; Dixon, T.

    2006-12-01

    Wetlands are transition zones where the flow of water, the nutrient cycling, and the sun energy meet to produce a unique and very productive ecosystem. They provide critical habitat for a wide variety of plant and animal species, including the larval stages of many ocean fish. Wetlands also have a valuable economical importance, as they filter nutrients and pollutants from fresh water used by human and provide aquatic habitats for outdoor recreation, tourism, and fishing. Globally, many such regions are under severe environmental stress, mainly from urban development, pollution, and rising sea level. However, there is increasing recognition of the importance of these habitats, and mitigation and restoration activities have begun in a few regions. A key element in wetlands conservation, management, and restoration involves monitoring its hydrologic system, as the entire ecosystem depends on its water supply. Heretofore, hydrologic monitoring of wetlands are conducted by stage (water level) stations, which provide good temporal resolution, but suffer from poor spatial resolution, as stage station are typically distributed several, or even tens of kilometers, from one another. Wetland application of InSAR provides the needed high spatial resolution hydrological observations, complementing the high temporal resolution terrestrial observations. Although conventional wisdom suggests that interferometry does not work in vegetated areas, several studies have shown that both L- and C-band interferograms with short acquisition intervals (1-105 days) can maintain excellent coherence over wetlands. In this study we explore the usage of InSAR for detecting water level changes in various wetland environments around the world, including the Everglades (south Florida), Louisiana Coast (southern US), Chesapeake Bay (eastern US), Pantanal (Brazil), Okavango Delta (Botswana), and Lena Delta (Siberia). Our main study area is the Everglades wetland (south Florida), which is covered by

  19. Methods of InSAR atmosphere correction for volcano activity monitoring

    Science.gov (United States)

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Zhiming

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  20. Research on Inversion Models for Forest Height Estimation Using Polarimetric SAR Interferometry

    Science.gov (United States)

    Zhang, L.; Duan, B.; Zou, B.

    2017-09-01

    The forest height is an important forest resource information parameter and usually used in biomass estimation. Forest height extraction with PolInSAR is a hot research field of imaging SAR remote sensing. SAR interferometry is a well-established SAR technique to estimate the vertical location of the effective scattering center in each resolution cell through the phase difference in images acquired from spatially separated antennas. The manipulation of PolInSAR has applications ranging from climate monitoring to disaster detection especially when used in forest area, is of particular interest because it is quite sensitive to the location and vertical distribution of vegetation structure components. However, some of the existing methods can't estimate forest height accurately. Here we introduce several available inversion models and compare the precision of some classical inversion approaches using simulated data. By comparing the advantages and disadvantages of these inversion methods, researchers can find better solutions conveniently based on these inversion methods.

  1. Information compression and speckle reduction for multifrequency polarimetric SAR images based on kernel PCA

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Lei Xiaogang; Bai Bendu; Zhang Yanning

    2008-01-01

    Multifrequency polarimetric SAR imagery provides a very convenient approach for signal processing and acquisition of radar image. However, the amount of information is scattered in several images, and redundancies exist between different bands and polarizations. Similar to signal-polarimetric SAR image, multifrequency polarimetric SAR image is corrupted with speckle noise at the same time. A method of information compression and speckle reduction for multifrequency polarimetric SAR imagery is presented based on kernel principal component analysis (KPCA). KPCA is a nonlinear generalization of the linear principal component analysis using the kernel trick. The NASA/JPL polarimetric SAR imagery of P, L, and C bands quadpolarizations is used for illustration. The experimental results show that KPCA has better capability in information compression and speckle reduction as compared with linear PCA.

  2. SAR imaging simulation for an inhomogeneous undulated lunar surface based on triangulated irregular network

    Institute of Scientific and Technical Information of China (English)

    FA WenZhe; XU Feng; JIN YaQiu

    2009-01-01

    Based on the statistics of the lunar cratered terrain, e.g., population, dimension and shape of craters, the terrain feature of cratered lunar surface is numerically generated. According to the Inhomogeneous distribution of the lunar surface slope, the triangulated irregular network (TIN) is employed to make the digital elevation of lunar surface model. The Kirchhoff approximation of surface scattering is then applied to simulation of lunar surface scattering. The synthetic aperture radar (SAR) image for compre-hensive cratered lunar surface is numerically generated using back projection (BP) algorithm of SAR Imaging. Making use of the digital elevation and Clementlne UVVIS data at Apollo 15 landing site as the ground truth, an SAR Image at Apollo 15 landing site Is simulated. The image simulation is verified using real SAR image and echoes statistics.

  3. Multi-scale segmentation of polarimetric SAR imagery guided by scattering properties%散射特性引导的极化SAR图像多尺度分割

    Institute of Scientific and Technical Information of China (English)

    巫兆聪; 欧阳群东

    2012-01-01

    Considering the different segmentation scales required for various ground objects, a novel multi-scale segmentation method guided by scattering properties was proposed in this paper. To implement this method, it firstly obtained the initial segmentation results with different scales by iteratively merging regions, which are derived from watershed transformation. Then, ground objects were divided into surface, double and volume scattering categoric* in terms of their segmentation scales, using the feature of polarimetric scattering powers. Finally, the desired segmentation result was achieved by selecting and svnthesiiing suitable scales for each scattering category, according to segmentation quality evaluation. The effectiveness of this method was demonstrated using L-band polarimetric data acquired by ESAR system.%为满足不同地物分割的尺度需求,本文提出一种散射特性引导的极化SAR图像多尺度分割算法.该算法以分水岭初始分割为基础,通过迭代合并相邻区域获取极化SAR图像在不同尺度下的分割结果;以极化散射功率为特征,将地物按尺度相似性划分成表面散射、二次散射和体散射3种散射类型;以分割质量评价为指导,从多尺度分割结果中为每种散射类型地物选取适宜的分割尺度并进行叠置合成,形成最终分割结果.ESAR系统获取的L波段极化SAR数据验证了该算法的可行性.

  4. Analysis of factors influencing the accuracy of CRDInSAR

    Science.gov (United States)

    Fu, Wenxue; Guo, Huadong; Tian, Qingjiu; Guo, Xiaofang

    2010-11-01

    In recent years, the method of Corner Reflectors Differential Interferometric Synthetic Aperture Radar (CRDInSAR) was proposed for overcoming the limitations of decorrelations of the conventional differential interferometric synthetic aperture radar (DInSAR) technique. In general, the corner reflector has very high RCS (Radar Cross Section) for a small size, and the maximum RCS occurs when it points directly along the boresight of the SAR antenna. The beam width of a trihedral corner reflector is rather broad (having a 3dB beam width of 40° in both elevation and azimuth), so it is fairly tolerant to installation errors. It can be made available as artificial PS (Permanent Scatterers) points by installing them on a study area due to the stable amplitude and phase performance. However, some errors of CRDInSAR system will still affect the results of measurement. In this paper, the factors influence the accuracy of CRDInSAR are discussed, which include the errors of baseline and its angle, look angle and height of corner reflector respectively.

  5. SAR Data Fusion Imaging Method Oriented to Target Feature Extraction

    Directory of Open Access Journals (Sweden)

    Yang Wei

    2015-02-01

    Full Text Available To deal with the difficulty for target outlines extracting precisely due to neglect of target scattering characteristic variation during the processing of high-resolution space-borne SAR data, a novel fusion imaging method is proposed oriented to target feature extraction. Firstly, several important aspects that affect target feature extraction and SAR image quality are analyzed, including curved orbit, stop-and-go approximation, atmospheric delay, and high-order residual phase error. Furthermore, the corresponding compensation methods are addressed as well. Based on the analysis, the mathematical model of SAR echo combined with target space-time spectrum is established for explaining the space-time-frequency change rule of target scattering characteristic. Moreover, a fusion imaging strategy and method under high-resolution and ultra-large observation angle range conditions are put forward to improve SAR quality by fusion processing in range-doppler and image domain. Finally, simulations based on typical military targets are used to verify the effectiveness of the fusion imaging method.

  6. Experiments of Tomography-Based SAR Techniques with P-Band Polarimetric Data

    Science.gov (United States)

    Lombardini, F.; Pardini, M.

    2009-04-01

    New opportunities are arising in the synthetic aperture radar (SAR) observation of forest scenarios, especially with decimetric and metric radio wavelengths, which possess the capability of penetrating into volumes. Given its capabilities in the three-dimensional imaging of the scattering properties of the observed scene, SAR Tomography (Tomo-SAR) constitutes a good candidate for the analysis of the vertical structure of the forest. In this work, the results are presented of the application of tomography-based SAR techniques to P-band airborne data over a boreal forest from the ESA BioSAR-1 project. Results of an adaptive tomographic analysis are presented, also with a low resolution dataset, which emulates a satellite acquisition. In order to mitigate the geometric perspective effects due to the poor range resolution, the principle is introduced of the application of a common band pre-filtering to tomography. Then, a coherent layer canceller is derived to possibly apply interferometric techniques conceived for single layer scenarios to two layer scenarios. Finally, a stabilized adaptive polarimetric Tomo-SAR (PolTomo-SAR) method is proposed for estimating the 3D polarimetric scattering mechanism of the scene with low distorsions.

  7. Effect of wind turbine micro-Doppler on SAR and GMTI signatures

    Science.gov (United States)

    Bhalla, Rajan; Ling, Hao

    2014-05-01

    In this paper, we present the results of a modeling study to examine the interference effect of microDopplers caused by offshore wind farms on airborne sensors operating in the synthetic aperture radar (SAR) and ground moving target indicator (GMTI) modes. The modeling is carried out by generating CAD instantiations of the dynamic wind turbine and using the high-frequency electromagnetic code Xpatch to perform the scattering calculations. Artifacts in the resulting SAR and GMTI signatures are evaluated for interference with tracking of boats in coastal waters. Results of signal filtering algorithms to reduce the dynamic turbine clutter in both SAR images and GMTI displays are presented.

  8. Recovering Seasat SAR Data

    Science.gov (United States)

    Logan, T. A.; Arko, S. A.; Rosen, P. A.

    2013-12-01

    To demonstrate the feasibility of orbital remote sensing for global ocean observations, NASA launched Seasat on June 27th, 1978. Being the first space borne SAR mission, Seasat produced the most detailed SAR images of Earth from space ever seen to that point in time. While much of the data collected in the USA was processed optically, a mere 150 scenes had been digitally processed by March 1980. In fact, only an estimated 3% of Seasat data was ever digitally processed. Thus, for over three decades, the majority of the SAR data from this historic mission has been dormant, virtually unavailable to scientists in the 21st century. Over the last year, researchers at the Alaska Satellite Facility (ASF) Distributed Active Archive Center (DAAC) have processed the Seasat SAR archives into imagery products. A telemetry decoding system was created and the data were filtered into readily processable signal files. Due to nearly 35 years of bit rot, the bit error rate (BER) for the ASF DAAC Seasat archives was on the order of 1 out of 100 to 1 out of 100,000. This extremely high BER initially seemed to make much of the data undecodable - because the minor frame numbers are just 7 bits and no range line numbers exist in the telemetry even the 'simple' tasks of tracking the minor frame number or locating the start of each range line proved difficult. Eventually, using 5 frame numbers in sequence and a handful of heuristics, the data were successfully decoded into full range lines. Concurrently, all metadata were stored into external files. Recovery of this metadata was also problematic, the BER making the information highly suspect and, initially at least, unusable in any sort of automated fashion. Because of the BER, all of the single bit metadata fields proved unreliable. Even fields that should be constant for a data take (e.g. receiving station, day of the year) showed high variability, each requiring a median filter to be usable. The most challenging, however, were the

  9. Analytical SAR-GMTI principles

    Science.gov (United States)

    Soumekh, Mehrdad; Majumder, Uttam K.; Barnes, Christopher; Sobota, David; Minardi, Michael

    2016-05-01

    This paper provides analytical principles to relate the signature of a moving target to parameters in a SAR system. Our objective is to establish analytical tools that could predict the shift and smearing of a moving target in a subaperture SAR image. Hence, a user could identify the system parameters such as the coherent processing interval for a subaperture that is suitable to localize the signature of a moving target for detection, tracking and geolocating the moving target. The paper begins by outlining two well-known SAR data collection methods to detect moving targets. One uses a scanning beam in the azimuth domain with a relatively high PRF to separate the moving targets and the stationary background (clutter); this is also known as Doppler Beam Sharpening. The other scheme uses two receivers along the track to null the clutter and, thus, provide GMTI. We also present results on implementing our SAR-GMTI analytical principles for the anticipated shift and smearing of a moving target in a simulated code. The code would provide a tool for the user to change the SAR system and moving target parameters, and predict the properties of a moving target signature in a subaperture SAR image for a scene that is composed of both stationary and moving targets. Hence, the SAR simulation and imaging code could be used to demonstrate the validity and accuracy of the above analytical principles to predict the properties of a moving target signature in a subaperture SAR image.

  10. Initial assessment of an airborne Ku-band polarimetric SAR.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2013-02-01

    Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.

  11. Reovirus, isolated from SARS patients

    Institute of Scientific and Technical Information of China (English)

    DUAN Qing; SONG Lihua; GAN Yonghua; TAN Hua; JIN Baofeng; LI Huiyan; ZUO Tingting; CHEN Dehui; ZHANG Xuemin; ZHU Hong; YANG Yi; LI Weihua; ZHOU Yusen; HE Jun; HE Kun; ZHANG Haojie; ZHOU Tao

    2003-01-01

    Beijing has been severely affected by SARS, and SARS-associated coronavirus has been confirmed as its cause. However, clinical and experimental evidence implicates the possibility of co-infection. In this report, reovirus was isolated from throat swabs of SARS patients, including the first case in Beijing andher mother. Identification with the electron microscopy revealed the characteristic features of reovirus. 24 of 38 samples from other SARS cases were found to have serologic responses to the reovirus. Primers designed for reovirus have amplified several fragments of DNA, one of which was sequenced (S2 gene fragment), which indicates it as a unique reovirus (orthoreovirus). Preliminary animal experiment showed that inoculation of the reovirus in mice caused death with atypical pneumonia. Nevertheless, the association of reovirus with SARS outbreak requires to be further investigated.

  12. SAR Altimetry Applications over Water

    CERN Document Server

    Martin-Puig, C; Ruffini, G; Raney, R K; Benveniste, J

    2008-01-01

    The application of Synthetic Aperture Radar (SAR) techniques to classical radar altimetry offers the potential for greatly improved Earth surface mapping. This paper provides an overview of the progress of SAMOSA, Development of SAR Altimetry Studies and Applications over Ocean, Coastal zones and Inland waters, an on-going ESA-funded project. The main objective of SAMOSA is to better quantify the improvement of SAR altimetry over conventional altimetry on water surfaces. More specifically, one of the tasks focuses on the reduction of SAR mode data to pulse-limited altimeter data, and a theoretical modelling to characterize the expected gain between high Pulse Repetition Frequency (PRF) reduced SAR mode data and low PRF classical Low-Resolution Mode (LRM) data. To this end, theoretical modelling using the Cramer-Rao bound (CRB) will be used and the results will be compared to previous theoretical estimates [7], using an analysis akin to that in [8].

  13. Anatomy of a SAR impulse response.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  14. Localized landslide risk assessment with multi pass L band DInSAR analysis

    Science.gov (United States)

    Yun, HyeWon; Rack Kim, Jung; Lin, Shih-Yuan; Choi, YunSoo

    2014-05-01

    In terms of data availability and error correction, landslide forecasting by Differential Interferometric SAR (DInSAR) analysis is not easy task. Especially, the landslides by the anthropogenic construction activities frequently occurred in the localized cutting side of mountainous area. In such circumstances, it is difficult to attain sufficient enough accuracy because of the external factors inducing the error component in electromagnetic wave propagation. For instance, the local climate characteristics such as orographic effect and the proximity to water source can produce the significant anomalies in the water vapor distribution and consequently result in the error components of InSAR phase angle measurements. Moreover the high altitude parts of target area cause the stratified tropospheric delay error in DInSAR measurement. The other obstacle in DInSAR observation over the potential landside site is the vegetation canopy which causes the decorrelation of InSAR phase. Thus rather than C band sensor such as ENVISAT, ERS and RADARSAT, DInSAR analysis with L band ALOS PLASAR is more recommendable. Together with the introduction of L band DInSAR analysis, the improved DInSAR technique to cope all above obstacles is necessary. Thus we employed two approaches i.e. StaMPS/MTI (Stanford Method for Persistent Scatterers/Multi-Temporal InSAR, Hopper et al., 2007) which was newly developed for extracting the reliable deformation values through time series analysis and two pass DInSAR with the error term compensation based on the external weather information in this study. Since the water vapor observation from spaceborne radiometer is not feasible by the temporal gap in this case, the quantities from weather Research Forecasting (WRF) with 1 km spatial resolution was used to address the atmospheric phase error in two pass DInSAR analysis. Also it was observed that base DEM offset with time dependent perpendicular baselines of InSAR time series produce a significant error

  15. Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle

    Directory of Open Access Journals (Sweden)

    Takashi Shibayama

    2015-11-01

    Full Text Available This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR, have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

  16. State-of-art of Geosynchronous SAR

    Institute of Scientific and Technical Information of China (English)

    MAO Er-ke; LONG Teng; ZENG Tao; HU Cheng; TIAN Ye

    2012-01-01

    Geosynchronous Earth Orbit Synthetic Aperture Radar (GEO SAR) runs in the height of 360000Km geosynchronous earth orbit,compared with traditional Low Earth Orbit (LEO) SAR (orbit height under 1000Km),GEO SAR has advantages of shorter repeat period,wider swath and so on.Firstly,the basic principle and state-of-art of GEO SAR in domestic and overseas are introduced.Secondly,coverage characteristic of GEO SAR is analyzed.Thirdly,the key problems of yaw steering and imaging on curved trajectory in GEO SAR are discussed in detail,and the corresponding primary solutions are presented in order to promote future research on GEO SAR.

  17. High Resolution Processing with an Active Phased Array SAR

    NARCIS (Netherlands)

    Nijenboer, F.J.; Otten, M.P.G.

    1999-01-01

    The Dutch PHARUS system is a polarimetric active phased array SAR capable of performing advanced SAR modes. Advanced SAR modes that are being investigated are: spotlight SAR, sliding spotlight SAR, stepped frequency SAR and interferometric SAR. The flight experiments and automatic beam steering

  18. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection.

    Science.gov (United States)

    Kim, Sungho; Song, Woo-Jin; Kim, So-Hyun

    2016-07-19

    Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR) images or infrared (IR) images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT) and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter) and an asymmetric morphological closing filter (AMCF, post-filter) into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC)-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic database generated

  19. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection

    Directory of Open Access Journals (Sweden)

    Sungho Kim

    2016-07-01

    Full Text Available Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR images or infrared (IR images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter and an asymmetric morphological closing filter (AMCF, post-filter into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic

  20. DEM FROM SAR:PRINCIPLE AND APPLICATION

    Institute of Scientific and Technical Information of China (English)

    Li Deren; Yang Jie

    2003-01-01

    The paper gives an overview of the principle and application of generating DEM from SAR, including the principle and processing flow of generating DEM from single SAR and SAR interferometry. Afterwards, the application fields of InSAR for terrain surveying, volcanic terrain surveying and D-InSAR for monitoring ground subsiding are listed and described as well.The problem and prospect of application are also pointed out in the last part of this paper.

  1. sar Ades

    Directory of Open Access Journals (Sweden)

    Aparecida Angélica Zoqui Paulovic Sabadini

    Full Text Available Este artigo é uma homenagem ao ilustre professor César Ades (1943-2012. Etólogo, Especialista em comportamento animal, Ades foi professor titular do Instituto de Psicologia da Universidade de São Paulo (IPUSP, atuando como docente do Departamento de Psicologia Experimental. O artigo descreve parte de sua rica vida acadêmica e profissional e apresenta, de forma resumida, sua trajetória na Universidade de São Paulo, como aluno, professor, pesquisador e orientador e sua atuação como administrador no Instituto de Psicologia e no Instituto de Estudos Avançados, além de sua atuação na Academia Paulista de Psicologia e em sociedades científicas. São destacados a importância de suas contribuições para a área de Psicologia e seu respeito pela vida, pelas pessoas e pelos animais.

  2. Severe acute respiratory syndrome (SARS)

    Science.gov (United States)

    ... include: Arterial blood tests Blood clotting tests Blood chemistry tests Chest x-ray or chest CT scan ... The death rate from SARS was 9 to 12% of those diagnosed. In people over age 65, the death ...

  3. Two dimensional estimates from ocean SAR images

    Directory of Open Access Journals (Sweden)

    J. M. Le Caillec

    1996-01-01

    Full Text Available Synthetic Aperture Radar (SAR images of the ocean yield a lot of information on the sea-state surface providing that the mapping process between the surface and the image is clearly defined. However it is well known that SAR images exhibit non-gaussian statistics and that the motion of the scatterers on the surface, while the image is being formed, may yield to nonlinearities. The detection and quantification of these nonlinearities are made possible by using Higher Order Spectra (HOS methods and more specifically, bispectrum estimation. The development of the latter method allowed us to find phase relations between different parts of the image and to recognise their level of coupling, i.e. if and how waves of different wavelengths interacted nonlinearly. This information is quite important as the usual models assume strong nonlinearities when the waves are propagating in the azimuthal direction (i.e. along the satellite track and almost no nonlinearities when propagating in the range direction. In this paper, the mapping of the ocean surface to the SAR image is reinterpreted and a specific model (i.e. a Second Order Volterra Model is introduced. The nonlinearities are thus explained as either produced by a nonlinear system or due to waves propagating into selected directions (azimuth or range and interacting during image formation. It is shown that quadratic nonlinearities occur for waves propagating near the range direction while for those travelling in the azimuthal direction the nonlinearities, when present, are mostly due to wave interactions but are almost completely removed by the filtering effect coming from the surface motion itself (azimuth cut-off. An inherent quadratic interaction filtering (azimuth high pass filter is also present. But some other effects, apparently nonlinear, are not detected with the methods described here, meaning that either the usual relation developed for the Ocean-to-SAR transform is somewhat incomplete

  4. TerraSAR-X mission

    Science.gov (United States)

    Werninghaus, Rolf

    2004-01-01

    The TerraSAR-X is a German national SAR- satellite system for scientific and commercial applications. It is the continuation of the scientifically and technologically successful radar missions X-SAR (1994) and SRTM (2000) and will bring the national technology developments DESA and TOPAS into operational use. The space segment of TerraSAR-X is an advanced high-resolution X-Band radar satellite. The system design is based on a sound market analysis performed by Infoterra. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification. The Ground Segment is optimized for flexible response to (scientific and commercial) User requests and fast image product turn-around times. The TerraSAR-X mission will serve two main goals. The first goal is to provide the strongly supportive scientific community with multi-mode X-Band SAR data. The broad spectrum of scientific application areas include Hydrology, Geology, Climatology, Oceanography, Environmental Monitoring and Disaster Monitoring as well as Cartography (DEM Generation) and Interferometry. The second goal is the establishment of a commercial EO-market in Europe which is driven by Infoterra. The commercial goal is the development of a sustainable EO-business so that the e.g. follow-on systems can be completely financed by industry from the profit. Due to its commercial potential, the TerraSAR-X project will be implemented based on a public-private partnership with the Astrium GmbH. This paper will describe first the mission objectives as well as the

  5. Focusing of bistatic SAR data

    Science.gov (United States)

    Bia, Pietro; Ricci, Nicola; Zonno, Mariantonietta; Nico, Giovanni; Catalao, Joao; Tesauro, Manlio

    2014-10-01

    The problems of simulation of bistatic SAR raw data and focusing are studied. A discrete target simulator is described. The simulator introduces the scene topography and compute the integration time of general bistatic configurations providing a means to derived maps of the range and azimuth spatial resolutions. The problem of focusing of bistatic SAR data acquired in a translational-invariant bistatic configuration is studied by deriving the bistatic Point Target Reference spectrum and presenting an analytical solution for its stationary points.

  6. The Effect of Sub-Aperture in DRIA Framework Applied on Multi-Aspect PolSAR Data

    Science.gov (United States)

    Xue, Feiteng; Yin, Qiang; Lin, Yun; Hong, Wen

    2016-08-01

    Multi-aspect SAR is a new remote sensing technology, achieves consecutive data in large look angle as platform moves. Multi- aspect observation brings higher resolution and SNR to SAR picture. Multi-aspect PolSAR data can increase the accuracy of target identify and classification because it contains the 3-D polarimetric scattering properties.DRIA(detecting-removing-incoherent-adding)framework is a multi-aspect PolSAR data processing method. In this method, the anisotropic and isotropic scattering is separated by maximum- likelihood ratio test. The anisotropic scattering is removed to gain a removal series. The isotropic scattering is incoherent added to gain a high resolution picture. The removal series describes the anisotropic scattering property and is used in features extraction and classification.This article focuses on the effect brought by difference of sub-aperture numbers in anisotropic scattering detection and removal. The more sub-apertures are, the less look angle is. Artificial target has anisotropic scattering because of Bragg resonances. The increase of sub-aperture number brings more accurate observation in azimuth though the quality of each single image may loss. The accuracy of classification in agricultural fields is affected by the anisotropic scattering brought by Bragg resonances. The size of the sub-aperture has a significant effect in the removal result of Bragg resonances.

  7. The Performance Analysis Based on SAR Sample Covariance Matrix

    Directory of Open Access Journals (Sweden)

    Esra Erten

    2012-03-01

    Full Text Available Multi-channel systems appear in several fields of application in science. In the Synthetic Aperture Radar (SAR context, multi-channel systems may refer to different domains, as multi-polarization, multi-interferometric or multi-temporal data, or even a combination of them. Due to the inherent speckle phenomenon present in SAR images, the statistical description of the data is almost mandatory for its utilization. The complex images acquired over natural media present in general zero-mean circular Gaussian characteristics. In this case, second order statistics as the multi-channel covariance matrix fully describe the data. For practical situations however, the covariance matrix has to be estimated using a limited number of samples, and this sample covariance matrix follow the complex Wishart distribution. In this context, the eigendecomposition of the multi-channel covariance matrix has been shown in different areas of high relevance regarding the physical properties of the imaged scene. Specifically, the maximum eigenvalue of the covariance matrix has been frequently used in different applications as target or change detection, estimation of the dominant scattering mechanism in polarimetric data, moving target indication, etc. In this paper, the statistical behavior of the maximum eigenvalue derived from the eigendecomposition of the sample multi-channel covariance matrix in terms of multi-channel SAR images is simplified for SAR community. Validation is performed against simulated data and examples of estimation and detection problems using the analytical expressions are as well given.

  8. Classification and monitoring of reed belts using dual-polarimetric TerraSAR-X time series

    Science.gov (United States)

    Heine, Iris; Jagdhuber, Thomas; Itzerott, Sibylle

    2016-04-01

    The shorelines of lakes in northeastern Germany are often covered by reed. These reed belts fulfill an important function as erosion protection, biotope for animals, carbon storage, and as cleaning filter for lake water. However, despite their importance for the limnic ecosystem, reed vegetation in northeastern Germany is not regularly monitored. In this research study we investigate the potential of synthetic aperture radar polarimetry (PolSAR) for seasonal monitoring of reed vegetation. SAR imagery enables sunlight- and (almost) weather-independent monitoring. Polarimetric decomposition techniques allow the physical characterization of the scattering scenario and the involved scatterers. Our study is based on 19 dual-polarimetric (HH/VV) TerraSAR-X images acquired between August 2014 and May 2015. We calculated different polarimetric indices comprising the HH and VV intensities, the dual-polarimetric coherency matrix with dominant and mean alpha scattering angles, entropy and anisotropy (normalized eigen-value difference) as well as combinations of entropy and anisotropy for the analysis of the scattering scenarios. The reed areas in the TerraSAR-X images were classified using a random forest algorithm and validated with high-resolution digital orthophotos. The time series analysis of the reed belts revealed significant seasonal changes in the double bounce sensitive parameters (intensity ratio HH/VV and intensity difference HH-VV, the co-polarimetric coherence phase and the dominant and mean alpha scattering angles). Additionally, the dual-polarimetric coherence (amplitude), anisotropy, entropy, and anisotropy-entropy-combinations showed seasonal changes of reed. In summer, the reed areas are characterized within the X-band SAR data by volume scattering, whereas in winter double-bounce scattering dominates. The volume scattering in summer is caused predominantly by reed leaves. In autumn, the leaves start to wither and fall off, so that in winter predominately

  9. 利用高分辨率聚束模式TerraSAR-X影像的PSInSAR监测地表变形%Monitoring Land Deformation Using PSInSAR with TerraSAR-X High Resolution Spotlight SAR Images

    Institute of Scientific and Technical Information of China (English)

    李永生; 张景发; 罗毅; 姜文亮

    2012-01-01

    利用20景于2010-03~2010-11期间采集的高分辨率聚束(1m分辨率)模式的TerraSAR-X SAR数据,采用永久散射体干涉测量技术(PSInSAR)获取了西藏羊八井地区由地热电站开采地下水引起的地面沉降。结果显示,羊八井地热电站周边及地热开采井地区在2010年期间的地面沉降速率最大达到25mm·a-1,而盆地其他地区的地面平均沉降速率为1mm·a-1。将其与ASAR获取的平均沉降速率结果对比,两者的相关性达到了0.76,这说明TerraSAR-X高分辨率SAR数据不仅可以提供高密度PS点,而且更好地体现了散射体的细节变化和微量位移情况。%Persistent scatterer InSAR was used to detect surface subsidence in the the Yangbajing geothermal power plant due to extraction of ground water with area aroun twent resolution TerraSAR-X spotlight SAR images collected between March and November y hig 2010 d h The results suggest that land subsidence in the areas of geothermal wells is up to 25 mm · a^-1 whilst the subsidence in the basin is less than 1 mm · a^- 1. And the correlation between TerraSAR-X and ASAR derived mean velocities is 0.76. TerraSAR-X high resolution spot- light SAR images can provide higher density of PS points than ASAR data, and also can re- veal the detail change and micro-displacement in a single ground object.

  10. Monitoring land subsidence by PS-DInSAR and SBAS methods in Tianjin City

    Science.gov (United States)

    Fan, Hongdong; Deng, Kazhong; Zhu, Chuanguang; Xue, Jiqun

    2011-10-01

    Because of groundwater over-exploitation, the land subsidence of Tianjin city has become more and more serious. Some researchers tried to use D-InSAR technique to monitor the subsidence of this area. However, D-InSAR has some problems such as space and time baseline decorrelation and atmospheric influence. In order to obtain long time series land deformation with high accuracy, SAR image set to monitor land subsidence has become a research focus. PSDInSAR (Persistent Scatterers-DInSAR) and SBAS (Small Baseline Sets) are two classical methods to monitor land subsidence by SAR images. The former chooses one image as the master and the latter chooses several images as the masters according to the threshold of baselines. Using eighteen ERS images and SRTM DEM data the land subsidence of Tianjin city from 1992 to 1998 was obtained by two methods mentioned. 18906 and 42041 PS points were identified respectively by PS-DInSAR and SBAS. While, 16.4 mm/a and 24.2 mm/a of the mean maximal subsidence velocities were obtained respectively. Although they are different in values, the distributions and subsidence laws of points are nearly same.

  11. Comparisons of Circular Transmit and Linear Receive Compact Polarimetric SAR Features for Oil Slicks Discrimination

    Directory of Open Access Journals (Sweden)

    Yu Li

    2015-01-01

    Full Text Available Compact polarimetric (CP synthetic aperture radar (SAR has proven its potential in distinguishing oil slicks and look-alikes. Polarimetric information can be retrieved directly from scattering vector or from reconstructed pseudo-Quad-Pol covariance matrix of CP SAR data. In this paper, we analysed features from Circular Transmit and Linear Receive (CTLR CP SAR data that are derived by taking both of these two methods. K-means clustering followed by accuracy assessment was also implemented for performance evaluation. Through experiments that were conducted based on L-band UAVSAR fully polarimetric data, it was found that optimum extraction methods varied for different features. The histogram analysis and segmentation results also demonstrated the comparable performance of CP SAR features in distinguishing different damping properties within oil slicks. This study proposed a framework of statistically analyzing polarimetric SAR (Pol-SAR features and provided guidelines for determining optimum feature extraction methods from CP SAR data and for marine oil-spills detection and classification.

  12. Staphylococcus aureus sarA regulates inflammation and colonization during central nervous system biofilm formation.

    Directory of Open Access Journals (Sweden)

    Jessica N Snowden

    Full Text Available Infection is a frequent and serious complication following the treatment of hydrocephalus with CSF shunts, with limited therapeutic options because of biofilm formation along the catheter surface. Here we evaluated the possibility that the sarA regulatory locus engenders S. aureus more resistant to immune recognition in the central nervous system (CNS based on its reported ability to regulate biofilm formation. We utilized our established model of CNS catheter-associated infection, similar to CSF shunt infections seen in humans, to compare the kinetics of bacterial titers, cytokine production and inflammatory cell influx elicited by wild type S. aureus versus an isogenic sarA mutant. The sarA mutant was more rapidly cleared from infected catheters compared to its isogenic wild type strain. Consistent with this finding, several pro-inflammatory cytokines and chemokines, including IL-17, CXCL1, and IL-1β were significantly increased in the brain following infection with the sarA mutant versus wild type S. aureus, in agreement with the fact that the sarA mutant displayed impaired biofilm growth and favored a planktonic state. Neutrophil influx into the infected hemisphere was also increased in the animals infected with the sarA mutant compared to wild type bacteria. These changes were not attributable to extracellular protease activity, which is increased in the context of SarA mutation, since similar responses were observed between sarA and a sarA/protease mutant. Overall, these results demonstrate that sarA plays an important role in attenuating the inflammatory response during staphylococcal biofilm infection in the CNS via a mechanism that remains to be determined.

  13. Compressive Sensing in High-resolution 3D SAR Tomography of Urban Scenarios

    Directory of Open Access Journals (Sweden)

    Liao Ming-sheng

    2015-04-01

    Full Text Available In modern high resolution SAR data, due to the intrinsic side-looking geometry of SAR sensors, layover and foreshortening issues inevitably arise, especially in dense urban areas. SAR tomography provides a new way of overcoming these problems by exploiting the back-scattering property for each pixel. However, traditional non-parametric spectral estimators, e.g. Truncated Singular Value Decomposition (TSVD, are limited by their poor elevation resolution, which is not comparable to the azimuth and slant-range resolution. In this paper, the Compressive Sensing (CS approach using Basis Pursuit (BP and TWo-step Iterative Shrinkage/Thresholding (TWIST are introduced. Experimental studies with real spotlight-mode TerraSAR-X dataset are carried out using both BP and TWIST, to demonstrate the merits of compressive sensing approaches in terms of robustness, computational efficiency, and super-resolution capability.

  14. Present-day strain distribution across a segment of the central bend of the North Anatolian Fault Zone from a Persistent-Scatterers InSAR analysis of the ERS and Envisat archives

    Science.gov (United States)

    Peyret, M.; Masson, F.; Yavasoglu, H.; Ergintav, S.; Reilinger, R.

    2013-03-01

    The North Anatolian Fault Zone (NAFZ) is the major transform system that accommodates the westward movement of the relatively rigid Anatolian block with respect to Eurasia. Mitigating the hazard associated with devastating earthquakes requires understanding how the NAFZ accumulates and releases the potential energy of elastic deformation both in space and in time. In this study, we focus on the central bend of the NAFZ where the strike of the North Anatolian Fault (NAF) changes from N75° to N105° within less than 100 km, and where a secondary fault system veers southwards within the interior of Anatolia. We present interseismic velocity fields obtained from a Persistent-Scatterers (PS) Interferometric radar analysis of ERS and Envisat radar archives. Despite the high vegetation cover, the spatial density of measurements is high (˜10 PS/km2 in average). Interseismic velocities presented below indicate a velocity change of ˜6-8 mm/yr along the satellite line-of-sight (LOS) mainly centred on the NAF surface trace, and are in good agreement with the GPS velocity field published previously. The observed deformation is accommodated within a zone of ˜20 to 30 km width, in this area where no surface creep has been reported, contrary to the Ismetpasa segment located ˜30 km to the west of this study zone. Although less conspicuous, ˜2-3 mm/yr (˜1 mm/yr along the LOS) of the total deformation seems to be localized along the Lacin Fault. The overall agreement with horizontal GPS measurements suggests that the vertical component of the ground deformation is minor. This is confirmed, over the western part of our study zone, by the 3-D estimation of the ground deformation from the combination of the GPS- and the PS-mean velocity fields. However, a specific pattern of the PS velocity fields suggests that an area, enclosed between two faults with roughly south-north orientation, experiences uplift. The PS analyses of radar time-series both prior and posterior to the Izmit

  15. Modifications to the three-component classification algorithm for SAR data

    Science.gov (United States)

    Moghaddam, M.; Freeman, A.

    1993-01-01

    Previously, a scattering model was used to classify SAR data as due to three mechanisms: surface or odd-bounce scattering; double-bounce scattering; and volume scattering. A Bragg rough-surface model was used for odd-bounce scattering, and two reflecting surfaces, as in a dihedral corner reflector, represented the double-bounce scattering mechanism. A random collection of infinitely thin cylinders was used to model the volume scattering contribution. It was assumed that the cylinders are uniformly oriented in all directions. In this work, modifications are made to the above model, which include specifying a preferred orientation for the cylinders representing branches and using thin cylinders of finite thickness as opposed to infinitely thin ones. In the first case, the preferred orientation is represented by a probability density function in the form of a dirac delta function. For the second case, small argument asymptotic expansions of Bessel functions are used to express the volume scattering contributions in terms of quantities containing the average radius of the cylinders. Since in each case the number of unknowns exceeds that of equations, simplifying assumptions are made. The solutions are applied to multifrequency polarimetric SAR data to obtain the new unknowns in addition to the relative contributions of each scattering mechanism. Several results are presented. It is found that the calculated percentage of each mechanism does not change significantly compared to the original model; however, additional information is gained about the scatterers.

  16. Inversion Algorithms and PS Detection in SAR Tomography, Case Study of Bucharest City

    Directory of Open Access Journals (Sweden)

    C. Dănişor

    2016-06-01

    Full Text Available Synthetic Aperture Radar (SAR tomography can reconstruct the elevation profile of each pixel based on a set of co-registered complex images of a scene. Its main advantage over classical interferometric methods consists in the capability to improve the detection of single persistent scatterers as well as to enable the detection of multiple scatterers interfering within the same pixel. In this paper, three tomographic algorithms are compared and applied to a dataset of 32 images to generate the elevation map of dominant scatterers from a scene. Targets which present stable proprieties over time - Persistent Scatterers (PS are then detected based on reflectivity functions reconstructed with Capon filtering.

  17. Improved Three-stage Algorithm of Forest Height Retrieval with PolInSAR

    Directory of Open Access Journals (Sweden)

    Xu Li-ying

    2014-02-01

    Full Text Available Employing Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR data to inverse forest parameters is a hot topic in the research field of PolInSAR. The typical forest parameter inversion algorithm is the three-stage inversion algorithm based on Random Volume over Ground (RVoG model. The errors of linear fitting and volume scattering correlation estimation are the major factors for parameter estimation accuracy. In this paper, straight line fitting employing the total least squares method is used to estimate the ground phase. Then, the Gamma function is applied as the line measure to adaptively estimate the volume scattering correlation. The improved three-stage inversion algorithm with PolInSAR is presented. The experiment result proves the forest parameters inversion result is accurate and reliable.

  18. Semi-supervised Learning for Classification of Polarimetric SAR Images Based on SVM-Wishart

    Directory of Open Access Journals (Sweden)

    Hua Wen-qiang

    2015-02-01

    Full Text Available In this study, we propose a new semi-supervised classification method for Polarimetric SAR (PolSAR images, aiming at handling the issue that the number of train set is small. First, considering the scattering characters of PolSAR data, this method extracts multiple scattering features using target decomposition approach. Then, a semi-supervised learning model is established based on a co-training framework and Support Vector Machine (SVM. Both labeled and unlabeled data are utilized in this model to obtain high classification accuracy. Third, a recovery scheme based on the Wishart classifier is proposed to improve the classification performance. From the experiments conducted in this study, it is evident that the proposed method performs more effectively compared with other traditional methods when the number of train set is small.

  19. The behavioral impacts of SARS and its implication for societal preparedness for other emerging infections

    Directory of Open Access Journals (Sweden)

    Kathleen Pik-san Kwok

    2008-07-01

    Full Text Available Introduction: This study examined public attitudes toward Severe Acute Respiratory Syndrome (SARS in Hong Kong three months after the peak of the 2003 outbreak in order to shed light on SARS-related complaints received by the Equal Opportunities Commission of Hong Kong. Methods: A cross-sectional telephone survey was conducted three months after the SARS outbreak of 1,023 randomly selected Chinese-speaking residents in Hong Kong. Results: Most of the respondents (72.2% reported worry about contracting SARS. They attributed their anxiety to the perceived danger of the disease, the government’s unsatisfactory style of crisis management, and inconsistent health information dissemination. The majority of respondents endorsed up to 3 avoidant (67.8% and 3 imposing (72.7% attitudes toward individuals and/or situations considered to be at risk of spreading SARS. Logistic Regression analyses indicated that the odds for avoidant and imposing attitudes increased significantly for those who were middle aged (35-54, employed full-time or part-time, and worried over contracting SARS. Conclusions: Public attitudes that endorsed avoidant and imposing behaviors were common during the outbreak of SARS. While essential for preventive health practices, they might bring about workplace conflicts, stigma, and other negative interpersonal experiences. These problems may complicate public health efforts to control the epidemic. They may also suggest ways in which societal preparedness for future emerging infections can be improved.

  20. Severe acute respiratory syndrome: 'SARS' or 'not SARS'.

    Science.gov (United States)

    Li, A M; Hon, K L E; Cheng, W T; Ng, P C; Chan, F Y; Li, C K; Leung, T F; Fok, T F

    2004-01-01

    Accurate clinical diagnosis of severe acute respiratory syndrome (SARS) based on the current World Health Organization definition is difficult and at times impossible at the early stage of the disease. Both false positive and false negative cases are commonly encountered and this could have far-reaching detrimental effects on the patients, their family and the clinicians alike. Contact history is particularly important in diagnosing SARS in children as their presenting features are often non-specific. The difficulty in making a correct diagnosis is further compounded by the lack of a sensitive rapid diagnostic test. Serology is not particularly helpful in the initial triaging of patients as it takes at least 3 weeks to become positive. Co-infection and other treatable conditions should not be missed and conventional antibiotics should remain as part of the first-line treatment regimen. We report five cases to illustrate the difficulties and dilemmas faced by clinicians in diagnosing SARS in children.

  1. Geodetic imaging of tectonic deformation with InSAR

    Science.gov (United States)

    Fattahi, Heresh

    evaluated the rate of strain accumulation along the Chaman fault system (Chapter 5). I also evaluate the co-seismic and post-seismic displacement of a moderate M5.5 earthquake on the Ghazaband fault (Chapter 6). The developed methods to mitigate the systematic noise from InSAR time-series, significantly improve the accuracy of the InSAR displacement time-series and velocity. The approaches to evaluate the effect of the stochastic components of noise in InSAR displacement time-series enable us to obtain the variance-covariance matrix of the InSAR displacement time-series and to express their uncertainties. The effect of the topographic residuals in the InSAR range-change time-series is proportional to the perpendicular baseline history of the set of SAR acquisitions. The proposed method for topographic residual correction, efficiently corrects the displacement time-series. Evaluation of the uncertainty of velocity due to the orbital errors shows that for modern SAR satellites with precise orbits such as TerraSAR-X and Sentinel-1, the uncertainty of 0.2 mm/yr per 100 km and for older satellites with less accurate orbits such as ERS and Envisat, the uncertainty of 1.5 and 0.5mm/yr per 100 km, respectively are achievable. However, the uncertainty due to the orbital errors depends on the orbital uncertainties, the number and time span of SAR acquisitions. Contribution of the tropospheric delay to the InSAR range-change time-series can be subdivided to systematic (seasonal delay) and stochastic components. The systematic component biases the displacement times-series and velocity field as a function of the acquisition time and the non-seasonal component significantly contributes to the InSAR uncertainty. Both components are spatially correlated and therefore the covariance of noise between pixels should be considered for evaluating the uncertainty due to the random tropospheric delay. The relative velocity uncertainty due to the random tropospheric delay depends on the scatter of

  2. Estimating soil moisture using the Danish polarimetric SAR

    DEFF Research Database (Denmark)

    Jiankang, Ji; Thomsen, A.; Skriver, Henning

    1995-01-01

    The results of applying data from the Danish polarimetric SAR (EMISAR) to estimate soil moisture for bare fields are presented. Fully calibrated C-band SAR images for hh, vv and cross polarizations have been used in this study. The measured surface roughness data showed that classical roughness...... autocorrelation functions (Gaussian and Exponential) were not able to fit natural surfaces well. A Gauss-Exp hybrid model which agreed better with the measured data has been proposed. Theoretical surface scattering models (POM, IEM), as well as an empirical model for retrieval of soil moisture and surface rms...... height from coand cross-polarized ratio, have been examined, but the results are less satisfactory. As soil moisture response to backscattering coefficient σo is mainly coupled to surface roughness effect for bare fields, a bilinear model coupling volumetric soil moisture mv and surface rms height σ...

  3. Mapping ground surface deformation using temporarily coherent point SAR interferometry: Application to Los Angeles Basin

    Science.gov (United States)

    Zhang, L.; Lu, Zhiming; Ding, X.; Jung, H.-S.; Feng, G.; Lee, C.-W.

    2012-01-01

    Multi-temporal interferometric synthetic aperture radar (InSAR) is an effective tool to detect long-term seismotectonic motions by reducing the atmospheric artifacts, thereby providing more precise deformation signal. The commonly used approaches such as persistent scatterer InSAR (PSInSAR) and small baseline subset (SBAS) algorithms need to resolve the phase ambiguities in interferogram stacks either by searching a predefined solution space or by sparse phase unwrapping methods; however the efficiency and the success of phase unwrapping cannot be guaranteed. We present here an alternative approach - temporarily coherent point (TCP) InSAR (TCPInSAR) - to estimate the long term deformation rate without the need of phase unwrapping. The proposed approach has a series of innovations including TCP identification, TCP network and TCP least squares estimator. We apply the proposed method to the Los Angeles Basin in southern California where structurally active faults are believed capable of generating damaging earthquakes. The analysis is based on 55 interferograms from 32 ERS-1/2 images acquired during Oct. 1995 and Dec. 2000. To evaluate the performance of TCPInSAR on a small set of observations, a test with half of interferometric pairs is also performed. The retrieved TCPInSAR measurements have been validated by a comparison with GPS observations from Southern California Integrated GPS Network. Our result presents a similar deformation pattern as shown in past InSAR studies but with a smaller average standard deviation (4.6. mm) compared with GPS observations, indicating that TCPInSAR is a promising alternative for efficiently mapping ground deformation even from a relatively smaller set of interferograms. ?? 2011.

  4. Rotating Parabolic-Reflector Antenna Target in SAR Data: Model, Characteristics, and Parameter Estimation

    Directory of Open Access Journals (Sweden)

    Bin Deng

    2013-01-01

    Full Text Available Parabolic-reflector antennas (PRAs, usually possessing rotation, are a particular type of targets of potential interest to the synthetic aperture radar (SAR community. This paper is aimed to investigate PRA’s scattering characteristics and then to extract PRA’s parameters from SAR returns, for supporting image interpretation and target recognition. We at first obtain both closed-form and numeric solutions to PRA’s backscattering by geometrical optics (GO, physical optics, and graphical electromagnetic computation, respectively. Based on the GO solution, a migratory scattering center model is at first presented for representing the movement of the specular point with aspect angle, and then a hybrid model, named the migratory/micromotion scattering center (MMSC model, is proposed for characterizing a rotating PRA in the SAR geometry, which incorporates PRA’s rotation into its migratory scattering center model. Additionally, we in detail analyze PRA’s radar characteristics on radar cross-section, high-resolution range profiles, time-frequency distribution, and 2D images, which also confirm the models proposed. A maximal likelihood estimator is developed for jointly solving the MMSC model for PRA’s multiple parameters by optimization. By exploiting the aforementioned characteristics, the coarse parameter estimation guarantees convergency upon global minima. The signatures recovered can be favorably utilized for SAR image interpretation and target recognition.

  5. Wave directional spectrum from SAR imagery

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.; Vethamony, P.

    Gaussian smoothed SAR image spectra have been evaluated from 512 x 512 pixel sub- scenes of image mode ERS-1 SAR scenes off Goa, Visakhapatnam, Paradeep and Portugal. The two recently acquired scenes off Portugal showed the signature of swell...

  6. SAR Image Enhancement using Particle Filters

    Data.gov (United States)

    National Aeronautics and Space Administration — In this paper, we propose a novel approach to reduce the noise in Synthetic Aperture Radar (SAR) images using particle filters. Interpretation of SAR images is a...

  7. Novel Polarimetric SAR Interferometry Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  8. SARS Patients and Their Close Contacts

    Science.gov (United States)

    ... Links Clinician Registry Travelers' Health Fact Sheet for SARS Patients and Their Close Contacts Format: Select one ... of the World Health Organization (WHO) . Symptoms of SARS The illness usually begins with a fever (measured ...

  9. Wave directional spectrum from SAR imagery

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.; Vethamony, P.

    Gaussian smoothed SAR image spectra have been evaluated from 512 x 512 pixel subscenes of image mode ERS-1 SAR scenes off Goa, Visakhapatnam, Paradeep and Portugal. The two recently acquired scenes off Portugal showed the signature of swell...

  10. Accelerated Scientific InSAR Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Neva Ridge Technologies proposes to develop a suite of software tools for the analysis of SAR and InSAR data, focused on having a robust and adopted capability well...

  11. Precision Rectification of Airborne SAR Image

    DEFF Research Database (Denmark)

    Dall, Jørgen; Liao, M.; Zhang, Zhe

    1997-01-01

    A simple and direct procedure for the rectification of a certain class of airborne SAR data is presented. The relief displacements of SAR data are effectively removed by means of a digital elevation model and the image is transformed to the ground coordinate system. SAR data from the Danish EMISAR...... for the application of SAR data in the difficult process of map revision and updating....

  12. SARS Vaccine: Progress and Challenge

    Institute of Scientific and Technical Information of China (English)

    Yan Zhi; James M. Wilson; Hao Shen

    2005-01-01

    Severe acute respiratory syndrome (SARS) emerged in 2002 as a severe and highly contagious infectious disease that rapidly spread to a number of different countries. The collaborative efforts of the global scientific community have provided, within a short period of time, substantial insights into the molecular biology and immunology of SARS-CoV. Although the outbreak has been contained, there is continuous concern that the virus may resurface into the human population through seasonal changes, animal reservoirs or laboratory accidents. The severe morbidity and mortality associated with SARS make it imperative that an effective vaccine be developed to prevent reemergence and epidemics in the future. Cellular & Molecular Immunology. 2005;2(2):101-105.

  13. Reduct and Attribute Order

    Institute of Scientific and Technical Information of China (English)

    Su-Qing Han; Jue Wang

    2004-01-01

    Based on the principle of discernibility matrix,a kind of reduction algorithm with attribute order has been developed and its solution has been proved to be complete for reduct and unique for a given attribute order.Being called the reduct problem,this algorithm can be regarded as a mapping R = Reduct(S)from the attribute order space θ to the reduct space R for an information system ,where U is the universe and C and D are two sets of condition and decision attributes respectively.This paper focuses on the reverse problem of reduct problem S = Order(R),i.e.,for a given reduct R of an information system,we determine the solution of S = Order(R)in the space θ.First,we need to prove that there is at least one attribute order S such that S = Order(R).Then,some decision rules are proposed,which can be used directly to decide whether the pair of attribute orders has the same reduct.The main method is based on the fact that an attribute order can be transformed into another one by moving the attribute for limited times.Thus,the decision of the pair of attribute orders can be altered to the decision of the sequence of neighboring pairs of attribute orders.Therefore,the basic theorem of neighboring pair of attribute orders is first proved,then,the decision theorem of attribute order is proved accordingly by the second attribute.

  14. SIMULATION STUDY ON AIRBORNE SAR ECHO SIGNAL

    Institute of Scientific and Technical Information of China (English)

    Bao Houbing; Liu Zhao

    2004-01-01

    Through analyzing the influence on echo signal by factors of kinematical parameters of airborne SAR platform and radar antenna direction, this letter, on the basis of classical SAR echo signal analogue algorithm, puts forward certain airborne SAR echo signal analogue algorithm of distance directional frequency domain pulse coherent accumulation, and goes through simulation. The simulation results have proved the effectiveness of this algorithm.

  15. Convolutional Neural Networks for SAR Image Segmentation

    DEFF Research Database (Denmark)

    Malmgren-Hansen, David; Nobel-Jørgensen, Morten

    2015-01-01

    Segmentation of Synthetic Aperture Radar (SAR) images has several uses, but it is a difficult task due to a number of properties related to SAR images. In this article we show how Convolutional Neural Networks (CNNs) can easily be trained for SAR image segmentation with good results. Besides...

  16. SAR Systems and Related Signal Processing

    NARCIS (Netherlands)

    Hoogeboom, P.; Dekker, R.J.; Otten, M.P.G.

    1996-01-01

    Synthetic Aperture Radar (SAR) is today a valuable source of remote sensing information. SAR is a side-looking imaging radar and operates from airborne and spacebome platforms. Coverage, resolution and image quality are strongly influenced by the platform. SAR processing can be performed on standard

  17. SAR Systems and Related Signal Processing

    NARCIS (Netherlands)

    Hoogeboom, P.; Dekker, R.J.; Otten, M.P.G.

    1996-01-01

    Synthetic Aperture Radar (SAR) is today a valuable source of remote sensing information. SAR is a side-looking imaging radar and operates from airborne and spacebome platforms. Coverage, resolution and image quality are strongly influenced by the platform. SAR processing can be performed on standard

  18. The aetiology of SARS: Koch's postulates fulfilled

    NARCIS (Netherlands)

    A.D.M.E. Osterhaus (Albert); R.A.M. Fouchier (Ron); T. Kuiken (Thijs)

    2004-01-01

    textabstractProof that a newly identified coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV) is the primary cause of severe acute respiratory syndrome (SARS) came from a series of studies on experimentally infected cynomolgus macaques (Macaca, fascicularis). SARS-CoV-infected

  19. Recent Advances in Radar Polarimetry and Polarimetric SAR Interferometry

    Science.gov (United States)

    Boerner, Wolfgang-Martin

    2005-01-01

    The development of Radar Polarimetry and Radar Interferometry is advancing rapidly, and these novel radar technologies are revamping Synthetic Aperture Radar Imaging decisively. In this exposition the successive advancements are sketched; beginning with the fundamental formulations and high-lighting the salient points of these diverse remote sensing techniques. Whereas with radar polarimetry the textural fine-structure, target-orientation and shape, symmetries and material constituents can be recovered with considerable improvements above that of standard amplitude-only Polarization Radar ; with radar interferometry the spatial (in depth) structure can be explored. In Polarimetric-Interferometric Synthetic Aperture Radar (POL-IN-SAR) Imaging it is possible to recover such co-registered textural plus spatial properties simultaneously. This includes the extraction of Digital Elevation Maps (DEM) from either fully Polarimetric (scattering matrix) or Interferometric (dual antenna) SAR image data takes with the additional benefit of obtaining co-registered three-dimensional POL-IN-DEM information. Extra-Wide-Band POL-IN-SAR Imaging - when applied to Repeat-Pass Image Overlay Interferometry - provides differential background validation and measurement, stress assessment, and environmental stress-change monitoring capabilities with hitherto unattained accuracy, which are essential tools for improved global biomass estimation. More recently, by applying multiple parallel repeat-pass EWB-POL-D(RP)-IN-SAR imaging along stacked (altitudinal) or displaced (horizontal) flight-lines will result in Tomographic (Multi- Interferometric) Polarimetric SAR Stereo-Imaging , including foliage and ground penetrating capabilities. It is shown that the accelerated advancement of these modern EWB-POL-D(RP)-IN-SAR imaging techniques is of direct relevance and of paramount priority to wide-area dynamic homeland security surveillance and local-to-global environmental ground-truth measurement

  20. Pol(In)SAR Soil Moisture Study by using Pi-SAR 2L and GB-SAR Data in Preparation of the upcoming ALOS-2/PALSAR-2 Mission

    Science.gov (United States)

    Koyama, C.; Sato, M.

    2013-12-01

    Recently Earth Observation by means of active microwave is advancing rapidly. The evolution started from first-generation classical single-channel systems like JERS (JAXA), ERS (ESA) or Radarsat-1 (CSA). With the launch of ALOS-1 (JAXA), the first fully polarimetric SAR measurements became available followed by Radarsat-2 (CSA) and TerraSAR-X (DLR), making polarimetric L-, C-, and X-band data available. In Japanese fiscal year 2013, the third generation of SAR satellites will begin with the launch of ALOS-2. The JAXA cutting-edge follow-on mission to the highly acclaimed ALOS-1 will carry the state-of-the-art PALSAR-2 sensor aboard. Due to its much better orbital revisit cycle of only 14 days and its very high spatial resolution (3 m) the system will be highly suitable for interferometric analysis of polarimetric data obtained from repeat-pass acquisitions. The combination of polarimetry and interferometry is probably the most promising approach for a better estimation of geophysical parameters from SAR data acquired over natural terrain and thus will greatly improve the capabilities to estimate soil moisture under all kinds of vegetation with high accuracy and with high temporal and spatial resolutions. In advent of the 3rd generation of Japanese SAR EO satellites, our group conducts a variety of fundamental research on low-frequency SAR surface scattering/interactions. Here, we present first results from soil moisture experiments based on fully polarimetric GB-SAR (Tohoku University) and Pi-SAR 2L (JAXA) measurements. These experiments comprise investigations of the effective soil moisture measuring depth of L-band SAR. The experimental set-up consists of an array of receiving di-pole antennas installed in different depths to quantify the penetration (and reflection) capabilities of the incoming EM waves. We use a fully polarimetric GB-SAR system based on a high-end VNA capable of coherent measurement of the [S2] scattering matrix. It uses 2 large horn antennas

  1. Slow-Moving Landslide Monitoring with Multi-Temporal TerraSAR-X Data by Means of DInSAR Techniques in Crotone Province (Southern Italy)

    Science.gov (United States)

    Confuorto, P.; Plank, S.; Di Martire, D.; Ramondini, M.; Thuro, K.; Calcaterra, D.

    2015-05-01

    The Differential SAR Interferometry (DInSAR) is one of the most powerful devices for monitoring deformation processes on the Earth surface. Here, a dataset of TerraSAR-X StripMap imagery covering almost the whole Crotone province territory, located in the south of the Italian peninsula, has been selected and processed. The time span goes from April 2008 to June 2010. In this work, two different multitemporal interferometry (MTI) approaches and two different software packages have been used and compared in order to identify benefits/constraints of each MTI approach and each software. Such approaches are: the ‘permanent’ (or ‘persistent’, or ‘point-like’) scatterers [1] implemented on the SARscape® software [2], and the Temporal Sublook Spectral Coherence (TSSC), derived from Coherent Pixel Technique algorithm and works on SUBSOFT processor, developed by the Remote Sensing Laboratory (RSLab) group, from the Universitat Politècnica de Catalunya (UPC) [3-5].

  2. Stochastic modeling for time series InSAR: with emphasis on atmospheric effects

    Science.gov (United States)

    Cao, Yunmeng; Li, Zhiwei; Wei, Jianchao; Hu, Jun; Duan, Meng; Feng, Guangcai

    2017-08-01

    Despite the many applications of time series interferometric synthetic aperture radar (TS-InSAR) techniques in geophysical problems, error analysis and assessment have been largely overlooked. Tropospheric propagation error is still the dominant error source of InSAR observations. However, the spatiotemporal variation of atmospheric effects is seldom considered in the present standard TS-InSAR techniques, such as persistent scatterer interferometry and small baseline subset interferometry. The failure to consider the stochastic properties of atmospheric effects not only affects the accuracy of the estimators, but also makes it difficult to assess the uncertainty of the final geophysical results. To address this issue, this paper proposes a network-based variance-covariance estimation method to model the spatiotemporal variation of tropospheric signals, and to estimate the temporal variance-covariance matrix of TS-InSAR observations. The constructed stochastic model is then incorporated into the TS-InSAR estimators both for parameters (e.g., deformation velocity, topography residual) estimation and uncertainty assessment. It is an incremental and positive improvement to the traditional weighted least squares methods to solve the multitemporal InSAR time series. The performance of the proposed method is validated by using both simulated and real datasets.

  3. Signal processing for FMCW SAR

    NARCIS (Netherlands)

    Meta, A.; Hoogeboom, P.; Ligthart, L.P.

    2007-01-01

    The combination of frequency-modulated continuous-wave (FMCW) technology and synthetic aperture radar (SAR) techniques leads to lightweight cost-effective imaging sensors of high resolution. One limiting factor to the use of FMCW sensors is the well-known presence of nonlinearities in the

  4. Canopy reconstruction from interferometric SAR

    NARCIS (Netherlands)

    Varekamp, C.

    2001-01-01

    Interferometric Synthetic Aperture Radar (InSAR) is investigated as a method for 3D tree mapping. When operational, the method may be important for monitoring forests with a persistent cloud cover such as tropical rain forests. The problem of crown displacement due to lay-over in a vegetation with a

  5. Stalking SARS: CDC at Work

    Centers for Disease Control (CDC) Podcasts

    2014-05-22

    In this podcast for kids, the Kidtastics talk about the SARS outbreak and how CDC worked to solve the mystery.  Created: 5/22/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 5/22/2014.

  6. Light weight digital array SAR

    NARCIS (Netherlands)

    Otten, M.; Maas, N.; Bolt, R.; Anitori, L.

    2010-01-01

    A light weight SAR has been designed, suitable for short range tactical UAVs, consisting of a fully digital receive array, and a very compact active transmit antenna. The weight of the complete RF front is expected to be below 3 kg, with a power consumption below 30 W. This X-band system can provide

  7. Bird flu: lessons from SARS.

    Science.gov (United States)

    Wong, Gary W K; Leung, Ting F

    2007-06-01

    Severe acute respiratory syndrome (SARS) and avian influenza are two important newly emerged infections with pandemic potential. Both infections have crossed the species barrier to infect humans. SARS originated from southern China and spread to many countries in early 2003. The close collaboration of scientists around the world resulted in a rapid identification of the causative agent, and the early isolation of infected cases and meticulous infection control measures were the key to successfully controlling the outbreak of SARS. The first outbreak of human cases of avian influenza was reported in 1997 in Hong Kong. Since 2003, there have been many small outbreaks of human cases around the world, and the reported mortality is greater than 50%. Current evidence suggests that the human-to-human transmission of avian influenza is rather inefficient, but mutation might occur in the future resulting in improved transmission and possibly a pandemic in humans. As with the outbreak of SARS, the development of sensitive and accurate early diagnostic tests is extremely important for successful control of the outbreak at source. The availability of isolation facilities, the stockpiling of antiviral agents and effective and safe vaccination will be extremely important in minimising the damage of a new influenza pandemic.

  8. [Medical history from SARS to pneumonia].

    Science.gov (United States)

    Zhen, Cheng

    2003-05-31

    SARS is a new kind of pneumonia. From the end of 2002 to the beginning of 2003, SARS broke in Guangdong province, Hong Kong and Beijing, and then gradually spread to the world. SARS is extremely contagious. The symptoms of SARS progress very quickly. SARS smashes the people's tranquil life and many people live in horror, worry and anxiety. But if we review the medical history of pneumonia, we would have a better understanding of SARS. This article focuses the history of people's understanding of pneumonia on the historical documents, diagnosis, etiology and treatment. Through the epidemic of SARS, the author hopes to express that contagion will live with us for a long time, but it is not a deadly disease. It is preventable and good care is essential for contagious patients. As Chinese people, we should have the best use of TCM in our combat with contagion.

  9. Validation of DEMs Derived from High Resolution SAR Data: a Case Study on Barcelona

    Science.gov (United States)

    Sefercik, U. G.; Schunert, A.; Soergel, U.; Watanabe, K.

    2012-07-01

    In recent years, Synthetic Aperture Radar (SAR) data have been widely used for scientific applications and several SAR missions were realized. The active sensor principle and the signal wavelength in the order of centimeters provide all-day and all-weather capabilities, respectively. The modern German TerraSAR-X (TSX) satellite provides high spatial resolution down to one meter. Based on such data SAR Interferometry may yield high quality digital surface models (DSMs), which includes points located on 3d objects such as vegetation, forest, and elevated man-made structures. By removing these points, digital elevation model (DEM) representing the bare ground of Earth is obtained. The primary objective of this paper is the validation of DEMs obtained from TSX SAR data covering Barcelona area, Spain, in the framework of a scientific project conducted by ISPRS Working Group VII/2 "SAR Interferometry" that aims the evaluation of DEM derived from data of modern SAR satellite sensors. Towards this purpose, a DSM was generated with 10 m grid spacing using TSX StripMap mode SAR data and converted to a DEM by filtering. The accuracy results have been presented referring the comparison with a more accurate (10 cm-1 m) digital terrain model (DTM) derived from large scale photogrammetry. The results showed that the TSX DEM is quite coherent with the topography and the accuracy is in between ±8-10 m. As another application, the persistent scatterer interferometry (PSI) was conducted using TSX data and the outcomes were compared with a 3d city model available in Google Earth, which is known to be very precise because it is based on LIDAR data. The results showed that PSI outcomes are quite coherent with reference data and the RMSZ of differences is around 2.5 m.

  10. Comparison of SAR-derived wind speed with the wind energy simulation toolkit (WEST)

    Energy Technology Data Exchange (ETDEWEB)

    Beaucage, P.; Lafrance, G.; Bernier, M. [Quebec Univ., Quebec City, PQ (Canada). Institut National de la Recherche Scientifique-Eau, Terre et Environnement; Glazer, A.; Benoit, R.; Yu, W. [Environment Canada, Gatineau, PQ (Canada)

    2005-07-01

    Wind power increases with air density, wind speed, and the surface area of wind turbine blades. Wind speed increases with altitude and topographic effects such as lower surface roughness, and high pressure gradient forcing. A comparative evaluation of a mesoscale compressible community numerical model (MC2) and synthetic aperture radar satellites (SAR) was presented. Wind speed predictions were presented, and details of both models were reviewed. Features of the MC2 included non hydrostatic Euler equations; a 3-D Lagrangian advection; full physical processes; resolution to a few km; self-nesting capabilities; topography adjustable at start-up; and open sourcing. Inputs included climatological fields; geophysical fields; initial and boundary atmospheric conditions; and dynamical and physical simulation settings. Outputs included wind speed vectors, pressure, temperature and humidity. Wind measurements from SAR satellites is conducted by observing wind friction in water. Radar signals are related to sea waves by Bragg resonant scattering. A geophysical model function establishes a semi-empirical relationship between the radar signal and wind vector. Several sources of wind direction inputs for SAR included scatterometer data; FFT of wind streaks on SAR images; local gradient filters on SAR images; NWP data; offshore coastal buoys and masts data. It was noted that with SAR, wind patterns were well represented and wind accuracy was improved. Micro-scale resolution is available and further improvements are expected with the launch of new satellites. Results of various studies comparing the use of MC2 and SAR in coastal waters were presented. It was concluded that wind features are well resolved by SAR and MC2 methods. A fusion of both methods was recommended to improve coastal and offshore wind assessments. refs., tabs., figs.

  11. On The TerraSAR-X Dual-Mode For Oil Slick Observation

    Science.gov (United States)

    Velotto, D.; Migliaccio, M.; Nunziata, F.; Lehner, S.

    2010-04-01

    In this study a polarimetric approach is for the first time developed and applied to X-band Synthetic Aperture Radar (SAR) data for sea oil slick observation. Following this an electromagnetic model which, based on the Co-polarized Phase Difference (CPD), allows describing the slick-free and slick-covered sea surface scattering is proposed. Single Look Complex (SSC) TerraSAR-X (TSX) data, gathered in dual polarimetric mode, in which both certified oil slicks and look-alikes are present, are analyzed. Several experiments are shown here and discussed in detail.

  12. Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2016-08-01

    Full Text Available In this paper, a semi-empirical algorithm for significant wave height (Hs and mean wave period (Tmw retrieval from C-band VV-polarization Sentinel-1 synthetic aperture radar (SAR imagery is presented. We develop a semi-empirical function for Hs retrieval, which describes the relation between Hs and cutoff wavelength, radar incidence angle, and wave propagation direction relative to radar look direction. Additionally, Tmw can be also calculated through Hs and cutoff wavelength by using another empirical function. We collected 106 C-band stripmap mode Sentinel-1 SAR images in VV-polarization and wave measurements from in situ buoys. There are a total of 150 matchup points. We used 93 matchups to tune the coefficients of the semi-empirical algorithm and the rest 57 matchups for validation. The comparison shows a 0.69 m root mean square error (RMSE of Hs with a 18.6% of scatter index (SI and 1.98 s RMSE of Tmw with a 24.8% of SI. Results indicate that the algorithm is suitable for wave parameters retrieval from Sentinel-1 SAR data.

  13. Monitoring of Land Subsidence in Coal Mining Area Based on D-InSAR Technology%基于 D-InSAR 技术的煤矿区地面沉降监测研究

    Institute of Scientific and Technical Information of China (English)

    宋继德; 邸志众

    2014-01-01

    概要叙述了差分合成孔径雷达(D-InSAR)的技术原理和数据处理方法,介绍了 D-InSAR 在地表形变监测中的应用技术和方法,针对研究区域的地表沉降特点选择常规 D-InSAR 和永久性散射体干涉测量(PSI)作为 InSAR 差分处理方式,分析并选取适合本项目研究的 InSAR 雷达数据,对兖州-济宁区域因煤矿开采产生的地表缓慢沉降和快速沉降进行数据分析并得出结论,达到了研究的目的。%This paper briefly described the principle and data processing methods of the Differential Interferometric SAR(D-InSAR)technology,and introduced the application techniques and methods of D-InSAR on monitoring of the ground surface deformation.According to the characteristics of the ground surface subsidence in study area,we choosed conventional D-InSAR and Permanent Scatterer Interferometry(PSI)as the InSAR differential treatment,and analyzed and selected the InSAR radar data that is suitable for the study.Finally,we have drawn some conclusions by analyzing data of both the slow and rapid ground surface subsidence caused by the coal mining in Yanzhou-Jining area,and have achieved the purpose of the research.

  14. The Effect of Topography on Target Decomposition of Polarimetric SAR Data

    Directory of Open Access Journals (Sweden)

    Sang-Eun Park

    2015-04-01

    Full Text Available Polarimetric target decomposition enables the interpretation of radar images more easily, mostly based on physical assumptions, i.e., fitting physically-based scattering models to the polarimetric SAR observations. However, the model-fitting result cannot be always successful. Particularly, the performance of model-fitting in sloping forests is still an open question. In this study, the effect of ground topography on the model-fitting-based polarimetric decomposition techniques is investigated. The estimation accuracy of each scattering component in the decomposition results are evaluated based on the simulated target matrix by using the incoherent vegetation scattering model that accounts for the tilted scattering surface beneath the forest canopy. Experimental results show that the surface and the double-bounce scattering components can be significantly misestimated due to the topographic slope, even when the volume scattering power is successfully estimated.

  15. Three-dimensional Reconstruction Method Study Based on Interferometric Circular SAR

    Directory of Open Access Journals (Sweden)

    Hou Liying

    2016-10-01

    Full Text Available Circular Synthetic Aperture Radar (CSAR can acquire targets’ scattering information in all directions by a 360° observation, but a single-track CSAR cannot efficiently obtain height scattering information for a strong directive scatter. In this study, we examine the typical target of the three-dimensional circular SAR interferometry theoryand validate the theory in a darkroom experiment. We present a 3D reconstruction of the actual tank metal model of interferometric CSAR for the first time, verify the validity of the method, and demonstrate the important potential applications of combining 3D reconstruction with omnidirectional observation.

  16. Refocusing vibrating targets in SAR images

    Science.gov (United States)

    Wang, Qi; Santhanam, Balu; Pepin, Matthew; Atwood, Tom; Hayat, Majeed M.

    2012-06-01

    In synthetic-aperture radar (SAR) returned signals, ground-target vibrations introduce a phase modulation that is linearly proportional to the vibration displacement. Such modulation, termed the micro-Doppler effect, introduces ghost targets along the azimuth direction in reconstructed SAR images that prevents SAR from forming focused images of the vibrating targets. Recently, a discrete fractional Fourier transform (DFrFT) based method was developed to estimate the vibration frequencies and instantaneous vibration accelerations of the vibrating targets from SAR returned signals. In this paper, a demodulation-based algorithm is proposed to reconstruct focused SAR images of vibrating targets by exploiting the estimation results of the DFrFT-based vibration estimation method. For a single-component harmonic vibration, the history of the vibration displacement is first estimated from the estimated vibration frequency and the instantaneous vibration accelerations. Then a reference signal whose phase is modulated by the estimated vibration displacement with a delay of 180 degree is constructed. After that, the SAR phase history from the vibration target is multiplied by the reference signal and the vibration-induced phase modulation is canceled. Finally, the SAR image containing the re-focused vibration target is obtained by applying the 2-D Fourier transform to the demodulated SAR phase history. This algorithm is applied to simulated SAR data and successfully reconstructs the SAR image containing the re-focused vibrating target.

  17. PSI Deformation Map Retrieval by Means of Temporal Sublook Coherence on Reduced Sets of SAR Images

    Directory of Open Access Journals (Sweden)

    Rubén Iglesias

    2015-01-01

    Full Text Available Prior to the application of any persistent scatterer interferometry (PSI technique for the monitoring of terrain displacement phenomena, an adequate pixel selection must be carried out in order to prevent the inclusion of noisy pixels in the processing. The rationale is to detect the so-called persistent scatterers, which are characterized by preserving their phase quality along the multi-temporal set of synthetic aperture radar (SAR images available. Two criteria are mainly available for the estimation of pixels’ phase quality, i.e., the coherence stability and the amplitude dispersion or permanent scatterers (PS approach. The coherence stability method allows an accurate estimation of the phase statistics, even when a reduced number of SAR acquisitions is available. Unfortunately, it requires the multi-looking of data during the coherence estimation, leading to a spatial resolution loss in the final results. In contrast, the PS approach works at full-resolution, but it demands a larger number of SAR images to be reliable, typically more than 20. There is hence a clear limitation when a full-resolution PSI processing is to be carried out and the number of acquisitions available is small. In this context, a novel pixel selection method based on exploiting the spectral properties of point-like scatterers, referred to as temporal sublook coherence (TSC, has been recently proposed. This paper seeks to demonstrate the advantages of employing PSI techniques by means of TSC on both orbital and ground-based SAR (GB-SAR data when the number of images available is small (10 images in the work presented. The displacement maps retrieved through the proposed technique are compared, in terms of pixel density and phase quality, with traditional criteria. Two X-band datasets composed of 10 sliding spotlight TerraSAR-X images and 10 GB-SAR images, respectively, over the landslide of El Forn de Canillo (Andorran Pyrenees, are employed for this study. For both

  18. Controlling Data Collection to Support SAR Image Rotation

    Science.gov (United States)

    Doerry, Armin W.; Cordaro, J. Thomas; Burns, Bryan L.

    2008-10-14

    A desired rotation of a synthetic aperture radar (SAR) image can be facilitated by adjusting a SAR data collection operation based on the desired rotation. The SAR data collected by the adjusted SAR data collection operation can be efficiently exploited to form therefrom a SAR image having the desired rotational orientation.

  19. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)

    1996-12-31

    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  20. New algorithm of target classification in polarimetric SAR

    Institute of Scientific and Technical Information of China (English)

    Wang Yang; Lu Jiaguo; Wu Xianliang

    2008-01-01

    The different approaches used for target decomposition (TD) theory in radar polarimetry are reviewed and three main types of theorems are introduced: those based on Mueller matrix, those using an eigenvector analysis of the coherency matrix, and those employing coherent decomposition of the scattering matrix. Support vector machine (SVM), as a novel approach in pattern recognition, has demonstrated success in many fields. A new algorithm of target classification, by combining target decomposition and the support vector machine, is proposed.To conduct the experiment, the polarimetric synthetic aperture radar (SAR) data are used. Experimental results show that it is feasible and efficient to target classification by applying target decomposition to extract scattering mechanisms, and the effects of kernel function and its parameters on the classification efficiency are significant.

  1. Learning multimodal latent attributes.

    Science.gov (United States)

    Fu, Yanwei; Hospedales, Timothy M; Xiang, Tao; Gong, Shaogang

    2014-02-01

    The rapid development of social media sharing has created a huge demand for automatic media classification and annotation techniques. Attribute learning has emerged as a promising paradigm for bridging the semantic gap and addressing data sparsity via transferring attribute knowledge in object recognition and relatively simple action classification. In this paper, we address the task of attribute learning for understanding multimedia data with sparse and incomplete labels. In particular, we focus on videos of social group activities, which are particularly challenging and topical examples of this task because of their multimodal content and complex and unstructured nature relative to the density of annotations. To solve this problem, we 1) introduce a concept of semilatent attribute space, expressing user-defined and latent attributes in a unified framework, and 2) propose a novel scalable probabilistic topic model for learning multimodal semilatent attributes, which dramatically reduces requirements for an exhaustive accurate attribute ontology and expensive annotation effort. We show that our framework is able to exploit latent attributes to outperform contemporary approaches for addressing a variety of realistic multimedia sparse data learning tasks including: multitask learning, learning with label noise, N-shot transfer learning, and importantly zero-shot learning.

  2. Study on Geosynchronous Circular SAR

    Directory of Open Access Journals (Sweden)

    Hong Wen

    2015-06-01

    Full Text Available The concept of Geosynchronous Circular SAR (Geo-CSAR is introduced in this paper. With the design of the geosynchronous orbit parameters, a near-circular satellite sub-track could be formed to enable the staring imaging mode, which supports the advanced applications for wide-field and 3-D information acquisition under long-term consistent observation. This paper also analyzes Geo-CSAR's imaging formation capabilities, and concludes its attractive advantages over low-earth orbit spaceborne SAR in terms of instantaneous coverage, consistent observing area, 3-D positioning accuracy and etc.. Encouraging expectations for Geo-CSAR thus could be positively predicted in military investigation and disaster monitoring management applications.

  3. Attributing illness to food

    DEFF Research Database (Denmark)

    Batz, M. B.; Doyle, M. P.; Morris, J. G.

    2005-01-01

    Identification and prioritization of effective food safety interventions require an understanding of the relationship between food and pathogen from farm to consumption. Critical to this cause is food attribution, the capacity to attribute cases of foodborne disease to the food vehicle or other s...... of a risk-based approach to improving food safety.......Identification and prioritization of effective food safety interventions require an understanding of the relationship between food and pathogen from farm to consumption. Critical to this cause is food attribution, the capacity to attribute cases of foodborne disease to the food vehicle or other...... source responsible for illness. A wide variety of food attribution approaches and data are used around the world including the analysis of outbreak data, case-control studies, microbial subtyping and source tracking methods, and expert judgment, among others. The Food Safety Research Consortium sponsored...

  4. Reflectors for SAR performance testing.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2008-01-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  5. SAR Image Complex Pixel Representations

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  6. Random Forest Classification of Sediments on Exposed Intertidal Flats Using ALOS-2 Quad-Polarimetric SAR Data

    Science.gov (United States)

    Wang, W.; Yang, X.; Liu, G.; Zhou, H.; Ma, W.; Yu, Y.; Li, Z.

    2016-06-01

    Coastal zones are one of the world's most densely populated areas and it is necessary to propose an accurate, cost effective, frequent, and synoptic method of monitoring these complex ecosystems. However, misclassification of sediments on exposed intertidal flats restricts the development of coastal zones surveillance. With the advent of SAR (Synthetic Aperture Radar) satellites, polarimetric SAR satellite imagery plays an increasingly important role in monitoring changes in coastal wetland. This research investigated the necessity of combining SAR polarimetric features with optical data, and their contribution in accurately sediment classification. Three experimental groups were set to make assessment of the most appropriate descriptors. (i) Several SAR polarimetric descriptors were extracted from scattering matrix using Cloude-Pottier, Freeman-Durden and Yamaguchi methods; (ii) Optical remote sensing (RS) data with R, G and B channels formed the second feature combinations; (iii) The chosen SAR and optical RS indicators were both added into classifier. Classification was carried out using Random Forest (RF) classifiers and a general result mapping of intertidal flats was generated. Experiments were implemented using ALOS-2 L-band satellite imagery and GF-1 optical multi-spectral data acquired in the same period. The weights of descriptors were evaluated by VI (RF Variable Importance). Results suggested that optical data source has few advantages on sediment classification, and even reduce the effect of SAR indicators. Polarimetric SAR feature sets show great potentials in intertidal flats classification and are promising in classifying mud flats, sand flats, bare farmland and tidal water.

  7. Multi-temporal SAR data analysis for landcover, water-level changes, and subsidence studies in Southeastern Louisiana

    Science.gov (United States)

    Kwoun, O.; Lu, Z.

    2006-12-01

    We used multi-temporal European Remote Sensing Satellites 1 and 2 (ERS-1/2), Environment Satellite (ENVISAT), and Canadian RADARSAT-1 Synthetic Aperture Radar (SAR) images for ecological, hydrological, and geological studies of the Southeastern Louisiana coastal flood zone. First, we present a distinctive correlation among the seasonal changes in SAR backscatter, interferometric coherence, and land cover types with the associated normalized difference vegetation indices. Second, we demonstrate the use of C-band SAR images to measure changes in the water-level beneath moderately dense swamp forests, at a vertical accuracy and spatial resolution that is not possible with the current gauge-based measurements. Finally, we apply the conventional SAR interferometry (InSAR) and the Permanent Scatterer InSAR techniques to map land surface subsidence in New Orleans and the surrounding area; the comparison of measured subsidence patterns shows certain discrepancies that are probably due to atmospheric delays in this humid area. Our study demonstrates the importance of SAR data for understanding this coastal flood zone and the associated ecological, hydrological, and geological processes.

  8. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    Directory of Open Access Journals (Sweden)

    Zhiwei Qiu

    Full Text Available This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR research and application.

  9. Signal Processing for Digital Beamforming FMCW SAR

    Directory of Open Access Journals (Sweden)

    Qin Xin

    2014-01-01

    Full Text Available According to the limitations of single channel Frequency Modulation Continuous Wave (FMCW Synthetic Aperture Radar (SAR, Digital Beamforming (DBF technology is introduced to improve system performance. Combined with multiple receive apertures, DBF FMCW SAR can obtain high resolution in low pulse repetition frequency, which can increase the processing gain and decrease the sampling frequency. The received signal model of DBF FMCW SAR is derived. The continuous antenna motion which is the main characteristic of FMCW SAR received signal is taken into account in the whole signal processing. The detailed imaging diagram of DBF FMCW SAR is given. A reference system is also demonstrated in the paper by comparing with a single channel FMCW SAR. The validity of the presented diagram is demonstrated with a point target simulation results.

  10. Building Detection in SAR Imagery

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, Ryan Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Koch, Mark William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moya, Mary M [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Goold, Jeremy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-08-01

    Current techniques for building detection in Synthetic Aperture Radar (SAR) imagery can be computationally expensive and/or enforce stringent requirements for data acquisition. The desire is to present a technique that is effective and efficient at determining an approximate building location. This approximate location can be used to extract a portion of the SAR image to then perform a more robust detection. The proposed technique assumes that for the desired image, bright lines and shadows, SAR artifact effects, are approximately labeled. These labels are enhanced and utilized to locate buildings, only if the related bright lines and shadows can be grouped. In order to find which of the bright lines and shadows are related, all of the bright lines are connected to all of the shadows. This allows the problem to be solved from a connected graph viewpoint. Where the nodes are the bright lines and shadows and the arcs are the connections between bright lines and shadows. Constraints based on angle of depression and the relationship between connected bright lines and shadows are applied to remove unrelated arcs. Once the related bright lines and shadows are grouped, their locations are combined to provide an approximate building location. Experimental results are provided showing the outcome of the technique.

  11. Satellite SAR geocoding with refined RPC model

    Science.gov (United States)

    Zhang, Lu; Balz, Timo; Liao, Mingsheng

    2012-04-01

    Recent studies have proved that the Rational Polynomial Camera (RPC) model is able to act as a reliable replacement of the rigorous Range-Doppler (RD) model for the geometric processing of satellite SAR datasets. But its capability in absolute geolocation of SAR images has not been evaluated quantitatively. Therefore, in this article the problems of error analysis and refinement of SAR RPC model are primarily investigated to improve the absolute accuracy of SAR geolocation. Range propagation delay and azimuth timing error are identified as two major error sources for SAR geolocation. An approach based on SAR image simulation and real-to-simulated image matching is developed to estimate and correct these two errors. Afterwards a refined RPC model can be built from the error-corrected RD model and then used in satellite SAR geocoding. Three experiments with different settings are designed and conducted to comprehensively evaluate the accuracies of SAR geolocation with both ordinary and refined RPC models. All the experimental results demonstrate that with RPC model refinement the absolute location accuracies of geocoded SAR images can be improved significantly, particularly in Easting direction. In another experiment the computation efficiencies of SAR geocoding with both RD and RPC models are compared quantitatively. The results show that by using the RPC model such efficiency can be remarkably improved by at least 16 times. In addition the problem of DEM data selection for SAR image simulation in RPC model refinement is studied by a comparative experiment. The results reveal that the best choice should be using the proper DEM datasets of spatial resolution comparable to that of the SAR images.

  12. Utility of Characterizing and Monitoring Suspected Underground Nuclear Sites with VideoSAR

    Science.gov (United States)

    Dauphin, S. M.; Yocky, D. A.; Riley, R.; Calloway, T. M.; Wahl, D. E.

    2016-12-01

    Sandia National Laboratories proposed using airborne synthetic aperture RADAR (SAR) collected in VideoSAR mode to characterize the Underground Nuclear Explosion Signature Experiment (UNESE) test bed site at the Nevada National Security Site (NNSS). The SNL SAR collected airborne, Ku-band (16.8 GHz center frequency), 0.2032 meter ground resolution over NNSS in August 2014 and X-band (9.6 GHz), 0.1016 meter ground resolution fully-polarimetric SAR in April 2015. This paper reports the findings of processing and exploiting VideoSAR for creating digital elevation maps, detecting cultural artifacts and exploiting full-circle polarimetric signatures. VideoSAR collects a continuous circle of phase history data, therefore, imagery can be formed over the 360-degrees of the site. Since the Ku-band VideoSAR had two antennas suitable for interferometric digital elevation mapping (DEM), DEMs could be generated over numerous aspect angles, filling in holes created by targets with height by imaging from all sides. Also, since the X-band VideoSAR was fully-polarimetric, scattering signatures could be gleaned from all angles also. Both of these collections can be used to find man-made objects and changes in elevation that might indicate testing activities. VideoSAR provides a unique, coherent measure of ground objects allowing one to create accurate DEMS, locate man-made objects, and identify scattering signatures via polarimetric exploitation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. The authors would like to thank the National Nuclear Security Administration, Defense Nuclear Nonproliferation Research and Development, for sponsoring this work. We would also like to thank the Underground Nuclear Explosion Signatures Experiment team, a multi

  13. MiniSAR: a miniature, lightweight, low cost, scalable SAR system

    NARCIS (Netherlands)

    Steeghs, T.P.H.; Halsema, D. van; Hoogeboom, P.

    2001-01-01

    TNO-FEL is developing a miniature, lightweight, low cost, and scalable SAR/MTI system called 'MiniSAR'. The MiniSAR system will be unique in its size and architecture. Initially the demonstrator system will be integrated in a two-seater motorglider platform. Wherever possible,

  14. A Research on Airborne Squint Hybrid SAR

    Institute of Scientific and Technical Information of China (English)

    BIANYong; ZHOUYinqing; LIChunsheng

    2004-01-01

    In this paper, we establish the squint mode hybrid SAR (Synthetic aperture radar) geometry. Based on the squint mode SAR geometry, the hybrid SAR signal model in squint case is derived. Based on this signal model, the hybrid SAR imaging process parameter is discussed. Aimed at the squint case, we analyze not only the relationship between the resolution and SAR system parameters, but also the relation between the time extension of the maximum azimuth signal and SAR system parameters. This research establishes the theoretical foundation for the design of squint hybrid SAR and serves as a good guide for the future work of improving the resolution of squint hybrid SAR. Based on the two-step algorithm, by considering the squint angle and cubic phase term, we are going to use the deramp SC-Chirp Scaling algorithm for squint hybrid SAR imaging. This algorithm uses the deramp method for the first step processing, and the SC-Chirp Scaling algorithm for the second step processing. The process procedure of this algorithm includes the squint angle, has the explicit physical meaning, therefore is convenient for analysis. The computer simulation result proves the validity of the analysis.

  15. Bistatic SAR: Signal Processing and Image Formation.

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, Daniel E.; Yocky, David A.

    2014-10-01

    This report describes the significant processing steps that were used to take the raw recorded digitized signals from the bistatic synthetic aperture RADAR (SAR) hardware built for the NCNS Bistatic SAR project to a final bistatic SAR image. In general, the process steps herein are applicable to bistatic SAR signals that include the direct-path signal and the reflected signal. The steps include preprocessing steps, data extraction to for a phase history, and finally, image format. Various plots and values will be shown at most steps to illustrate the processing for a bistatic COSMO SkyMed collection gathered on June 10, 2013 on Kirtland Air Force Base, New Mexico.

  16. TanDEM-X Bistatic SAR Processing

    OpenAIRE

    Balss, Ulrich; Niedermeier, Andreas; Breit, Helko

    2010-01-01

    In June, 2010 the German SAR satellite TanDEM-X (TerraSAR-X-Add-on for Digital Elevation Measurements) will be launched. Together with TerraSAR-X, launched June 15, 2007, it will form the first spaceborne bistatic SAR platform. Usually one of the satellite is transmitting (active satellite), while both are receiving. As both satellites fly in a helix orbit constellation, during a recording a satellite has to be passive, if the other one is close to the line of sight to the observation targ...

  17. DETEKCIJA SPREMEMB V RADARSKIH SLIKAH SAR

    OpenAIRE

    Izak, Rok

    2016-01-01

    V magistrskem delu je opisan princip detekcije sprememb površja Zemlje s pomočjo radarskih slik SAR, ki so bile zajete s satelitom TanDEM-X. Opisani so tudi principi delovanja radarja z umetno odprtino, načini zajema podatkov ter osnove interferometrije V prvem sklopu magistrskega dela, je bil cilj predlagati metodo za zaznavo gozdne površine v slikah SAR. V drugem delu so bile s pomočjo SAR interferometrije zaznane spremembe na kroni gozdov v okolici Postojne. Slike SAR, so bile zajete v raz...

  18. High resolution SAR applications and instrument design

    Science.gov (United States)

    Dionisio, C.; Torre, A.

    1993-01-01

    The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

  19. Use of Sub-Aperture Decomposition for Supervised PolSAR Classification in Urban Area

    Directory of Open Access Journals (Sweden)

    Lei Deng

    2015-01-01

    Full Text Available A novel approach is proposed for classifying the polarimetric SAR (PolSAR data by integrating polarimetric decomposition, sub-aperture decomposition and decision tree algorithm. It is composed of three key steps: sub-aperture decomposition, feature extraction and combination, and decision tree classification. Feature extraction and combination is the main contribution to the innovation of the proposed method. Firstly, the full-resolution PolSAR image and its two sub-aperture images are decomposed to obtain the scattering entropy, average scattering angle and anisotropy, respectively. Then, the difference information between the two sub-aperture images are extracted, and combined with the target decomposition features from full-resolution images to form the classification feature set. Finally, C5.0 decision tree algorithm is used to classify the PolSAR image. A comparison between the proposed method and commonly-used Wishart supervised classification was made to verify the improvement of the proposed method on the classification. The overall accuracy using the proposed method was 88.39%, much higher than that using the Wishart supervised classification, which exhibited an overall accuracy of 69.82%. The Kappa Coefficient was 0.83, whereas that using the Wishart supervised classification was 0.56. The results indicate that the proposed method performed better than Wishart supervised classification for landscape classification in urban area using PolSAR data. Further investigation was carried out on the contribution of difference information to PolSAR classification. It was found that the sub-aperture decomposition improved the classification accuracy of forest, buildings and grassland effectively in high-density urban area. Compared with support vector machine (SVM and QUEST classifier, C5.0 decision tree classifier performs more efficient in time consumption, feature selection and construction of decision rule.

  20. Attributing illness to food

    DEFF Research Database (Denmark)

    Batz, M. B.; Doyle, M. P.; Morris, J. G.

    2005-01-01

    Identification and prioritization of effective food safety interventions require an understanding of the relationship between food and pathogen from farm to consumption. Critical to this cause is food attribution, the capacity to attribute cases of foodborne disease to the food vehicle or other...... of a risk-based approach to improving food safety....... source responsible for illness. A wide variety of food attribution approaches and data are used around the world including the analysis of outbreak data, case-control studies, microbial subtyping and source tracking methods, and expert judgment, among others. The Food Safety Research Consortium sponsored...

  1. Robust discrimination of permanent scatterers using Cameron Decomposition

    Science.gov (United States)

    Kouroupis, G.; Elias, P.; Anastassopoulos, V.

    2014-10-01

    One of the main difficulties encountered in Differential Interferometry (DInSAR) applications is temporal and spatial decorrelation over time. Single pixels, called Permanent Scatterers (PS), overcome this difficulty since they are coherent over time and over wide look-angle variations. Permanent Scatterers identification using interferographic techniques is unfeasible since they require the use of many acquisitions. Samsonov and Tiampo have presented a technique that selects Permanent Scatterers by analyzing their Polarization Phase Difference (PPD). The PPD approach would work just fine looking for single bounce scatterers because they are invariant to any initial arbitrary rotation between the scatterer and the radar Line of Sight (LOS). We propose to replace the PPD technique with Cameron's Coherent Target Decomposition (CTD) because it is more accurate in finding the single and double bounce scatterers as it eliminates the initial orientation angle of the scatterer. Additionally, Cameron's CTD is capable of recognizing more scattering mechanisms which means that more pixels, depending on their amplitude and stability over time, can be classified as Permanent Scatterers. A sample scene of fully polarimetric SAR image depicting the San Francisco bay was employed for experimentation. Our results demonstrate the superiority of the Cameron's CTD approach compared to PPD's approach for the selection of pixels classified as Permanent Scatterers.

  2. Three-dimensional surface reconstruction from multistatic SAR images.

    Science.gov (United States)

    Rigling, Brian D; Moses, Randolph L

    2005-08-01

    This paper discusses reconstruction of three-dimensional surfaces from multiple bistatic synthetic aperture radar (SAR) images. Techniques for surface reconstruction from multiple monostatic SAR images already exist, including interferometric processing and stereo SAR. We generalize these methods to obtain algorithms for bistatic interferometric SAR and bistatic stereo SAR. We also propose a framework for predicting the performance of our multistatic stereo SAR algorithm, and, from this framework, we suggest a metric for use in planning strategic deployment of multistatic assets.

  3. Improved characterization of slow-moving landslides by means of adaptive NL-InSAR filtering

    Science.gov (United States)

    Albiol, David; Iglesias, Rubén.; Sánchez, Francisco; Duro, Javier

    2014-10-01

    Advanced remote sensing techniques based on space-borne Synthetic Aperture Radar (SAR) have been developed during the last decade showing their applicability for the monitoring of surface displacements in landslide areas. This paper presents an advanced Persistent Scatterer Interferometry (PSI) processing based on the Stable Point Network (SPN) technique, developed by the company Altamira-Information, for the monitoring of an active slowmoving landslide in the mountainous environment of El Portalet, Central Spanish Pyrenees. For this purpose, two TerraSAR-X data sets acquired in ascending mode corresponding to the period from April to November 2011, and from August to November 2013, respectively, are employed. The objective of this work is twofold. On the one hand, the benefits of employing Nonlocal Interferomtric SAR (NL-InSAR) adaptive filtering techniques over vegetated scenarios to maximize the chances of detecting natural distributed scatterers, such as bare or rocky areas, and deterministic point-like scatterers, such as man-made structures or poles, is put forward. In this context, the final PSI displacement maps retrieved with the proposed filtering technique are compared in terms of pixels' density and quality with classical PSI, showing a significant improvement. On the other hand, since SAR systems are only sensitive to detect displacements in the line-of-sight (LOS) direction, the importance of projecting the PSI displacement results retrieved along the steepest gradient of the terrain slope is discussed. The improvements presented in this paper are particularly interesting in these type of applications since they clearly allow to better determine the extension and dynamics of complex landslide phenomena.

  4. Terrain topographic inversion using single-pass polarimetric SAR image data

    Institute of Scientific and Technical Information of China (English)

    JIN Yaqiu; LUO Lin

    2004-01-01

    The shift of polarization orientation angle ψat the maximum of co-polarized or cross-polarized back-scattering signature can be used to estimate the surface slopes. It has been utilized to generate the digital elevation mapping (DEM) and terrain topography using two-pass fully polarimetric SAR or interferometric SAR (INSAR) image data. This paper presents an approach to DEM inversion by using a single pass of polarimetric SAR data. The ψ shift is derived, by using the Mueller matrix solution, as a function of three Stokes parameters, /vs, Ihs, Us, which are measured by the SAR polarimetry. Using the Euler angles transformation, the orientation angle ψ is related to both the range and azimuth angles of the tilted surface and radar viewing geometry, as has been discussed by many authors. When only a single-pass SAR data is available, the adaptive thresholding method and image morphological thinning algorithm for linear textures are proposed to first determine the azimuth angle. Then, making use of full multi-grid algorithm, both the range and azimuth angles are utilized to solve the Poisson equation of DEM to produce the terrain topography.

  5. Titan's surface from the Cassini RADAR radiometry data during SAR mode

    Science.gov (United States)

    Paganelli, F.; Janssen, M.A.; Lopes, R.M.; Stofan, E.; Wall, S.D.; Lorenz, R.D.; Lunine, J.I.; Kirk, R.L.; Roth, L.; Elachi, C.

    2008-01-01

    We present initial results on the calibration and interpretation of the high-resolution radiometry data acquired during the Synthetic Aperture Radar (SAR) mode (SAR-radiometry) of the Cassini Radar Mapper during its first five flybys of Saturn's moon Titan. We construct maps of the brightness temperature at the 2-cm wavelength coincident with SAR swath imaging. A preliminary radiometry calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, outlining signatures that characterize various terrains and surface features. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007.

  6. RESEARCH ON INVERSION MODELS FOR FOREST HEIGHT ESTIMATION USING POLARIMETRIC SAR INTERFEROMETRY

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2017-09-01

    Full Text Available The forest height is an important forest resource information parameter and usually used in biomass estimation. Forest height extraction with PolInSAR is a hot research field of imaging SAR remote sensing. SAR interferometry is a well-established SAR technique to estimate the vertical location of the effective scattering center in each resolution cell through the phase difference in images acquired from spatially separated antennas. The manipulation of PolInSAR has applications ranging from climate monitoring to disaster detection especially when used in forest area, is of particular interest because it is quite sensitive to the location and vertical distribution of vegetation structure components. However, some of the existing methods can’t estimate forest height accurately. Here we introduce several available inversion models and compare the precision of some classical inversion approaches using simulated data. By comparing the advantages and disadvantages of these inversion methods, researchers can find better solutions conveniently based on these inversion methods.

  7. Comparing the results of PSInSAR and GNSS on slow motion landslides, Koyulhisar, Turkey

    Directory of Open Access Journals (Sweden)

    Kemal Ozgur Hastaoglu

    2016-03-01

    Full Text Available There are numerous methods used nowadays to monitor landslide movements. Of these methods, Global Navigation Satellite System (GNSS and Interferometric Synthetic Aperture Radar (InSAR are the ones that are most commonly used. In this study, the amounts of movements acquired via these two methods were compared and relations between them were analysed. The Koyulhisar landslide region was selected as the field of study. In this study, 10 Envisat images of the region taken between 2006 and 2008 were evaluated using Persistent Scatterers Interferometric Synthetic Aperture Radar (PSInSAR technique and annual velocity values at the direction of line of slight at PS points were obtained for the region of interest. The velocity values were then obtained from PSInSAR results and compared with those obtained from six periods of GNSS measurements that were performed between April 2007 and November 2008 on Koyulhisar Landslide area after which the relationship between the two was analysed. Two different movement models from GNSS and PSInSAR results were fit to the landslide region. The velocity values estimated from these movement models for the region were compared and correlation between them was determined. As a conclusion, a high correlation of r = 0.84 was determined between the models obtained from nine GNSS points, except one point at the city centre, and PSInSAR.

  8. Refocusing of Moving Targets in SAR Images via Parametric Sparse Representation

    Directory of Open Access Journals (Sweden)

    Yichang Chen

    2017-08-01

    Full Text Available In this paper, a parametric sparse representation (PSR method is proposed for refocusing of moving targets in synthetic aperture radar (SAR images. In regular SAR images, moving targets are defocused due to unknown motion parameters. Refocusing of moving targets requires accurate phase compensation of echo data. In the proposed method, the region of interest (ROI data containing the moving targets are extracted from the complex SAR image and represented in a sparse fashion through a parametric transform, which is related to the phase compensation parameter. By updating the reflectivities of moving target scatterers and the parametric transform in an iterative fashion, the phase compensation parameter can be accurately estimated and the SAR images of moving targets can be refocused well. The proposed method directly operates on small-size defocused ROI data, which helps to reduce the computational burden and suppress the clutter. Compared to other existing ROI-based methods, the proposed method can suppress asymmetric side-lobes and improve the image quality. Both simulated data and real SAR data collected by GF-3 satellite are used to validate the effectiveness of the proposed method.

  9. Canadian SAR remote sensing for the Terrestrial Wetland Global Change Research Network (TWGCRN)

    Science.gov (United States)

    Kaya, Shannon; Brisco, Brian; Cull, Andrew; Gallant, Alisa L.; Sadinski, Walter J.; Thompson, Dean

    2010-01-01

    The Canada Centre for Remote Sensing (CCRS) has more than 30 years of experience investigating the use of SAR remote sensing for many applications related to terrestrial water resources. Recently, CCRS scientists began contributing to the Terrestrial Wetland Global Change Research Network (TWGCRN), a bi-national research network dedicated to assessing impacts of global change on interconnected wetland-upland landscapes across a vital portion of North America. CCRS scientists are applying SAR remote sensing to characterize wetland components of these landscapes in three ways. First, they are using a comprehensive set of RADARSAT-2 SAR data collected during April to September 2009 to extract multi-temporal surface water information for key TWGCRN study landscapes in North America. Second, they are analyzing polarimetric RADARSAT-2 data to determine areas where double-bounce represents the primary scattering mechanism and is indicative of flooded vegetation in these landscapes. Third, they are testing advanced interferometric SAR techniques to estimate water levels with RADARSAT-2 Fine Quad polarimetric image pairs. The combined information from these three SAR analysis activities will provide TWGCRN scientists with an integrated view and monitoring capability for these dynamic wetland-upland landscapes. These data are being used in conjunction with other remote sensing and field data to study interactions between landscape and animal (birds and amphibians) responses to climate/global change.

  10. Numerical weather prediction models and SAR interferometry: synergic use for meteorological and INSAR applications

    Science.gov (United States)

    Pierdicca, Nazzareno; Rocca, Fabio; Perissin, Daniele; Ferretti, Rossella; Pichelli, Emanuela; Rommen, Bjorn; Cimini, Nico

    2011-11-01

    Spaceborne Interferometric Synthetic Aperture Radar (InSAR) is a well established technique useful in many land applications, such as landslide monitoring and digital elevation model extraction. One of its major limitation is the atmospheric effect, and in particular the high water vapour spatial and temporal variability which introduces an unknown delay in the signal propagation. However, the sensitivity of SAR interferometric phase to atmospheric conditions could in principle be exploited and InSAR could become in certain conditions a tool to monitor the atmosphere, as it happens with GPS receiver networks. This paper describes a novel attempt to assimilate InSAR derived information on the atmosphere, based on the Permanent Scatterer multipass technique, into a numerical weather forecast model. The methodology is summarised and the very preliminary results regarding the forecast of a precipitation event in Central Italy are analysed. The work was done in the framework of an ESA funded project devoted to the mapping of the water vapour with the aim to mitigate its effect for InSAR applications.

  11. Detecting Emergence, Growth, and Senescence of Wetland Vegetation with Polarimetric Synthetic Aperture Radar (SAR Data

    Directory of Open Access Journals (Sweden)

    Alisa L. Gallant

    2014-03-01

    Full Text Available Wetlands provide ecosystem goods and services vitally important to humans. Land managers and policymakers working to conserve wetlands require regularly updated information on the statuses of wetlands across the landscape. However, wetlands are challenging to map remotely with high accuracy and consistency. We investigated the use of multitemporal polarimetric synthetic aperture radar (SAR data acquired with Canada’s Radarsat-2 system to track within-season changes in wetland vegetation and surface water. We speculated, a priori, how temporal and morphological traits of different types of wetland vegetation should respond over a growing season with respect to four energy-scattering mechanisms. We used ground-based monitoring data and other ancillary information to assess the limits and consistency of the SAR data for tracking seasonal changes in wetlands. We found the traits of different types of vertical emergent wetland vegetation were detected well with the SAR data and corresponded with our anticipated backscatter responses. We also found using data from Landsat’s optical/infrared sensors in conjunction with SAR data helped remove confusion of wetland features with upland grasslands. These results suggest SAR data can provide useful monitoring information on the statuses of wetlands over time.

  12. Tropical-Forest Profiles and Biomass from TanDEM-X, Single-Baseline Interferometric SAR: InSAR Performance at Higher Frequencies and Bandwidths

    Science.gov (United States)

    Treuhaft, R. N.; Goncalves, F. G.; Neumann, M.; Keller, M. M.; Santos, J. R.

    2015-12-01

    The principal method for remotely sensing forest biomass, particularly high-biomass tropical forests, is to measure vertical structural properties of the forest and relate them to biomass. Interferometric SAR (InSAR) and lidar are the two principal technologies applied to this task. InSAR profile information is constrained in the traditional, look-averaged analysis, because it measures the vertical Fourier transform of the radar power at one and only one vertical frequency specified by the baseline. Lidar produces a full profile, including all Fourier frequencies—all vertical scales of fluctuation. In TanDEM-X data over tropical forests at the Tapajos National Forest, Brazil, we show the results of potentially improving InSAR's Fourier coverage. This is done by estimating many Fourier frequencies with a single baseline, based on the assumption that sampling of the phase height of small (~1.5 m x 2.5 m) looks of TanDEM-X is equivalent to sampling the vertical structure of the forest; a spatial ergodicity. We show a similarity between the distribution of InSAR look-phase-heights (LPH) and lidar and field profiles over 0.25-ha areas. Using Fourier transforms of the histogram of LPH over 0.25 ha areas, biomass estimation improved by about 17% over using InSAR coherence and mean forest height, making it competitive with some lidar results. The RMS of biomasses estimated about field biomass was 48 Mg/ha, with biomasses as high as 430 Mg/ha, and an average of 174 Mg/ha. Perhaps LPH distributions bear a similarity to lidar and field profiles because shorter wavelengths (~3 cm) can penetrate holes in the canopy to scatter off a sample of the vegetation with each look. This "hole mechanism" favors higher frequencies, which are able to penetrate smaller holes. Because they increase the number of look samples, higher bandwidths are also preferred.

  13. InfoTerra/TerraSAR initiative

    Science.gov (United States)

    Wahl, Manfred W.

    2004-01-01

    The overarching goal of the InfoTerra/TerraSAR Initiative is to establish a self-sustaining operational/commercial business built on Europe"s know-how and experience in space-borne Synthetic Aperture Radar (SAR) technology, in SAR data processing as well as in SAR applications. InfoTerra stands for a new business concept based on supplying innovative geo-information products and services. TerraSAR is a space and ground system conceived to consist of an initial deployment and operation of 2 Radar satellites (one in X- and one in L-band) flying in a tandem configuration in the same orbit. The design of TerraSAR is driven by the market and is user-oriented. TerraSAR is key to capturing a significant proportion of the existing market and to opening new market opportunities, when it becomes operational. The InfoTerra/TerraSAR Initiative has evolved gradually. It started in 1997 as a joint venture between German (DSS) and British (MMS-UK) space industry, strongly supported by both space agencies, DLR and BNSC. In early 2001, DLR and BNSC submitted to ESA the Formal Programme Proposal for InfoTerra/TerraSAR to become an essential element of ESA"s Earth Watch Programme. In summer 2001, when it became evident that there was not yet sufficient support from the ESA Member States to allow immediate start entering into TerraSAR Phase C/D, it has been decided to implement first a TerraSAR consolidation phase. In early 2002, in order to avoid further delays, a contract was signed between DLR and Astrium GmbH on the development of one component of TerraSAR, the TerraSAR-X, in the frame of a national programme, governed by a Public Private Partnership Agreement. Even if now the different launch dates for TerraSAR-X and TerraSAR-L are narrowing down the window of common data acquisition, it is a reasonable starting point, but it should always be kept in mind that the utmost goal for the longterm is to achieve self sustainability by supplying geo-information products and services

  14. Monitoring Landslides in Western Mountainous Areas of China Using Advanced Multi-Temporal InSAR Techniques

    Science.gov (United States)

    Dong, Jie; Liao, Mingsheng; Zhang, Lu; Gong, Jianya

    2016-08-01

    Disasters, caused by landslide, rock fall, debris flow, ground fissure, etc., are one of the significant natural catastrophes, threatening and influencing the socio-economic conditions around the world. China is one of the countries that suffer heavily from such geo-hazards. And most landslides take place in the mountainous valley areas of western China. With its wide coverage and sub-centimeter accuracy, radar remote sensing has already proven its potential for remotely measuring unstable slopes. Differential InSAR (D-InSAR) is used to recognize known landslides and find potential unstable slopes in a region scale. Then, for a specific landslide, advanced multi-temporal InSAR method is exploited to characterize its surface deformation by obtaining time-series displacement on coherent targets. Among them, the PSI technique exploits only PSs exhibiting high phase stability in a stack of interferograms, which generally exist in urban areas. But, in the case of rural environment characterized by vegetated or low reflectivity homogeneous regions, few PSs could be identified. As a complement of persistent scatterers, distributed scatterers widely existing in rural areas can be exploited. DSs decorrelate slowly and can be found from homogeneous ground, scattered outcrops, debris flows, non-cultivated lands and desert areas. In this poster, a distributed scatterers-based InSAR technique, making use of PSs and DSs, is proposed. At first, we will use D-InSAR technique to detect landslides. Then, both PSI and DS-InSAR will be implemented to monitor interested landslides. And a comparison study of these two methods are conducted.

  15. Random forest regression modelling for forest aboveground biomass estimation using RISAT-1 PolSAR and terrestrial LiDAR data

    Science.gov (United States)

    Mangla, Rohit; Kumar, Shashi; Nandy, Subrata

    2016-05-01

    SAR and LiDAR remote sensing have already shown the potential of active sensors for forest parameter retrieval. SAR sensor in its fully polarimetric mode has an advantage to retrieve scattering property of different component of forest structure and LiDAR has the capability to measure structural information with very high accuracy. This study was focused on retrieval of forest aboveground biomass (AGB) using Terrestrial Laser Scanner (TLS) based point clouds and scattering property of forest vegetation obtained from decomposition modelling of RISAT-1 fully polarimetric SAR data. TLS data was acquired for 14 plots of Timli forest range, Uttarakhand, India. The forest area is dominated by Sal trees and random sampling with plot size of 0.1 ha (31.62m*31.62m) was adopted for TLS and field data collection. RISAT-1 data was processed to retrieve SAR data based variables and TLS point clouds based 3D imaging was done to retrieve LiDAR based variables. Surface scattering, double-bounce scattering, volume scattering, helix and wire scattering were the SAR based variables retrieved from polarimetric decomposition. Tree heights and stem diameters were used as LiDAR based variables retrieved from single tree vertical height and least square circle fit methods respectively. All the variables obtained for forest plots were used as an input in a machine learning based Random Forest Regression Model, which was developed in this study for forest AGB estimation. Modelled output for forest AGB showed reliable accuracy (RMSE = 27.68 t/ha) and a good coefficient of determination (0.63) was obtained through the linear regression between modelled AGB and field-estimated AGB. The sensitivity analysis showed that the model was more sensitive for the major contributed variables (stem diameter and volume scattering) and these variables were measured from two different remote sensing techniques. This study strongly recommends the integration of SAR and LiDAR data for forest AGB estimation.

  16. PHARUS: Airborne SAR Development in the Netherlands

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Snoeij, P.; Pouwels, H.

    1992-01-01

    The PHARUS project (PHARUS stands for Phased Array Universal SAR) aims for a polarimetric C-band aircraft SAR that will be finalized in 1994. The system will make use of a phased array antenna with solid state amplifiers. The project consists of two phases, a definition phase and a realization

  17. PHARUS: Airborne SAR Development in the Netherlands

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Snoeij, P.; Pouwels, H.

    1992-01-01

    The PHARUS project (PHARUS stands for Phased Array Universal SAR) aims for a polarimetric C-band aircraft SAR that will be finalized in 1994. The system will make use of a phased array antenna with solid state amplifiers. The project consists of two phases, a definition phase and a realization phase

  18. Advanced antennas for SAR spacecraft

    Science.gov (United States)

    Gail, William B.

    1993-01-01

    Single and multi-frequency antenna concepts were developed to evaluate the feasibility of building large aperture polarimetric synthetic aperture radar (SAR) systems to be launched in low cost vehicles such as the Delta 2. The antennas are 18.9 m long by 2.6 m wide (L-band) and achieve single polarization imaging to an incidence angle of 55 degrees and dual/quad imaging to 42 degrees. When combined with strawman spacecraft designs, both concepts meet the mass and volume constraints imposed by a Delta 2 launch.

  19. Two-dimensional Fast ESPRIT Algorithm for Linear Array SAR Imaging

    Directory of Open Access Journals (Sweden)

    Zhao Yi-chao

    2015-10-01

    Full Text Available The linear array Synthetic Aperture Radar (SAR system is a popular research tool, because it can realize three-dimensional imaging. However, owning to limitations of the aircraft platform and actual conditions, resolution improvement is difficult in cross-track and along-track directions. In this study, a twodimensional fast Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT algorithm for linear array SAR imaging is proposed to overcome these limitations. This approach combines the Gerschgorin disks method and the ESPRIT algorithm to estimate the positions of scatterers in cross and along-rack directions. Moreover, the reflectivity of scatterers is obtained by a modified pairing method based on “region growing”, replacing the least-squares method. The simulation results demonstrate the applicability of the algorithm with high resolution, quick calculation, and good real-time response.

  20. SAR processing using SHARC signal processing systems

    Science.gov (United States)

    Huxtable, Barton D.; Jackson, Christopher R.; Skaron, Steve A.

    1998-09-01

    Synthetic aperture radar (SAR) is uniquely suited to help solve the Search and Rescue problem since it can be utilized either day or night and through both dense fog or thick cloud cover. Other papers in this session, and in this session in 1997, describe the various SAR image processing algorithms that are being developed and evaluated within the Search and Rescue Program. All of these approaches to using SAR data require substantial amounts of digital signal processing: for the SAR image formation, and possibly for the subsequent image processing. In recognition of the demanding processing that will be required for an operational Search and Rescue Data Processing System (SARDPS), NASA/Goddard Space Flight Center and NASA/Stennis Space Center are conducting a technology demonstration utilizing SHARC multi-chip modules from Boeing to perform SAR image formation processing.

  1. Composite SAR imaging using sequential joint sparsity

    Science.gov (United States)

    Sanders, Toby; Gelb, Anne; Platte, Rodrigo B.

    2017-06-01

    This paper investigates accurate and efficient ℓ1 regularization methods for generating synthetic aperture radar (SAR) images. Although ℓ1 regularization algorithms are already employed in SAR imaging, practical and efficient implementation in terms of real time imaging remain a challenge. Here we demonstrate that fast numerical operators can be used to robustly implement ℓ1 regularization methods that are as or more efficient than traditional approaches such as back projection, while providing superior image quality. In particular, we develop a sequential joint sparsity model for composite SAR imaging which naturally combines the joint sparsity methodology with composite SAR. Our technique, which can be implemented using standard, fractional, or higher order total variation regularization, is able to reduce the effects of speckle and other noisy artifacts with little additional computational cost. Finally we show that generalizing total variation regularization to non-integer and higher orders provides improved flexibility and robustness for SAR imaging.

  2. SARS: systematic review of treatment effects.

    Directory of Open Access Journals (Sweden)

    Lauren J Stockman

    2006-09-01

    Full Text Available BACKGROUND: The SARS outbreak of 2002-2003 presented clinicians with a new, life-threatening disease for which they had no experience in treating and no research on the effectiveness of treatment options. The World Health Organization (WHO expert panel on SARS treatment requested a systematic review and comprehensive summary of treatments used for SARS-infected patients in order to guide future treatment and identify priorities for research. METHODS AND FINDINGS: In response to the WHO request we conducted a systematic review of the published literature on ribavirin, corticosteroids, lopinavir and ritonavir (LPV/r, type I interferon (IFN, intravenous immunoglobulin (IVIG, and SARS convalescent plasma from both in vitro studies and in SARS patients. We also searched for clinical trial evidence of treatment for acute respiratory distress syndrome. Sources of data were the literature databases MEDLINE, EMBASE, BIOSIS, and the Cochrane Central Register of Controlled Trials (CENTRAL up to February 2005. Data from publications were extracted and evidence within studies was classified using predefined criteria. In total, 54 SARS treatment studies, 15 in vitro studies, and three acute respiratory distress syndrome studies met our inclusion criteria. Within in vitro studies, ribavirin, lopinavir, and type I IFN showed inhibition of SARS-CoV in tissue culture. In SARS-infected patient reports on ribavirin, 26 studies were classified as inconclusive, and four showed possible harm. Seven studies of convalescent plasma or IVIG, three of IFN type I, and two of LPV/r were inconclusive. In 29 studies of steroid use, 25 were inconclusive and four were classified as causing possible harm. CONCLUSIONS: Despite an extensive literature reporting on SARS treatments, it was not possible to determine whether treatments benefited patients during the SARS outbreak. Some may have been harmful. Clinical trials should be designed to validate a standard protocol for dosage

  3. Multi-temporal SAR Interferometry for Monitoring of Man-Made Sfructures.

    OpenAIRE

    Patrício, Glória; Guimarães, Pedro; Sousa, Joaquim S.; Ruiz, António M.; Bastos, Luísa

    2016-01-01

    Multi-temporal InSAR (MTI) methods are effective tools for monitoring and investigating surface displacement on Earth based on conventional radar interferometry. These techniques allow us to measure deformation with uncertainties up to one millimeter per year, interpreting time series of interferometric phases at coherent/stable point scatterers. Considering the regular revisit time and wide-area coverage of satellite radar sensors, and that stable points usually correspond to buildings and o...

  4. MERGING AIRBORNE LIDAR DATA AND SATELLITE SAR DATA FOR BUILDING CLASSIFICATION

    Directory of Open Access Journals (Sweden)

    T. Yamamoto

    2015-05-01

    Full Text Available A frequent map revision is required in GIS applications, such as disaster prevention and urban planning. In general, airborne photogrammetry and LIDAR measurements are applied to geometrical data acquisition for automated map generation and revision. However, attribute data acquisition and classification depend on manual editing works including ground surveys. In general, airborne photogrammetry and LiDAR measurements are applied to geometrical data acquisition for automated map generation and revision. However, these approaches classify geometrical attributes. Moreover, ground survey and manual editing works are finally required in attribute data classification. On the other hand, although geometrical data extraction is difficult, SAR data have a possibility to automate the attribute data acquisition and classification. The SAR data represent microwave reflections on various surfaces of ground and buildings. There are many researches related to monitoring activities of disaster, vegetation, and urban. Moreover, we have an opportunity to acquire higher resolution data in urban areas with new sensors, such as ALOS2 PALSAR2. Therefore, in this study, we focus on an integration of airborne LIDAR data and satellite SAR data for building extraction and classification.

  5. Validation of burst overlapping for ALOS-2 PALSAR-2 ScanSAR-ScanSAR interferometry

    Science.gov (United States)

    Natsuaki, Ryo; Motohka, Takeshi; Ohki, Masato; Watanabe, Manabu; Suzuki, Shinichi

    2016-10-01

    The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite- 2 (ALOS-2, "DAICHI-2") is the latest L-band spaceborne synthetic aperture radar (SAR). PALSAR-2 observes the world mainly with 10 m resolution / 70 km swath Stripmap mode and 25 m resolution / 350 km swath ScanSAR mode. The 3-m resolution Stripmap mode is mainly used upon Japan. 350 km ScanSAR observation could detect large scale deformation e.g., the Mw 7.8 Gorkha, Nepal earthquake and its aftershocks in 2015. ALOS-2 ScanSAR is the first one that supports ScanSAR-ScanSAR interferometry in L-band spaceborne SAR. However, because of the parameter setting error for the orbit estimation, ALOS-2 PALSAR-2 ScanSAR could achieve little number of interferometric pair until the software modification on February 8, 2015. That is, the burst overlap timing required for the interferometric analysis was insufficient and it depends on the observation date. In this paper, we report the investigation results of this case and discuss the current status of the ALOS-2 ScanSAR InSAR. Some archives achieved before February 8, 2015 can be used for interferometric analysis with after Feb. 8. However, most of them have no interferometric pair. We also report that the archives acquired after February 8, have enough burst overlapping.

  6. Phenomenology and Meaning Attribution

    African Journals Online (AJOL)

    ... may be both confusing and disorienting to academic and clinical practitioners who ... questions of students of phenomenology often are the most appropriate ... Meaning attribution is the psychological study of the ... a best-seller with my publisher. But, except for ..... perhaps listening to music, having a chat, and things are ...

  7. Basics of SAR Polarimetry I

    Science.gov (United States)

    2007-02-01

    radar dates back to the 1940s. In 1945 G.W. Sinclair introduced the concept of the scattering matrix as a descriptor of the radar cross section of a...linear dipole and/or circular helical scatterers, the dihedral and trihedral corner reflectors , and so on - - observed in a linearly superimposed...Another target matrix parameter that should be familiar to all who are interested in microwave remote sensing is the radar cross section (RCS

  8. Ship Analysis and Detection in High-resolution Pol-SAR Imagery Based on Peak Zone

    Directory of Open Access Journals (Sweden)

    Xu Cheng-bin

    2015-06-01

    Full Text Available To deal with the problem of false alarm in the ship detection, a method base on proportion of spiral scattering in the peak zone is proposed. By comparing the proportion of spiral scattering in the peak zone, which is available from Krogager decomposition, the ships and interfering targets are identified and analyzed. The effectiveness of this method is justified with C-band full-polarization data from RADARSAT-2. The result show that this method can discriminate ships from interfering targets such as island, water-break, nautical platforms and bridges, thus reducing the false alarm rate of ship targets detection in SAR images.

  9. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics

    1996-12-31

    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  10. Antenna motion errors in bistatic SAR imagery

    Science.gov (United States)

    Wang, Ling; Yazıcı, Birsen; Cagri Yanik, H.

    2015-06-01

    Antenna trajectory or motion errors are pervasive in synthetic aperture radar (SAR) imaging. Motion errors typically result in smearing and positioning errors in SAR images. Understanding the relationship between the trajectory errors and position errors in reconstructed images is essential in forming focused SAR images. Existing studies on the effect of antenna motion errors are limited to certain geometries, trajectory error models or monostatic SAR configuration. In this paper, we present an analysis of position errors in bistatic SAR imagery due to antenna motion errors. Bistatic SAR imagery is becoming increasingly important in the context of passive imaging and multi-sensor imaging. Our analysis provides an explicit quantitative relationship between the trajectory errors and the positioning errors in bistatic SAR images. The analysis is applicable to arbitrary trajectory errors and arbitrary imaging geometries including wide apertures and large scenes. We present extensive numerical simulations to validate the analysis and to illustrate the results in commonly used bistatic configurations and certain trajectory error models.

  11. SARS - infectious disease of 21st century

    Directory of Open Access Journals (Sweden)

    Tjandra Y. Aditama

    2005-03-01

    Full Text Available Severe acute respiratory syndrome (SARS is an emerging viral infectious disease. According to the World Health Organization, a suspected case of SARS is defined as documented fever (temperature >38°C, lower respiratory tract symptoms, and contact with a person believed to have had SARS or history of travel to an area of documented transmission. A probable case is a suspected case with chest radiographic findings of pneumonia, acute respiratory distress syndrome (ARDS, or an unexplained respiratory illness resulting in death, with autopsy findings of ARDS without identifiable cause. In this article some SARS epidemiological data in Indonesia will also presented. There are 7 SARS suspected cases and 2 probable cases were registered in Indonesia on the period of 1 March to 9 July 2003, and no more cases were reported after that time. How will be SARS progression in the future will be a subject of discussion among scientist, and we will have to wait and be prepared for any development might occur. (Med J Indones 2005; 14: 59-63Keywords: SARS, Case Definition, Etiology, Indonesia

  12. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.

    2008-01-01

    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random sequentia

  13. The inhibitory effect of Chinese herb on SARS virus infection

    Institute of Scientific and Technical Information of China (English)

    Rika; Furuta; Jyunichi; Fujisawa; Toshio; Hattori

    2005-01-01

    [Subject]Severe acute respiratory syndrome(SARS)is a contagious atypical pneumonia with a high mortality rate.SARS coronavirus(SARS-CoV)is the pathogenof SARS.We established SARS-CoVS/HIVpseudotyped(SHP)virussystemandthe cell fusion assay systemto screeninhibitors for entry of SARS-CoV.[Materials and methods]SHPor VSV-Gpseudotype(VHP)virus was made bytransfecting pCMVΔR8·2,pHR’CMV-Luc and pCMV/R-SARS-S or pMDGplasmids into293Tcells.5ng p24of SHPor VHPvirus was addedfor eachinfec-tion.Twelve Chinese herbs,wh...

  14. Offshore wind mapping Mediterranean area using SAR

    DEFF Research Database (Denmark)

    Calaudi, Rosamaria; Arena, Felice; Badger, Merete;

    2013-01-01

    Satellite observations of the ocean surface, for example from Synthetic Aperture Radars (SAR), provide information about the spatial wind variability over large areas. This is of special interest in the Mediterranean Sea, where spatial wind information is only provided by sparse buoys, often...... with long periods of missing data. Here, we focus on evaluating the use of SAR for offshore wind mapping. Preliminary results from the analysis of SAR-based ocean winds in Mediterranean areas show interesting large scale wind flow features consistent with results from previous studies using numerical models...

  15. SAR ATR Based on Convolutional Neural Network

    Directory of Open Access Journals (Sweden)

    Tian Zhuangzhuang

    2016-06-01

    Full Text Available This study presents a new method of Synthetic Aperture Radar (SAR image target recognition based on a convolutional neural network. First, we introduce a class separability measure into the cost function to improve this network’s ability to distinguish between categories. Then, we extract SAR image features using the improved convolutional neural network and classify these features using a support vector machine. Experimental results using moving and stationary target acquisition and recognition SAR datasets prove the validity of this method.

  16. Geologic mapping in Greenland with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Madsen, Søren Nørvang; Brooks, C. K.

    1995-01-01

    The application of synthetic aperture radar (SAR) for geologic mapping in Greenland is investigated by the Danish Center for Remote Sensing (DCRS) in co-operation with the Danish Lithosphere Centre (DLC). In 1994 a pilot project was conducted in East Greenland. The Danish airborne SAR, EMISAR......, acquired fully polarimetric C-band data which, upon processing and calibration, was interpreted jointly by DCRS and DLC. Several geologic phenomena are readily identified in the SAR imagery, while different lithologies seem to be indistinguishable because they have similar geomorphologies. The geologic...

  17. Analysis of Resolution of Bistatic SAR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, the spatial resolutions at different directions of bistatic synthetic aperture radar (BiSAR) have been derived from the ambiguity function. Compared with monostatic signal to noise ratio, BiSAR's resolutions of a fixed point target are varying with slow time since BiSAR system is space-variant. Constraints for the assumption of space-invariant bistatic topology are proposed in the paper. Moreover, under the assumption of invariance, the change of resolutions at different point in the image scene is taken into account, and we have specified two key parameters that affect resolutions directly and analyzed the way how they influence on the resolutions.

  18. Geometric calibration of ERS satellite SAR images

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Madsen, Søren Nørvang

    2001-01-01

    Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed...... on a seven-year ERS-1 and a four-year ERS-2 time series, the long term stability is found to be sufficient to allow a single calibration covering the entire mission period. A descending and an ascending orbit tandem pair of the ESA calibration site on Flevoland, suitable for calibration of ERS SAR processors...

  19. SAR observations of coastal zone conditions

    Science.gov (United States)

    Meadows, G. A.; Kasischke, E. S.; Shuchman, R. A.

    1980-01-01

    Applications of Synthetic Aperture Radar (SAR) technology to the observation of coastal zones phenomena are detailed. The conditions observed include gravity wave detection, surf zone location, surface currents, and long-period 'surf beats'. Algorithms have been developed and successfully tested that determine significant wave and current parameters from the sea surface backscatter of microwave energy. Doppler information from the SAR optical correlator allows a rough estimation of near shore surface flow velocities that has been found in agreement with both theory and in situ observations as well. Seasat SAR data of the Scotland and North Carolina coasts are considered, as well as the results of bathymetric updating of coastal area charts.

  20. Bounding SAR ATR performance based on model similarity

    Science.gov (United States)

    Boshra, Michael; Bhanu, Bir

    1999-08-01

    Similarity between model targets plays a fundamental role in determining the performance of target recognition. We analyze the effect of model similarity on the performance of a vote- based approach for target recognition from SAR images. In such an approach, each model target is represented by a set of SAR views sampled at a variety of azimuth angles and a specific depression angle. Both model and data views are represented by locations of scattering centers, which are peak features. The model hypothesis (view of a specific target and associated location) corresponding to a given data view is chosen to be the one with the highest number of data-supported model features (votes). We address three issues in this paper. Firstly, we present a quantitative measure of the similarity between a pair of model views. Such a measure depends on the degree of structural overlap between the two views, and the amount of uncertainty. Secondly, we describe a similarity- based framework for predicting an upper bound on recognition performance in the presence of uncertainty, occlusion and clutter. Thirdly, we validate the proposed framework using MSTAR public data, which are obtained under different depression angles, configurations and articulations.

  1. Evaluation of RISAT-1 SAR data for tropical forestry applications

    Science.gov (United States)

    Padalia, Hitendra; Yadav, Sadhana

    2017-01-01

    India launched C band (5.35 GHz) RISAT-1 (Radar Imaging Satellite-1) on 26th April, 2012, equipped with the capability to image the Earth at multiple-resolutions and -polarizations. In this study the potential of Fine Resolution Strip (FRS) modes of RISAT-1 was evaluated for characterization and classification forests and estimation of biomass of early growth stages. The study was carried out at the two sites located in the foothills of western Himalaya, India. The pre-processing and classification of FRS-1 SAR data was performed using PolSAR Pro ver. 5.0 software. The scattering mechanisms derived from m-chi decomposition of FRS-1 RH/RV data were found physically meaningful for the characterization of various surface features types. The forest and land use type classification of the study area was developed applying Support Vector Machine (SVM) algorithm on FRS-1 derived appropriate polarimetric features. The biomass of early growth stages of Eucalyptus (up to 60 ton/ha) was estimated developing a multi-linear regression model using C band σ0 HV and σ0 HH backscatter information. The study outcomes has promise for wider application of RISAT-1 data for forest cover monitoring, especially for the tropical regions.

  2. Relating polarization phase difference of SAR signals to scene properties

    Science.gov (United States)

    Ulaby, Fawwaz T.; Dobson, Myron C.; Mcdonald, Kyle C.; Senior, Thomas B. A.; Held, Daniel

    1987-01-01

    This paper examines the statistical behavior of the phase difference Delta-phi between the HH-polarized and VV-polarized backscattered signals recorded by an L-band SAR over an agricultural test site in Illinois. Polarization-phase difference distributions were generated for about 200 agricultural fields for which ground information had been acquired in conjunction with the SAR mission. For the overwhelming majority of cases, the Delta-phi distribution is symmetric and has a single major lobe centered at the mean value of the distribution Delta-phi. Whereas the mean Delta-phi was found to be close to zero degrees for bare soil, cut vegetation, alfalfa, soybeans, and clover, a different pattern was observed for the corn fields; the mean Delta-phi increased with increasing incidence angle Theta = 35 deg. The explanation proposed for this variation is that the corn canopy, most of whose mass is contained in its vertical stalks, acts like a uniaxial crystal characterized by different velocities of propagation for waves with horizontal and vertical polarization. Thus, it is hypothesized that the observed backscatter is contributed by a combination of propagation delay, forward scatter by the soil surface, and specular bistatic reflection by the stalks. Model calculations based on this assumption were found to be in general agreement with the phase observations.

  3. Polarimetric SAR Image Supervised Classification Method Integrating Eigenvalues

    Directory of Open Access Journals (Sweden)

    Xing Yanxiao

    2016-04-01

    Full Text Available Since classification methods based on H/α space have the drawback of yielding poor classification results for terrains with similar scattering features, in this study, we propose a polarimetric Synthetic Aperture Radar (SAR image classification method based on eigenvalues. First, we extract eigenvalues and fit their distribution with an adaptive Gaussian mixture model. Then, using the naive Bayesian classifier, we obtain preliminary classification results. The distribution of eigenvalues in two kinds of terrains may be similar, leading to incorrect classification in the preliminary step. So, we calculate the similarity of every terrain pair, and add them to the similarity table if their similarity is greater than a given threshold. We then apply the Wishart distance-based KNN classifier to these similar pairs to obtain further classification results. We used the proposed method on both airborne and spaceborne SAR datasets, and the results show that our method can overcome the shortcoming of the H/α-based unsupervised classification method for eigenvalues usage, and produces comparable results with the Support Vector Machine (SVM-based classification method.

  4. Recognizing articulated objects and object articulation in SAR images

    Science.gov (United States)

    Bhanu, Bir; Jones, Grinnell, III; Ahn, Joon S.

    1998-09-01

    The focus of this paper is recognizing articulated objects and the pose of the articulated parts in SAR images. Using SAR scattering center locations as features, the invariance with articulation (i.e. turret rotation for the T72, T80 and M1a tanks, missile erect vs. down for the SCUD launcher) is shown as a function of object azimuth. Similar data is shown for configuration differences in the MSTAR (Public) Targets. The UCR model-based recognition engine (which uses non- articulated models to recognize articulated, occluded and non-standard configuration objects) is described and target identification performance results are given as confusion matrices and ROC curves for six inch and one foot resolution XPATCH images and the one foot resolution MSTAR data. Separate body and turret models are developed that are independent of the relative positions between the body and the turret. These models are used with a subsequent matching technique to refine the pose of the body and determine the pose of the turret. An expression of the probability that a random match will occur is derived and this function is used to set thresholds to minimize the probability of a random match for the recognition system. Results for identification, body pose and turret pose are presented as a function of percent occlusion for articulated XPATCH data and results are given for identification and body pose for articulated MSTAR data.

  5. Satellite SAR observation of the sea surface wind field caused by rain cells

    Institute of Scientific and Technical Information of China (English)

    YE Xiaomin; LIN Mingsen; YUAN Xinzhe; DING Jing; XIE Xuetong; ZHANG Yi; XU Ying

    2016-01-01

    Rain cells or convective rain, the dominant form of rain in the tropics and subtropics, can be easy detected by satellite Synthetic Aperture Radar (SAR) images with high horizontal resolution. The footprints of rain cells on SAR images are caused by the scattering and attenuation of the rain drops, as well as the downward airflow. In this study, we extract sea surface wind field and its structure caused by rain cells by using a RADARSAT-2 SAR image with a spatial resolution of 100 m for case study. We extract the sea surface wind speeds from SAR image by using CMOD4 geophysical model function with outside wind directions of NCEP final operational global analysis data, Advance Scatterometer (ASCAT) onboard European MetOp-A satellite and microwave scatterometer onboard Chinese HY-2 satellite, respectively. The root-mean-square errors (RMSE) of these SAR wind speeds, validated against NCEP, ASCAT and HY-2, are 1.48 m/s, 1.64 m/s and 2.14 m/s, respectively. Circular signature patterns with brighter on one side and darker on the opposite side on SAR image are interpreted as the sea surface wind speed (or sea surface roughness) variety caused by downdraft associated with rain cells. The wind speeds taken from the transect profile which superposes to the wind ambient vectors and goes through the center of the circular footprint of rain cell can be fitted as a cosine or sine curve in high linear correlation with the values of no less than 0.80. The background wind speed, the wind speed caused by rain cell and the diameter of footprint of the rain cell with kilometers or tens of kilometers can be acquired by fitting curve. Eight cases interpreted and analyzed in this study all show the same conclusion.

  6. Tropical Forest Biomass Estimation from Vertical Fourier Transforms of Lidar and InSAR Profiles

    Science.gov (United States)

    Treuhaft, R. N.; Goncalves, F.; Drake, J.; Hensley, S.; Chapman, B. D.; Michel, T.; Dos Santos, J. R.; Dutra, L.; Graca, P. A.

    2010-12-01

    Structural forest biomass estimation from lidar or interferometric SAR (InSAR) has demonstrated better performance than radar-power-based approaches for the higher biomasses (>150 Mg/ha) found in tropical forests. Structural biomass estimation frequently regresses field biomass to some function of forest height. With airborne, 25-m footprint lidar data and fixed-baseline C-band InSAR data over tropical wet forests of La Selva Biological Station, Costa Rica, we compare the use of Fourier transforms of vertical profiles at a few frequencies to the intrinsically low-frequency “average height”. RMS scatters of Fourier-estimated biomass about field-measured biomass improved by 40% and 20% over estimates base on average height from lidar and fixed-baseline InSAR, respectively. Vertical wavelengths between 14 and 100 m were found to best estimate biomass. The same airborne data acquisition over La Selva was used to generate many 10’s of repeat-track L-band InSAR baselines with time delays of 1-72 hours, and vertical wavelengths of 5-100 m. We will estimate biomass from the Fourier transforms of L-band radar power profiles (InSAR complex coherence). The effects of temporal decorrelation will be modeled in the Fourier domain to try to model and reduce their impact. Using L-band polarimetric interferometry, average heights will be estimated as well and biomass regression performance compared to the Fourier transform approach. The more traditional approach of using L-band radar polarimetry will also be compared to structural biomass estimation.

  7. Monitoring land subsidence process in the urban area of Ho Chi Minh city, Vietnam using multi-temporal SAR Interferometry

    Science.gov (United States)

    Nguyen, Xuan; Chang, Chung-Pai; Le, Tuan

    2016-04-01

    Land subsidence has become the most common hazard in urban area that could led to cracking buildings and infrastructures, extending the flooding area or even change the river path. Despite deriving precise information, conventional subsidence monitoring techniques are considered as costly, man-power consuming and lack of comprehensive information. Recently, SAR Interferometry (InSAR) has become a widely used geodetic technique for monitoring the deformation of the Earth's surface, especially methods based on the use of a multi-temporal dataset. In this study, we use a stack of 18 SAR images acquired from L-band PALSAR sensor onboard the ALOS satellite to derive the subsidence information of Ho Chi Minh city, Vietnam over the period of December 2006 to December 2010. The Stanford Method for Persistent Scatterers (StaMPS) Multi-Temporal Interferometry (MTI) approach is chosen to take advantages of both the persistent scatterers and the distributed scatterers, which could be used as monitoring points to measure the subsidence process. Assume the subsidence in this area mostly corresponds to vertical components, we found subsidence patterns along Saigon river and in the South of the city. Maximum subsidence rate reaches up to -66 mm/year in vertical direction. Finally, InSAR derived result and previous levelling data are taken into comparison to find the correlation between the two results.

  8. Bistatic Experiment Using TerraSAR-X and DLR’s new F-SAR System

    OpenAIRE

    Baumgartner, Stefan; Rodriguez-Cassolà, Marc; Nottensteiner, Anton; Horn, Ralf; Scheiber, Rolf; Steinbrecher, Ulrich; Metzig, Robert; Limbach, Markus; Mittermayer, Josef; Krieger, Gerhard; Moreira, Alberto; Schwerdt, Marco

    2008-01-01

    A bistatic X-band experiment was successfully performed early November 2007. TerraSAR-X was used as transmitter and DLR’s new airborne radar system F-SAR, which was programmed to acquire data in a quasi-continuous mode to avoid echo window synchronization issues, was used as bistatic receiver. Precise phase and time referencing between both systems, which is essential for obtaining high resolution SAR images, was derived during the bistatic processing. Hardware setup and performance analyses ...

  9. SAR-SIFT: A SIFT-LIKE ALGORITHM FOR SAR IMAGES

    OpenAIRE

    Dellinger, Flora; Delon, Julie; Gousseau, Yann; Michel, Julien; Tupin, Florence

    2015-01-01

    International audience; The Scale Invariant Feature Transform (SIFT) algorithm is widely used in computer vision to match features between images or to localize and recognize objets. However, mostly because of speckle noise, it does not perform well on synthetic aperture radar (SAR) images. We present here an improvement of this algorithm for SAR images, named SAR-SIFT. A new gradient computation, yielding an orientation and a magnitude robust to speckle noise, is first introduced. It is then...

  10. GRECO-SAR: An Orbital Polarimetric SAR Simulator of Deterministic Complex Targets for Vessel Classification Studies

    OpenAIRE

    Margarit Martín, Gerard; Mallorquí Franquet, Jordi Joan; Rius Casals, Juan Manuel; Sanz Marcos, Jesús

    2006-01-01

    This paper presents a synthetic aperture radar (SAR) simulator that is able to generate polarimetric SAR (POLSAR) and polarimetric inverse SAR data of complex targets. It solves the electromagnetic problem via high-frequency approximations, such as physical optics and the physical theory of diffraction, with notable computational efficiency. In principle, any orbital monostatic sensor working at any band, resolution, and operating mode can be modeled. To make simulations more realistic, the t...

  11. SARS-A Worldwide Threat

    Institute of Scientific and Technical Information of China (English)

    姜保华

    2003-01-01

    所谓SARS,即严重急性呼吸道综合症,是一种传染力很强的呼吸道疾病。这种新的疾病最先由世界卫生组织医生Carlo Urbani博士确诊,患者是一位48岁的商人,后来因该病而死亡。Urbani医生本人也因感染该病而于2003年3月29日去世,死时年仅46岁。在此期间,SARS开始蔓延。自SARS发现后的一个半月里,全球已有数千人被感染。

  12. Atmosphere Observations by Geosynchronous SARs

    Science.gov (United States)

    Monti guarnieri, Andrea; Rocca, Fabio; Wadge, Geoff; Schulz, Detlef

    2014-05-01

    We analyze different geosynchronous Synthetic Aperture RADAR concepts aimed to get both tropospheric and ionospheric delay maps with a revisit time of minutes and sub-continental coverage. Such products could be used either to compensate the delay in LEO-SAR missions and GNSS, or to generate integrated water-vapor maps to be used for Numerical Weather Forecast. The system exploits the principle of RADAR location, by transmitting a pulse with a suitable bandwidth, and the residual non-zero eccentricity of COMmunication SATellites. Different concepts are proposed as payload in COMSAT, or constellations of small satellites, that is monostatic or bistatic/multistatic RADARS. The selection of the best frequency, from L to Ku, and the analysis of performances is presented.

  13. Novel Topic Authorship Attribution

    Science.gov (United States)

    2011-03-01

    cross-validation, genre shift, vector projection, singular value decomposition, principal component analysis Unclassified Unclassified Unclassified...by eight students. Each student wrote a total of 24 documents in three different genres about three different topics. They found that compensating for...Baayen, H. Halteren, A. Neijt, and F. Tweedie, “Outside the cave of shadows: Using syntactic annotation to enhance authorship attribution,” Literary

  14. Improved Persistent Scatterer analysis using Amplitude Dispersion Index optimization of dual polarimetry data

    Science.gov (United States)

    Esmaeili, Mostafa; Motagh, Mahdi

    2016-07-01

    Time-series analysis of Synthetic Aperture Radar (SAR) data using the two techniques of Small BAseline Subset (SBAS) and Persistent Scatterer Interferometric SAR (PSInSAR) extends the capability of conventional interferometry technique for deformation monitoring and mitigating many of its limitations. Using dual/quad polarized data provides us with an additional source of information to improve further the capability of InSAR time-series analysis. In this paper we use dual-polarized data and combine the Amplitude Dispersion Index (ADI) optimization of pixels with phase stability criterion for PSInSAR analysis. ADI optimization is performed by using Simulated Annealing algorithm to increase the number of Persistent Scatterer Candidate (PSC). The phase stability of PSCs is then measured using their temporal coherence to select the final sets of pixels for deformation analysis. We evaluate the method for a dataset comprising of 17 dual polarization SAR data (HH/VV) acquired by TerraSAR-X data from July 2013 to January 2014 over a subsidence area in Iran and compare the effectiveness of the method for both agricultural and urban regions. The results reveal that using optimum scattering mechanism decreases the ADI values in urban and non-urban regions. As compared to single-pol data the use of optimized polarization increases initially the number of PSCs by about three times and improves the final PS density by about 50%, in particular in regions with high rate of deformation which suffer from losing phase stability over the time. The classification of PS pixels based on their optimum scattering mechanism revealed that the dominant scattering mechanism of the PS pixels in the urban area is double-bounce while for the non-urban regions (ground surfaces and farmlands) it is mostly single-bounce mechanism.

  15. Detecting, mapping and monitoring of land subsidence in Jharia Coalfield, Jharkhand, India by spaceborne differential interferometric SAR, GPS and precision levelling techniques

    Indian Academy of Sciences (India)

    R S Chatterjee; Shailaja Thapa; K B Singh; G Varunakumar; E V R Raju

    2015-08-01

    The study aims at detection, mapping and monitoring of land subsidence in Jharia Coalfield, Jharkhand, India by spaceborne DInSAR, GPS and precision levelling techniques. Using multi-frequency C- and L-band DInSAR, both slowly and rapidly subsiding areas were identified and DInSAR-based subsidence maps were prepared. C-band DInSAR was found useful for detection of slowly subsiding areas whereas L-band DInSAR for rapidly subsiding and/or adverse land cover areas. Due to dynamic nature of mining and adverse land cover, temporal decorrelation poses a serious problem particularly in C-band DInSAR. Specially designed InSAR coherence guided adaptive filtering was found useful to highlight the deformation fringes. Collateral GPS and levelling observations were conducted in three test sites to validate DInSAR measurements and to determine the net displacement vectors. We observed an appreciable horizontal displacement component of land subsidence in all the test sites. For comparison of results, we calculated InSAR coherence weighted LOS displacement rates from the unwrapped differential interferograms of smaller spatial subsets and LOS projected ground-based displacement rates in three test sites. We found good agreement between DInSAR and ground-based measurements except for C-band observation in Dobari test site primarily due to large difference in observation periods and temporally inconsistent land subsidence. Collateral spaceborne and ground-based observations were also found useful for characterization of subsidence phenomena to determine net displacement vector and horizontal displacement component. In coal mining areas with spatially scattered and temporally irregular land subsidence phenomena, the adopted methodology can be used successfully for detection, mapping and monitoring of the subsiding areas vulnerable to future collapse. This will facilitate efficient planning and designing of surface infrastructures and other developmental structures in the mining

  16. Oil Detection in a Coastal Marsh with Polarimetric SAR

    Science.gov (United States)

    Ramsey, E., III; Rangoonwala, A.; Suzuoki, Y.; Bannister, T.

    2011-09-01

    The NASA UAVSAR was deployed June 2010 to support Deep Water Horizon oil spill response activities specifically, oil detection and characterization, oil extent mapping in wetlands, coastal resource impact detection, and ecosystem recovery. The UAVSAR platform demonstrated enhanced capability to act rapidly and provide targeted mapping response. Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band Synthetic Aperture Radar (PolSAR) for mapping oil in wetlands, specifically within Barataria Bay in eastern coastal Louisiana. Barataria Bay contained a numerous site observations confirming spatially extensive shoreline oil impacts, multiple oil spill UAVSAR collections, and a near anniversary 2009 collection. PolSAR oil detection relied on decomposition and subsequent classifications of the single look complex (SLC) calibrated radar cross sections representing the complex elements of the scattering matrix. Initial analyses results found that shoreline marsh structural damage as well as oil on marsh plants and sediments without canopy structural damage were exhibited as anomalous features on post-spill SLC scenes but were not evident on the pre-spill SLC scene collected in 2009. Pre-spill and post-spill Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions and the Wishart classifications seeded with the FD and CP classes (Wishart-FD) also highlighted these nearshore features as a change in dominate scatter from pre-spill to post-spill. SLC analyses also indicated penetration of oil ladened waters into interior marshes well past the immediate shorelines; however, these post-spill SLC analyses results could not be validated due to the lack of observational data and possible flooding in the pre-spill SLC scene.

  17. Advanced Antenna for Digital Beamforming SAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop a wideband (500 MHz) L-band phased-array antenna for airborne Synthetic Aperture Radar (SAR) applications based on a novel approach that will make possible...

  18. Introduction to Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    2006-09-01

    18 m L RADARSAT 1995 10 m × 9 m C ENVISAT 2002 25 m × 25 m C TerraSAR-X 2006 < 1 m × 1 m X Radarsat II 2005 3 m × 3 m C SAR-Lupe 2005 < 1 m...1 m X IGS-2b 2008 30 cm × 30 cm X Airborne SAR DOSAR 1989 < 1 m × 1 m S,C,X,Ka CARABAS- II 1997 3 m × 3 m VHF PAMIR 2003 10 cm × 10 cm X...Lynx 1999 10 cm × 10 cm Ku MISAR 2003 0.5 m × 0.5 m Ka RAMSES 1994 10 cm × 10 cm P,L,S,C,X,Ku,Ka,W MEMPHIS 1997 20 cm × 20 cm Ka,W E-SAR 1994 1.5

  19. Ionosphere correction algorithm for spaceborne SAR imaging

    Institute of Scientific and Technical Information of China (English)

    Lin Yang; Mengdao Xing; Guangcai Sun

    2016-01-01

    For spaceborne synthetic aperture radar (SAR) ima-ging, the dispersive ionosphere has significant effects on the pro-pagation of the low frequency (especial y P-band) radar signal. The ionospheric effects can be a significant source of the phase error in the radar signal, which causes a degeneration of the image quality in spaceborne SAR imaging system. The background ionospheric effects on spaceborne SAR through modeling and simulation are analyzed, and the qualitative and quantitative analysis based on the spatio-temporal variability of the ionosphere is given. A novel ionosphere correction algorithm (ICA) is proposed to deal with the ionospheric effects on the low frequency spaceborne SAR radar signal. With the proposed algorithm, the degradation of the image quality caused by the ionosphere is corrected. The simulation re-sults show the effectiveness of the proposed algorithm.

  20. Polarimetric SAR Interferometry Evaluation in Mangroves

    Science.gov (United States)

    Lee, Seung-Kuk; Fatoyinbo,Temilola; Osmanoglu, Batuhan; Sun, Guoqing

    2014-01-01

    TanDEM-X (TDX) enables to generate an interferometric coherence without temporal decorrelation effect that is the most critical factor for a successful Pol-InSAR inversion, as have recently been used for forest parameter retrieval. This paper presents mangrove forest height estimation only using single-pass/single-baseline/dual-polarization TDX data by means of new dual-Pol-InSAR inversion technique. To overcome a lack of one polarization in a conventional Pol- InSAR inversion (i.e. an underdetermined problem), the ground phase in the Pol-InSAR model is directly estimated from TDX interferograms assuming flat underlying topography in mangrove forest. The inversion result is validated against lidar measurement data (NASA's G-LiHT data).

  1. Progress in Circular SAR Imaging Technique

    Directory of Open Access Journals (Sweden)

    Hong Wen

    2012-06-01

    Full Text Available Circular SAR (CSAR is a newly developed all-directional high resolution 3D imaging mode in recent years, to satisfy the demand of finer observation. The National Key Laboratory of Science and Technology on Microwave Imaging, Institute of Electronics, Chinese Academy of Sciences (MITL, IECAS, had the first test flight experiment in Aug. 2011 with a P-band full polarization SAR system, and successfully obtained the all-directional high resolution circular SAR image. The initial results show that CSAR technique has the encouraging potential capability in the fields of high precision mapping, disaster evaluation, resource management and the other related applications. This paper firstly makes a detailed discussion on the progress of circular SAR imaging technique, which emphases on the several airborne experiments performed these years to show CSAR’s attractive features, then studies and illustrates the key techniques, and finally discusses the development trends.

  2. Cross-calibration of interferometric SAR data

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2003-01-01

    Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully...

  3. Optimal Approach to SAR Image Despeckling

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Speckle filtering of synthetic aperture radar (SAR) images while preserving the spatial signal variability (texture and fine structures) still remains a challenge. Many algorithms have been proposed for the SAR imagery despeckling. However,simulated annealing (SA) method is one of excellent choices currently. A critical problem in the study on SA is to provide appropriate cooling schedules that ensure fast convergence to near-optimal solutions. This paper gives a new necessary and sufficient condition for the cooling schedule so that the algorithm state converges in all probability to the set of globally minimum cost states.Moreover, it constructs an appropriate objective function for SAR image despeckling. An experimental result of the actual SAR image processing is obtained.

  4. Satellite sar detection of hurricane helene (2006)

    DEFF Research Database (Denmark)

    Ju, Lian; Cheng, Yongcun; Xu, Qing

    2013-01-01

    In this paper, the wind structure of hurricane Helene (2006) over the Atlantic Ocean is investigated from a C-band RADARSAT-1 synthetic aperture radar (SAR) image acquired on 20 September 2006. First, the characteristics, e.g., the center, scale and area of the hurricane eye (HE) are determined....... There is a good agreement between the SAR-estimated HE center location and the best track data from the National Hurricane Center. The wind speeds at 10 m above the ocean surface are also retrieved from the SAR data using the geophysical model function (GMF), CMOD5, and compared with in situ wind speed...... observations from the stepped frequency microwave radiometer (SFMR) on NOAA P3 aircraft. All the results show the capability of hurricane monitoring by satellite SAR. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE)....

  5. Enhanced SAR data processing for land instability forecast.

    Science.gov (United States)

    Argentiero, Ilenia; Pellicani, Roberta; Spilotro, Giuseppe; Parisi, Alessandro; Bovenga, Fabio; Pasquariello, Guido; Refice, Alberto; Nutricato, Raffaele; Nitti, Davide Oscar; Chiaradia, Maria Teresa

    2017-04-01

    Monitoring represents the main tool for carrying out evaluation procedures and criteria for spatial and temporal landslide forecast. The forecast of landslide behaviour depends on the possibility to identify either evidences of activity (displacement, velocity, volume of unstable mass, direction of displacement, and their temporal variation) or triggering parameters (rainfalls). Generally, traditional geotechnical landslide monitoring technologies permit to define, if correctly positioned and with adequate accuracy, the critical value of displacement and/or acceleration into landslide body. In most cases, they do not allow real time warning signs to be generated, due to environmental induced errors, and the information is related to few points on unstable area. Remote-sensing monitoring instruments are capable of inspecting an unstable slope with high spatial and temporal frequency, but allow solely measurements of superficial displacements and deformations. Among these latest technologies, the satellite Persistent Scatterer SAR Interferometry (PSInSAR) is very useful to investigate the unstable area both in terms of space and time. Indeed, this technique allows to analyse wide areas, individuate critical unstable areas, not identifiable by means detailed in situ surveys, and study the phenomenon evolution in a long time-scale. Although this technique usually adopts, as first approximation, a linear model to describe the displacement of the detected targets, also non-linear models can be used. However, the satellite revisit time, which defines the time sampling of the detected displacement signal, limits the maximum measurable velocity and acceleration. This makes it difficult to assess in the short time any acceleration indicating a loss of equilibrium and, therefore, a probable reactivation of the landslide. The recent Sentinel-1 mission from the European Space Agency (ESA), provides a spatial resolution comparable to the previous ESA missions, but a nominal

  6. On Bistatic Forward-looking SAR Imaging

    OpenAIRE

    Vu, Viet Thuy; Pettersson, Mats

    2014-01-01

    Left/right ambiguity and low angular (azimuth) resolution are severe problems for monostatic forward-looking SAR imaging. It is strongly believed that these technical issues can definitely be solved with bistatic forward-looking SAR. The analysis presented in this paper points out that the left/right ambiguity problem still exits. However, an appropriate selection of the position of bistatic base line and antenna beamwidth allows us to conceal it. The paper also gives some recommendations whi...

  7. Modelling strategies for controlling SARS outbreaks.

    Science.gov (United States)

    Gumel, Abba B.; Ruan, Shigui; Day, Troy; Watmough, James; Brauer, Fred; van den Driessche, P.; Gabrielson, Dave; Bowman, Chris; Alexander, Murray E.; Ardal, Sten; Wu, Jianhong; Sahai, Beni M.

    2004-01-01

    Severe acute respiratory syndrome (SARS), a new, highly contagious, viral disease, emerged in China late in 2002 and quickly spread to 32 countries and regions causing in excess of 774 deaths and 8098 infections worldwide. In the absence of a rapid diagnostic test, therapy or vaccine, isolation of individuals diagnosed with SARS and quarantine of individuals feared exposed to SARS virus were used to control the spread of infection. We examine mathematically the impact of isolation and quarantine on the control of SARS during the outbreaks in Toronto, Hong Kong, Singapore and Beijing using a deterministic model that closely mimics the data for cumulative infected cases and SARS-related deaths in the first three regions but not in Beijing until mid-April, when China started to report data more accurately. The results reveal that achieving a reduction in the contact rate between susceptible and diseased individuals by isolating the latter is a critically important strategy that can control SARS outbreaks with or without quarantine. An optimal isolation programme entails timely implementation under stringent hygienic precautions defined by a critical threshold value. Values below this threshold lead to control, but those above are associated with the incidence of new community outbreaks or nosocomial infections, a known cause for the spread of SARS in each region. Allocation of resources to implement optimal isolation is more effective than to implement sub-optimal isolation and quarantine together. A community-wide eradication of SARS is feasible if optimal isolation is combined with a highly effective screening programme at the points of entry. PMID:15539347

  8. Multi-Attribute Sequential Search

    Science.gov (United States)

    Bearden, J. Neil; Connolly, Terry

    2007-01-01

    This article describes empirical and theoretical results from two multi-attribute sequential search tasks. In both tasks, the DM sequentially encounters options described by two attributes and must pay to learn the values of the attributes. In the "continuous" version of the task the DM learns the precise numerical value of an attribute when she…

  9. SARS: Key factors in crisis management.

    Science.gov (United States)

    Tseng, Hsin-Chao; Chen, Thai-Form; Chou, Shieu-Ming

    2005-03-01

    This study was conducted at a single hospital selected in Taipei during the SARS (Severe Acute Respiratory Syndrome) outbreak from March to July, 2003 in Taiwan. During this period of time, 104 SARS patients were admitted to the hospital. There were no negative reports related to the selected hospital despite its being located right in the center of an area struck by the epidemic. The purpose of this study was to identify the key factors enabling the hospital to survive SARS unscathed. Data were collected from in-depth interviews with the nursing directors and nursing managers of the SARS units, along with a review of relevant hospital documents. The five key elements identified as survival factors during this SARS crisis are as follows: 1. good control of timing for crisis management, 2. careful decision-making, 3. thorough implementation, 4. effective communication, and 5. trust between management and employees. The results of this study reconfirmed the selected hospital as a model for good crisis management during the SARS epidemic.

  10. Airborne S-Band SAR for Forest Biophysical Retrieval in Temperate Mixed Forests of the UK

    Directory of Open Access Journals (Sweden)

    Ramesh K. Ningthoujam

    2016-07-01

    Full Text Available Radar backscatter from forest canopies is related to forest cover, canopy structure and aboveground biomass (AGB. The S-band frequency (3.1–3.3 GHz lies between the longer L-band (1–2 GHz and the shorter C-band (5–6 GHz and has been insufficiently studied for forest applications due to limited data availability. In anticipation of the British built NovaSAR-S satellite mission, this study evaluates the benefits of polarimetric S-band SAR for forest biophysical properties. To understand the scattering mechanisms in forest canopies at S-band the Michigan Microwave Canopy Scattering (MIMICS-I radiative transfer model was used. S-band backscatter was found to have high sensitivity to the forest canopy characteristics across all polarisations and incidence angles. This sensitivity originates from ground/trunk interaction as the dominant scattering mechanism related to broadleaved species for co-polarised mode and specific incidence angles. The study was carried out in the temperate mixed forest at Savernake Forest and Wytham Woods in southern England, where airborne S-band SAR imagery and field data are available from the recent AirSAR campaign. Field data from the test sites revealed wide ranges of forest parameters, including average canopy height (6–23 m, diameter at breast-height (7–42 cm, basal area (0.2–56 m2/ha, stem density (20–350 trees/ha and woody biomass density (31–520 t/ha. S-band backscatter-biomass relationships suggest increasing backscatter sensitivity to forest AGB with least error between 90.63 and 99.39 t/ha and coefficient of determination (r2 between 0.42 and 0.47 for the co-polarised channel at 0.25 ha resolution. The conclusion is that S-band SAR data such as from NovaSAR-S is suitable for monitoring forest aboveground biomass less than 100 t/ha at 25 m resolution in low to medium incidence angle range.

  11. Change detection of polarimetric SAR images based on the KummerU Distribution

    Science.gov (United States)

    Chen, Quan; Zou, Pengfei; Li, Zhen; Zhang, Ping

    2014-11-01

    In the society of PolSAR image segmentation, change detection and classification, the classical Wishart distribution has been used for a long time, but it especially suit to low-resolution SAR image, because in traditional sensors, only a small number of scatterers are present in each resolution cell. With the improving of SAR systems these years, the classical statistical models can therefore be reconsidered for high resolution and polarimetric information contained in the images acquired by these advanced systems. In this study, SAR image segmentation algorithm based on level-set method, added with distance regularized level-set evolution (DRLSE) is performed using Envisat/ASAR single-polarization data and Radarsat-2 polarimetric images, respectively. KummerU heterogeneous clutter model is used in the later to overcome the homogeneous hypothesis at high resolution cell. An enhanced distance regularized level-set evolution (DRLSE-E) is also applied in the later, to ensure accurate computation and stable level-set evolution. Finally, change detection based on four polarimetric Radarsat-2 time series images is carried out at Genhe area of Inner Mongolia Autonomous Region, NorthEastern of China, where a heavy flood disaster occurred during the summer of 2013, result shows the recommend segmentation method can detect the change of watershed effectively.

  12. Individual Building Extraction from TerraSAR-X Images Based on Ontological Semantic Analysis

    Directory of Open Access Journals (Sweden)

    Rong Gui

    2016-08-01

    Full Text Available Accurate building information plays a crucial role for urban planning, human settlements and environmental management. Synthetic aperture radar (SAR images, which deliver images with metric resolution, allow for analyzing and extracting detailed information on urban areas. In this paper, we consider the problem of extracting individual buildings from SAR images based on domain ontology. By analyzing a building scattering model with different orientations and structures, the building ontology model is set up to express multiple characteristics of individual buildings. Under this semantic expression framework, an object-based SAR image segmentation method is adopted to provide homogeneous image objects, and three categories of image object features are extracted. Semantic rules are implemented by organizing image object features, and the individual building objects expression based on an ontological semantic description is formed. Finally, the building primitives are used to detect buildings among the available image objects. Experiments on TerraSAR-X images of Foshan city, China, with a spatial resolution of 1.25 m × 1.25 m, have shown the total extraction rates are above 84%. The results indicate the ontological semantic method can exactly extract flat-roof and gable-roof buildings larger than 250 pixels with different orientations.

  13. Topography and Penetration of the Greenland Ice Sheet Measured with Airborne SAR Interferometry

    DEFF Research Database (Denmark)

    Dall, Jørgen; Madsen, Søren Nørvang; Keller, K.

    2001-01-01

    A digital elevation model (DEM) of the Geikie ice sap in East Greenland has been generated from interferometric C-band synthetic aperture radar (SAR) data acquired with the airborne EMISAR system. GPS surveyed radar reflectors and an airborne laser altimeter supplemented the experiment. The accur......A digital elevation model (DEM) of the Geikie ice sap in East Greenland has been generated from interferometric C-band synthetic aperture radar (SAR) data acquired with the airborne EMISAR system. GPS surveyed radar reflectors and an airborne laser altimeter supplemented the experiment....... The accuracy of the SAR DEM is about 1.5 m. The mean difference between the laser heights and the SAR heights changes from 0 m in the soaked zone to a maximum of 13 m in the percolation zone. This is explained by the fact that the snow in the soaked zone contains liquid water which attenuates the radar signals......, while the transparency of the firn in the percolation zone makes volume scattering dominate at the higher elevations. For the first time, the effective penetration has been measured directly as the difference between the interferometric heights and reference heights obtained with GPS and laser altimetry....

  14. Potential of C and X Band SAR for Shrub Growth Monitoring in Sub-Arctic Environments

    Directory of Open Access Journals (Sweden)

    Yannick Duguay

    2015-07-01

    Full Text Available The Arctic and sub-Arctic environments have seen a rapid growth of shrub vegetation at the expense of the Arctic tundra in recent decades. In order to develop better tools to assess and understand this phenomenon, the sensitivity of multi-polarized SAR backscattering at C and X band to shrub density and height is studied under various conditions. RADARSAT-2 and TerraSAR-X images were acquired from November 2011 to March 2012 over the Umiujaq community in northern Quebec (56.55°N, 76.55°W and compared to in situ measurements of shrub vegetation density and height collected during the summer of 2009. The results show that σ0 is sensitive to changes in shrub coverage up to 20% and is sensitive to changes in shrub height up to around 1 m. The cross-polarized backscattering (σ0 HV displays the best sensitivity to both shrub height and density, and RADARSAT-2 is more sensitive to shrub height, as TerraSAR-X tends to saturate more rapidly with increasing volume scattering from the shrub branches. These results demonstrate that SAR data could provide essential information, not only on Remote Sens. 2015, 7 9411 the spatial expansion of shrub vegetation, but also on its vertical growth, especially at early stages of colonization.

  15. Fusion of Spaceborne Optical and SAR Images for Building Height Quick Extraction in Big Urban Areas

    Directory of Open Access Journals (Sweden)

    TIAN Feng

    2017-07-01

    Full Text Available The spaceborne high-resolution optical images and synthetic aperture radar (SAR images are applied to extract building height in urban areas widely. But the lack of optical satellite parameters along with the SAR images' incomplete scattering characteristics and inefficient extraction make the application flawed. To cure the above problems, we investigated the joint use of the spaceborne high-resolution optical images and SAR images to extract building height information quickly in big urban areas. The chain is decomposed into the main following steps: First, the building shadows are extracted by integrating support vector machines (SVM with morphological shadow index (MSI and their lengths are measured automatically. Then, the height extraction from SAR images based on a model matching technique for some appropriate samples. Finally, obtain the other heights based on the simple linear regression analysis. This approach which combines the data and feature from different satellite systems to make up the flaws for each other is not only efficient and low-cost, but also satisfy the basic accuracy requirement.

  16. Sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 2: Scaling in situ to Radarsat-2

    Directory of Open Access Journals (Sweden)

    R. K. Scharien

    2014-01-01

    Full Text Available Observed changes in the Arctic have motivated efforts to understand and model its components as an integrated and adaptive system at increasingly finer scales. Sea ice melt pond fraction, an important summer sea ice component affecting surface albedo and light transmittance across the ocean-sea ice–atmosphere interface, is inadequately parameterized in models due to a lack of large scale observations. In this paper, results from a multi-scale remote sensing program dedicated to the retrieval of pond fraction from satellite C-band synthetic aperture radar (SAR are detailed. The study was conducted on first-year sea (FY ice in the Canadian Arctic Archipelago during the summer melt period in June 2012. Approaches to retrieve the subscale FY ice pond fraction from mixed pixels in RADARSAT-2 imagery, using in situ, surface scattering theory, and image data are assessed. Each algorithm exploits the dominant effect of high dielectric free-water ponds on the VV/HH polarisation ratio (PR at moderate to high incidence angles (about 40° and above. Algorithms are applied to four images corresponding to discrete stages of the seasonal pond evolutionary cycle, and model performance is assessed using coincident pond fraction measurements from partitioned aerial photos. A RMSE of 0.07, across a pond fraction range of 0.10 to 0.70, is achieved during intermediate and late seasonal stages. Weak model performance is attributed to wet snow (pond formation and synoptically driven pond freezing events (all stages, though PR has utility for identification of these events when considered in time series context. Results demonstrate the potential of wide-swath, dual-polarisation, SAR for large-scale observations of pond fraction with temporal frequency suitable for process-scale studies and improvements to model parameterizations.

  17. Sensitivity Analysis of the Scattering-Based SARBM3D Despeckling Algorithm.

    Science.gov (United States)

    Di Simone, Alessio

    2016-06-25

    Synthetic Aperture Radar (SAR) imagery greatly suffers from multiplicative speckle noise, typical of coherent image acquisition sensors, such as SAR systems. Therefore, a proper and accurate despeckling preprocessing step is almost mandatory to aid the interpretation and processing of SAR data by human users and computer algorithms, respectively. Very recently, a scattering-oriented version of the popular SAR Block-Matching 3D (SARBM3D) despeckling filter, named Scattering-Based (SB)-SARBM3D, was proposed. The new filter is based on the a priori knowledge of the local topography of the scene. In this paper, an experimental sensitivity analysis of the above-mentioned despeckling algorithm is carried out, and the main results are shown and discussed. In particular, the role of both electromagnetic and geometrical parameters of the surface and the impact of its scattering behavior are investigated. Furthermore, a comprehensive sensitivity analysis of the SB-SARBM3D filter against the Digital Elevation Model (DEM) resolution and the SAR image-DEM coregistration step is also provided. The sensitivity analysis shows a significant robustness of the algorithm against most of the surface parameters, while the DEM resolution plays a key role in the despeckling process. Furthermore, the SB-SARBM3D algorithm outperforms the original SARBM3D in the presence of the most realistic scattering behaviors of the surface. An actual scenario is also presented to assess the DEM role in real-life conditions.

  18. Sensitivity Analysis of the Scattering-Based SARBM3D Despeckling Algorithm

    Directory of Open Access Journals (Sweden)

    Alessio Di Simone

    2016-06-01

    Full Text Available Synthetic Aperture Radar (SAR imagery greatly suffers from multiplicative speckle noise, typical of coherent image acquisition sensors, such as SAR systems. Therefore, a proper and accurate despeckling preprocessing step is almost mandatory to aid the interpretation and processing of SAR data by human users and computer algorithms, respectively. Very recently, a scattering-oriented version of the popular SAR Block-Matching 3D (SARBM3D despeckling filter, named Scattering-Based (SB-SARBM3D, was proposed. The new filter is based on the a priori knowledge of the local topography of the scene. In this paper, an experimental sensitivity analysis of the above-mentioned despeckling algorithm is carried out, and the main results are shown and discussed. In particular, the role of both electromagnetic and geometrical parameters of the surface and the impact of its scattering behavior are investigated. Furthermore, a comprehensive sensitivity analysis of the SB-SARBM3D filter against the Digital Elevation Model (DEM resolution and the SAR image-DEM coregistration step is also provided. The sensitivity analysis shows a significant robustness of the algorithm against most of the surface parameters, while the DEM resolution plays a key role in the despeckling process. Furthermore, the SB-SARBM3D algorithm outperforms the original SARBM3D in the presence of the most realistic scattering behaviors of the surface. An actual scenario is also presented to assess the DEM role in real-life conditions.

  19. Persistent scatterers detection on synthetic aperture radar images acquired by Sentinel-1 satellite

    Science.gov (United States)

    Dǎnişor, Cosmin; Popescu, Anca; Datcu, Mihai

    2016-12-01

    Persistent Scatterers Interferometry (PS-InSAR) has become a popular method in remote sensing because of its capability to measure terrain deformations with very high accuracy. It relies on multiple Synthetic Aperture Radar (SAR) acquisitions, to monitor points with stable proprieties over time, called Persistent Scatterers (PS)[1]. These points are unaffected by temporal decorrelation, therefore by analyzing their interferometric phase variation we can estimate the scene's deformation rates within a given time interval. In this work, we apply two incoherent detection algorithms to identify Persistent Scatterers candidates in the city of Focșani, Romania. The first method studies the variation of targets' intensities along the SAR acquisitions and the second method analyzes the spectral proprieties of the scatterers. The algorithms were implemented on a dataset containing 11 complex images of the region covering Buzău, Brăila and Focșani cities. Images were acquired by Sentinel-1 satellite in a time span of 5 months, from October 2014 to February 2015. The processing chain follows the requirements imposed by the new C-band SAR images delivered by the Sentinel-1 satellite (launched in April 2014) imaging in Interferometric Wide (IW) mode. Considering the particularities of the TOPS (Terrain Observation with Progressive Scans in Azimuth) imaging mode[2], special requirements had to be considered for pre-processing steps. The PS detection algorithms were implemented in Gamma RS program, a software which contains various function packages dedicated to SAR images focalization, analysis and processing.

  20. Strictness Analysis for Attribute Grammars

    DEFF Research Database (Denmark)

    Rosendahl, Mads

    1992-01-01

    interpretation of attribute grammars. The framework is used to construct a strictness analysis for attribute grammars. Results of the analysis enable us to transform an attribute grammar such that attributes are evaluated during parsing, if possible. The analysis is proved correct by relating it to a fixpoint...... semantics for attribute grammars. An implementation of the analysis is discussed and some extensions to the analysis are mentioned....

  1. Anti-SARS virus antibody responses against human SARS-associated coronavirus and animal SARS-associated coronavirus-like virus

    Institute of Scientific and Technical Information of China (English)

    王鸣; 徐慧芳; 莫自耀; 郑伯健; 高阳; 顾菁; 秦鹏哲; 张周斌; 邹晓忠; 梁彩云; 赵宇腾; 高凯

    2004-01-01

    @@ Severe acute respiratory syndrome (SARS) is an infectious disease first recognized in November 2002 in Guangdong province, China. It was spread to many countries all over the world within a few months.1,2 By April 2003, SARS-associated coronavirus (SARS-CoV) was found to be the etiological agent.

  2. SAR-PC: Edge Detection in SAR Images via an Advanced Phase Congruency Model

    Directory of Open Access Journals (Sweden)

    Yuming Xiang

    2017-02-01

    Full Text Available Edge detection in Synthetic Aperture Radar (SAR images has been a challenging task due to the speckle noise. Ratio-based edge detectors are robust operators for SAR images that provide constant false alarm rates, but they are only optimal for step edges. Edge detectors developed by the phase congruency model provide the identification of different types of edge features, but they suffer from speckle noise. By combining the advantages of the two edge detectors, we propose a SAR phase congruency detector (SAR-PC. Firstly, an improved local energy model for SAR images is obtained by replacing the convolution of raw image and the quadrature filters by the ratio responses. Secondly, a new noise level is estimated for the multiplicative noise. Substituting the SAR local energy and the new noise level into the phase congruency model, SAR-PC is derived. Edge response corresponds to the max moment of SAR-PC. We compare the proposed detector with the ratio-based edge detectors and the phase congruency edge detectors. Receiver Operating Characteristic (ROC curves and visual effects are used to evaluate the performance. Experimental results of simulated images and real-world images show that the proposed edge detector is robust to speckle noise and it provides a consecutive edge response.

  3. Online Health Education on SARS to University Students during the SARS Outbreak

    Science.gov (United States)

    Wong, Mee Lian; Koh, David; Iyer, Prasad; Seow, Adeline; Goh, Lee Gan; Chia, Sin Eng; Lim, Meng Kin; Ng, Daniel; Ong, Choon Nam; Phua, Kai Hong; Tambyah, Paul; Chow, Vincent T K; Chew, Suok Kai; Chandran, Ravi; Lee, Hin Peng

    2005-01-01

    Little is known about how online learning may be used to disseminate health information rapidly and widely to large university populations if there is an infectious disease outbreak. During the SARS outbreak in Singapore in 2003, a six-lesson elearning module on SARS was developed for a large university population of 32,000 students. The module…

  4. Imaging of downward-looking linear array SAR using three-dimensional spatial smoothing MUSIC algorithm

    Science.gov (United States)

    Zhang, Siqian; Kuang, Gangyao

    2014-10-01

    In this paper, a novel three-dimensional imaging algorithm of downward-looking linear array SAR is presented. To improve the resolution, multiple signal classification (MUSIC) algorithm has been used. However, since the scattering centers are always correlated in real SAR system, the estimated covariance matrix becomes singular. To address the problem, a three-dimensional spatial smoothing method is proposed in this paper to restore the singular covariance matrix to a full-rank one. The three-dimensional signal matrix can be divided into a set of orthogonal three-dimensional subspaces. The main idea of the method is based on extracting the array correlation matrix as the average of all correlation matrices from the subspaces. In addition, the spectral height of the peaks contains no information with regard to the scattering intensity of the different scattering centers, thus it is difficulty to reconstruct the backscattering information. The least square strategy is used to estimate the amplitude of the scattering center in this paper. The above results of the theoretical analysis are verified by 3-D scene simulations and experiments on real data.

  5. Synthetic SAR Image Generation using Sensor, Terrain and Target Models

    DEFF Research Database (Denmark)

    Kusk, Anders; Abulaitijiang, Adili; Dall, Jørgen

    2016-01-01

    A tool to generate synthetic SAR images of objects set on a clutter background is described. The purpose is to generate images for training Automatic Target Recognition and Identification algorithms. The tool employs a commercial electromagnetic simulation program to calculate radar cross sections...... of the object using a CAD-model. The raw measurements are input to a SAR system and terrain model, which models thermal noise, terrain clutter, and SAR focusing to produce synthetic SAR images. Examples of SAR images at 0.3m and 0.1m resolution, and a comparison with real SAR imagery from the MSTAR dataset...

  6. Attribution and reciprocity

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher

    2010-01-01

    , in turn, influence behavior. Dufwenberg and Kirchsteiger [Dufwenberg, M., Kirchsteiger, G., 2004. A theory of sequential reciprocity. Games Econ. Behav. 47 (2), 268-298] formalize this empirical finding in their ‘theory of sequential reciprocity'. This paper extends their analysis by moves of chance. More...... precisely, an extended framework is presented which allows for the analysis of strategic interactions of reciprocal agents in situations in which material outcomes also depend on chance. Moves of chance influence the attribution of responsibilities, people's perceptions about the (un)kindness of others and......, hence, their reciprocal behavior. Furthermore, with the help of two applications it is demonstrated how this framework can be used to explain experimental findings showing that people react very differently in outcomewise-identical situations depending on the moves of chance involved....

  7. Multiresolution analysis of SAR data

    Science.gov (United States)

    Hummel, Robert

    1993-01-01

    The 'Multiresolution Analysis of SAR Data' program supported research work in five areas. Geometric hashing theory can now be viewed as a Bayesian approach to object recognition. False alarm rates can be greatly reduced by using certain enhancements and modifications developed under this project. Geometric hashing algorithms now exist for the Connection Machine. Recognition of synthetically-produced dot arrays was demonstrated using a model base of 1024 objects. The work represents a substantial advance over existing model-based vision capabilities. Algorithms were developed for determining the translation and rotation of a sensor given only the image flow field data. These are new algorithms, and are much more stable than existing computer vision algorithms for this task. The algorithms might provide independent verification of gyroscopic data, or might be used to compute relative motion with respect to a moving scene object, or may be useful for motion-based segmentation. Our theories explaining the Dempster/Shafer calculus and developing new uncertainty reasoning calculi were extended, and presented at a conference and were incorporated into the Bayesian interpretation of geometric hashing. 'Wavelet Slice Theorem' was developed in several different versions, any of which yields an alternate approach to image formation. The result may well provide a more stable approach to image formation than the standard Fourier-based projection slide theorem, since interpolation of unknown spectra values is better-founded.

  8. Streamlining and core genome conservation among highly divergent members of the SAR11 clade.

    Science.gov (United States)

    Grote, Jana; Thrash, J Cameron; Huggett, Megan J; Landry, Zachary C; Carini, Paul; Giovannoni, Stephen J; Rappé, Michael S

    2012-01-01

    oxidation and sequestration in the oceans. The discovery of small genomes in SAR11 provided crucial support for the theory that streamlining selection can drive genome reduction in low-nutrient environments. Study of isolates in culture revealed atypical organic nutrient requirements that can be attributed to genome reduction, such as conditional auxotrophy for glycine and its precursors, a requirement for reduced sulfur compounds, and evidence for widespread cycling of C1 compounds in marine environments. However, understanding the genetic variation and distribution of such pathways and characteristics like streamlining throughout the group has required the isolation and genome sequencing of diverse SAR11 representatives, an analysis of which we provide here.

  9. Performance evaluation of SAR/GMTI algorithms

    Science.gov (United States)

    Garber, Wendy; Pierson, William; Mcginnis, Ryan; Majumder, Uttam; Minardi, Michael; Sobota, David

    2016-05-01

    There is a history and understanding of exploiting moving targets within ground moving target indicator (GMTI) data, including methods for modeling performance. However, many assumptions valid for GMTI processing are invalid for synthetic aperture radar (SAR) data. For example, traditional GMTI processing assumes targets are exo-clutter and a system that uses a GMTI waveform, i.e. low bandwidth (BW) and low pulse repetition frequency (PRF). Conversely, SAR imagery is typically formed to focus data at zero Doppler and requires high BW and high PRF. Therefore, many of the techniques used in performance estimation of GMTI systems are not valid for SAR data. However, as demonstrated by papers in the recent literature,1-11 there is interest in exploiting moving targets within SAR data. The techniques employed vary widely, including filter banks to form images at multiple Dopplers, performing smear detection, and attempting to address the issue through waveform design. The above work validates the need for moving target exploitation in SAR data, but it does not represent a theory allowing for the prediction or bounding of performance. This work develops an approach to estimate and/or bound performance for moving target exploitation specific to SAR data. Synthetic SAR data is generated across a range of sensor, environment, and target parameters to test the exploitation algorithms under specific conditions. This provides a design tool allowing radar systems to be tuned for specific moving target exploitation applications. In summary, we derive a set of rules that bound the performance of specific moving target exploitation algorithms under variable operating conditions.

  10. Extracting hurricane eye morphology from spaceborne SAR images using morphological analysis

    Science.gov (United States)

    Lee, Isabella K.; Shamsoddini, Ali; Li, Xiaofeng; Trinder, John C.; Li, Zeyu

    2016-07-01

    Hurricanes are among the most destructive global natural disasters. Thus recognizing and extracting their morphology is important for understanding their dynamics. Conventional optical sensors, due to cloud cover associated with hurricanes, cannot reveal the intense air-sea interaction occurring at the sea surface. In contrast, the unique capabilities of spaceborne synthetic aperture radar (SAR) data for cloud penetration, and its backscattering signal characteristics enable the extraction of the sea surface roughness. Therefore, SAR images enable the measurement of the size and shape of hurricane eyes, which reveal their evolution and strength. In this study, using six SAR hurricane images, we have developed a mathematical morphology method for automatically extracting the hurricane eyes from C-band SAR data. Skeleton pruning based on discrete skeleton evolution (DSE) was used to ensure global and local preservation of the hurricane eye shape. This distance weighted algorithm applied in a hierarchical structure for extraction of the edges of the hurricane eyes, can effectively avoid segmentation errors by reducing redundant skeletons attributed to speckle noise along the edges of the hurricane eye. As a consequence, the skeleton pruning has been accomplished without deficiencies in the key hurricane eye skeletons. A morphology-based analyses of the subsequent reconstructions of the hurricane eyes shows a high degree of agreement with the hurricane eye areas derived from reference data based on NOAA manual work.

  11. Automatic analysis of change detection of multi-temporal ERS-2 SAR images by using two-threshold EM and MRF algorithms

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; LUO Lin; JIN Yaqiu

    2004-01-01

    To automatically detect and analyze the surface change in the urban area from multi-temporal SAR images, an algorithm of two-threshold expectation maximum (EM) and Markov random field (MRF) is developed. Difference of the SAR images demonstrates variation of backscattering caused by the surface change all over the image pixels. Two thresholds are obtained by the EM iterative process and categorized to three classes: enhanced scattering, reduced scattering and unchanged regimes. Initializing from the EM result, the iterated conditional modes (ICM) algorithm of the MRF is then used to analyze the detection of contexture change in the urban area. As an example, two images of the ERS-2 SAR in 1996 and 2002 over the Shanghai City are studied.

  12. Hydrodynamics of the groundwater-fed Sian Ka'an Wetlands, Mexico, From InSAR and SAR Data

    DEFF Research Database (Denmark)

    Gondwe, Bibi Ruth Neuman; Hong, S.; Wdowinski, S.

    2008-01-01

    to understand, quantify and predict the wetland dynamics. Remotely sensed Interferometric Synthetic Aperture Radar (InSAR) and Synthetic Aperture Radar (SAR) data offer new opportunities to get hydrodynamic information, which is useful for wetland management. InSAR data produces temporal phase......-changes of the backscattered radar signal, which can be related to the water level changes in vegetated wetlands. SAR data reveals information of surface properties such as the degree of flooding through the amplitude of the backscattered signal. We used RADARSAT-1 InSAR and SAR data to form 36 interferograms and 13 flooding...

  13. Image enhancements of Landsat 8 (OLI) and SAR data for preliminary landslide identification and mapping applied to the central region of Kenya

    Science.gov (United States)

    Mwaniki, M. W.; Kuria, D. N.; Boitt, M. K.; Ngigi, T. G.

    2017-04-01

    Image enhancements lead to improved performance and increased accuracy of feature extraction, recognition, identification, classification and hence change detection. This increases the utility of remote sensing to suit environmental applications and aid disaster monitoring of geohazards involving large areas. The main aim of this study was to compare the effect of image enhancement applied to synthetic aperture radar (SAR) data and Landsat 8 imagery in landslide identification and mapping. The methodology involved pre-processing Landsat 8 imagery, image co-registration, despeckling of the SAR data, after which Landsat 8 imagery was enhanced by Principal and Independent Component Analysis (PCA and ICA), a spectral index involving bands 7 and 4, and using a False Colour Composite (FCC) with the components bearing the most geologic information. The SAR data were processed using textural and edge filters, and computation of SAR incoherence. The enhanced spatial, textural and edge information from the SAR data was incorporated to the spectral information from Landsat 8 imagery during the knowledge based classification. The methodology was tested in the central highlands of Kenya, characterized by rugged terrain and frequent rainfall induced landslides. The results showed that the SAR data complemented Landsat 8 data which had enriched spectral information afforded by the FCC with enhanced geologic information. The SAR classification depicted landslides along the ridges and lineaments, important information lacking in the Landsat 8 image classification. The success of landslide identification and classification was attributed to the enhanced geologic features by spectral, textural and roughness properties.

  14. Tracking lava flow emplacement on the east rift zone of Kilauea, Hawai’i with synthetic aperture radar (SAR) coherence

    Science.gov (United States)

    Dietterich, Hannah R.; Poland, Michael P.; Schmidt, David; Cashman, Katharine V.; Sherrod, David R.; Espinosa, Arkin Tapia

    2012-01-01

    Lava flow mapping is both an essential component of volcano monitoring and a valuable tool for investigating lava flow behavior. Although maps are traditionally created through field surveys, remote sensing allows an extraordinary view of active lava flows while avoiding the difficulties of mapping on location. Synthetic aperture radar (SAR) imagery, in particular, can detect changes in a flow field by comparing two images collected at different times with SAR coherence. New lava flows radically alter the scattering properties of the surface, making the radar signal decorrelated in SAR coherence images. We describe a new technique, SAR Coherence Mapping (SCM), to map lava flows automatically from coherence images independent of look angle or satellite path. We use this approach to map lava flow emplacement during the Pu‘u ‘Ō‘ō-Kupaianaha eruption at Kīlauea, Hawai‘i. The resulting flow maps correspond well with field mapping and better resolve the internal structure of surface flows, as well as the locations of active flow paths. However, the SCM technique is only moderately successful at mapping flows that enter vegetation, which is also often decorrelated between successive SAR images. Along with measurements of planform morphology, we are able to show that the length of time a flow stays decorrelated after initial emplacement is linearly related to the flow thickness. Finally, we use interferograms obtained after flow surfaces become correlated to show that persistent decorrelation is caused by post-emplacement flow subsidence.

  15. The Temporal-Spatial Distribution of Shule River Alluvial Fan Units in China Based on SAR Data and OSL Dating

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    2013-12-01

    Full Text Available Alluvial fans in arid and semi-arid regions can provide important evidence of geomorphic and climatic changes, which reveal the evolution of the regional tectonic activity and environment. Synthetic aperture radar (SAR remote sensing technology, which is sensitive to geomorphic features, plays an important role in quickly mapping alluvial fan units of different ages. In this paper, RADARSAT-2 (Canada’s C-band new-generation radar satellite and ALOS-PALSAR (Japan’s advanced land observing satellite, phased array type L-band SAR sensor data, acquired over the Shule River Alluvial Fan (SRAF, are used to extract backscattering coefficients, scattering mechanism-related information, and polarimetric characteristic parameters. The correlation between these SAR characteristic parameters and fan units of the SRAF of different ages was studied, and the spatial distribution of fan units, since the Late Pleistocene, was extracted based on the Maximum Likelihood classification method. The results prove that (1 some C-band SAR parameters can describe the geomorphic characteristics of alluvial fan units of different ages in the SRAF; (2 SAR data can be used to map the SRAF’s surface between the Late Pleistocene and the Holocene and to extract the spatial distribution of fan units; and (3 the time-spatial distribution of the SRAF can provide valuable information for tectonic and paleoenvironmental research of the study area.

  16. Review of edge detection from polarimetric SAR imagery%极化SAR影像边缘检测综述

    Institute of Scientific and Technical Information of China (English)

    邓少平; 张继贤; 李平湘

    2011-01-01

    极化合成孔径雷达(SAR)图像包含目标丰富的散射信息,在边缘检测中具有重大的潜力.对极化SAR影像边缘检测问题进行了系统的研究,从单极化SAR出发,分析了极化SAR边缘检测问题,对已有的方法进行了分类总结,重点介绍了极化SAR边缘检测的最新进展,指出了当前存在的问题,对极化SAR边缘检测的发展趋势进行了展望.%Polarimetric SAR images include plenty of scattering mechanism information of targets, which are of important potential in edge detection.In this review, edge detection for polarimetric SAR images is studied systematically, the issues are analyzed which are in edge detection of SAR images along with single polarized images,the existing detectors are classified, the newest progress in polarimetric SAR edge detection is introduced and problems are pointed.In the end, conclusions are made and the possible future work is explained.

  17. Improved SAR Amplitude Image Offset Measurements for Deriving Three-Dimensional Coseismic Displacements

    KAUST Repository

    Wang, Teng

    2015-02-03

    Offsets of synthetic aperture radar (SAR) images have played an important role in deriving complete three-dimensional (3-D) surface displacement fields in geoscientific applications. However, offset maps often suffer from multiple outliers and patch-like artifacts, because the standard offset-measurement method is a regular moving-window operation that does not consider the scattering characteristics of the ground. Here, we show that by focusing the offset measurements on predetected strong reflectors, the reliability and accuracy of SAR offsets can be significantly improved. Application to the 2011 Van (Turkey) earthquake reveals a clear deformation signal from an otherwise decorrelated interferogram, making derivation of the 3-D coseismic displacement field possible. Our proposed method can improve mapping of coseismic deformation and other ground displacements, such as glacier flow and landslide movement when strong reflectors exist.

  18. The Potential of Polarimetric and Compact SAR Data in Rice Identification

    Science.gov (United States)

    Shao, Y.; Li, K.; Brisco, B.; Liu, L.; Yang, Z.

    2014-03-01

    Rice is a major food staple in the world, and provides food for more than one-third of the global population. The monitoring and mapping of paddy rice in a timely and efficient manner is very important for governments and decision makers. Synthetic Aperture Radar (SAR) has been proved to be a significant data source in rice monitoring. In this study, RADARSAT-2 polarimetric data were used to simulate compact polarimetry data. The simulated compact data and polarimetric data were then used to evaluate the information content for rice identification. The results indicate that polarimetric SAR can be used for rice identification based on the scattering mechanisms. The compact polarization RH and the RH/RL ratio are very promising for the discrimination of transplanted rice and direct-sown rice. These results require verification in further research.

  19. Scattering theory

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Harald [Technische Univ. Muenchen, Garching (Germany). Physik-Department

    2013-08-01

    Written by the author of the widely acclaimed textbook. Theoretical Atomic Physics Includes sections on quantum reflection, tunable Feshbach resonances and Efimov states. Useful for advanced students and researchers. This book presents a concise and modern coverage of scattering theory. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. The level of abstraction is kept as low as at all possible, and deeper questions related to mathematical foundations of scattering theory are passed by. The book should be understandable for anyone with a basic knowledge of nonrelativistic quantum mechanics. It is intended for advanced students and researchers, and it is hoped that it will be useful for theorists and experimentalists alike.

  20. Scattering theory

    CERN Document Server

    Friedrich, Harald

    2016-01-01

    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  1. The impact of SARS on hospital performance

    Directory of Open Access Journals (Sweden)

    Chen Ran-Chou

    2008-11-01

    Full Text Available Abstract Background During the SARS epidemic, healthcare utilization and medical services decreased significantly. However, the long-term impact of SARS on hospital performance needs to be further discussed. Methods A municipal hospital in Taipei City was shut down for a month due to SARS and then became the designated SARS and infectious disease hospital for the city. This study collected the outpatient, inpatient and emergency service volumes for every year from April to March over four years. Average monthly service amount ± standard deviation were used to compare patient volume for the whole hospital, as well as the outpatient numbers accessing different departments. The ARIMA model of outpatient volume in the pre-SARS year was developed. Results The average monthly service volume of outpatient visits for the base year 2002 was 52317 ± 4204 visits per month, and number for 2003 and the following two years were 55%, 82% and 84% of the base year respectively. The average emergency service volume was 4382 ± 356 visits per month at the base year and this became 45%, 77% and 87% of the base year for the following three years respectively. Average inpatient service volume was 8520 ± 909 inpatient days per month at the base year becoming 43%, 81% and 87% of the base year for the following three years respectively. Only the emergency service volume had recovered to the level of a non-significant difference at the second year after SARS. In addition, the departments of family medicine, metabolism and nephrology reached the 2002 patient number in 2003. The ARIMA (2,1,0 model was the most suitable for outpatient volume in pre-SARS year. The MAPE of the ARIMA (2,1,0 model for the pre-SARS year was 6.9%, and 43.2%, 10.6%, 6.2% for following 3 years. Conclusion This study demonstrates that if a hospital is completely shut down due to SARS or a similar disease, the impact is longer than previous reported and different departments may experience

  2. Possible SARS coronavirus transmission during cardiopulmonary resuscitation.

    Science.gov (United States)

    Christian, Michael D; Loutfy, Mona; McDonald, L Clifford; Martinez, Kennth F; Ofner, Mariana; Wong, Tom; Wallington, Tamara; Gold, Wayne L; Mederski, Barbara; Green, Karen; Low, Donald E

    2004-02-01

    Infection of healthcare workers with the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) is thought to occur primarily by either contact or large respiratory droplet transmission. However, infrequent healthcare worker infections occurred despite the use of contact and droplet precautions, particularly during certain aerosol-generating medical procedures. We investigated a possible cluster of SARS-CoV infections in healthcare workers who used contact and droplet precautions during attempted cardiopulmonary resuscitation of a SARS patient. Unlike previously reported instances of transmission during aerosol-generating procedures, the index case-patient was unresponsive, and the intubation procedure was performed quickly and without difficulty. However, before intubation, the patient was ventilated with a bag-valve-mask that may have contributed to aerosolization of SARS-CoV. On the basis of the results of this investigation and previous reports of SARS transmission during aerosol-generating procedures, a systematic approach to the problem is outlined, including the use of the following: 1) administrative controls, 2) environmental engineering controls, 3) personal protective equipment, and 4) quality control.

  3. A modified algorithm for SAR parallel imaging

    Institute of Scientific and Technical Information of China (English)

    HU Ju-rong; WANG Fei; CAO Ning; LU Hao

    2009-01-01

    Synthetic aperture radar can provide two dimension images by converting the acquired echoed SAR signal to targets coordinate and reflectivity. With the advancement of sophisticated SAR signal processing, more and more SAR imaging methods have been proposed for synthetic aperture radar which works at near field and the Fresnel approximation is not appropriate. Time domain correlation is a kind of digital reconstruction method based on processing the synthetic aperture radar data in the two-dimensional frequency domain via Fourier transform. It reconstructs SAR image via simply correlation without any need for approximation or interpolation. But its high computational cost for correlation makes it unsuitable for real time imaging. In order to reduce the computational burden a modified algorithm about time domain correlation was given in this paper. It also can take full advantage of parallel computations of the imaging processor. Its practical implementation was proposed and the preliminary simulation results were presented. Simulation results show that the proposed algorithm is a computationally efficient way of implementing the reconstruction in real time SAR image processing.

  4. Automated rectification and geocoding of SAR imagery

    Science.gov (United States)

    Kwok, R.; Curlander, J. C.

    1987-01-01

    An automated post-processing system has been developed for rectification and geocoding of SAR (Synthetic Aperture Radar) imagery. The system uses as input a raw uncorrected image from the operational SAR correlator, and produces as a standard output a rectified and geocoded product. The accurate geolocation of SAR image pixels is provided by a spatial transformation model which maps the slant range-azimuth SAR image pixels into their location on a prespecified map grid. This model predicts the geodetic location of each pixel by utilizing: the sensor platform position; a geoid model; the parameters of the data collection system and the processing parameters used in the SAR correlator. Based on their geodetic locations, the pixels are mapped by using the desired cartographic projection equations. This rectification and geocoding technique has been tested with Seasat and SIR-B images. The test results demonstrate absolute location uncertainty of less than 50 m and relative distortion (scale factor and skew) of less than 0.1 percent relative to local variations from the assumed geoid.

  5. Low complexity efficient raw SAR data compression

    Science.gov (United States)

    Rane, Shantanu; Boufounos, Petros; Vetro, Anthony; Okada, Yu

    2011-06-01

    We present a low-complexity method for compression of raw Synthetic Aperture Radar (SAR) data. Raw SAR data is typically acquired using a satellite or airborne platform without sufficient computational capabilities to process the data and generate a SAR image on-board. Hence, the raw data needs to be compressed and transmitted to the ground station, where SAR image formation can be carried out. To perform low-complexity compression, our method uses 1-dimensional transforms, followed by quantization and entropy coding. In contrast to previous approaches, which send uncompressed or Huffman-coded bits, we achieve more efficient entropy coding using an arithmetic coder that responds to a continuously updated probability distribution. We present experimental results on compression of raw Ku-SAR data. In those we evaluate the effect of the length of the transform on compression performance and demonstrate the advantages of the proposed framework over a state-of-the-art low complexity scheme called Block Adaptive Quantization (BAQ).

  6. ICAO's anti-SARS airport activities.

    Science.gov (United States)

    Finkelstein, Silvio; Curdt-Christiansen, Claus M

    2003-11-01

    To prevent SARS from spreading through air travel and in order to rebuild the confidence of the traveling public in the safety of air travel, ICAO has set up an "Anti-SARS Airport Evaluation Project." The first phase of this project was to develop a set of protective measures for international airports in affected areas to adopt and implement and then to send out, on the request of Contracting States, a team of inspectors to evaluate and assess airports and issue a "statement of evaluation" that the airport inspected complies with the ICAO anti-SARS protective measures. In cooperation with the World Health Organization (WHO), the first part of phase 1 was completed in early June this year, and the second part of phase 1 followed soon after. By mid-July, five international airports in Southeast Asia had been inspected and found to be in full compliance with the ICAO anti-SARS protective measures. The success of this ICAO project is believed to have contributed significantly to the recovery of international air travel and related industries now taking place. Phase 2 of the project is now being developed. It is aimed at preventing a resurgence of SARS, but it also contains elements to make the methodology developed applicable to future outbreaks of any other communicable disease in which the mode of transmission could involve aviation and/or the need to prevent the spread of the disease by air travel.

  7. Monitoring of ground surface deformation in mining area with InSAR technique%利用InSAR技术监测矿区地表形变

    Institute of Scientific and Technical Information of China (English)

    朱建军; 邢学敏; 胡俊; 李志伟

    2011-01-01

    The application status and research progress of InSAR technique in the monitoring of the ground surface deformation in mining area were introduced. Firstly, the advantages of D-InSAR technique were analyzed by comparing to the traditional surveying methods. Then, the limitations of D-InSAR in the mining deformation detection were described. According to the limitations of the traditional D-InSAR method, the advanced InSAR technique, e.g., small baseline subset (SBAS), permanent scatterer (PS) and corner reflector (CR) techniques were discussed. Using real mining subsidence monitoring as example, the characteristics and application status of those advanced InSAR techniques were studied, and the key problems still existing in the current research were summarized. Finally, it is indicated that the development trend of InSAR monitoring surface deformation in mining area is the combination of advanced InSAR and high-resolution SAR images.%介绍了InSAR技术在矿区地表形变监测中的应用现状及进展,分析了D-InSAR技术相比于传统测量手段的优势,并指出其在矿区地表形变监测中的不足.针对传统D-InSAR技术的局限性,重点讨论了短基线(SBAS)、永久散射体(PS)和角反射器(CR)等高级差分干涉技术,并结合矿区沉降监测实例,分析了其特点与应用现状,讨论了现有研究中仍存在的问题.高级InSAR技术和高分辨率SAR影像的结合将是矿区地表形变监测的发展趋势.

  8. Paranormal belief and attributional style.

    Science.gov (United States)

    Dudley, R T; Whisnand, E A

    2000-06-01

    52 college students completed Tobacyk's 1988 Revised Paranormal Belief Scale and Peterson, Semmel, von Baeyer, Abramson, Metalsky, and Seligman's 1982 Attributional Style Questionnaire. Analysis showed significantly higher depressive attributional styles among high scorers on paranormal phenomena than low scorers.

  9. Satellite SAR data assessment for Silk Road archaeological prospection

    Science.gov (United States)

    Chen, Fulong; Lasaponara, Rosa; Masini, Nicola; Yang, Ruixia

    2015-04-01

    direction of observed targets is beneficial for improved detection of potential linear remains (e.g. Great Wall in Han-dynasty surrounding the Yumen Frontier Pass) owing to the formation of dihedral and helix scatterings based on the theory of radar physics. Morevorer, spatial resolution of multi-mode SAR images for archaeology was compared in the sites of Niya, Yumen Frontier Pass and suspected protectorate of the western regions. Results indicated that high resolution tended to easier detection of ancient targets through the identification of backscattering anomalies. Finally, interferometric analysis was also evaluated to provide complementary information rather than the backscattering. The variation of coherence is closely related to the physical parameters of observed surface, e.g. soil moisture, mild-relief as well as materials; and consequently it is useful for the relic feature enhancement and identification, validated by the PALSAR coherence images in Niya site. Acknowledgement This research was performed within the framework of the project "Smart management of cultural heritage sites in Italy and China: Earth Observation and pilot projects", funded by the Italian Ministry of Foreign Affairs and the Hundred Talents Program of the Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences (Y2ZZ27101B). The PALSAR data were provided by the European Space Agency to the authors through the Category-1 Project Id. 28640. Reference [1] Lasaponara R., Masini N. 2013, Satellite Synthetic Aperture Radar in Archaeology and Cultural Landscape: An Overview. Archaeological Prospection, 20, 71-78, doi: 10.1002/arp.1452 [2] Chen F., Masini N., Yang R., Milillo P., Feng D., Lasaponara R., 2015 A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data. Remote Sens. 2015, 7, 24-50; doi:10.3390/rs70100024. [3] Cigna, F.; Tapete, D.; Lasaponara, R.; Masini, N. Amplitude change detection with Envisat ASAR to image the cultural landscape

  10. Detecting sparse earthquake damages in high density urban settlements by VHR SAR data

    Science.gov (United States)

    Anniballe, R.; Bignami, C.; Chini, M.; Pierdicca, N.; Stramondo, S.

    2014-10-01

    Nowadays, space-borne Synthetic Aperture Radar (SAR) sensors, can achieve spatial resolutions in the order of 1 m. However, the exploitation of SAR at very high resolution (VHR) for detecting sparse and isolated damages in urban areas, caused by earthquakes, is still a challenging task. Within urban settlements, the scattering mechanisms are extremely complex and simple change detection analyses or classification procedures can hardly be performed. In this work the 2009, L'Aquila (Italy), earthquake has been considered as case study. Despite about 300 people were killed by the earthquake, few buildings were completely collapsed, and many others were heavily/partially damaged, resulting in a quite sparse damage distribution. We have visually analyzed pairs of VHR SAR data acquired by COSMO-SkyMed satellites, in SPOTLIGHT mode, before and after the earthquake. Such analyses were performed to understand the SAR response of damaged structures surrounded by unaffected buildings, with the aim to identify possible strategies to map the damaged buildings by using an automatic classification procedure. The preliminary analyses based on RGB images, generated by combining pre- and post-event backscattering images, allowed us to figure out how the completely collapsed and the partially damaged buildings are characterized in the SAR response. These outcomes have been taken into account to set up a decision tree algorithm (DTA). Decision rules and related thresholds were identified by statistically analyzing the values of backscattering and derived features. This study point out that many pieces of information and discrimination rules must be exploited to obtain reliable results when dealing with non-extensive and sparse damage within a dense urban settlement.

  11. A very bright SAR arc: implications for extreme magnetosphere-ionosphere coupling

    Directory of Open Access Journals (Sweden)

    J. Baumgardner

    2008-01-01

    Full Text Available In contrast to the polar aurora visible during geomagnetic storms, stable auroral red (SAR arcs offer a sub-visual manifestation of direct magnetosphere-ionosphere (M-I coupling at midlatitudes. The SAR arc emission at 6300 Å is driven by field-aligned magnetospheric energy transport from ring current/plasmapause locations into the ionosphere-thermosphere system. The first SAR arc was observed at the dawn of the space age (1956, and the typical brightness levels and occurrence patterns obtained from subsequent decades of observations appear to be consistent with the downward heat conduction theory, i.e., heated ambient F-layer electrons excite oxygen atoms to produce a spectrally pure emission. On very rare occasions, a SAR arc has been reported to be at brightness levels visible to the naked eye. Here we report on the first case of a very bright SAR arc (~13 kilo-Rayleighs observed by four diagnostic systems that sampled various aspects of the sub-auroral domain near Millstone Hill, MA, on the night of 29 October 1991: an imaging spectrograph, an all-sky camera, an incoherent scatter radar (ISR, and a DMSP satellite. Simulations of emission using the ISR and DMSP data with the MSIS neutral atmosphere succeed in reproducing the brightness levels observed. This provides a robust confirmation of M-I coupling theory in its most extreme aeronomic form within the innermost magnetosphere (L~2 during a rare superstorm event. The unusually high brightness value appears to be due to the rare occurrence of the heating of dense ionospheric plasma just equatorward of the trough/plasmapause location, in contrast to the more typical heating of the less dense F-layer within the trough.

  12. L-Band Polarimetric SAR Signatures of Lava Flows in the Northern Volcanic Zone, Iceland

    DEFF Research Database (Denmark)

    Dierking, Wolfgang; Haack, Henning

    1998-01-01

    of polarimetric L-band radar signatures observed over different lava flows located in the Northern Volcanic Zone in Iceland. Intensity images with a high spatial resolution are well suited for geological interpretation, both in the discrimination of lava flows from the surrounding terrain and in the recognition......Studies of radar scattering signatures typical for lava surfaces are needed in order to interprete SAR images of volcanic terrain on the Earth and on other planets, and to establish a physical basis for the choice of optimal radar configurations for geological mapping. The authors focus on a study...... of different morphologic types within a flow. The largest contrasts are observed at cross-polarization. The phase difference between the VV- and HH-channels may provide information about a vegetation cover on the lava. The radar signal scattered from the flows is dominated by surface scattering contributions...

  13. Exploration of Advanced Bistatic SAR Experiments (in English

    Directory of Open Access Journals (Sweden)

    Deng Yun-kai

    2014-02-01

    Full Text Available This study concentrates on the results of several advanced hybrid bistatic SAR experiments. The hybrid bistatic configuration applies to the case in which the transmitter and receiver are mounted on different types of platforms, e.g., spaceborne/airborne, airborne/stationary, spaceborne/stationary, and so on. Several hybrid bistatic SAR experiments have been performed successfully, i.e., TerraSAR-X/PAMIR, PAMIR/stationary, and TerraSAR-X/stationary. Furthermore, Multiple Baseline Interferometry SAR (MB-InSAR and Digital Beam-Forming (DBF technologies are validated in the TerraSAR-X/stationary configuration. Note that the DBF experiment results based on the spaceborne illuminator are discussed for the first time in SAR community. In addition, this paper emphasizes imaging geometry, image analysis, and focusing results.

  14. Application of SAR Imagery in Submarine Topography Surveys

    Institute of Scientific and Technical Information of China (English)

    张宁川; 梁开龙; 桂力民

    2004-01-01

    An important research area in oceanographic surveying and mapping is to obtain submarine topography by remote sensing technique, especially by SAR imagery. In this article, problems related to SAR imagery are analyzed to provide references for the further research.

  15. Method of Monitoring Urban Area Deformation Based on Differential TomoSAR

    Directory of Open Access Journals (Sweden)

    WANG Aichun

    2016-12-01

    Full Text Available While the use of differential TomoSAR based on compressive sensing (CS makes it possible to solve the layover problem and reconstruct the deformation information of an observed urban area scene acquired by moderate-high resolution SAR satellite, the performance of the reconstruction decreases for a sparse and structural observed scene due to ignoring the structural characteristics of the observed scene. To deal with this issue, the method for differential SAR tomography based on Khatri-Rao subspace and block compressive sensing (KRS-BCS is proposed. The proposed method changes the reconstruction of the sparse and structural observed scene into a BCS problem under Khatri-Rao subspace, using the structure information of the observed scene and Khatri-Rao product property of the reconstructed observation matrix for differential TomoSAR, such that the KRS-BCS problem is efficiently solved with a block sparse l1/l2 norm optimization signal model, and the performance of resolution capability and reconstruction estimation is compared and analyzed qualitatively and quantitatively by the theoretical analysis and the simulation experiments, all of the results show the propose KRS-BCS method practicably overcomes the problems of CS method, as well as, quite maintains the high resolution characteristics, effectively reduces the probability of false scattering target and greatly improves the reconstruction accurate of scattering point. Finally, the application is taking the urban area of the Mobara(in Chiba, Japan as the test area and using 34 ENVISAT-ASAR images, the accuracy is verifying with the reference deformations derived from first level point data and GPS tracking data, the results show the trend is consistent and the overall deviation is small between reconstruction deformations of the propose KRS-BCS method and the reference deformations, and the accuracy is high in the estimation of the urban area deformation.

  16. SARS Transmission among Hospital Workers in Hong Kong

    OpenAIRE

    Lau, Joseph T F; Fung, Kitty S.; Wong, Tze Wai; Kim, Jean H; Wong, Eric; Chung, Sydney; Ho, Deborah; Chan, Louis Y; Lui, S F; Cheng, Augustine

    2004-01-01

    Despite infection control measures, breakthrough transmission of severe acute respiratory syndrome (SARS) occurred for many hospital workers in Hong Kong. We conducted a case-control study of 72 hospital workers with SARS and 144 matched controls. Inconsistent use of goggles, gowns, gloves, and caps was associated with a higher risk for SARS infection (unadjusted odds ratio 2.42 to 20.54, p < 0.05). The likelihood of SARS infection was strongly associated with the amount of personal protectio...

  17. PRF Ambiguity Detrmination for Radarsat ScanSAR System

    Science.gov (United States)

    Jin, Michael Y.

    1998-01-01

    PRF ambiguity is a potential problem for a spaceborne SAR operated at high frequencies. For a strip mode SAR, there were several approaches to solve this problem. This paper, however, addresses PRF ambiguity determination algorithms suitable for a burst mode SAR system such as the Radarsat ScanSAR. The candidate algorithms include the wavelength diversity algorithm, range look cross correlation algorithm, and multi-PRF algorithm.

  18. Exploration of Advanced Bistatic SAR Experiments (in English)

    OpenAIRE

    Deng Yun-kai; Robert Wang

    2014-01-01

    This study concentrates on the results of several advanced hybrid bistatic SAR experiments. The hybrid bistatic configuration applies to the case in which the transmitter and receiver are mounted on different types of platforms, e.g., spaceborne/airborne, airborne/stationary, spaceborne/stationary, and so on. Several hybrid bistatic SAR experiments have been performed successfully, i.e., TerraSAR-X/PAMIR, PAMIR/stationary, and TerraSAR-X/stationary. Furthermore, Multiple Baseline Interferomet...

  19. Verification of L-band SAR calibration

    Science.gov (United States)

    Larson, R. W.; Jackson, P. L.; Kasischke, E.

    1985-01-01

    Absolute calibration of a digital L-band SAR system to an accuracy of better than 3 dB has been verified. This was accomplished with a calibration signal generator that produces the phase history of a point target. This signal relates calibration values to various SAR data sets. Values of radar cross-section (RCS) of reference reflectors were obtained using a derived calibration relationship for the L-band channel on the ERIM/CCRS X-C-L SAR system. Calibrated RCS values were compared to known RCS values of each reference reflector for verification and to obtain an error estimate. The calibration was based on the radar response to 21 calibrated reference reflectors.

  20. Instantaneous Frequency Attribute Comparison

    Science.gov (United States)

    Yedlin, M. J.; Margrave, G. F.; Ben Horin, Y.

    2013-12-01

    The instantaneous seismic data attribute provides a different means of seismic interpretation, for all types of seismic data. It first came to the fore in exploration seismology in the classic paper of Taner et al (1979), entitled " Complex seismic trace analysis". Subsequently a vast literature has been accumulated on the subject, which has been given an excellent review by Barnes (1992). In this research we will compare two different methods of computation of the instantaneous frequency. The first method is based on the original idea of Taner et al (1979) and utilizes the derivative of the instantaneous phase of the analytic signal. The second method is based on the computation of the power centroid of the time-frequency spectrum, obtained using either the Gabor Transform as computed by Margrave et al (2011) or the Stockwell Transform as described by Stockwell et al (1996). We will apply both methods to exploration seismic data and the DPRK events recorded in 2006 and 2013. In applying the classical analytic signal technique, which is known to be unstable, due to the division of the square of the envelope, we will incorporate the stabilization and smoothing method proposed in the two paper of Fomel (2007). This method employs linear inverse theory regularization coupled with the application of an appropriate data smoother. The centroid method application is straightforward and is based on the very complete theoretical analysis provided in elegant fashion by Cohen (1995). While the results of the two methods are very similar, noticeable differences are seen at the data edges. This is most likely due to the edge effects of the smoothing operator in the Fomel method, which is more computationally intensive, when an optimal search of the regularization parameter is done. An advantage of the centroid method is the intrinsic smoothing of the data, which is inherent in the sliding window application used in all Short-Time Fourier Transform methods. The Fomel technique

  1. Implementing the HDF-EOS5 software library for data products in the UNAVCO InSAR archive

    Science.gov (United States)

    Baker, Scott; Meertens, Charles; Crosby, Christopher

    2017-04-01

    final data products. A metadata attribute is added to the HDF-EOS5 file when a DOI is minted for a data product. These data products are searchable through the SSARA federated query providing access to processed data for both expert and non-expert InSAR users. The archive facilitates timely distribution of processed data with particular importance for geohazards and event response.

  2. InSAR imagery pattern matching validation for landslide assessment

    Science.gov (United States)

    Serbulea, Manole-Stelian; Gogu, Radu; Teleaga, Delia; Marcel Manoli, Daniel; Priceputu, Adrian; Gaitanaru, Dragos Stefan; Ungureanu, Constantin; Anghel, Alexandra; Andronic, Adrian; Niculescu, Alexandru; Liviu Bugea, Adrian

    2013-04-01

    The need for identifying over large areas ongoing instability phenomena and spotting the old ones pushed the boundaries of geotechnical engineering from numerical modeling and point-wise in-situ measurements towards geodesic and geographic sciences. Regardless of the ground-based monitoring techniques' precision and reliability, a larger scale monitoring is often useful to either better correlate the scattered results or to identify additional monitoring points. Using aerial ortho-photogrammetry and site visit recognition represent a good, yet costly method to obtain qualitative information about old inactive landslides. A more suitable approach is using ground-based or satellite radar interferometry (InSAR). The obvious disadvantage of the ground-based system is that the monitoring has to be carried out on a predetermined site while the space-borne system may be set to collect information from various sites in range by each successive passing. The quantitative results acquired through the means of InSAR provide a precise set of information regarding the soil surface displacement, with high accuracy and reliability. They provide a great means of identifying danger zones as well as a way of calibrating and augmenting the classical monitoring techniques. This work describes the possibility of integrating the InSAR measurements with the ground monitoring techniques to identify landslide occurrence hazard and reveal the whole of affected areas even when minute symptoms develop. One of the objectives is to propose InSAR monitoring as a fast and efficient mapping tool to help authorities minimize the damage produced by landslides. It can also provide engineers and scientists additional information to further study landslides dynamics phenomena (such as propagation). Interferometry on SAR data uses phase values from two radar images. When a point changes position, the distance between it and the sensor alters, modifying the phase of the signal. This change is used to

  3. Physiological attributes of triathletes.

    Science.gov (United States)

    Suriano, R; Bishop, D

    2010-05-01

    Triathlons of all distances can be considered endurance events and consist of the individual disciplines of swimming, cycling and running which are generally completed in this sequential order. While it is expected that elite triathletes would possess high values for submaximal and maximal measures of aerobic fitness, little is known about how these values compare with those of single-sport endurance athletes. Earlier reviews, conducted in the 1980s, concluded that triathletes possessed lower V(O2(max)) values than other endurance athletes. An update of comparisons is of interest to determine if the physiological capacities of elite triathletes now reflect those of single-sport athletes or whether these physiological capacities are compromised by the requirement to cross-train for three different disciplines. It was found that although differences in the physiological attributes during swimming, cycling and running are evident among triathletes, those who compete at an international level possess V(O2(max)) values that are indicative of success in endurance-based individual sports. Furthermore, various physiological parameters at submaximal workloads have been used to describe the capacities of these athletes. Only a few studies have reported the lactate threshold among triathletes with the majority of studies reporting the ventilatory threshold. Although observed differences among triathletes for both these submaximal measures are complicated by the various methods used to determine them, the reported values for triathletes are similar to those for trained cyclists and runners. Thus, from the limited data available, it appears that triathletes are able to obtain similar physiological values as single-sport athletes despite dividing their training time among three disciplines.

  4. Efficacy of various disinfectants against SARS coronavirus.

    Science.gov (United States)

    Rabenau, H F; Kampf, G; Cinatl, J; Doerr, H W

    2005-10-01

    The recent severe acute respiratory syndrome (SARS) epidemic in Asia and Northern America led to broad use of various types of disinfectant in order to control the public spread of the highly contagious virus. However, only limited data were available to demonstrate their efficacy against SARS coronavirus (SARS-CoV). We therefore investigated eight disinfectants for their activity against SARS-CoV according to prEN 14476. Four hand rubs were tested at 30s (Sterillium, based on 45% iso-propanol, 30% n-propanol and 0.2% mecetronium etilsulphate; Sterillium Rub, based on 80% ethanol; Sterillium Gel, based on 85% ethanol; Sterillium Virugard, based on 95% ethanol). Three surface disinfectants were investigated at 0.5% for 30 min and 60 min (Mikrobac forte, based on benzalkonium chloride and laurylamine; Kohrsolin FF, based on benzalkonium chloride, glutaraldehyde and didecyldimonium chloride; Dismozon pur, based on magnesium monoperphthalate), and one instrument disinfectant was investigated at 4% for 15 min, 3% for 30 min and 2% for 60 min [Korsolex basic, based on glutaraldehyde and (ethylenedioxy)dimethanol]. Three types of organic load were used: 0.3% albumin, 10% fetal calf serum, and 0.3% albumin with 0.3% sheep erythrocytes. Virus titres were determined by a quantitative test (endpoint titration) in 96-well microtitre plates. With all tested preparations, SARS-CoV was inactivated to below the limit of detection (reduction factor mostly > or =4), regardless of the type of organic load. In summary, SARS-CoV can be inactivated quite easily with many commonly used disinfectants.

  5. Severe Acute Respiratory Syndrome (SARS) Prevention in Taiwan

    Science.gov (United States)

    Liu, Hsueh-Erh

    2004-01-01

    Severe Acute Respiratory Syndrome (SARS) is a newly identified respiratory disease that threatened Taiwan between April 14 and July 5, 2003. Chang Gung University experienced various SARS-related episodes, such as the postponement of classes for 7 days, the reporting of probable SARS cases, and the isolation of students under Level A and B…

  6. Progress Toward Demonstrating SAR Monitoring of Chinese Seas

    Science.gov (United States)

    Huang, Weigen; Johannessen, Johnny; Alpers, Werner; Yang, Jingsong

    2010-12-01

    "Demonstrating SAR monitoring of Chinese seas" is a project of the ESA-MOST Dragon 2 program. This paper presents the progress of the project. Retrieval algorithms for SAR monitoring of sea surface currents, oceanic internal waves, sea surface winds, oil spills and ships have been advanced. SAR monitoring of Chinese seas in near-real-time is now in demonstration phase.

  7. (Q)SARs for human toxicological endpoints: a literature search

    NARCIS (Netherlands)

    Hulzebos E; Schielen P; Masilankiewicz L; CSR; NVIC

    1999-01-01

    Het doel van dit rapport is het beschrijven van humaan toxicologische SARs (structuur-activiteitsrelaties) die beschikbaar zijn in de literatuur alsmede de SARs die gebruikt worden door de US EPA (Environmental Protection Agency). De implementatie van het gebruik van SARs voor de effect assessment

  8. (Q)SARs for human toxicological endpoints: a literature search

    NARCIS (Netherlands)

    Hulzebos E; Schielen P; Masilankiewicz L; CSR; NVIC

    1999-01-01

    The goal here was to describe human toxicological SARs (structure-activity relationships) available in the literature and used by the US EPA (Environmental Protection Agency). The CSR laboratory investigated implementation of SARs for the effect assessment. SARs correlate the molecular structure

  9. InSAR Used for Subsidence Monitoring of Mining Area OKR, Czech Republic

    Science.gov (United States)

    Lazecky, Milan

    2010-03-01

    The abilities of InSAR processing techniques to detect and monitor subsidence of mining areas were already proved in several works, e.g. of Dr. Perski that used them in Poland. As an ESA project of VSB-TU Ostrava using data from ERS 1,2 and Envisat ASAR, the InSAR has been applied also for the Northern Moravian OKR region in Czech Republic, a region with a long black coal mining history. Mining activities in this area have caused damages and destructions of many buildings, tramlines etc. The problem is still actual, even that only 4 mines are active, since 2007. Via the InSAR processing, an evolution of subsidence during last 10 years is monitored using the Doris software. Due to highly decorrelated interferograms created from newer data (since 2001), the actual state is hardly interpretable though. The critical subsiding objects were detected by pointwise multitemporal InSAR techniques (MT- InSAR) - the permanent scatterers and small baselines methods using the StaMPS software. The results were compared with the in-situ levelling revealing that the estimated rate of subsidence was underestimated. Only the ERS-2 data from period 1999-2000 were successfully used in these advanced InSAR techniques to achieve some reasonable results. Because of gyroscopes failure of ERS-2, the data since January 2001 couldn't be processed successfully by StaMPS due to big differences in the Doppler centroid frequencies of each images - an abortive result of a small baselines method attempt can be presented. Because of used long- wall mining method, that evokes spatial movement of subsidence epicenters in time, a longer time period of dataset usable in MT-InSAR would decrease the processing merit (the character of subsidence in the area is not pointwise in longer time period). This project will continue with a processing of newer datasets to achieve a complete overview of terrain changes in the mining area during the last decade.

  10. Estimating IMU heading error from SAR images.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2009-03-01

    Angular orientation errors of the real antenna for Synthetic Aperture Radar (SAR) will manifest as undesired illumination gradients in SAR images. These gradients can be measured, and the pointing error can be calculated. This can be done for single images, but done more robustly using multi-image methods. Several methods are provided in this report. The pointing error can then be fed back to the navigation Kalman filter to correct for problematic heading (yaw) error drift. This can mitigate the need for uncomfortable and undesired IMU alignment maneuvers such as S-turns.

  11. Fighting SARS in grand collaboration: Our strategies

    Institute of Scientific and Technical Information of China (English)

    钟南山

    2003-01-01

    @@ The war without gunsmoke against severe acute respiratory syndrome(SARS), a type of communicable atypical pneumonia (AP), is now outspreading throughout China and many other countries in the world. So far, the disease has swept through nearly 30 countries and regions. Globally, more than 7,000 people have been infected, with a total of over 550 deaths. More than 5,000 people in mainland of China have been affected and approximately 200 have died. In some areas, the current situation remains at large. It is estimated that SARS has caused a financial loss of over 30 billion dollars (US) worldwide.

  12. Stochastic dynamic model of SARS spreading

    Institute of Scientific and Technical Information of China (English)

    SHI Yaolin

    2003-01-01

    Based upon the simulation of the stochastic process of infection, onset and spreading of each SARS patient, a system dynamic model of SRAS spreading is constructed. Data from Vietnam is taken as an example for Monte Carlo test. The preliminary results indicate that the time-dependent infection rate is the most important control factor for SARS spreading. The model can be applied to prediction of the course with fluctuations of the epidemics, if the previous history of the epidemics and the future infection rate under control measures are known.

  13. Science data collection with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Woelders, Kim; Madsen, Søren Nørvang

    1996-01-01

    Discusses examples on the use of polarimetric SAR in a number of Earth science studies. The studies are presently being conducted by the Danish Center for Remote Sensing. A few studies of the European Space Agency's EMAC programme are also discussed. The Earth science objectives are presented, an......, and the potential of polarimetric SAR is discussed and illustrated with data collected by the Danish airborne EMISAR system during a number of experiments in 1994 and 1995. The presentation will include samples of data acquired for the different studies...

  14. Strictness Analysis for Attribute Grammars

    DEFF Research Database (Denmark)

    Rosendahl, Mads

    1992-01-01

    Attribute grammars may be seen as a (rather specialised) lazy or demand-driven programming language. The ``programs'' in this language take text or parse trees as input and return values of the synthesised attributes to the root as output. From this observation we establish a framework for abstract...... interpretation of attribute grammars. The framework is used to construct a strictness analysis for attribute grammars. Results of the analysis enable us to transform an attribute grammar such that attributes are evaluated during parsing, if possible. The analysis is proved correct by relating it to a fixpoint...... semantics for attribute grammars. An implementation of the analysis is discussed and some extensions to the analysis are mentioned....

  15. Studies of microwave scattering and canopy architecture for boreal forests

    Science.gov (United States)

    Lockhart, G. Lance; Gogineni, S. P.

    1995-01-01

    This is an annual report on the project titled 'Study of Microwave Scattering and Canopy Architecture for Boreal Forests.' The objectives of our work are to study the interaction of microwave signals with vegetation components and to determine the radar's ability to provide accurate estimates of biophysical parameters such as biomass. Our research is aimed at refining the current microwave models and using these improvements to facilitate more accurate interpretations of SAR (synthetic aperture radar) imagery.

  16. Superradiant Forward Scattering in Multiple Scattering

    CERN Document Server

    Chabe, Julien; Bienaime, Tom; Bachelard, Romain; Piovella, Nicola; Kaiser, Robin

    2012-01-01

    We report on an interference effect in multiple scattering by resonant scatterers resulting in enhanced forward scattering, violating Ohm's law for photons. The underlying mechanism of this wave effect is superradiance, which we have investigated using cold atoms as a toy model. We present numerical and experimental evidences for this superradiant forward scattering, which is robust against disorder and configuration averaging.

  17. GOTCHA experience report: three-dimensional SAR imaging with complete circular apertures

    Science.gov (United States)

    Ertin, Emre; Austin, Christian D.; Sharma, Samir; Moses, Randolph L.; Potter, Lee C.

    2007-04-01

    We study circular synthetic aperture radar (CSAR) systems collecting radar backscatter measurements over a complete circular aperture of 360 degrees. This study is motivated by the GOTCHA CSAR data collection experiment conducted by the Air Force Research Laboratory (AFRL). Circular SAR provides wide-angle information about the anisotropic reflectivity of the scattering centers in the scene, and also provides three dimensional information about the location of the scattering centers due to a non planar collection geometry. Three dimensional imaging results with single pass circular SAR data reveals that the 3D resolution of the system is poor due to the limited persistence of the reflectors in the scene. We present results on polarimetric processing of CSAR data and illustrate reasoning of three dimensional shape from multi-view layover using prior information about target scattering mechanisms. Next, we discuss processing of multipass (CSAR) data and present volumetric imaging results with IFSAR and three dimensional backprojection techniques on the GOTCHA data set. We observe that the volumetric imaging with GOTCHA data is degraded by aliasing and high sidelobes due to nonlinear flightpaths and sparse and unequal sampling in elevation. We conclude with a model based technique that resolves target features and enhances the volumetric imagery by extrapolating the phase history data using the estimated model.

  18. Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis

    NARCIS (Netherlands)

    Hamming, [No Value; Timens, W; Bulthuis, MLC; Lely, AT; Navis, GJ; van Goor, H

    2004-01-01

    Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin-converting enzyme 2 (ACE2) has been identifie

  19. Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis

    NARCIS (Netherlands)

    Hamming, [No Value; Timens, W; Bulthuis, MLC; Lely, AT; Navis, GJ; van Goor, H

    Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin-converting enzyme 2 (ACE2) has been

  20. SARS knowledge, perceptions, and behaviors: a comparison between Finns and the Dutch during the SARS outbreak in 2003

    NARCIS (Netherlands)

    Vartti, A.M.; Oenema, A.; Schreck, M.; Uutela, A.; Zwart, de O.; Brug, J.; Aro, A.R.

    2009-01-01

    BACKGROUND: The SARS outbreak served to test both local and international outbreak management and risk communication practices. PURPOSE: The study compares SARS knowledge, perceptions, behaviors, and information between Finns and the Dutch during the SARS outbreak in 2003. METHOD: The participants

  1. Feasibility of sea ice typing with synthetic aperture radar (SAR): Merging of Landsat thematic mapper and ERS 1 SAR satellite imagery

    Science.gov (United States)

    Steffen, Konrad; Heinrichs, John

    1994-01-01

    Earth Remote-Sensing Satellite (ERS) 1 synthetic aperture radar (SAR) and Landsat thematic mapper (TM) images were acquired for the same area in the Beaufort Sea, April 16 and 18, 1992. The two image pairs were colocated to the same grid (25-m resolution), and a supervised ice type classification was performed on the TM images in order to classify ice free, nilas, gray ice, gray-white ice, thin first-year ice, medium and thick first-year ice, and old ice. Comparison of the collocated SAR pixels showed that ice-free areas can only be classified under calm wind conditions (less than 3 m/s) and for surface winds greater than 10 m/s based on the backscattering coefficient alone. This is true for pack ice regions during the cold months of the year where ice-free areas are spatially limited and where the capillary waves that cause SAR backscatter are dampened by entrained ice crystals. For nilas, two distinct backscatter classes were found at -17 dB and at -10 dB. The higher backscattering coefficient is attributed to the presence of frost flowers on light nilas. Gray and gray-white ice have a backscatter signature similar to first-year ice and therefore cannot be distinguished by SAR alone. First-year and old ice can be clearly separated based on their backscattering coefficient. The performance of the Geophysical Processor System ice classifier was tested against the Landsat derived ice products. It was found that smooth first-year ice and rough first-year ice were not significantly different in the backscatter domain. Ice concentration estimates based on ERS 1 C band SAR showed an error range of 5 to 8% for high ice concentration regions, mainly due to misclassified ice-free and smooth first-year ice areas. This error is expected to increase for areas of lower ice concentration. The combination of C band SAR and TM channels 2, 4, and 6 resulted in ice typing performance with an estimated accuracy of 90% for all seven ice classes.

  2. Building damage assessment using a single post-earthquake PolSAR image: a case of the 2010 Yushu earthquake

    Science.gov (United States)

    Zhai, Wei; Zeng, Wenhao

    2017-02-01

    Earthquakes are one of the most destructive natural disasters. Efficiently and quickly acquiring building earthquake damage information can help to reduce the casualties after an earthquake. In this paper, building damage information is extracted using a single post-earthquake PolSAR image. In PolSAR images, since the undamaged oriented buildings characterized by volume scattering with weaker scattering power are very similar to collapsed buildings, the collapsed buildings are difficult to extract accurately. In this paper, the difference in the relative contribution change rate of scattering components before and after polarization orientation angle (POA) compensation is proposed to enhance the difference between collapsed buildings and oriented buildings, in order that the collapsed buildings can be extracted more accurately. The “4.14” Yushu earthquake, which occurred in Yushu County, Qinghai province of China, is used as the case study to test the proposed method, and an airborne high-resolution PolSAR image of the urban region of Yushu County is used in the experiment. The experimental results show that the accuracy of building damage information extraction can be improved by the use of the proposed method, compared with the traditional polarimetric classification.

  3. Quantum-SAR extension of the spectral-SAR algorithm: application to polyphenolic anticancer bioactivity.

    Science.gov (United States)

    Putz, Mihai V; Putz, Ana-Maria; Lazea, Marius; Ienciu, Luciana; Chiriac, Adrian

    2009-03-01

    Aiming to assess the role of individual molecular structures in the molecular mechanism of ligand-receptor interaction correlation analysis, the recent Spectral-SAR approach is employed to introduce the Quantum-SAR (QuaSAR) "wave" and "conversion factor" in terms of difference between inter-endpoint inter-molecular activities for a given set of compounds; this may account for inter-conversion (metabolization) of molecular (concentration) effects while indicating the structural (quantum) based influential/detrimental role on bio-/eco- effect in a causal manner rather than by simple inspection of measured values; the introduced QuaSAR method is then illustrated for a study of the activity of a series of flavonoids on breast cancer resistance protein.

  4. Quantum-SAR Extension of the Spectral-SAR Algorithm. Application to Polyphenolic Anticancer Bioactivity

    Science.gov (United States)

    Putz, Mihai V.; Putz, Ana-Maria; Lazea, Marius; Ienciu, Luciana; Chiriac, Adrian

    2009-01-01

    Aiming to assess the role of individual molecular structures in the molecular mechanism of ligand-receptor interaction correlation analysis, the recent Spectral-SAR approach is employed to introduce the Quantum-SAR (QuaSAR) “wave” and “conversion factor” in terms of difference between inter-endpoint inter-molecular activities for a given set of compounds; this may account for inter-conversion (metabolization) of molecular (concentration) effects while indicating the structural (quantum) based influential/detrimental role on bio-/eco- effect in a causal manner rather than by simple inspection of measured values; the introduced QuaSAR method is then illustrated for a study of the activity of a series of flavonoids on breast cancer resistance protein. PMID:19399244

  5. An Optical Flow Method Applied to Co-Registration of Remote Sensing Images: Example for SAR/SAR, SAR/LIDAR, SAR/Optical Images of BIOSAR 2010 Campaign

    Science.gov (United States)

    Colin-Koeniguer, Elise

    2016-08-01

    This article proposes an optical flow type method for coregistration of forest remote sensing images. The principle of the algorithm called GeFolki is first explained. Results are shown on the images of the BioSAR 3 campaign, for the production of SAR interferograms, the coregistration a SAR and LIDAR image, and the coregistration an optical image and SAR image.The advantages of such an algorithm over conventional algorithms are explained. Finally, we propose various applications within the operating data for future BIOMASS mission: massive interferometry, ground truth production, upscaling by fusion of LIDAR and SAR data, and image mining.

  6. A Review About SAR Technique for Shallow Water Bathymetry Surveys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Synthetic Aperture Radar (SAR) has become one of the important tools for shallow water bathymetry surveys. This has significant economic efficiency compared with the traditional bathymetry surveys. Numerical models have been developed to simulate shallow water bathymetry SAR images. Inversion of these models makes it possible to assess the water depths from SAR images. In this paper, these numerical models of SAR technique are reviewed, and examples are illustrated including in the coastal areas of China. Some issues about SAR technique available and the research orientation in future are also discussed.

  7. Spatiotemporal Characterization of Land Subsidence and Uplift (2009–2010 over Wuhan in Central China Revealed by TerraSAR-X InSAR Analysis

    Directory of Open Access Journals (Sweden)

    Lin Bai

    2016-04-01

    Full Text Available The effects of ground deformation pose a significant geo-hazard to the environment and infrastructure in Wuhan, the most populous city in Central China, in the eastern Jianghan Plain at the intersection of the Yangtze and Han rivers. Prior to this study, however, rates and patterns of region-wide ground deformation in Wuhan were little known. Here we employ multi-temporal SAR interferometry to detect and characterize spatiotemporal variations of ground deformation in major metropolitan areas in Wuhan. A total of twelve TerraSAR-X images acquired during 2009–2010 are used in the InSAR time series analysis. InSAR-derived results are validated by levelling survey measurements and reveal a distinct subsidence pattern within six zones in major commercial and industrial areas, with a maximum subsidence rate up to −67.3 mm/year. A comparison analysis between subsiding patterns and urban developments as well as geological conditions suggests that land subsidence in Wuhan is mainly attributed to anthropogenic activities, natural compaction of soft soil, and karst dissolution of subsurface carbonate rocks. However, anthropogenic activities related to intensive municipal construction and industrial production have more significant impacts on the measured subsidence than natural factors. Moreover, remarkable signals of secular land uplift are found along both banks of the Yangtze River, especially along the southern bank, with deformation rates ranging mostly from +5 mm/year to +17.5 mm/year. A strong temporal correlation is highlighted between the detected displacement evolutions and the water level records of the Yangtze River, inferring that this previously unknown deformation phenomenon is likely related to seasonal fluctuations in water levels of the Yangtze River.

  8. Adaptive InSAR combined with surveying techniques for an improved characterisation of active landslides (El Portalet)

    Science.gov (United States)

    Duro, Javier; Albiol, David; Sánchez, Francisco; Herrera, Gerardo; García Davalillo, Juan Carlos; Fernandez Merodo, Jose Antonio; Allasia, Paolo; Lollino, Piernicola; Manconi, Andrea

    2014-05-01

    InSAR and the Persistent Scatterer Interferometry (PSI) are well established techniques for monitoring urban and rural areas. Besides the large number of available SAR data in the past, the current and forthcoming space-borne SAR sensors offer the possibility of selecting the optimal acquisition configuration (wavelength, resolution, incidence angle, etc.) for each application. However, optimal data takes are not always possible and/or the processing area is difficult to analyse under an InSAR point of view. In such situations, additional and adaptive InSAR developments combined with other surveying techniques provide consistent solutions that meet the requirements of different application cases This work presents an advanced InSAR processing adapted for an active slow deformation landslide in a mountainous area. The presentation will show the benefits of applying advanced and adaptive filtering strategies for improving the InSAR quality in highly decorrelated environments. The availability of Artificial Corner Reflectors over the area of interest enables to tune the filtering procedure and thus maximize the detection and exploitation of natural targets (bare soil, roads, rocks) as measurement points while preserving the phase characteristics over individual and punctual targets (building corners, poles). The new results will be evaluated in terms of final density and quality of measurement points that can be retrieved. The results will show that a very high density of measurements improves the detection of the deformation gradients and its perimeters resulting in a more accurate characterization of the landslide area. The area of study is El Portalet, an active slow deformation landslide area in Central Spanish Pyrenees. During many years the slope of interest has been monitored with several surveying techniques like DGPS, extensometers, inclinometers, GB-SAR and InSAR jointly with an extensive geological interpretation. Currently, in the frame of the FP7 Project

  9. Integration of Canopy Height Information Derived from Stereo Imagery with SAR Backscatter Data to Improve Biomass Mapping

    Science.gov (United States)

    Sun, G.; Ranson, J.; Montesano, P. M.; Ni, W.

    2015-12-01

    Accurate forest biomass estimation over large areas is important for studies of global climate change and the carbon cycle. Synthetic Aperture Radar (SAR) is known to be effective for assessing forest biomass. SAR penetrates farther into forest canopies than optical sensors, so SAR data from forested areas can be related to standing woody biomass, especially at longer L and P bands wavelength. The effect of forest structure on radar signature reduces its sensitivity to biomass when the biomass reaches a threshold level (e.g. ~100Mg/ha at L-band). Therefore the ability for forest biomass mapping using only backscattering coefficients is limited. However, including height data in forest biomass mapping using SAR data will improve the sensitivity beyond saturation levels. There are many ways to get information related to forest canopy height including: 1) Lidar, a direct measurement of canopy height; 2) Height of scattering phase center (HSPC) from InSAR; 3) HSPC difference from two bands of InSAR, and 4) Polarimetric Interferometric SAR, which employs the polarization-dependent coherences. Photogrammetry (or stereo imagery) is another technique for quantifying forest vertical structure and is a traditional technique for the extraction of a digital surface model. The launch of spaceborne sensors, the application of digital cameras, the maturation of photogrammetry theory and the development of fully digital and automatic image processing make the application of photogrammetric methods feasible. Our previous studies using ALOS PRISM data have shown that the canopy height derived from PRISM stereo data were highly correlated with LVIS RH50 data. In this study we have integrated this canopy height with L-band SAR imagery data to map forest biomass in our test site in Howland, Maine. The point cloud data from multi-pair stereo imageries of five PRISM scenes were co-registered and used along with the USGS NED data to calculate the mean canopy height at 30m pixels. Multi

  10. SAR Image Texture Analysis of Oil Spill

    Science.gov (United States)

    Ma, Long; Li, Ying; Liu, Yu

    Oil spills are seriously affecting the marine ecosystem and cause political and scientific concern since they have serious affect on fragile marine and coastal ecosystem. In order to implement an emergency in case of oil spills, it is necessary to monitor oil spill using remote sensing. Spaceborne SAR is considered a promising method to monitor oil spill, which causes attention from many researchers. However, research in SAR image texture analysis of oil spill is rarely reported. On 7 December 2007, a crane-carrying barge hit the Hong Kong-registered tanker "Hebei Spirit", which released an estimated 10,500 metric tons of crude oil into the sea. The texture features on this oil spill were acquired based on extracted GLCM (Grey Level Co-occurrence Matrix) by using SAR as data source. The affected area was extracted successfully after evaluating capabilities of different texture features to monitor the oil spill. The results revealed that the texture is an important feature for oil spill monitoring. Key words: oil spill, texture analysis, SAR

  11. Ambiguity noise analysis of a SAR system

    Science.gov (United States)

    Tian, Haishan; Chang, Wenge; Li, Xiangyang

    2015-12-01

    The presence of range and azimuth (or Doppler) ambiguities in synthetic aperture radars (SARs) is well known. The ambiguity noise is related to the antenna pattern and the value of pulse repetition frequency (PRF). Because a new frequency modulated continuous wave (FMCW) SAR has the characters of low cost and small size, and the capacity of real-time signal processing, the antenna will likely vibrate or deform due to a lack of the stabilized platform. And the value of PRF cannot be much high because of the high computation burden for the real-time processing. The aim of this study is to access and improve the performance of a new FMCW SAR system based on the ambiguity noise. First, the quantitative analysis of the system's ambiguity noise level is performed; an antenna with low sidelobes is designed. The conclusion is that the range ambiguity noise is small; the azimuth ambiguity noise is somewhat increased, however, it is sufficiently small to have marginal influence on the image quality. Finally, the ambiguity noise level is measured using the imaging data from a Ku-band FMCW SAR. The results of this study show that the measured noise level coincides with the theoretical noise level.

  12. CFAR Edge Detector for Polarimetric SAR Images

    DEFF Research Database (Denmark)

    Schou, Jesper; Skriver, Henning; Nielsen, Allan Aasbjerg;

    2003-01-01

    Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector...

  13. Multichannel imaging with the AMBER FMCW SAR

    NARCIS (Netherlands)

    Otten, M.P.G.; Rossum, W.L. van; Graaf, M.W. van der; Vlothuizen, W.J.; Tan, R.G.

    2014-01-01

    An X-band Digital Array Synthetic Aperture Radar for a Short Range Tactical UAV is presented. The Frequency Modulated Continuous Wave radar principle in combination with digital beam forming over 24 receive channels is used to achieve low power and advanced imaging SAR capabilities on small platform

  14. Satellite sar detection of hurricane helene (2006)

    DEFF Research Database (Denmark)

    Ju, Lian; Cheng, Yongcun; Xu, Qing;

    2013-01-01

    In this paper, the wind structure of hurricane Helene (2006) over the Atlantic Ocean is investigated from a C-band RADARSAT-1 synthetic aperture radar (SAR) image acquired on 20 September 2006. First, the characteristics, e.g., the center, scale and area of the hurricane eye (HE) are determined...

  15. What is Gammarus campylops of Sars, 1894

    NARCIS (Netherlands)

    Stock, J.H.; Kant, P.

    1966-01-01

    A revision of the specimens described by Sars, 1894, as Gammarus campylops Leach, 1814, proved that they did not belong to that species, nor to Gammarus ochlos Reid, 1945 (= G. sarsi Reid, 1943), as Reid believed. Reid’s species, of which also original specimens have been reexamined, is identical

  16. Multichannel imaging with the AMBER FMCW SAR

    NARCIS (Netherlands)

    Otten, M.P.G.; Rossum, W.L. van; Graaf, M.W. van der; Vlothuizen, W.J.; Tan, R.G.

    2014-01-01

    An X-band Digital Array Synthetic Aperture Radar for a Short Range Tactical UAV is presented. The Frequency Modulated Continuous Wave radar principle in combination with digital beam forming over 24 receive channels is used to achieve low power and advanced imaging SAR capabilities on small platform

  17. Epidemic Models for SARS and Measles

    Science.gov (United States)

    Rozema, Edward

    2007-01-01

    Recent events have led to an increased interest in emerging infectious diseases. This article applies various deterministic models to the SARS epidemic of 2003 and a measles outbreak in the Netherlands in 1999-2000. We take a historical approach beginning with the well-known logistic curve and a lesser-known extension popularized by Pearl and Reed…

  18. Living in the Shadow of SARS

    Institute of Scientific and Technical Information of China (English)

    LUZHU

    2003-01-01

    I Was born in April, when spring is in the air, the sun shines, the sky is blue, and the fragrance of lilacs is everywhere. This year's birthday was unforgettable.As the SARS epidemic had broken out in Beijing, it was spent under the threat of this killer disease.

  19. Multichannel imaging with the AMBER FMCW SAR

    NARCIS (Netherlands)

    Otten, M.P.G.; Rossum, W.L. van; Graaf, M.W. van der; Vlothuizen, W.J.; Tan, R.G.

    2014-01-01

    An X-band Digital Array Synthetic Aperture Radar for a Short Range Tactical UAV is presented. The Frequency Modulated Continuous Wave radar principle in combination with digital beam forming over 24 receive channels is used to achieve low power and advanced imaging SAR capabilities on small

  20. What is Gammarus campylops of Sars, 1894

    NARCIS (Netherlands)

    Stock, J.H.; Kant, P.

    1966-01-01

    A revision of the specimens described by Sars, 1894, as Gammarus campylops Leach, 1814, proved that they did not belong to that species, nor to Gammarus ochlos Reid, 1945 (= G. sarsi Reid, 1943), as Reid believed. Reid’s species, of which also original specimens have been reexamined, is identical wi

  1. Peptide Mimicrying Between SARS Coronavirus Spike Protein and Human Proteins Reacts with SARS Patient Serum

    Directory of Open Access Journals (Sweden)

    K.-Y. Hwa

    2008-01-01

    Full Text Available Molecular mimicry, defined as similar structures shared by molecules from dissimilar genes or proteins, is a general strategy used by pathogens to infect host cells. Severe acute respiratory syndrome (SARS is a new human respiratory infectious disease caused by SARS coronavirus (SARS-CoV. The spike (S protein of SARS-CoV plays an important role in the virus entry into a cell. In this study, eleven synthetic peptides from the S protein were selected based on its sequence homology with human proteins. Two of the peptides D07 (residues 927–937 and D08 (residues 942–951 were recognized by the sera of SARS patients. Murine hyperimmune sera against these peptides bound to proteins of human lung epithelial cells A549. Another peptide D10 (residues 490–502 stimulated A549 to proliferate and secrete IL-8. The present results suggest that the selected S protein regions, which share sequence homology with human proteins, may play important roles in SARS-CoV infection.

  2. Forest Height Inversion Using Dual-pol Polarimetric SAR Interferometry

    Science.gov (United States)

    Fu, W. X.; Guo, H. D.; Xie, C.; Lu, Y. C.; Li, X. W.

    2014-03-01

    Polarimetric Synthetic Aperture Radar Interferometry (PolInSAR) has been extensively applied for forest parameter inversion over different frequencies and polarimetric conditions. So far, most research was based on full-pol SAR images with relatively small coverage. A spaceborne SAR system will have the potential for PolInSAR applications used for global forest monitoring. Spaceborne dual-pol SAR images usually have higher resolution and larger swath than full-pol mode. In this paper, forest height retrieval was attempted by PolInSAR from a L-band spaceborne dual-pol SAR pairs using HH and HV channels. The random volume over ground (RVoG) model was used to retrieve the height and the coherence optimization method was extended to the dual-pol PolInSAR, which makes use of polarimetry to enhance the quality of SAR interferograms. The three-stage process is also used in the dual-pol PolInSAR technique. Finally, the experimental test was performed for forest height estimation on the dual-pol L-band SAR data of the Saihanba forest acquired by the ALOS PALSAR sensor in 2009.

  3. The outbreak pattern of the SARS cases in Asia

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhibin; SHENG Chengfa; MA Zufei; LI Dianmo

    2004-01-01

    The severe acute respiratory syndrome (SARS) caused tremendous damage to many Asia countries, especially China. The transmission process and outbreak pattern of SARS is still not well understood. This study aims to find a simple model to describe the outbreak pattern of SARS cases by using SARS case data commonly released by governments. The outbreak pattern of cumulative SARS cases is expected to be a logistic type because the infection will be slowed down due to the increasing control effort by people and/or due to depletion of susceptible individuals. The increase rate of SARS cases is expected to decrease with the cumulative SARS cases, as described by the traditional logistical model, which is widely used in population dynamic studies. The instantaneous rate of increases were significantly and negatively correlated with the cumulative SARS cases in mainland of China (including Beijing, Hebei, Tianjin, Shanxi, the Autonomous Region of Inner Mongolia) and Singapore. The basic reproduction number R0 in Asia ranged from 2.0 to 5.6 (except for Taiwan, China). The R0 of Hebei and Tianjinwere much higher than that of Singapore, Hongkong, Beijing, Shanxi, Inner Mongolia, indicating SARS virus might have originated differently or new mutations occurred during transmission. We demonstrated that the outbreaks of SARS in many regions of Asia were well described by the logistic model, and the control measures implemented by governments are effective. The maximum instantaneous rate of increase, basic reproductive number, and maximum cumulative SARS cases were also calculated by using the logistic model.

  4. An Analysis of Displacement Measurements for Lisbon, Portugal Using Combined InSAR and GNSS Data

    Science.gov (United States)

    Roque, D.; Simonetto, E.; Falcao, A. P.; Perissin, D.; Durand, F.; Morel, L.; Fonseca, A. M.; Polidori, L.

    2016-08-01

    Atmospheric effects are still a limitation to the application of InSAR techniques for displacement measurement. In this study, zenith total delay (ZTD) values derived from global navigation satellite system (GNSS) are used to correct interferograms from tropospheric effects. Displacement measurements are obtained from the corrected interferograms through a persistent scatterer interferometry approach. The influence of different interpolation methods on the construction of ZTD maps is tested through two different algorithms: cubic spline and ordinary kriging. Differences are observed between the cumulative displacement maps obtained with both interpolators, but atmospheric effects are still present, possibly due to the small number of available GNSS stations.

  5. InSAR Measurements of Flank Stability at Cumbre Vieja Volcano, La Palma (Spain)

    Science.gov (United States)

    Holley, Rachel; Thomas, Adam; Li, Zhenhong; McGuire, Bill; Ziebart, Marek; Day, Simon

    2010-03-01

    It has been suggested that instability of the western flank of Cumbre Vieja volcano, on the island of La Palma (Canary Islands), could have the potential to result in a lateral collapse of the flank, which in turn could generate an Atlantic tsunami. InSAR measurements provide an excellent way to corroborate data from GPS and structural surveys to provide independent corroboration. This work will use maps of atmospheric phase delay to improve the accuracy of persistent scatterer interferometry results over the island, and integrate these measurements with new GPS data, to give a complete assessment of flank stability and allow better assessment of the risks posed by the volcano.

  6. The first Sentinel-1 SAR image of a typhoon

    Institute of Scientific and Technical Information of China (English)

    LI Xiaofeng

    2015-01-01

    In this note, we present the first Sentinel-1 synthetic aperture radar (SAR) typhoon image acquired in the northwest Pacific on October 4, 2014. The eye shape and sea surface wind patterns associated with Typhoon Phanfone are clearly shown in the high-quality SAR image. SAR winds retrieval procedure was given but the actual wind estimates will only be available after the European Space Agency (ESA) releases the official calibration coefficients in order to accurately derive the SAR-measured normalized radar cross section. This study demonstrates the advantage of Sentinel-1 SAR with regards to imaging fine scale typhoon patterns on the sea surface beneath storm clouds. This paper also advocates the use of Sentinel-1 SAR data that is made freely and openly available worldwide for the first time in civilian SAR history.

  7. Citizens’ Health Information Behaviors During SARS Spread Periods in Taiwan

    Directory of Open Access Journals (Sweden)

    Nei-Ching Yeh

    2003-09-01

    Full Text Available The purpose of this study is to investigate the information behaviors of citizens during the periods of SARS spreading in Taiwan. This study is exploratory in nature, and the naturalistic inquiry approach was applied. Sixteen persons, aged from 20 to 62 years old, were interviewed in order to understand their primary information channels of obtaining SARS information, the characteristics of information communication, the methods of infection, the attitudes toward SARS news, and the influences of SARS to life. The findings show that most participants obtained SARS information from televisions. SARS became the major topic of chatting between people, but telephone communication replaced face to face communication. Part of interviewers applied folk medicine to guard against SARS. Participant dissatisfied that governments did not announce much more authoritative information. The results also found participants’ information sharing and information avoidance behaviors.[Article content in Chinese

  8. Attribute-Value Functions as Global Interpretations of Attribute Importance

    NARCIS (Netherlands)

    Ittersum, van K.; Pennings, J.M.E.

    2012-01-01

    In order to better understand decision maker’s perceptions of the importance of attributes, Goldstein (1990) differentiates between global and local interpretations of attribute importance. While the appreciation for the distinction is growing, research on the relationship between measures of global

  9. Transition constraints for temporal attributes

    CSIR Research Space (South Africa)

    Ongoma, EAN

    2014-07-01

    Full Text Available over time as the object migrates from one class to the next. Research on transition constraints has covered only object migration [3] and relation migration [14]. However, to efficiently represent and reason over data, we need to also look at attribute... transition, which is the migration of attributes along an object’s life cycle. Temporal attributes have been used and studied less in comparison to classes and relations. Yet in databases, we have a direct contact with attributes, and if those (temporal...

  10. Theory and approach of information retrievals from electromagnetic scattering and remote sensing

    CERN Document Server

    Jin, Ya-Qiu

    2006-01-01

    Covers several hot topics in current research of electromagnetic scattering, and radiative transfer in complex and random media, polarimetric scattering and SAR imagery technology, data validation and information retrieval from space-borne remote sensing, computational electromagnetics, etc.Including both forward modelling and inverse problems, analytic theory and numerical approachesAn overall summary of the author's works during most recent yearsAlso presents some insight for future research topics.

  11. The Effects of Sand Sediment Volume Heterogeneities on Sound Propagation and Scattering

    Science.gov (United States)

    2012-09-30

    14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 7 19a. NAME OF RESPONSIBLE...Jones and D. R. Jackson, “Small perturbation method of high-frequency bistatic volume scattering from marine sediments,” Oceanic Engineering, IEEE J. of

  12. Severe acute respiratory syndrome (SARS): knowledge, attitudes, practices and sources of information among physicians answering a SARS fever hotline service.

    Science.gov (United States)

    Deng, J-F; Olowokure, B; Kaydos-Daniels, S C; Chang, H-J; Barwick, R S; Lee, M-L; Deng, C-Y; Factor, S H; Chiang, C-E; Maloney, S A

    2006-01-01

    In June 2003, Taiwan introduced a severe acute respiratory syndrome (SARS) telephone hotline service to provide concerned callers with rapid access to information, advice and appropriate referral where necessary. This paper reports an evaluation of the knowledge, attitude, practices and sources of information relating to SARS among physicians who staffed the SARS fever hotline service. A retrospective survey was conducted using a self-administered postal questionnaire. Participants were physicians who staffed a SARS hotline during the SARS epidemic in Taipei, Taiwan from June 1 to 10, 2003. A response rate of 83% was obtained. All respondents knew the causative agent of SARS, and knowledge regarding SARS features and preventive practices was good. However, only 54% of respondents knew the incubation period of SARS. Hospital guidelines and news media were the major information sources. In responding to two case scenarios most physicians were likely to triage callers at high risk of SARS appropriately, but not callers at low risk. Less than half of all respondents answered both scenarios correctly. The results obtained suggest that knowledge of SARS was generally good although obtained from both medical and non-medical sources. Specific knowledge was however lacking in certain areas and this affected the ability to appropriately triage callers. Standardized education and assessment of prior knowledge of SARS could improve the ability of physicians to triage callers in future outbreaks.

  13. LE NUOVE FRONTIERE DELL’ARCHEOLOGIA DALLA FOTOGRAFIA AEREA AL TELERILEVAMENTO SATELLITARE SAR

    Directory of Open Access Journals (Sweden)

    Nicole Dore

    2012-04-01

    Full Text Available

    Il grande progresso tecnologico ha dato la possibilità a campi di indagine più tradizionali, come l’archeologia, di usufruire di tecnologie per trarne il massimo vantaggio ai fini di indagini preventive sul campo. È sulla sciadi conquiste come il telerilevamento satellitare ottico ad alta risoluzione spaziale, che la presente ricerca si è spinta oltre tali confini, con lo scopo di indagare la tecnica polarimetrica SAR (Synthetic Aperture Radar.

     

    New Frontiers in Archaeology. From Aerial Photography to Satellite Remote Sensing SAR

    This work is part of an ongoing PhD project held at the Area di Geodesia e Geomatica – University ofRome ‘La Sapienza’. The work involves the study of archaeological sites through the analysis of polarimetric L-band data from the PALSAR sensor (on the Japanese ALOS satellite, launched in May 2006 with the aim of understanding the spectral signature of archaeologicalremains (above and below ground. The Italian sites of Vulci (VTand Arpi (FG, analyzed through polarimetric imagery, were chosen according to the availability of polarimetric SAR data at the time of the study and to the different geomorphologic characteristics of theterrain, with the purpose of observing the scattering mechanisms associated to the features present in the scene.

  14. Monitoring CO2 sequestration with a network inversion InSAR method

    Science.gov (United States)

    Rabus, B.; Ghuman, P.; MacDonald, B.

    2009-05-01

    The capture, containment and long-term storage of CO2 is increasingly discussed as an important means to counter climate change resulting from the ongoing release of greenhouse gases into the atmosphere. This CO2 sequestration often requires the pumping of the gas into deep saline aquifers. However, before sequestration can be regarded as a longterm solution it is necessary to investigate under which conditions permanent and leakless capture of the CO2 is achieved in the substrate. We demonstrate that a combination of spaceborne synthetic aperture interferometry (InSAR) and ground based measurements of ground uplift caused by the underground release and spreading of the CO2 can be forged into a powerful tool to monitor sequsetration. We use a novel InSAR approach, which combines the benefits of a point-based persistent scatterer algorithm with a network inversion approach, and an additional temporal filter to remove atmospheric disturbances also at smaller scales down to 1 km and less. Using case studies from several injection wells we show that InSAR and ground based data in conjunction with geological and structural information above the aquifer, as well as detailed injection logs, allow to monitor the volumetric spread of CO2 at the mm per year level. For the majority of the studied wells CO2 appears to approach a stable sequestration state, however, in at least one case our results suggest leakage outside the aquifer.

  15. Land Cover Classification for Polarimetric SAR Images Based on Mixture Models

    Directory of Open Access Journals (Sweden)

    Wei Gao

    2014-04-01

    Full Text Available In this paper, two mixture models are proposed for modeling heterogeneous regions in single-look and multi-look polarimetric SAR images, along with their corresponding maximum likelihood classifiers for land cover classification. The classical Gaussian and Wishart models are suitable for modeling scattering vectors and covariance matrices from homogeneous regions, while their performance deteriorates for regions that are heterogeneous. By comparison, the proposed mixture models reduce the modeling error by expressing the data distribution as a weighted sum of multiple component distributions. For single-look and multi-look polarimetric SAR data, complex Gaussian and complex Wishart components are adopted, respectively. Model parameters are determined by employing the expectation-maximization (EM algorithm. Two maximum likelihood classifiers are then constructed based on the proposed mixture models. These classifiers are assessed using polarimetric SAR images from the RADARSAT-2 sensor of the Canadian Space Agency (CSA, the AIRSAR sensor of the Jet Propulsion Laboratory (JPL and the EMISAR sensor of the Technical University of Denmark (DTU. Experiment results demonstrate that the new models fit heterogeneous regions preferably to the classical models and are especially appropriate for extremely heterogeneous regions, such as urban areas. The overall accuracy of land cover classification is also improved due to the more refined modeling.

  16. Authorship Attribution of Source Code

    Science.gov (United States)

    Tennyson, Matthew F.

    2013-01-01

    Authorship attribution of source code is the task of deciding who wrote a program, given its source code. Applications include software forensics, plagiarism detection, and determining software ownership. A number of methods for the authorship attribution of source code have been presented in the past. A review of those existing methods is…

  17. Causal Attributions of Shy Subjects.

    Science.gov (United States)

    Teglasi, Hedwig; Hoffman, Mary Ann

    1982-01-01

    Causal attributions of shy students (N=36) were compared with those of a comparison group of students (N=36) in ten situations. Significant differences between the two groups emerged when explaining outcomes of situations considered to be problematic for shy individuals. Causal attributions may reflect realistic and situation-specific…

  18. Advanced InSAR techniques for the management and characterization of geothermal resources

    Science.gov (United States)

    Bellotti, F.; Falorni, G.; Morgan, J.; Rucci, A.; Ferretti, A.

    2012-04-01

    InSAR is a remote sensing tool that has applications in both geothermal exploitation and in the management of producing fields. The technique has developed rapidly in recent years and the most evolved algorithms, now capable of providing precise ground movement measurements with unprecedented spatial density over large areas, allow the monitoring of the effects of fluid injection and extraction on surface deformation and the detection of active faults. Multi-interferogram approaches have been used at several geothermal sites in different stages of development. SqueeSAR™, which represents the latest breakthrough in InSAR technology, provides a significant increase in the spatial density of measurement points by exploiting signal returns from both point-like and distributed scatterers. Furthermore, recent satellite radar sensors have a higher spatial resolution (down to 1 m), as well as a higher temporal frequency of image acquisitions (down to a few days). The coupling of the new algorithm with this new generation of satellites provides a valuable tool for monitoring the different phases of geothermal production and in support of the decision making process. Some examples from the US are presented here: the first case study involves the use of InSAR within a suite of tools for exploration of the San Emidio geothermal field in Nevada. This project aimed to develop geophysical techniques to identify and map large aperture fractures for the placement of new production/exploration wells. The second and third examples examine two zones in California: the Salton Sea area, where multi-interferogram InSAR provided an overview of surface deformation at a producing geothermal reservoir. Surface deformation in this area was complex, and the added detail provided insight into the interplay of tectonics and production activities. Additional InSAR studies have also been carried out at the Geysers field in order to evaluate the behavior of an Enhanced Geothermal System (EGS) in

  19. SAR Ice Classification Using Fuzzy Screening Method

    Science.gov (United States)

    Gill, R. S.

    2003-04-01

    A semi-automatic SAR sea ice classification algorithm is described. It is based on combining the information in the original SAR data with those in the three 'image' products derived from it, namely Power-to-Mean Ratio (PMR), the Gamma distribution and the second order texture parameter entropy, respectively. The latter products contain information which is often useful during the manual interpretation of the images. The technique used to fuse the information in these products is based on a method c lled Multi Experts Multi Criteria Decision Making fuzzy a screening. The Multiple Experts in this case are the above four 'image' products. The two criteria used currently for making decisions are the Kolmogorov-Smirnov distribution matching and the statistical mean of different surface classes. The algorithm classifies an image into any number of predefined classes of sea ice and open water. The representative classes of these surface types are manually identified by the user. Further, as SAR signals from sea ice covered regions and open water are ambiguous, it was found that a minimum of 4 pre-identified surface classes (calm and turbulent water and sea ice with low and high backscatter values) are required to accurately classify an image. Best results are obtained when a total of 8 surface classes (2 each of sea ice and open water in the near range and a similar number in the far range of the SAR image) are used. The main advantage of using this image classification scheme is that, like neural networks, no prior knowledge is required of the statistical distribution of the different surface types. Furthermore, unlike the methods based on neural networks, no prior data sets are required to train the algorithm. All the information needed for image classification by the method is contained in the individual SAR images and associated products. Initial results illustrating the potential of this ice classification algorithm using the RADARSAT ScanSAR Wide data are presented

  20. Federated query services provided by the Seamless SAR Archive project

    Science.gov (United States)

    Baker, S.; Bryson, G.; Buechler, B.; Meertens, C. M.; Crosby, C. J.; Fielding, E. J.; Nicoll, J.; Youn, C.; Baru, C.

    2013-12-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a 2-year collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived data products (i.e. interferograms). A major milestone for the first year of the SSARA project was a unified application programming interface (API) for SAR data search and results at ASF and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives (http://www.unavco.org/ws/brokered/ssara/sar/search). A command line client that utilizes this new service is provided as an open source utility for the community on GitHub (https://github.com/bakerunavco/SSARA). Further API development and enhancements added more InSAR specific keywords and quality control parameters (Doppler centroid, faraday rotation, InSAR stack size, and perpendicular baselines). To facilitate InSAR processing, the federated query service incorporated URLs for DEM (from OpenTopography) and tropospheric corrections (from the JPL OSCAR service) in addition to the URLs for SAR data. This federated query service will provide relevant QC metadata for selecting pairs of SAR data for InSAR processing and all the URLs necessary for interferogram generation. Interest from the international community has prompted an effort to incorporate other SAR data archives (the ESA Virtual Archive 4 and the DLR TerraSAR-X_SSC Geohazard Supersites and Natural Laboratories collections) into the federated query service which provide data for researchers outside the US and North America.

  1. On scattered subword complexity

    CERN Document Server

    Kása, Zoltán

    2011-01-01

    Special scattered subwords, in which the gaps are of length from a given set, are defined. The scattered subword complexity, which is the number of such scattered subwords, is computed for rainbow words.

  2. Preliminary Assessment of Wind and Wave Retrieval from Chinese Gaofen-3 SAR Imagery.

    Science.gov (United States)

    Shao, Weizeng; Sheng, Yexin; Sun, Jian

    2017-07-25

    The Chinese Gaofen-3 (GF-3) synthetic aperture radar (SAR) launched by the China Academy of Space Technology (CAST) has operated at C-band since September 2016. To date, we have collected 16/42 images in vertical-vertical (VV)/horizontal-horizontal (HH) polarization, covering the National Data Buoy Center (NDBC) buoy measurements of the National Oceanic and Atmospheric Administration (NOAA) around U.S. western coastal waters. Wind speeds from NDBC in situ buoys are up to 15 m/s and buoy-measured significant wave height (SWH) has ranged from 0.5 m to 3 m. In this study, winds were retrieved using the geophysical model function (GMF) together with the polarization ratio (PR) model and waves were retrieved using a new empirical algorithm based on SAR cutoff wavelength in satellite flight direction, herein called CSAR_WAVE. Validation against buoy measurements shows a 1.4/1.9 m/s root mean square error (RMSE) of wind speed and a 24/23% scatter index (SI) of SWH for VV/HH polarization. In addition, wind and wave retrieval results from 166 GF-3 images were compared with the European Centre for Medium-Range Weather Forecasts (ECMWF) re-analysis winds, as well as the SWH from the WaveWatch-III model, respectively. Comparisons show a 2.0 m/s RMSE for wind speed with a 36% SI of SWH for VV-polarization and a 2.2 m/s RMSE for wind speed with a 37% SI of SWH for HH-polarization. Our work gives a preliminary assessment of the wind and wave retrieval results from GF-3 SAR images for the first time and will provide guidance for marine applications of GF-3 SAR.

  3. High Resolution Digital Surface Model For Production Of Airport Obstruction Charts Using Spaceborne SAR Sensors

    Science.gov (United States)

    Oliveira, Henrique; Rodrigues, Marco; Radius, Andrea

    2012-01-01

    Airport Obstruction Charts (AOCs) are graphical representations of natural or man-made obstructions (its locations and heights) around airfields, according to International Civil Aviation Organization (ICAO) Annexes 4, 14 and 15. One of the most important types of data used in AOCs production/update tasks is a Digital Surface Model (first reflective surface) of the surveyed area. The development of advanced remote sensing technologies provide the available tools for obstruction data acquisition, while Geographic Information Systems (GIS) present the perfect platform for storing and analyzing this type of data, enabling the production of digital ACOs, greatly contributing to the increase of the situational awareness of pilots and enhancing the air navigation safety level [1]. Data acquisition corresponding to the first reflective surface can be obtained through the use of Airborne Laser-Scanning and Light Detection and Ranging (ALS/LIDAR) or Spaceborne SAR Systems. The need of surveying broad areas, like the entire territory of a state, shows that Spaceborne SAR systems are the most adequate in economic and feasibility terms of the process, to perform the monitoring and producing a high resolution Digital Surface Model (DSM). The high resolution DSM generation depends on many factors: the available data set, the used technique and the setting parameters. To increase the precision and obtain high resolution products, two techniques are available using a stack of data: the PS (Permanent Scatterers) technique [2], that uses large stack of data to identify many stable and coherent targets through multi- temporal analysis, removing the atmospheric contribution and to minimize the estimation errors, and the Small Baseline Subset (SBAS) technique ([3],[4]), that relies on the use of small baseline SAR interferograms and on the application of the so called singular value decomposition (SVD) method, in order to link independent SAR acquisition data sets, separated by large

  4. Multichannel and Wide-Angle SAR Imaging Based on Compressed Sensing

    Science.gov (United States)

    Sun, Chao; Wang, Baoping; Fang, Yang; Song, Zuxun; Wang, Shuzhen

    2017-01-01

    The multichannel or wide-angle imaging performance of synthetic aperture radar (SAR) can be improved by applying the compressed sensing (CS) theory to each channel or sub-aperture image formation independently. However, this not only neglects the complementary information between signals of each channel or sub-aperture, but also may lead to failure in guaranteeing the consistency of the position of a scatterer in different channel or sub-aperture images which will make the extraction of some scattering information become difficult. By exploiting the joint sparsity of the signal ensemble, this paper proposes a novel CS-based method for joint sparse recovery of all channel or sub-aperture images. Solving the joint sparse recovery problem with a modified orthogonal matching pursuit algorithm, the recovery precision of scatterers is effectively improved and the scattering information is also preserved during the image formation process. Finally, the simulation and real data is used for verifying the effectiveness of the proposed method. Compared with single channel or sub-aperture independent CS processing, the proposed method can not only obtain better imaging performance with fewer measurements, but also preserve more valuable scattering information for target recognition. PMID:28165433

  5. Operational Monitoring of Mines by COSMO-SkyMed PSP SAR Interferometry

    Science.gov (United States)

    Costantini, Mario; Malvarosa, Fabio; Miniati, Federico; de Assis, Luciano Mozer

    2016-08-01

    Synthetic aperture radar (SAR) interferometry is a powerful technology for detection and monitoring of slow ground surface movements. Monitoring of ground deformations in mining structures is an important application, particularly difficult because the scene changes with time. The persistent scatterer pair (PSP) approach, recently proposed to overcome some limitations of standard persistent scatter interferometry, proved to be effective also for mine monitoring. In this work, after resuming the main ideas of the PSP method, we describe the PSP measurements obtained from high- resolution X-band COSMO-SkyMed data over a large mining area in Minas Gerais state, Brazil. The outcomes demonstrate that dense and accurate ground deformation measurements can be obtained on the mining area and its structures (such as open pits, waste dumps, conveyor belts, water and tailings dams, etc.), achieving a consistent global view including also areas where field instruments are not installed.

  6. The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

    Science.gov (United States)

    Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

    2006-09-01

    This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

  7. Analysis of multi-dimensional SAR for determining the thickness of thin sea ice in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xi; ZHANG Jie; MENG Junmin; SU Tengfei

    2013-01-01

    Flat thin ice(30 cm thick) is a common ice type in the Bohai Sea, China. Ice thickness detection is important to offshore exploration and marine transport in winter. Synthetic aperture radar (SAR) can be used to acquire sea ice data in all weather conditions, and it is a useful tool for monitoring sea ice conditions. In this paper, we combine a multi-layered sea ice electromagnetic (EM) scattering model with a sea ice thermodynamic model to assess the determination of the thickness of flat thin ice in the Bohai Sea using SAR at different frequencies, polarization, and incidence angles. Our modeling studies suggest that co-polarization backscattering coefficients and the co-polarized ratio can be used to retrieve the thickness of flat thin ice from C- and X-band SAR, while the co-polarized correlation coefficient can be used to retrieve flat thin ice thickness from L-, C-, and X-band SAR. Importantly, small or moderate incidence angles should be chosen to avoid the effect of speckle noise.

  8. Land subsidence due to groundwater withdrawal detected by InSAR time-series in Tazerbo well field, Libya

    Science.gov (United States)

    Tufekci, Nesrin; Schoups, Gerrit; Mahapatra, Pooja; van de Giesen, Nick; Hanssen, Ramon F.

    2014-05-01

    The Tazerbo well field is one of the well fields designed within the Great Man-Made River Project (GMMRP), which aims to deliver water to the eastern coast of Libya through an underground pipe network. It consists of 108 wells in three rows, where the wells are separated 1.3 km in longitude and 10 km in latitude. The planned total groundwater withdrawal from all wells is 1 million m3/day. The water is pumped from the deep sandstone aquifer (Nubian sandstone), which is overlaid by a thick mudstone-siltstone aquitard. Being heavily pumped, the aquifer and fine-grained sediments of the aquitard are expected to compact in time resulting in land subsidence. In order to investigate the surface deformation caused by groundwater pumping in the Tazerbo well field, Interferometric Synthetic Aperture Radar (InSAR) technique was utilized. InSAR is widely used for monitoring land subsidence and can provide sub-cm scale deformation information over large areas. Using the Persistent Scatterer method, SAR time series of 20 Envisat images, spanning from 2004 to 2010, are employed to analyze spatial and temporal distribution of land subsidence induced by groundwater withdrawal. The results are in a good agreement with simulated subsidence. In addition, the spatial distribution of InSAR observations seems to be promising in terms of detecting spatial heterogeneity of aquifer material.

  9. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  10. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI) The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from...

  11. Prediction the soil erodibility and sediments load using soil attributes

    Directory of Open Access Journals (Sweden)

    Uones Mazllom

    2016-07-01

    Full Text Available Soil erodibility (K factor is the most important tool for estimation the erosion. The aim of this study was to estimate the soil erodibility in Sanganeh area located in Naderi Kalat, Khorasan Razavi Province of northeastern Iran. The sediments load collected during the 17 rainfall events were measured at the end of 12 plots during 2009-2012. The K factor was calculated according to the USLE for each plot and rainfall event. The relationships between K factor and measured sediments load with soil attributes were studied. The results showed that calcium carbonate, SAR (sodium absorption ratio, silt, clay contents, and SI (structural stability index were the most effective soil attributes for estimating the sediments load and OM (organic matter, sand, SI and calcium carbonate, silt, clay contents, and SI for K factor. The results of stepwise regression equations showed that the precision of regression equation derived from PCA for estimating the K factor and sediments load were more than ones derived from correlation test. According to the results of this research, it’s recommended that PCA be applied for determination the effective soil attributes for estimating the K factor in USLE and sediments load in studied area.

  12. SAR Target Recognition via Supervised Discriminative Dictionary Learning and Sparse Representation of the SAR-HOG Feature

    Directory of Open Access Journals (Sweden)

    Shengli Song

    2016-08-01

    Full Text Available Automatic target recognition (ATR in synthetic aperture radar (SAR images plays an important role in both national defense and civil applications. Although many methods have been proposed, SAR ATR is still very challenging due to the complex application environment. Feature extraction and classification are key points in SAR ATR. In this paper, we first design a novel feature, which is a histogram of oriented gradients (HOG-like feature for SAR ATR (called SAR-HOG. Then, we propose a supervised discriminative dictionary learning (SDDL method to learn a discriminative dictionary for SAR ATR and propose a strategy to simplify the optimization problem. Finally, we propose a SAR ATR classifier based on SDDL and sparse representation (called SDDLSR, in which both the reconstruction error and the classification error are considered. Extensive experiments are performed on the MSTAR database under standard operating conditions and extended operating conditions. The experimental results show that SAR-HOG can reliably capture the structures of targets in SAR images, and SDDL can further capture subtle differences among the different classes. By virtue of the SAR-HOG feature and SDDLSR, the proposed method achieves the state-of-the-art performance on MSTAR database. Especially for the extended operating conditions (EOC scenario “Training 17 ∘ —Testing 45 ∘ ”, the proposed method improves remarkably with respect to the previous works.

  13. SAR impulse response with residual chirps.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2009-06-01

    A Linear Frequency-Modulated (LFM) chirp is a function with unit amplitude and quadratic phase characteristic. In a focused Synthetic Aperture Radar (SAR) image, a residual chirp is undesired for targets of interest, as it coarsens the manifested resolution. However, for undesired spurious signals, a residual chirp is often advantageous because it spreads the energy and thereby diminishes its peak value. In either case, a good understanding of the effects of a residual LFM chirp on a SAR Impulse Response (IPR) is required to facilitate system analysis and design. This report presents an analysis of the effects of a residual chirp on the IPR. As reference, there is a rich body of publications on various aspects of LFM chirps. A quick search reveals a plethora of articles, going back to the early 1950s. We mention here purely as trivia one of the earlier analysis papers on this waveform by Klauder, et al.

  14. MCA: a multichannel approach to SAR autofocus.

    Science.gov (United States)

    Morrison, Robert L; Do, Minh N; Munson, David C

    2009-04-01

    We present a new noniterative approach to synthetic aperture radar (SAR) autofocus, termed the multichannel autofocus (MCA) algorithm. The key in the approach is to exploit the multichannel redundancy of the defocusing operation to create a linear subspace, where the unknown perfectly focused image resides, expressed in terms of a known basis formed from the given defocused image. A unique solution for the perfectly focused image is then directly determined through a linear algebraic formulation by invoking an additional image support condition. The MCA approach is found to be computationally efficient and robust and does not require prior assumptions about the SAR scene used in existing methods. In addition, the vector-space formulation of MCA allows sharpness metric optimization to be easily incorporated within the restoration framework as a regularization term. We present experimental results characterizing the performance of MCA in comparison with conventional autofocus methods and discuss the practical implementation of the technique.

  15. How SARS Taught Me to Cook

    Institute of Scientific and Technical Information of China (English)

    GUAVALEE

    2003-01-01

    DURING the week-long May Day holiday I usually hold a party, or enjoy the good weather on outings with friends, but thanks to the SARS epidemic in Beijing this year, I stayed at home the entire May Day holiday. It was no problem finding something to do with my ample spare time, as I can surf the Internet for hours on end. My biggest headache was eating.Having dined in cafeterias and restaurants for the previous ten years or so, I had never learned to cook, but as SARS had begun to spread in Beijing in late April, the cafeteria in my work unit and most restaurants were closed for the holiday.

  16. Non-parametric partitioning of SAR images

    Science.gov (United States)

    Delyon, G.; Galland, F.; Réfrégier, Ph.

    2006-09-01

    We describe and analyse a generalization of a parametric segmentation technique adapted to Gamma distributed SAR images to a simple non parametric noise model. The partition is obtained by minimizing the stochastic complexity of a quantized version on Q levels of the SAR image and lead to a criterion without parameters to be tuned by the user. We analyse the reliability of the proposed approach on synthetic images. The quality of the obtained partition will be studied for different possible strategies. In particular, one will discuss the reliability of the proposed optimization procedure. Finally, we will precisely study the performance of the proposed approach in comparison with the statistical parametric technique adapted to Gamma noise. These studies will be led by analyzing the number of misclassified pixels, the standard Hausdorff distance and the number of estimated regions.

  17. Automated preprocessing of spaceborne SAR data

    Science.gov (United States)

    Curlander, J. C.; Wu, C.; Pang, A.

    1982-01-01

    An efficient algorithm has been developed for estimation of the echo phase delay in spaceborne synthetic aperture radar (SAR) data. This algorithm utilizes the spacecraft ephemeris data and the radar echo data to produce estimates of two parameters: (1) the centroid of the Doppler frequency spectrum f(d) and (2) the Doppler frequency rate. Results are presented from tests conducted with Seasat SAR data. The test data indicates that estimation accuracies of 3 Hz for f(d) and 0.3 Hz/sec for the Doppler frequency rate are attainable. The clutterlock and autofocus techniques used for estimation of f(d) and the Doppler frequency rate, respectively are discussed and the algorithm developed for optimal implementation of these techniques is presented.

  18. SARS: Safeguards Accounting and Reporting Software

    Science.gov (United States)

    Mohammedi, B.; Saadi, S.; Ait-Mohamed, S.

    In order to satisfy the requirements of the SSAC (State System for Accounting and Control of nuclear materials), for recording and reporting objectives; this computer program comes to bridge the gape between nuclear facilities operators and national inspection verifying records and delivering reports. The SARS maintains and generates at-facility safeguards accounting records and generates International Atomic Energy Agency (IAEA) safeguards reports based on accounting data input by the user at any nuclear facility. A database structure is built and BORLAND DELPHI programming language has been used. The software is designed to be user-friendly, to make extensive and flexible management of menus and graphs. SARS functions include basic physical inventory tacking, transaction histories and reporting. Access controls are made by different passwords.

  19. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have...... attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR...... data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ΔE estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found...

  20. Fast SAR Imaging Algorithm for FLGPR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A fast SAR imaging algorithm for near- field subsurface forward-looking ground penetrating radar (FLGPR) is presented. By using nonstationary convolution filter, the refocused image spectrum can be reconstructed directly from the backscattered signal spectrum of target area. The experimental results show the proposed method can fast achieve image refocusing. Also it has higher computational efficiency than the phase-shift migration approach and the delay-and-sum (DAS) approach.

  1. Adaptive Filter in SAR Interferometry Derived DEM

    Institute of Scientific and Technical Information of China (English)

    XU Caijun; WANG Hua; WANG Jianglin; GE Linlin

    2005-01-01

    In this paper, the performance of median filter, elevation dependent adaptive sigma median filter, and directionally dependent adaptive sigma median filter are tested on both InSAR Tandem DEM and simulated high-level noisy DEM. Through the comparison, the directionally dependent adaptive sigma median filter is proved to be the most effective one not only in the noise removing but also in the boundary preserve.

  2. Bistatic SAR tomography: processing and experimental results

    OpenAIRE

    Duque Biarge, Sergio; López Dekker, Francisco J.; Merlano Duncan, Juan Carlos; Mallorquí Franquet, Jordi Joan

    2010-01-01

    This paper presents across-track tomography applied to a bistatic geometry with fixed receivers. This kind of geometry can overcome some of the classical monostatic tomography limitations such as temporal decorrelation and irregular baseline distribution. The Remote Sensing Laboratory (RSLab)of the Universitat Politècnica de Catalunya (UPC) has implemented a SAR Bistatic Receiver for INterferometric Applications,SABRINA, with 4-channels. SABRINA has been used to carry out a bistatic tomogr...

  3. Multiplier-free filters for wideband SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2001-01-01

    This paper derives a set of parameters to be optimized when designing filters for digital demodulation and range prefiltering in SAR systems. Aiming at an implementation in field programmable gate arrays (FPGAs), an approach for the design of multiplier-free filters is outlined. Design results ar...... are presented in terms of filter complexity and performance. One filter has been coded in VHDL and preliminary results indicate that the filter can meet a 2 GHz input sample rate....

  4. Digital demodulator for wide bandwidth SAR

    DEFF Research Database (Denmark)

    Jørgensen, Jørn Hjelm

    2000-01-01

    A novel approach to the design of efficient digital quadrature demodulators for wide bandwidth SAR systems is described. Efficiency is obtained by setting the intermediate frequency to 1/4 the ADC sampling frequency. One channel is made filter-free by synchronizing the local oscillator...... with the output decimator. The filter required by the other channel is optimized through global search using the system level performance metrics integrated sidelobe level ratio (ISLR) and peak sidelobe level ratio (PSLR)....

  5. SAR Product Improvements and Enhancements - SARprises

    Science.gov (United States)

    2013-09-30

    paper on current fields at Orkney, Scotland, was accepted for publication in IEEE - TGARS and is currently in press (available on IEEE Xplore as Early...Sea surface velocity vector retrieval using dual-beam interferometry: First demonstration, IEEE TGARS, 43, 2494- 2502, 2005. [2] Chapron, B., F...Bight by airborne along-track interferometric SAR, Proc. IGARSS 2002, 1822-1824, IEEE , 2002. [4] Bjerklie, D.M., S.L. Dingman, C.J. Vorosmarty, C.H

  6. Scattering angle resolved optical coherence tomography for in vivo murine retinal imaging

    Science.gov (United States)

    Gardner, Michael R.; Katta, Nitesh; McElroy, Austin; Baruah, Vikram; Rylander, H. G.; Milner, Thomas E.

    2017-02-01

    Optical coherence tomography (OCT) retinal imaging contributes to understanding central nervous system (CNS) diseases because the eye is an anatomical "window to the brain" with direct optical access to nonmylenated retinal ganglion cells. However, many CNS diseases are associated with neuronal changes beyond the resolution of standard OCT retinal imaging systems. Though studies have shown the utility of scattering angle resolved (SAR) OCT for particle sizing and detecting disease states ex vivo, a compact SAR-OCT system for in vivo rodent retinal imaging has not previously been reported. We report a fiber-based SAR-OCT system (swept source at 1310 nm +/- 65 nm, 100 kHz scan rate) for mouse retinal imaging with a partial glass window (center aperture) for angular discrimination of backscattered light. This design incorporates a dual-axis MEMS mirror conjugate to the ocular pupil plane and a high collection efficiency objective. A muring retina is imaged during euthanasia, and the proposed SAR-index is examined versus time. Results show a positive correlation between the SAR-index and the sub-cellular hypoxic response of neurons to isoflurane overdose during euthanasia. The proposed SAR-OCT design and image process technique offer a contrast mechanism able to detect sub-resolution neuronal changes for murine retinal imaging.

  7. A Combined Use of Decomposition and Texture for Terrain Classification of Fully Polarimetric SAR Images

    Science.gov (United States)

    Rodionova, N. V.

    2007-03-01

    This p aper presents two-stag e unsupervised terrain classification of fully polarimetr ic SA R data using Freeman and Durden decomposition based on three simp le scattering mechanisms: surface, volume and double bounce (first step), and textur al features (uncorrelated uniformity , contr ast, inv erse mo men t and entropy) obtained from grey lev el co-occurrence matr ices (GLCM) (second step). Textural f eatures ar e defined in moving w indow 5x5 pixels w ith N=32 (N - number of grey lev els) . This algorith m preserves th e purity of domin ant polarimetric scattering properties and defines textural features in each scatter ing category. It is shown better object discrimin ation after app lying textur e w ith in fix ed scattering category. Speckle r eduction is one of th e main mo ments in imag e interpr etation improvement because of its great influen ce on textur e. Results from unfiltered and Lee filtered polar imetr ic SAR imag es show that the v alues of contrast and en tropy decr ease and th e values of uniformity and inverse moment increase with speckle reduction, that's tru e for all polarizations (HH, VV, HV). Th e d iscr imination b etw een objects increases after speckle f ilter ing. Polar ization influen ce on textur e features is def ined by calculating th e features in SAR images w ith HH , VV and HV polarizations before and after speck le filter ing, and then creating RG B images. It is shown mor e polarization inf luence on textur e features (uniformity , inverse mo ment and entropy) before filtering and less influen ce - after speck le f iltering. I t's not true for contrast wher e polar ization influen ce is not ch anged practically w ith filtering. SIR-C/X-SA R SLC L-band imag es of Moscow r egion are used for illustr ation.

  8. Molecular phylogeny of coronaviruses including human SARS-CoV

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Phylogenetic tree of coronaviruses (CoVs) including the human SARS-associated virus is reconstructed from complete genomes by using our newly developed K- string composition approach. The relation of the human SARS-CoV to other coronaviruses, i.e. the rooting of the tree is suggested by choosing an appropriate outgroup. SARS-CoV makes a separate group closer but still distant from G2 (CoVs in mammalian host). The relation between different isolates of the human SARS virus is inferred by first constructing an ultrametric distance matrix from counting sequence variations in the genomes. The resulting tree is consistent with clinic relations between the SARS-CoV isolates. In addition to a larger variety of coronavirus genomes these results provide phylogenetic knowledge based on independent novel methodology as compared to recent phylogenetic studies on SARS-CoV.

  9. Low-SAR metamaterial-inspired printed monopole antenna

    Science.gov (United States)

    Hossain, M. I.; Faruque, M. R. I.; Islam, M. T.; Ali, M. T.

    2017-01-01

    In this paper, a low-SAR metamaterial-embedded planar monopole antenna is introduced for a wireless communication system. A printed monopole antenna is designed for modern mobile, which operates in GSM, UMTS, LTE, WLAN, and Bluetooth frequency bands. A metamaterial structure is designed to use in the mobile handset with a multi-band printed monopole antenna. The finite integration technique of the CST microwave studio is used in this study. The measurement of antenna performances is taken in an anechoic chamber, and the SAR values are measured using COMOSAR system. The results indicate that metamaterial structure leads to reduce SAR without affecting antenna performance significantly. According to the measured results, the metamaterial attachment leads to reduce 87.7% peak SAR, 68.2% 1-g SAR, and 46.78% 10-g SAR compared to antenna without metamaterial.

  10. Efficient Bistatic SAR Raw Signal Simulator of Extended Scenes

    Directory of Open Access Journals (Sweden)

    Liang Yang

    2014-01-01

    Full Text Available Bistatic SAR system is a new mode that allocates the radar transmitter and receiver on different platforms and has more advantages compared to the monostatic case. However, the existing bistatic SAR raw data simulator in the frequency domain can only handle the case of translation invariant system. In this paper, an efficient 2D frequency-domain raw data simulator of extended scenes for bistatic SAR of translation variant system is proposed by a geometric transformation method for the first time, where inverse STOLT interpolation is used to formulate the range migration terms. The presented simulator can accommodate the translation variant bistatic SAR system compared with existing bistatic SAR simulator. And it is more efficient than the time domain one by making use of Fast Fourier Transform (FFT. Simulation results for point targets and a real SAR image demonstrate its validity and effectiveness.

  11. SARS epidemical forecast research in mathematical model

    Institute of Scientific and Technical Information of China (English)

    DING Guanghong; LIU Chang; GONG Jianqiu; WANG Ling; CHENG Ke; ZHANG Di

    2004-01-01

    The SIJR model, simplified from the SEIJR model, is adopted to analyze the important parameters of the model of SARS epidemic such as the transmission rate, basic reproductive number. And some important parameters are obtained such as the transmission rate by applying this model to analyzing the situation in Hong Kong, Singapore and Canada at the outbreak of SARS. Then forecast of the transmission of SARS is drawn out here by the adjustment of parameters (such as quarantined rate) in the model. It is obvious that inflexion lies on the crunode of the graph, which indicates the big difference in transmission characteristics between the epidemic under control and not under control. This model can also be used in the comparison of the control effectiveness among different regions. The results from this model match well with the actual data in Hong Kong, Singapore and Canada and as a by-product, the index of the effectiveness of control in the later period can be acquired. It offers some quantitative indexes, which may help the further research in epidemic diseases.

  12. Abstract Interpretation and Attribute Gramars

    DEFF Research Database (Denmark)

    Rosendahl, Mads

    The objective of this thesis is to explore the connections between abstract interpretation and attribute grammars as frameworks in program analysis. Abstract interpretation is a semantics-based program analysis method. A large class of data flow analysis problems can be expressed as non......-standard semantics where the ``meaning'' contains information about the runtime behaviour of programs. In an abstract interpretation the analysis is proved correct by relating it to the usual semantics for the language. Attribute grammars provide a method and notation to specify code generation and program analysis...... directly from the syntax of the programming language. They are especially used for describing compilation of programming languages and very efficient evaluators have been developed for subclasses of attribute grammars. By relating abstract interpretation and attribute grammars we obtain a closer connection...

  13. Corporate attributes and corporate accruals

    National Research Council Canada - National Science Library

    Md Shamimul Hasan; Normah Omar; Rashidah Abdul Rahman; Syed Zabid Hossain

    2016-01-01

    ... (discretionary accruals) in Bangladesh. The behaviour of corporate accruals is explained by corporate attributes such as asset size, turnover, earnings per share, number of shareholders, year of listing, international link of audit firm...

  14. Spanning Tree Based Attribute Clustering

    DEFF Research Database (Denmark)

    Zeng, Yifeng; Jorge, Cordero Hernandez

    2009-01-01

    inconsistent edges from a maximum spanning tree by starting appropriate initial modes, therefore generating stable clusters. It discovers sound clusters through simple graph operations and achieves significant computational savings. We compare the Star Discovery algorithm against earlier attribute clustering...

  15. Study on the polarimetric characteristics of the Lop Nur arid area using PolSAR data

    Science.gov (United States)

    Gao, Zhihong; Gong, Huaze; Zhou, Xu; Shao, Yun; Yuan, Minghuan; Wang, Longfei

    2014-01-01

    The quantitative study of the arid Lop Nur lake basin is significant to investigate the environmental changes in the arid area of northwestern China and extremely arid areas of Eurasia in general. Synthetic aperture radar (SAR) imagery, with its penetration capability and advantages for studying geological phenomena on a large spatial scale, is very suitable for analyzing the subsurface of the Lop Nur area. Based on the full polarimetric ALOS PALSAR data and field investigation, it was found that the two-layer scattering mechanism of the dry sediments is very special and complex. The scattering mechanism in the bright strips is more complex than that in the gray strips according to the co-polarization correlation analysis. The experimental results show that the Cloude-Pottier decomposition method is more appropriate for this area. Moreover, the polarimetric characteristics and Cloude-Pottier decomposition results are very important for the study of the past climatic change in Lop Nur area. In conclusion, full polarimetric SAR data and target decomposition theory provide a new technique for obtaining information and quantitatively studying the subsurface characteristics of arid areas.

  16. Synthetic aperture radar (SAR-based mapping of volcanic flows: Manam Island, Papua New Guinea

    Directory of Open Access Journals (Sweden)

    J. K. Weissel

    2004-01-01

    Full Text Available We present new radar-based techniques for efficient identification of surface changes generated by lava and pyroclastic flows, and apply these to the 1996 eruption of Manam Volcano, Papua New Guinea. Polarimetric L- and P-band airborne synthetic aperture radar (SAR data, along with a C-band DEM, were acquired over the volcano on 17 November 1996 during a major eruption sequence. The L-band data are analyzed for dominant scattering mechanisms on a per pixel basis using radar target decomposition techniques. A classification method is presented, and when applied to the L-band polarimetry, it readily distinguishes bare surfaces from forest cover over Manam volcano. In particular, the classification scheme identifies a post-1992 lava flow in NE Valley of Manam Island as a mainly bare surface and the underlying 1992 flow units as mainly vegetated surfaces. The Smithsonian's Global Volcanism Network reports allow us to speculate whether the bare surface is a flow dating from October or November in the early part of the late-1996 eruption sequence. This work shows that fully polarimetric SAR is sensitive to scattering mechanism changes caused by volcanic resurfacing processes such as lava and pyroclastic flows. By extension, this technique should also prove useful in mapping debris flows, ash deposits and volcanic landslides associated with major eruptions.

  17. Death of a SARS case from secondary aspergillus infection

    Institute of Scientific and Technical Information of China (English)

    王慧君; 丁彦青; 徐军; 李欣; 李学锋; 杨磊; 张文丽; 耿健; 申洪; 蔡俊杰; 康伟; 吴正容; 赵菲; 钟南山

    2004-01-01

    @@ Severe acute respiratory syndrome (SARS) is an acute infectious disease which has been found to spread mainly via respiration. The first case was idnetified in Guangdong, southem China in November 2002. This disease has resulted in a severe epidemic outbreak in 27 countries and regions. In order to investigate the etiology and clinicopathologic characteristics of SARS, we reported here a patient with SARS who died of aspergillosis after prolonged treatment with corticosteroids.

  18. Efficient Bistatic SAR Raw Signal Simulator of Extended Scenes

    OpenAIRE

    Liang Yang; Weidong Yu; Shichao Zheng; Lei Zhang

    2014-01-01

    Bistatic SAR system is a new mode that allocates the radar transmitter and receiver on different platforms and has more advantages compared to the monostatic case. However, the existing bistatic SAR raw data simulator in the frequency domain can only handle the case of translation invariant system. In this paper, an efficient 2D frequency-domain raw data simulator of extended scenes for bistatic SAR of translation variant system is proposed by a geometric transformation method for the first t...

  19. Detecting the Depth of a Subsurface Brine Layer in Lop Nur Lake Basin Using Polarimetric L-Band SAR

    Directory of Open Access Journals (Sweden)

    Chang-An Liu

    2015-01-01

    Full Text Available Lop Nur once was a huge lake located in northwestern China. At present, there is no surface water in Lop Nur Lake basin and on SAR images it looks like an “Ear.” The objective of this paper is to retrieve the depth of subsurface brine layer in Lop Nur by copolarized phase difference of surface scattering. Based on field investigation and analysis of sample properties, a two-layer scattering structure was proposed with detailed explanations of scattering mechanisms. The relationship between copolarized phase difference and the brine layer depth in the region of Lop Nur were studied. The copolarized phase difference of surface scattering was extracted by model-based polarimetric decomposition method. A good linear correlation between measured subsurface brine layer depth and copolarized phase difference with R2 reaching 0.82 was found. Furthermore, the subsurface brine layer depth of the entire lake area was analyzed. According to the retrieved maps, some interesting phenomena were found, and several hypotheses about the past water withdrawal process and the environmental evolution had been proposed to theoretically explain these phenomena. Based on the penetration capability of SAR the reconstruction of historical evolution process of Lop Nur will be an interesting topic for future research.

  20. InSAR Scientific Computing Environment

    Science.gov (United States)

    Gurrola, E. M.; Rosen, P. A.; Sacco, G.; Zebker, H. A.; Simons, M.; Sandwell, D. T.

    2010-12-01

    The InSAR Scientific Computing Environment (ISCE) is a software development effort in its second year within the NASA Advanced Information Systems and Technology program. The ISCE will provide a new computing environment for geodetic image processing for InSAR sensors that will enable scientists to reduce measurements directly from radar satellites and aircraft to new geophysical products without first requiring them to develop detailed expertise in radar processing methods. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. The NRC Decadal Survey-recommended DESDynI mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment is planned to become a key element in processing DESDynI data into higher level data products and it is expected to enable a new class of analyses that take greater advantage of the long time and large spatial scales of these new data, than current approaches. At the core of ISCE is both legacy processing software from the JPL/Caltech ROI_PAC repeat-pass interferometry package as well as a new InSAR processing package containing more efficient and more accurate processing algorithms being developed at Stanford for this project that is based on experience gained in developing processors for missions such as SRTM and UAVSAR. Around the core InSAR processing programs we are building object-oriented wrappers to enable their incorporation into a more modern, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models, and a robust, intuitive user interface with

  1. Estimation of Bridge Height over Water from Polarimetric SAR Image Data Using Mapping and Projection Algorithm and De-Orientation Theory

    Science.gov (United States)

    Wang, Haipeng; Xu, Feng; Jin, Ya-Qiu; Ouchi, Kazuo

    An inversion method of bridge height over water by polarimetric synthetic aperture radar (SAR) is developed. A geometric ray description to illustrate scattering mechanism of a bridge over water surface is identified by polarimetric image analysis. Using the mapping and projecting algorithm, a polarimetric SAR image of a bridge model is first simulated and shows that scattering from a bridge over water can be identified by three strip lines corresponding to single-, double-, and triple-order scattering, respectively. A set of polarimetric parameters based on the de-orientation theory is applied to analysis of three types scattering, and the thinning-clustering algorithm and Hough transform are then employed to locate the image positions of these strip lines. These lines are used to invert the bridge height. Fully polarimetric image data of airborne Pi-SAR at X-band are applied to inversion of the height and width of the Naruto Bridge in Japan. Based on the same principle, this approach is also applicable to spaceborne ALOSPALSAR single-polarization data of the Eastern Ocean Bridge in China. The results show good feasibility to realize the bridge height inversion.

  2. Risk Factors for SARS-Related Deaths in 2003, Beijing

    Institute of Scientific and Technical Information of China (English)

    MIN LIU; WAN-NIAN LIANG; QI CHEN; XUE-QIN XIE; JIANG WU; XIONG HE; ZE-JUN LIU

    2006-01-01

    Objective To study the potential risk factors for severe acute respiratory syndromes (SARS)-related deaths in Beijing. Methods Epidemiological data were collected among the confirmed SARS patients officially reported by Beijing Centers for Disease Control and Prevention (BCDC), and information was also supplemented by a follow-up case survey. Chi-square test and multivariate stepwise logistic regression analysis were performed. Results Old age (over 60 years) was found to be significantly associated with SARS-related deaths in the univariate analysis. Also, history of contacting SARS patients within 2 weeks prior to the onset of illness, health occupation, and inferior hospital ranking as well as longer interval of clinic consulting (longer than 1 day) were the risk factors for SARS-related deaths. Multivariate stepwise logistic regression analysis found four risk factors for SARS-related deaths. Conclusion Old age (over 60 years) is the major risk factor for SARS-related deaths.Moreover, hospital health workers, the designated hospitals for SARS clinical services and the interval of consulting doctors (less than 1 day) are protective factors for surviving from SARS.

  3. Geometric registration and rectification of spaceborne SAR imagery

    Science.gov (United States)

    Curlander, J. C.; Pang, S. N.

    1982-01-01

    This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.

  4. Bistatic SAR: State of the Art and Development Trend

    Directory of Open Access Journals (Sweden)

    Zeng Tao

    2012-12-01

    Full Text Available Bistatic SAR (BiSAR systems have attracted the interests from global researchers and become a hotspot in the international radar community due to the progress of radar technology and rapidly increased applications nowadays. Based on the BiSAR experiments and breakthrough of the key technology, the paper summarized the general progresses of BiSAR systems, especially in European radar community, from different aspects such as system design, processing idea and topology etc. Different bistatic image formation algorithms have been analyzed and reviewed. Finally, the development trend is discussed in the paper.

  5. Motion measurement errors and autofocus in bistatic SAR.

    Science.gov (United States)

    Rigling, Brian D; Moses, Randolph L

    2006-04-01

    This paper discusses the effect of motion measurement errors (MMEs) on measured bistatic synthetic aperture radar (SAR) phase history data that has been motion compensated to the scene origin. We characterize the effect of low-frequency MMEs on bistatic SAR images, and, based on this characterization, we derive limits on the allowable MMEs to be used as system specifications. Finally, we demonstrate that proper orientation of a bistatic SAR image during the image formation process allows application of monostatic SAR autofocus algorithms in postprocessing to mitigate image defocus.

  6. Coastline detection in SAR images using discriminant cuts segmentation

    Science.gov (United States)

    Ding, Xianwen; Zou, Xiaolin; Yu, Tan

    2016-11-01

    The discriminant cut algorithm is used to detect coastlines in synthetic aperture radar (SAR) images. The proposed approach is a region-based one, which is able to capture and utilize spatial information in the image. The real SAR images, e.g. ALOS-1 PALSAR and COSMO-SkyMed SAR images, together with in-situ GPS data were collected and used to validate the performance of the proposed approach for coastline detection in SAR images. The accuracy is better than 4 times the image resolution. The efficiency is also tested.

  7. Crop identification of SAR data using digital textural analysis

    Science.gov (United States)

    Nuesch, D. R.

    1983-01-01

    After preprocessing SEASAT SAR data which included slant to ground range transformation, registration to LANDSAT MSS data and appropriate filtering of the raw SAR data to minimize coherent speckle, textural features were developed based upon the spatial gray level dependence method (SGLDM) to compute entropy and inertia as textural measures. It is indicated that the consideration of texture features are very important in SAR data analysis. The SEASAT SAR data are useful for the improvement of field boundary definitions and for an earlier season estimate of corn and soybean area location than is supported by LANDSAT alone.

  8. Anti-SARS coronavirus agents: a patent review (2008 - present).

    Science.gov (United States)

    Kumar, Vathan; Jung, Young-Sik; Liang, Po-Huang

    2013-10-01

    A novel coronavirus (CoV), unlike previous typical human coronaviruses (HCoVs), was identified as causative agent for severe acute respiratory syndrome (SARS). SARS first surfaced as a pandemic in late 2002 and originated in southern China. SARS-CoV rapidly spread to > 30 countries by 2003, infecting nearly 8,000 people and causing around 800 fatalities. After 10 years of silence, a 2012 report alarmed researchers about the emergence of a new strain of CoV causing SARS-like disease. To combat SARS, scientists applied for patents on various therapeutic agents, including small-molecule inhibitors targeting the essential proteases, helicase and other proteins of the virus, natural products, approved drugs, molecules binding to the virus, neutralizing antibodies, vaccines, anti-sense RNA, siRNA and ribozyme against SARS-CoV. In this article, the patents published from 2008 to the present for the new therapeutics that could potentially be used in the prophylaxis and treatment of SARS are reviewed. The therapeutic interventions or prophylaxis discussed in this review seems to offer promising solutions to tackle SARS. Rather than being complacent about the results, we should envisage how to transform them into drug candidates that may be useful in combating SARS and related viral infections in the future.

  9. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  10. SARS Patients-derived Human Recombinant Antibodies to S and M Proteins Efficiently Neutralize SARS-Coronavirus Infectivity

    Institute of Scientific and Technical Information of China (English)

    MI-FANG LIANG; KONG-XING WU; ZHAO-HUI XIONG; QI JIN; DE-XIN LI; RUN-LEI DU; JING-ZHI LIU; CHUAN LI; QUAN-FU ZHANG; LU-LU HAN; JIAN-SHI YU; SHU-MIN DUAN; XIAO-FANG WANG

    2005-01-01

    Objective To develop a specific SARS virus-targeted antibody preparation for emergent prophylaxis and treatment of SARS virus infection. Methods By using phage display technology, we constructed a naive antibody library from convalescent SARS patient lymphocytes. To obtain the neutralizing antibody to SARS virus surface proteins, the library panning procedure was performed on purified SARS virions and the specific Fab antibody clones were enriched by four rounds of repeated panning procedure and screened by highthroughput selection. The selected Fab antibodies expressed in the periplasma of E. Coli were soluble and further purified and tested for their binding properties and antiviral function to SARS virus. The functional Fab antibodies were converted to full human IgG antibodies with recombinant baculovirus/insect cell systems and their neutralizing activities were further determined. Results After four rounds of the panning, a number of SARS-CoV virus-targeted human recombinant Fab antibodies were isolated from the SARS patient antibody library. Most of these were identified to recognize both natural and recombinant SARS spike (S) proteins, two Fab antibodies were specific for the virus membrane (M) protein, only one bound to SARS-CoV nucleocapsid protein. The SARS-CoV S and M protein-targeted Fab or IgG antibodies showed significant neutralizing activities in cytopathic effect (CPE) inhibition neutralization test, these antibodies were able to completely neutralize the SARS virus and protect the Vero cells from CPE after virus infection. However, the N protein-targeted Fab or IgG antibodies failed to neutralize the virus. In addition, the SARS N protein-targeted human Fab antibody reacted with the denatured N proteins, whereas none of the S and M protein specific neutralizing antibodies did. These results suggested that the S and M protein-specific neutralizing antibodies could recognize conformational epitopes which might be involved in the binding of virions

  11. Spatial correlations in attribute communities.

    Directory of Open Access Journals (Sweden)

    Federica Cerina

    Full Text Available Community detection is an important tool for exploring and classifying the properties of large complex networks and should be of great help for spatial networks. Indeed, in addition to their location, nodes in spatial networks can have attributes such as the language for individuals, or any other socio-economical feature that we would like to identify in communities. We discuss in this paper a crucial aspect which was not considered in previous studies which is the possible existence of correlations between space and attributes. Introducing a simple toy model in which both space and node attributes are considered, we discuss the effect of space-attribute correlations on the results of various community detection methods proposed for spatial networks in this paper and in previous studies. When space is irrelevant, our model is equivalent to the stochastic block model which has been shown to display a detectability-non detectability transition. In the regime where space dominates the link formation process, most methods can fail to recover the communities, an effect which is particularly marked when space-attributes correlations are strong. In this latter case, community detection methods which remove the spatial component of the network can miss a large part of the community structure and can lead to incorrect results.

  12. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  13. Imaging with Scattered Neutrons

    OpenAIRE

    Ballhausen, H.; Abele, H.; Gaehler, R.; Trapp, M.; Van Overberghe, A.

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-re...

  14. Land Subsidence Detection in Agricultural Areas of Konya Closed Basin by PS-InSAR and GNSS Observations

    Science.gov (United States)

    Canaslan Comut, Fatma; Lazecky, Milan; Ustun, Aydin; Yalvack, Sefa

    2015-05-01

    The aim of this study is to determine and to monitor the areas affected by land subsidence caused by the decrease of groundwater, by using geodetic methods in Konya Closed Basin, Turkey. The GPS and InSAR techniques which complement each other perfectly will be used to deduce spatial deformations caused by the land subsidence. The land subsidence activity in the area of Küçükköy situated at the Konya Closed Basin (KCB) of the Central Anatolia Region in Turkey has been studied using the Stanford Method for Persistent Scatterers (StaMPS) InSAR technique. Significant movements of land subsidence ranging from mm to cm per year were detected with ENVISAT ASAR data between 2003 and 2010 above the city center. Results are also compared with GNSS measurements. Estimated deformation rate of KCKY GPS station is approximately - 2 cm/yr.

  15. Near real time monitoring of platform sourced pollution using TerraSAR-X over the North Sea.

    Science.gov (United States)

    Singha, Suman; Velotto, Domenico; Lehner, Susanne

    2014-09-15

    Continuous operational monitoring by means of remote sensing contributes significantly towards less occurrence of oil spills over European waters however, operational activities show regular occurrence of accidental and deliberate oil spills over the North Sea, particularly from offshore platform installations. Since the areas covered by oil spills are usually large and scattered over the North Sea, satellite remote sensing particularly Synthetic Aperture Radar (SAR) represents an effective tool for operational oil spill detection. This paper describes the development of a semi-automated approach for oil spill detection, optimized for near real time offshore platform sourced pollution monitoring context. Eight feature parameters are extracted from each segmented dark spot. The classification algorithm is based on artificial neural network. An initial evaluation of this methodology has been carried out on 156 TerraSAR-X images. Wind and current history information also have been analyzed for particular cases in order to evaluate their influences on spill trajectory.

  16. Estimates of ocean wave heights and attenuation in sea ice using the SAR wave mode on Sentinel-1A

    Science.gov (United States)

    Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand; Girard-Ardhuin, Fanny; Guitton, Gilles; Mouche, Alexis; Stopa, Justin E.

    2015-04-01

    Swell evolution from the open ocean into sea ice is poorly understood, in particular the amplitude attenuation expected from scattering and dissipation. New synthetic aperture radar (SAR) data from Sentinel-1A wave mode reveal intriguing patterns of bright oscillating lines shaped like instant noodles. We investigate cases in which the oscillations are in the azimuth direction, around a straight line in the range direction. This observation is interpreted as the distortion by the SAR processing of crests from a first swell, due to the presence of a second swell. Since deviations from a straight line should be proportional to the orbital velocity toward the satellite, swell height can be estimated, from 1.5 to 5 m in the present case. The evolution of this 13 s period swell across the ice pack is consistent with an exponential attenuation on a length scale of 200 km.

  17. Deorientation polarimetric analysis of bistatic SAR%双站合成孔径雷达去取向极化分析

    Institute of Scientific and Technical Information of China (English)

    黎贵玲; 吴霞

    2012-01-01

    The nonsymmetrical scattering matrices of bistatic Synthetic Aperture Radar(SAR) are studied on the basis of the analysis of the monostatic SAR deorientation parameters, and the bistatic deorientation parameters are obtained by using matrix algebra. Deorientation transformation matrix is deduced and the transformation of the target scattering vector is introduced to reduce the influence of randomly fluctuating orientation and make the targets' generic characteristics prominent. The targets' generic characteristics of the simulated bistatic SAR images are analyzed through the transformation in order to provide a rudimentary method for bistatic SAR images.%在分析单站合成孔径雷达去取向参数的基础上,研究了双站合成孔径雷达的非对称散射矩阵,利用矩阵代数知识得到双站去取向参数.推导了目标的去取向变换矩阵,将目标散射矢量进行矢量变换,使得研究目标具有相同的取向,目标本身的信息得以凸显.经过去取向变换,对双站模拟图像的特征参数进行分析,为进一步解读双站图像提供了初步手段.

  18. Attribution of blame in incest.

    Science.gov (United States)

    Jackson, T L; Ferguson, W P

    1983-06-01

    This study was designed to identify the empirical structure of attitudes relating to attribution of blame in incest. A second purpose was to determine how variables such as gender, physically abused status, and sexually abused status influence the attribution of blame in incest. A sample of 201 male and 211 female college students was administered the Jackson Incest Blame Scale. Four factors emerged from the factor analysis of the total sample supporting the hypothesis that attribution of blame in incest is a multidimensional construct including victim, offender, situational, and societal factors. A difference in the level of victim blame was found between male and female samples. Results are discussed with regard to their implications for further research and training. Other potential uses of the Jackson Incest Blame Scale are suggested.

  19. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Diego O Andrey

    Full Text Available Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1, encoded by tst(H, and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1, RNAIII, rot, and the alternative stress sigma factor sigB (σB. By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.

  20. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    Science.gov (United States)

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.

  1. Identification of Soil Freezing and Thawing States Using SAR Polarimetry at C-Band

    Directory of Open Access Journals (Sweden)

    Thomas Jagdhuber

    2014-03-01

    Full Text Available The monitoring of soil freezing and thawing states over large areas is very challenging on ground. In order to investigate the potential and the limitations of space-borne SAR polarimetry at C-band for soil state survey, analyses were conducted on an entire winter time series of fully polarimetric RADARSAT-2 data from 2011/2012 to identify freezing as well as thawing states within the soil. The polarimetric data were acquired over the Sodankylä test site in Finland together with in situ measurements of the soil and the snow cover. The analyses indicate clearly that the dynamics of the polarimetric entropy and mean scattering alpha angle are directly correlated to soil freezing and thawing states, even under distinct dry snow cover. First modeling attempts using the Extended Bragg soil scattering model justify the observed trends, which indicate surface-like scattering during frozen soil conditions and multiple/volume scattering for thawed soils. Hence, these first investigations at C-band foster motivation to work towards a robust polarimetric detection of soil freezing and thawing states as well as their transition phase.

  2. A Statistical Framework for Microbial Source Attribution

    Energy Technology Data Exchange (ETDEWEB)

    Velsko, S P; Allen, J E; Cunningham, C T

    2009-04-28

    This report presents a general approach to inferring transmission and source relationships among microbial isolates from their genetic sequences. The outbreak transmission graph (also called the transmission tree or transmission network) is the fundamental structure which determines the statistical distributions relevant to source attribution. The nodes of this graph are infected individuals or aggregated sub-populations of individuals in which transmitted bacteria or viruses undergo clonal expansion, leading to a genetically heterogeneous population. Each edge of the graph represents a transmission event in which one or a small number of bacteria or virions infects another node thus increasing the size of the transmission network. Recombination and re-assortment events originate in nodes which are common to two distinct networks. In order to calculate the probability that one node was infected by another, given the observed genetic sequences of microbial isolates sampled from them, we require two fundamental probability distributions. The first is the probability of obtaining the observed mutational differences between two isolates given that they are separated by M steps in a transmission network. The second is the probability that two nodes sampled randomly from an outbreak transmission network are separated by M transmission events. We show how these distributions can be obtained from the genetic sequences of isolates obtained by sampling from past outbreaks combined with data from contact tracing studies. Realistic examples are drawn from the SARS outbreak of 2003, the FMDV outbreak in Great Britain in 2001, and HIV transmission cases. The likelihood estimators derived in this report, and the underlying probability distribution functions required to calculate them possess certain compelling general properties in the context of microbial forensics. These include the ability to quantify the significance of a sequence 'match' or &apos

  3. Enhancing the Accessibility and Utility of UAVSAR L-band SAR Data

    Science.gov (United States)

    Atwood, D.; Arko, S. A.; Gens, R.; Sanches, R. R.

    2011-12-01

    The UAVSAR instrument, developed at NASA Jet Propulsion Lab, is a reconfigurable L-band, quad-polarimetric Synthetic Aperture Radar (SAR) developed specifically for repeat-track differential interferometry (InSAR). It offers resolution of approximately 5m and swaths greater than 16 km. Although designed to be flown aboard a UAV (Uninhabited Aerial Vehicle), it is currently being flown aboard a Gulfstream III in an ambitious set of campaigns around the world. The current archive from 2009 contains data from more than 100 missions from North America, Central America, the Caribbean, and Greenland. Compared with most SAR data from satellites, UAVSAR offers higher resolution, full-polarimetry, and an impressive noise floor. For scientists, these datasets present wonderful opportunities for understanding Earth processes and developing new algorithms for information extraction. Yet despite the diverse range of coverage, UAVSAR is still relatively under-utilized. In its capacity as the NASA SAR DAAC, the Alaska Satellite Facility (ASF) is interested in expanding recognition of this data and serving data products that can be readily downloaded into a Geographic Information System (GIS) environment. Two hurdles exist: one is the large size of the data products and the second is the format of the data. The data volumes are in excess of several GB; presenting slow downloads and overwhelming many software programs. Secondly, while the data is appropriately formatted for expert users, it may prove challenging for scientists who have not previously worked with SAR. This paper will address ways that ASF is working to reduce data volume while maintaining the integrity of the data. At the same time, the creation of value-added products that permit immediate visualization in a GIS environment will be described. Conversion of the UAVSAR polarimetric data to radiometrically terrain-corrected Pauli images in a GeoTIFF format will permit researchers to understand the scattering

  4. SAR Interferometry and Precise Leveling for the Determination of Vertical Displacements in the Upper Rhine Graben Area, Southwest Germany

    Science.gov (United States)

    Fuhrmann, T.; Schenk, A.; Westerhaus, M.; Zippelt, K.; Heck, B.

    2013-12-01

    The PS-InSAR (Persistent Scatterer SAR Interferometry) method and precise levelings provide a unique database to detect recent displacements of the Earth's surface. Data of both measurement techniques are analyzed at Geodetic Institute, Karlsruhe Institute of Technology, in order to gain detailed insight into the velocity field of the Upper Rhine Graben (URG). As central and most prominent segment of the European Cenozoic rift system, the seismically and tectonically active Rhine Graben is of steady geo-scientific interest. In the last decades, the URG is characterized by small tectonic movements (geothermal energy) inducing larger surface displacements. To assess the geohazards in the URG area, we aim to provide a map of the current 3D surface displacements with high precision and high spatial resolution. The InSAR and leveling data, and the location of permanent GNSS sites primarily analyzed for the horizontal velocity field, are displayed in Fig. 1. Precise levelings have been carried out by the surveying authorities of Germany, France and Switzerland over the last 100 years building a network of leveling lines. A kinematic network adjustment is applied on the leveling data, providing an accurate solution for vertical displacement rates with accuracies of 0.2 to 0.4 mm/a. The biggest disadvantage of the leveling database is the sparse spatial distribution of the measurement points. Therefore, PS-InSAR is used to significantly increase the number of points within the leveling loops. To obtain a high accuracy for line of sight displacement rates, ERS-1/2 and Envisat data from ascending and descending orbits covering a period from 1992 to 2000 and 2002 to 2010, resp., are processed using StaMPS (Stanford Method for Persistent Scatterers). As the tectonic displacements cover a large area, the separation of atmospheric effects and orbit errors plays an important role in the PS-InSAR processing chain. Besides the tectonic signal, man-induced surface displacements

  5. Change detection in a time series of polarimetric SAR data by an omnibus test statistic and its factorization (Conference Presentation)

    Science.gov (United States)

    Nielsen, Allan A.; Conradsen, Knut; Skriver, Henning

    2016-10-01

    ., Skriver, H., Nielsen, A. A., and Conradsen, K., "CFAR edge detector for polarimetric SAR images," IEEE Transactions on Geoscience and Remote Sensing 41(1): 20-32, 2003. [4] van Zyl, J. J. and Ulaby, F. T., "Scattering matrix representation for simple targets," in Radar Polarimetry for Geoscience Applications, Ulaby, F. T. and Elachi, C., eds., Artech, Norwood, MA (1990). [5] Canty, M. J., Image Analysis, Classification and Change Detection in Remote Sensing,with Algorithms for ENVI/IDL and Python, Taylor & Francis, CRC Press, third revised ed. (2014). [6] Nielsen, A. A., Conradsen, K., and Skriver, H., "Change detection in full and dual polarization, single- and multi-frequency SAR data," IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 8(8): 4041-4048, 2015. [7] Conradsen, K., Nielsen, A. A., and Skriver, H., "Determining the points of change in time series of polarimetric SAR data," IEEE Transactions on Geoscience and Remote Sensing 54(5), 3007-3024, 2016. [9] Christensen, E. L., Skou, N., Dall, J., Woelders, K., rgensen, J. H. J., Granholm, J., and Madsen, S. N., "EMISAR: An absolutely calibrated polarimetric L- and C-band SAR," IEEE Transactions on Geoscience and Remote Sensing 36: 1852-1865 (1998).

  6. InSAR Geodesy: The Next Phase

    Science.gov (United States)

    Simons, M.

    2016-12-01

    Published in 1993, the first prominent geophysical applications of repeat pass Interferometric Synthetic Aperture Radar (InSAR) demonstrated spatially continuous imaging of the velocity of a remote ice stream in Antarctica and the ground displacement from a large earthquake in California. These studies heralded comprehensive assessments of rapid changes in the ice sheets and novel perspectives on earthquake source physics, all enabled by a new era in geodetic imaging with sub-centimeter sensitivity, meter-scale spatial resolution and expansive coverage. Since 1993, the promise of InSAR has been to provide deformation measurements "everywhere and all the time". Indeed, the new generation of satellites are already providing shorter revisit times and the gradual move to constellations of nearly identical satellites allows sub-weekly revisits at selected radar frequencies for many regions of interest. This increase in temporal sampling has prompted the geodetic community to develop a variety of InSAR time series methods and corrections techniques to mitigate the impact of path delays accrued in the atmosphere, all while inferring one or more components of the 3D time-dependent motions of Earth's solid surface. We illustrate these capabilities with recent studies that include detection of shallow aseismic slip transients on a major strike slip fault, dynamics of a subglacial eruption, the signature of aquifer management, mapping of rapid aseismic fault slip following a major earthquake and the long-distance response of ice stream motion to ocean tides. The increased sampling rate of observations allows us to improve our sensitivity to small amplitude deformation processes, separate overlapping physical processes by their different spatio-temporal signatures, and increase the general utility of imaging geodesy for rapid disaster response. At the same time, we need to rethink how data is managed for users with different capabilities - a critical challenge as we aim for a

  7. Wave propagation, scattering and emission in complex media

    Science.gov (United States)

    Jin, Ya-Qiu

    I. Polarimetric scattering and SAR imagery. EM wave propagation and scattering in polarimetric SAR interferometry / S. R. Cloude. Terrain topographic inversion from single-pass polarimetric SAR image data by using polarimetric stokes parameters and morphological algorithm / Y. Q. Jin, L. Luo. Road detection in forested area using polarimetric SAR / G. W. Dong ... [et al.]. Research on some problems about SAR radiometric resolution / G. Dong ... [et al.]. A fast image matching algorithm for remote sensing applications / Z. Q. Hou ... [et al.]. A new algorithm of noised remote sensing image fusion based on steerable filters / X. Kang ... [et al.]. Adaptive noise reduction of InSAR data based on anisotropic diffusion models and their applications to phase unwrapping / C. Wang, X. Gao, H. Zhang -- II. Scattering from randomly rough surfaces. Modeling tools for backscattering from rough surfaces / A. K. Fung, K. S. Chen. Pseudo-nondiffracting beams from rough surface scattering / E. R. Méndez, T. A. Leskova, A. A. Maradudin. Surface roughness clutter effects in GPR modeling and detection / C. Rappaport. Scattering from rough surfaces with small slopes / M. Saillard, G. Soriano. Polarization and spectral characteristics of radar signals reflected by sea-surface / V. A. Butko, V. A. Khlusov, L. I. Sharygina. Simulation of microwave scattering from wind-driven ocean surfaces / M. Y. Xia ... [et al.]. HF surface wave radar tests at the Eastern China Sea / X. B. Wu ... [et al.] -- III. Electromagnetics of complex materials. Wave propagation in plane-parallel metamaterial and constitutive relations / A. Ishimaru ... [et al.]. Two dimensional periodic approach for the study of left-handed metamaterials / T. M. Grzegorczyk ... [et al.]. Numerical analysis of the effective constitutive parameters of a random medium containing small chiral spheres / Y. Nanbu, T. Matsuoka, M. Tateiba. Wave propagation in inhomogeneous media: from the Helmholtz to the Ginzburg -Landau equation / M

  8. The Danish polarimetric SAR for remote sensing applications

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Madsen, Søren Nørvang; Dall, Jørgen

    1994-01-01

    Presents the Danish polarimetric SAR system, EMISAR, and the approach taken in the system design to achieve a reliable high performance system. The design and implementation of the antenna system as well as the analog and digital hardware are discussed. The SAR utilises a dual polarised microstri...

  9. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    DEFF Research Database (Denmark)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel

    2016-01-01

    . Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world’s largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen...

  10. Genome organization of the SARS-CoV

    DEFF Research Database (Denmark)

    Xu, Jing; Hu, Jianfei; Wang, Jing;

    2003-01-01

    Annotation of the genome sequence of the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) is indispensable to understand its evolution and pathogenesis. We have performed a full annotation of the SARS-CoV genome sequences by using annotation programs publicly available or devel...

  11. Speckle filtering in satellite SAR change detection imagery

    NARCIS (Netherlands)

    Dekker, R.J.

    1998-01-01

    Repeat-pass Synthetic Aperture Radar (SAR) imagery is useful for change detection. A disadvantage of SAR is the system-inherent speckle noise. This can be reduced by filtering. Various filter types and methods are described in the literature, but not one fits the speckle noise in change detection

  12. Signal Processing for High Resolution FMCW SAR and Moving Target

    NARCIS (Netherlands)

    Meta, A.; Hoogeboom, P.

    2005-01-01

    The combination of Frequency Modulated ContinuousWave (FMCW) technology and Synthetic Aperture Radar (SAR) leads to lightweight, cost-effective imaging sensors of high resolution. In FMCW SAR applications the conventional stop-and-go approximation used in pulse radar algorithms cannot be considered

  13. The ONERA Airborne Multi Frequency SAR Imaging Systems (PREPRINT)

    Science.gov (United States)

    2014-10-09

    The ONERA Airborne Multi-Frequency SAR Imaging Systems Olivier Ruault du Plessis Electromagnetism and Radar Department ONERA Salon de...Provence FRANCE Olivier.Ruault_du_Plessis@onera.fr Philippe Dreuillet Electromagnetism and Radar Department ONERA Palaiseau FRANCE...Philippe.Dreuillet@onera.fr Abstract—RAMSES-NG and SETHI, the airborne SAR systems developed by ONERA , integrate new generation of radar and optronics

  14. SARS treatment: experience from a team in Guangdong, China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    @@ The epidemic of SARS in Guangdong province of China is beginning to be restrained. In May 2003, Dr. Zhong Nanshan, head of the Guangzhou Institute of Respiratory Disease, presented at a training course in Beijing for medical personnel. Some important issues have been addressed based on the experience concluded during their combating with SARS in Guangdong.

  15. Impact of SARS on China's economy limited

    Institute of Scientific and Technical Information of China (English)

    TaoRunyuan

    2003-01-01

    China's economic upsurge cannot be reversed by the severe acute respiratory syndrome (SARS) now ravaging some parts of the country. China's economy will maintain its steady growth momentum despite the SARS' impact to some extent on investment, consumption andexport, according to a number of noted Chinese experts.

  16. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery

    Directory of Open Access Journals (Sweden)

    Xiangguang Leng

    2016-08-01

    Full Text Available With the rapid development of spaceborne synthetic aperture radar (SAR and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way.

  17. Classification of Targets in SAR Images Using ISAR Data

    NARCIS (Netherlands)

    Wit, J.J.M. de; Dekker, R.J.; Broek, A.C. van den

    2005-01-01

    Feature-based classification of targets in SAR images by using ISAR measurements was studied, based on polarimetric SAR and ISAR data acquired with the MEMPHIS radar system of FGAN-FHR. The data contained one T-72 battle tank, one BMP combat vehicle, and several confusers. The resolution was 75 cm.

  18. Comparing satellite SAR and wind farm wake models

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Vincent, P.; Husson, R.

    2015-01-01

    The aim of the paper is to present offshore wind farm wake observed from satellite Synthetic Aperture Radar (SAR) wind fields from RADARSAT-1/-2 and Envisat and to compare these wakes qualitatively to wind farm wake model results. From some satellite SAR wind maps very long wakes are observed. Th...

  19. Understanding the T cell immune response in SARS coronavirus infection.

    Science.gov (United States)

    Janice Oh, Hsueh-Ling; Ken-En Gan, Samuel; Bertoletti, Antonio; Tan, Yee-Joo

    2012-09-01

    The severe acute respiratory syndrome (SARS) epidemic started in late 2002 and swiftly spread across 5 continents with a mortality rate of around 10%. Although the epidemic was eventually controlled through the implementation of strict quarantine measures, there continues a need to investigate the SARS coronavirus (SARS-CoV) and develop interventions should it re-emerge. Numerous studies have shown that neutralizing antibodies against the virus can be found in patients infected with SARS-CoV within days upon the onset of illness and lasting up to several months. In contrast, there is little data on the kinetics of T cell responses during SARS-CoV infection and little is known about their role in the recovery process. However, recent studies in mice suggest the importance of T cells in viral clearance during SARS-CoV infection. Moreover, a growing number of studies have investigated the memory T cell responses in recovered SARS patients. This review covers the available literature on the emerging importance of T cell responses in SARS-CoV infection, particularly on the mapping of cytotoxic T lymphocyte (CTL) epitopes, longevity, polyfunctionality and human leukocyte antigen (HLA) association as well as their potential implications on treatment and vaccine development.

  20. (Q)SAR: A Tool for the Toxicologist.

    Science.gov (United States)

    Steinbach, Thomas; Gad-McDonald, Samantha; Kruhlak, Naomi; Powley, Mark; Greene, Nigel

    2015-01-01

    A continuing education (CE) course at the 2014 American College of Toxicology annual meeting covered the topic of (Quantitative) Structure-Activity Relationships [(Q)SAR]. The (Q)SAR methodologies use predictive computer modeling based on predefined rules to describe the relationship between chemical structure and a chemical's associated biological activity or statistical tools to find correlations between biologic activity and the molecular structure or properties of a compound. The (Q)SAR has applications in risk assessment, drug discovery, and regulatory decision making. Pressure within industry to reduce the cost of drug development and societal pressure for government regulatory agencies to produce more accurate and timely risk assessment of drugs and chemicals have necessitated the use of (Q)SAR. Producing a high-quality (Q)SAR model depends on many factors including the choice of statistical methods and descriptors, but first and foremost the quality of the data input into the model. Understanding how a (Q)SAR model is developed and applied is critical to the successful use of such a tool. The CE session covered the basic principles of (Q)SAR, practical applications of these computational models in toxicology, how regulatory agencies use and interpret (Q)SAR models, and potential pitfalls of using them.

  1. Crop Classification Using Short-Revisit Multitemporal SAR Data

    DEFF Research Database (Denmark)

    Skriver, Henning; Mattia, Francesco; Satalino, Giuseppe;

    2011-01-01

    Classification of crops and other land cover types is an important application of both optical/infrared and SAR satellite data. It is already an import application of present satellite systems, as it will be for planned missions, such as the Sentinels. An airborne SAR data set with a short revisi...

  2. Investigation of Polarimetric SAR Data Acquired at Multiple Incidence Angles

    DEFF Research Database (Denmark)

    Svendsen, Morten Thougaard; Skriver, Henning; Thomsen, A.

    1998-01-01

    The dependence of different polarimetric parameters on the incidence angles in the range of 30° to 60° is investigated for a number of different crops using airborne SAR data. The purpose of the investigation is to determine the effect of the variation of incidence angle within a SAR image when...

  3. Immunological Responses against SARS-Coronavirus Infection in Humans

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Xu; Xiao-Ming Gao

    2004-01-01

    Since the outbreak of a SARS epidemic last year, significant advances have been made on our understanding of the mechanisms of interaction between the SARS coronavirus (CoV) and the immune system. Strong humoral responses have been found in most patients following SARS-CoV infection, with high titers of neutralizing Abspresent in their convalescent sera. The nucleocapsid (N) and spike (S) proteins of SARS-CoV appear to be the dominant antigens recognized by serum Abs. CD4+ T cell responses against the N protein have been observed in SARS patients and an HLA-A2-restricted cytotoxic T lymphocyte epitope in the S protein has been identified.It is likely that the immune responses induced by SARS-CoV infection could also cause pathological damage to the host, especially in the case of proinflammatory cytokines. There is also evidence suggesting that SARS-CoV might be able to directly invade cells of the immune system. Our understanding on the interaction between SARS-CoV, the immune system and local tissues is essential to future diagnosis, control and treatment of this very contagious disease.

  4. Immunological Responses against SARS-Coronavirus Infection in Humans

    Institute of Scientific and Technical Information of China (English)

    XiaojunXu; Xiao-MingGao

    2004-01-01

    Since the outbreak of a SARS epidemic last year, significant advances have been made on our understanding of the mechanisms of interaction between the SARS coronavirus (CoV) and the immune system. Strong humoral responses have been found in most patients following SARS-CoV infection, with high titers of neutralizing Abs present in their convalescent sera. The nucleocapsid (N) and spike (S) proteins of SARS-CoV appear to be the dominant antigens recognized by serum Abs. CD4+ T cell responses against the N protein have been observed in SARS patients and an HLA-A2-restricted cytotoxic T lymphocyte epitope in the S protein has been identified. It is likely that the immune responses induced by SARS-CoV infection could also cause pathological damage to the host, especially in the case of proinflammatory cytokines. There is also evidence suggesting that SARS-CoV might be able to directly invade cells of the immune system. Our understanding on the interaction between SARS-CoV, the immune system and local tissues is essential to future diagnosis, control and treatment of this very contagious disease. Cellular & Molecular Immunology. 2004;1(2):119-122.

  5. Ocean Surface Wind Speed of Hurricane Helene Observed by SAR

    DEFF Research Database (Denmark)

    Xu, Qing; Cheng, Yongcun; Li, Xiaofeng

    2011-01-01

    The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high-resolution hur......The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high......-resolution hurricane was conducted. A case study was carried out to retrieve ocean surface wind field from C-band RADARSAT-1 SAR image which captured the structure of hurricane Helene over the Atlantic Ocean on 20 September, 2006. With wind direction from the outputs of U.S. Navy Operational Global Atmospheric...... CIWRAP models have been tested to extract wind speed from SAR data. The SAR retrieved ocean surface winds were compared to the aircraft wind speed observations from stepped frequency microwave radiometer (SFMR). The results show the capability of hurricane wind monitoring by SAR....

  6. Cloaked similarity between HIV-1 and SARS-CoV suggests an anti-SARS strategy

    Directory of Open Access Journals (Sweden)

    Kliger Yossef

    2003-09-01

    Full Text Available Abstract Background Severe acute respiratory syndrome (SARS is a febrile respiratory illness. The disease has been etiologically linked to a novel coronavirus that has been named the SARS-associated coronavirus (SARS-CoV, whose genome was recently sequenced. Since it is a member of the Coronaviridae, its spike protein (S2 is believed to play a central role in viral entry by facilitating fusion between the viral and host cell membranes. The protein responsible for viral-induced membrane fusion of HIV-1 (gp41 differs in length, and has no sequence homology with S2. Results Sequence analysis reveals that the two viral proteins share the sequence motifs that construct their active conformation. These include (1 an N-terminal leucine/isoleucine zipper-like sequence, and (2 a C-terminal heptad repeat located upstream of (3 an aromatic residue-rich region juxtaposed to the (4 transmembrane segment. Conclusions This study points to a similar mode of action for the two viral proteins, suggesting that anti-viral strategy that targets the viral-induced membrane fusion step can be adopted from HIV-1 to SARS-CoV. Recently the FDA approved Enfuvirtide, a synthetic peptide corresponding to the C-terminal heptad repeat of HIV-1 gp41, as an anti-AIDS agent. Enfuvirtide and C34, another anti HIV-1 peptide, exert their inhibitory activity by binding to a leucine/isoleucine zipper-like sequence in gp41, thus inhibiting a conformational change of gp41 required for its activation. We suggest that peptides corresponding to the C-terminal heptad repeat of the S2 protein may serve as inhibitors for SARS-CoV entry.

  7. sar Aira y el exotismo

    Directory of Open Access Journals (Sweden)

    Ricardo Gutiérrez-Mouat

    2013-07-01

    Full Text Available The present paper analyses one of the less commonly studied aspects of the poetics of César Aira: exoticism, which in Aira stems from the unstable and paradoxical place proper of a post-modern writer from the Rio de la Plata facing traditional (and European representations of exoticism in a period of cultural globalisation. The paper examines such a paradox and concludes that Aira’s exoticism is manifest in the ethnographic simulation and in certain thoughts on the de-familiarisation of the mother tongue.

  8. Unparallel trajectory bistatic spotlight SAR imaging

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; JING Wei; XING MengDao; BAO Zheng

    2009-01-01

    A new approach for unparallel trajectory bistatic spotlight SAR imaging is proposed. The approach utilizes the concept of instantaneous Doppler wavenumber and introduces two variants, the sum-range and subtraction-range, to develop the 2D frequency analytical formula. Based on the assumption of plane wavefront, the transmitting and receiving Doppler are separated and formulated via series reversion. And frequency scaling is applied to focus image. The algorithm is with high computational efficiency, and provides well focus for limited scene imaging. Simulation result confirms the validity of the approach.

  9. Cross-calibration of interferometric SAR data

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2003-01-01

    Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully......, but not necessarily from map to map. It is based on natural distributed targets for which no a priori knowledge is needed. In particular, no DEM is required as in calibration techniques based on dedicated calibration scenes. To achieve absolute calibration, i.e. elimination of a constant elevation offset, a single...

  10. 极化干涉 SAR 相干最优理论及其验证分析%Basic Theory and Analysis of Polarimetric SAR Interferometry Optimization

    Institute of Scientific and Technical Information of China (English)

    尚玉双; 刘国林; 陶秋香

    2014-01-01

    极化干涉SAR树高反演是当前SAR研究领域的一个重要方向。相干最优化是在各种散射机制中寻求最优的散射机制,对于极化干涉SAR,它不仅可以改善不同极化通道之间的相干系数,还能改善地物分类和垂直结构参数估计。首先详细分析极化干涉SAR反演树高的相干最优化理论基础,然后利用仿真数据从不同极化通道对线极化、Pauli基极化和最优极化进行了试验,从定性和定量进行对比分析,研究结果进一步验证相干最优分解方法可以提高干涉相干系数,并获得更好的干涉图,从而有利于提高树高反演的精度。%Tree height inversion based on polarization interference SAR is an important direction in the current SAR research field .By searching for the optimal mechanism in various scattering mechanisms , for POL-InSAR system, it not only can be used to improve the coherence between different polarization channels , but also can help to improve classification and vertical structure parameters esti -mation process .The optimal mechanism of tree height inversion based on polarization interference SAR was elaborated and analyzed , and an experiment on the simulation data of line polarization , Pauli Base change and the optimal polarization was done .By making a contrastive analysis on aspects of qualitative and quantitative information , we confirmed that coherent optimal decomposition method can increase interference coherent coefficient and help us get better interferogram so as to improve tree height inversion ′s precision.

  11. Criterial Attributes of Interpersonal Solidarity.

    Science.gov (United States)

    Prisbell, Marshall

    An investigation was undertaken to further the conceptual and operational nature of interpersonal solidarity. Specifically, the investigation considered additional criterial attributes of solidarity to those previously studied by L. R. Wheeless. The sample consisted of 162 adults drawn from elementary and secondary school teachers, college…

  12. SOA: A Quality Attribute Perspective

    Science.gov (United States)

    2011-06-23

    JMS) – CORBA … • Infrastructure services available to service providers and/or service consumers to perform common tasks or satisfy QoS requirements...Services is one technology for SOA implementation SOA and Quality Attributes SOA WS* Web Services CORBA REST Services and POX Key Class Realization

  13. Subspace clustering through attribute clustering

    Institute of Scientific and Technical Information of China (English)

    Kun NIU; Shubo ZHANG; Junliang CHEN

    2008-01-01

    Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.

  14. k-visit Attribute Grammars

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Skyum, S.

    1981-01-01

    It is shown that any well-defined attribute grammar is k-visit for some k. Furthermore, it is shown that given a well-defined grammar G and an integer k, it is decidable whether G is k-visit. Finally it is shown that the k-visit grammars specify a proper hierarchy with respect to translations...

  15. Temporal context for authorship attribution

    DEFF Research Database (Denmark)

    Hansen, Niels Dalum; Lioma, Christina; Larsen, Birger;

    2014-01-01

    A study of temporal aspects of authorship attribution - a task which aims to distinguish automatically between texts written by different authors by measuring textual features. This task is important in a number of areas, including plagiarism detection in secondary education, which we study...

  16. Abstract Interpretation Using Attribute Grammar

    DEFF Research Database (Denmark)

    Rosendahl, Mads

    1990-01-01

    This paper deals with the correctness proofs of attribute grammars using methods from abstract interpretation. The technique will be described by defining a live-variable analysis for a small flow-chart language and proving it correct with respect to a continuation style semantics. The proof...

  17. The Accuratre Signal Model and Imaging Processing in Geosynchronous SAR

    Science.gov (United States)

    Hu, Cheng

    With the development of synthetic aperture radar (SAR) application, the disadvantage of low earth orbit (LEO) SAR becomes more and more apparent. The increase of orbit altitude can shorten the revisit time and enlarge the coverage area in single look, and then satisfy the application requirement. The concept of geosynchronous earth orbit (GEO) SAR system is firstly presented and deeply discussed by K.Tomiyasi and other researchers. A GEO SAR, with its fine temporal resolution, would overcome the limitations of current imaging systems, allowing dense interpretation of transient phenomena as GPS time-series analysis with a spatial density several orders of magnitude finer. Until now, the related literatures about GEO SAR are mainly focused in the system parameter design and application requirement. As for the signal characteristic, resolution calculation and imaging algorithms, it is nearly blank in the related literatures of GEO SAR. In the LEO SAR, the signal model analysis adopts the `Stop-and-Go' assumption in general, and this assumption can satisfy the imaging requirement in present advanced SAR system, such as TerraSAR, Radarsat2 and so on. However because of long propagation distance and non-negligible earth rotation, the `Stop-and-Go' assumption does not exist and will cause large propagation distance error, and then affect the image formation. Furthermore the long propagation distance will result in the long synthetic aperture time such as hundreds of seconds, therefore the linear trajectory model in LEO SAR imaging will fail in GEO imaging, and the new imaging model needs to be proposed for the GEO SAR imaging processing. In this paper, considering the relative motion between satellite and earth during signal propagation time, the accurate analysis method for propagation slant range is firstly presented. Furthermore, the difference between accurate analysis method and `Stop-and-Go' assumption is analytically obtained. Meanwhile based on the derived

  18. Classification and Monitoring of Reed Belts Using Dual-Polarimetric TerraSAR-X Time Series

    Directory of Open Access Journals (Sweden)

    Iris Heine

    2016-06-01

    Full Text Available Synthetic aperture radar polarimetry (PolSAR and polarimetric decomposition techniques have proven to be useful tools for wetland mapping. In this study we classify reed belts and monitor their phenological changes at a natural lake in northeastern Germany using dual-co-polarized (HH, VV TerraSAR-X time series. The time series comprises 19 images, acquired between August 2014 and May 2015, in ascending and descending orbit. We calculated different polarimetric indices using the HH and VV intensities, the dual-polarimetric coherency matrix including dominant and mean alpha scattering angles, and entropy and anisotropy (normalized eigenvalue difference as well as combinations of entropy and anisotropy for the analysis of the scattering scenarios. The image classifications were performed with the random forest classifier and validated with high-resolution digital orthophotos. The time series analysis of the reed belts revealed significant seasonal changes for the double-bounce–sensitive parameters (intensity ratio HH/VV and intensity difference HH-VV, the co-polarimetric coherence phase and the dominant and mean alpha scattering angles and in the dual-polarimetric coherence (amplitude, anisotropy, entropy, and anisotropy-entropy combinations; whereas in summer dense leaves cause volume scattering, in winter, after leaves have fallen, the reed stems cause predominately double-bounce scattering. Our study showed that the five most important parameters for the classification of reed are the intensity difference HH-VV, the mean alpha scattering angle, intensity ratio HH/VV, and the coherence (phase. Due to the better separation of reed and other vegetation (deciduous forest, coniferous forest, meadow, winter acquisitions are preferred for the mapping of reed. Multi-temporal stacks of winter images performed better than summer ones. The combination of ascending and descending images also improved the result as it reduces the influence of the sensor

  19. A prototype of an automated high resolution InSAR volcano-monitoring system in the MED-SUV project

    Science.gov (United States)

    Chowdhury, Tanvir A.; Minet, Christian; Fritz, Thomas

    2016-04-01

    Volcanic processes which produce a variety of geological and hydrological hazards are difficult to predict and capable of triggering natural disasters on regional to global scales. Therefore it is important to monitor volcano continuously and with a high spatial and temporal sampling rate. The monitoring of active volcanoes requires the reliable measurement of surface deformation before, during and after volcanic activities and it helps for the better understanding and modelling of the involved geophysical processes. Space-borne synthetic aperture radar (SAR) interferometry (InSAR), persistent scatterer interferometry (PSI) and small baseline subset algorithm (SBAS) provide a powerful tool for observing the eruptive activities and measuring the surface changes of millimetre accuracy. All the mentioned techniques with deformation time series extraction address the challenges by exploiting medium to large SAR image stacks. The process of selecting, ordering, downloading, storing, logging, extracting and preparing the data for processing is very time consuming has to be done manually for every single data-stack. In many cases it is even an iterative process which has to be done regularly and continuously. Therefore, data processing becomes slow which causes significant delays in data delivery. The SAR Satellite based High Resolution Data Acquisition System, which will be developed at DLR, will automate this entire time consuming tasks and allows an operational volcano monitoring system. Every 24 hours the system runs for searching new acquired scene over the volcanoes and keeps track of the data orders, log the status and download the provided data via ftp-transfer including E-Mail alert. Furthermore, the system will deliver specified reports and maps to a database for review and use by specialists. The user interaction will be minimized and iterative processes will be totally avoided. In this presentation, a prototype of SAR Satellite based High Resolution Data

  20. Radiometric and geometric calibration of JERS-1 SAR

    Science.gov (United States)

    Shimada, M.

    Since the beginning of April '92, the calibration and validation has been being conducted to characterize the JERS-1's SAR and qualify the SAR image products using the calibration instruments and evaluation software tools, such as the 2.4 meter trihedral corner reflectors and the active radar calibrators whose radar cross sections are known as well as their locations. Analysis of SAR data using such instruments derived the conversion factor (CF), which relates the digital number (DN) of SAR image pixel and the normalized radar cross section (NRCS) of the target, as -68.51 dB with the accuracy of 1.86 dB(1 sigma) for the full swath of SAR image. The image quality was also recognized as well as designed.

  1. Ionospheric effects on repeat-pass SAR interferometry

    Science.gov (United States)

    Feng, Jian; Zhen, Weimin; Wu, Zhensen

    2017-10-01

    InSAR measurements can be significantly affected by the atmosphere when the radar signal propagates through the atmosphere since it varies with space and time. Great efforts have been made in recent years to better understand the properties of the tropospheric effects and to develop methods for mitigating these effects. By using the basic principles of InSAR, the quantitative analysis of ionospheric delay effects on topography and surface deformation have been introduced for the first time. The measurement errors can be related to the vertical ionospheric total electron content (vTEC). By using the ionospheric observations, the effects of temporal ionospheric variations on InSAR have been analyzed. The results indicate that the ionospheric variations with time, season, solar cycle and geomagnetic activities can compromise the effectiveness of InSAR for both the measurement of topography and surface determination. The repeat-pass SAR interferometry errors induced by ionosphere should be corrected by actual measurements.

  2. Flood Mapping Using InSAR Coherence Map

    Science.gov (United States)

    Selmi, S.; Ben Abdallah, W.; Abdelfatteh, R.

    2014-09-01

    Classic approaches for the detection of flooded areas are based on a static analysis of optical images and/or SAR data during and after the event. In this paper, we aim to extract the flooded zones by using the SAR image coupled with the InSAR coherence. A new formulation of the ratio approach for flood detection is given considering InSAR coherence. Our contribution is to take advantage from the coherence map provided using the InSAR pairs (one before and one after the event) to enhance the detection of flooded areas. We explore the fact that the coherence values during and after the flood are mainly differents on the flooded zones and we give a more suitable flood decision rule using this assumption. The proposed approach is tested and validated in the case of the flood taken place in 2005 in the region of Kef in Tunisia.

  3. SAR Image Desp eckling by Sparse Reconstruction Based on Shearlets

    Institute of Scientific and Technical Information of China (English)

    JI Jian; LI Xiao; XU Shuang-Xing; LIU Huan; HUANG Jing-Jing

    2015-01-01

    Synthetic aperture radar (SAR) image is usually polluted by multiplicative speckle noise, which can affect further processing of SAR image. This paper presents a new approach for multiplicative noise removal in SAR images based on sparse coding by shearlets filtering. First, a SAR despeckling model is built by the theory of compressed sensing (CS). Secondly, obtain shearlets coefficient through shearlet transform, each scale coefficient is represented as a unit. For each unit, sparse coefficient is iteratively estimated by using Bayesian estimation based on shearlets domain. The represented units are finally collaboratively aggregated to construct the despeckling image. Our results in SAR image despeckling show the good performance of this algorithm, and prove that the algorithm proposed is robustness to noise, which is not only good for reducing speckle, but also has an advantage in holding information of the edge.

  4. Identification of an epitope of SARS-coronavirus nucleocapsid protein

    Institute of Scientific and Technical Information of China (English)

    YING LIN; JIN WANG; HONG XIA WANG; HUA LIANG JIANG; JIAN HUA SHEN; YOU HUA XIE; YUAN WANG; GANG PEI; BEI FEN SHEN; JIA RUI WU; BING SUN; XU SHEN; RUI FU YANG; YI XUE LI; YONG YONG JI; YOU YU HE; MUDE SHI; WEI LU; TIE LIU SHI

    2003-01-01

    The nucleocapsid (N) protein of severe acute respiratory syndrome-coronavirus (SARS-CoV) is a majorvirion structural protein. In this study, two epitopes (N1 and N2) of the N protein of SARS-CoV werepredicted by bioinformatics analysis. After immunization with two peptides, the peptides-specific antibodieswere isolated from the immunized rabbits. The further experiments demonstrated that N1 peptide-inducedpolyclonal antibodies had a high affinity to bind to E. coli expressed N protein of SARS-CoV. Furthermore, itwas confirmed that N1 peptide-specific IgG antibodies were detectable in the sera of severe acute respiratorysyndrome (SARS) patients. The results indicated that an epitope of the N protein has been identified andN protein specific Abs were produced by peptide immunization, which will be useful for the study of SARS-CoV.

  5. Ice flow mapping with P-band SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Nielsen, Ulrik; Kusk, Anders

    2013-01-01

    -band SAR data have been acquired in Greenland, and both offset tracking and DInSAR have been applied to the full resolution data as well as to data degraded to the resolution of Biomass. Generally, ice velocity maps are successfully generated, but in the ablation zone, DInSAR fails in the melt season......Glacier and ice sheet dynamics are currently mapped with X-, C-, and L-band SAR. With the prospect of a P-band SAR, Biomass, to be launched within the next decade it is interesting to look into the potential of P-band for ice velocity mapping. In this paper first results are presented. Airborne P...

  6. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    Science.gov (United States)

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-06-25

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model.

  7. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR

    Directory of Open Access Journals (Sweden)

    Weihao Jiang

    2016-06-01

    Full Text Available Following the development of synthetic aperture radar (SAR, SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD model, a rational polynomial coefficients (RPC model, a revised polynomial (PM model and an elevation derivation (EDM model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model.

  8. Real-time optical processor prototype for remote SAR applications

    Science.gov (United States)

    Marchese, Linda; Doucet, Michel; Harnisch, Bernd; Suess, Martin; Bourqui, Pascal; Legros, Mathieu; Desnoyers, Nichola; Guillot, Ludovic; Mercier, Luc; Savard, Maxime; Martel, Anne; Châteauneuf, François; Bergeron, Alain

    2009-09-01

    A Compact Real-Time Optical SAR Processor has been successfully developed and tested. SAR, or Synthetic Aperture Radar, is a powerful tool providing enhanced day and night imaging capabilities. SAR systems typically generate large amounts of information generally in the form of complex data that are difficult to compress. Specifically, for planetary missions and unmanned aerial vehicle (UAV) systems with limited communication data rates this is a clear disadvantage. SAR images are typically processed electronically applying dedicated Fourier transformations. This, however, can also be performed optically in real-time. Indeed, the first SAR images have been optically processed. The optical processor architecture provides inherent parallel computing capabilities that can be used advantageously for the SAR data processing. Onboard SAR image generation would provide local access to processed information paving the way for real-time decision-making. This could eventually benefit navigation strategy and instrument orientation decisions. Moreover, for interplanetary missions, onboard analysis of images could provide important feature identification clues and could help select the appropriate images to be transmitted to Earth, consequently helping bandwidth management. This could ultimately reduce the data throughput requirements and related transmission bandwidth. This paper reviews the design of a compact optical SAR processor prototype that would reduce power, weight, and size requirements and reviews the analysis of SAR image generation using the table-top optical processor. Various SAR processor parameters such as processing capabilities, image quality (point target analysis), weight and size are reviewed. Results of image generation from simulated point targets as well as real satellite-acquired raw data are presented.

  9. Development of a dose-response model for SARS coronavirus.

    Science.gov (United States)

    Watanabe, Toru; Bartrand, Timothy A; Weir, Mark H; Omura, Tatsuo; Haas, Charles N

    2010-07-01

    In order to develop a dose-response model for SARS coronavirus (SARS-CoV), the pooled data sets for infection of transgenic mice susceptible to SARS-CoV and infection of mice with murine hepatitis virus strain 1, which may be a clinically relevant model of SARS, were fit to beta-Poisson and exponential models with the maximum likelihood method. The exponential model (k= 4.1 x l0(2)) could describe the dose-response relationship of the pooled data sets. The beta-Poisson model did not provide a statistically significant improvement in fit. With the exponential model, the infectivity of SARS-CoV was calculated and compared with those of other coronaviruses. The does of SARS-CoV corresponding to 10% and 50% responses (illness) were estimated at 43 and 280 PFU, respectively. Its estimated infectivity was comparable to that of HCoV-229E, known as an agent of human common cold, and also similar to those of some animal coronaviruses belonging to the same genetic group. Moreover, the exponential model was applied to the analysis of the epidemiological data of SARS outbreak that occurred at an apartment complex in Hong Kong in 2003. The estimated dose of SARS-CoV for apartment residents during the outbreak, which was back-calculated from the reported number of cases, ranged from 16 to 160 PFU/person, depending on the floor. The exponential model developed here is the sole dose-response model for SARS-CoV at the present and would enable us to understand the possibility for reemergence of SARS.

  10. Woody savannah tree structural assessment in the greater Kruger National Park region, South Africa, using multi-seasonal polarimetric synthetic aperture radar (SAR) and optical data product approaches

    CSIR Research Space (South Africa)

    Naidoo, L

    2012-11-01

    Full Text Available scattering properties which is essential for building SAR related tree structure relationships. The use of Passive optical sensors alone has also played a role in accurately estimating tree structural parameters (Nichol and Sarker, 2011; Castillo..., J., Field, C.B., 2007. Carnegie Airborne Observatory: in-flight fusion of hyperspectral imaging and waveform light detection and ranging (wLiDAR) for three-dimensional studies of ecosystems. Journal of Applied Remote Sensing, 1 Castillo...

  11. Relations of SARS-Related Stressors and Coping to Chinese College Students' Psychological Adjustment during the 2003 Beijing SARS Epidemic

    Science.gov (United States)

    Main, Alexandra; Zhou, Qing; Ma, Yue; Luecken, Linda J.; Liu, Xin

    2011-01-01

    This study examined the main and interactive relations of stressors and coping related to severe acute respiratory syndrome (SARS) with Chinese college students' psychological adjustment (psychological symptoms, perceived general health, and life satisfaction) during the 2003 Beijing SARS epidemic. All the constructs were assessed by self-report…

  12. Vegetation, smegetation: How InSAR research on tectonics and land surface change has expanded from the deserts to the rain forests and beyond.

    Science.gov (United States)

    Lohman, R. B.

    2015-12-01

    The upcoming avalanche of openly available SAR imagery is expanding the horizons of what can and cannot be accomplished with InSAR. Historically, InSAR performed best in arid regions - an observation that became a bit of a self-fulfilling prophecy as satellite agencies acquired less data in regions with vegetation and agricultural activity. Here we present an overview of the development of InSAR research in tectonics and land surface change over the past 2+ decades, with a view towards some of the new advances in modeling and data management that will be necessary to fully take advantage of SAR data in the near future. One of the most basic breakthroughs will be that issues with decorrelation and the need for sophisticated time series analysis just to enable phase unwrapping will no longer be a major problem over many areas of the globe. New challenges will be the interpretation of coherent signal related to vegetation, soil moisture and time-variable phase scattering height in regions that previously would have just been flagged as "noise". We present results based on the ingestion of independent optical and radar observation types into SAR time series analysis, with applications to deformation sources in the Central and Eastern United States.The land surface properties in the Central and Eastern United States differ from those in the arid regions where InSAR has often been used, both in the presence of vegetation and the often very rapid changes in surface scattering characteristics that occur seasonally and during single events (snowfall, flooding, etc.). In the past, observations were so sparse that these changes resulted in decorrelation, rendering the data unusable. However, shorter acquisition times and a wider range of radar wavelengths allow the extraction of coherent signals from these areas, even spanning large snow storms. The resulting data contain signals that were often disregarded during InSAR time series analysis, but that must be either accounted

  13. Rapid inactivation of SARS-like coronaviruses.

    Energy Technology Data Exchange (ETDEWEB)

    Kapil, Sanjay (Kansas State University, Manhattan, KS); Oberst, R. D. (Kansas State University, Manhattan, KS); Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

    Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

  14. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; hide

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  15. Corner reflector deployment for X-band SAR interferometry to monitor the landslide of Carlantino, Daunia Region (Italy)

    Science.gov (United States)

    Bovenga, F.; Refice, A.; Pasquariello, G.

    2012-04-01

    Space-borne SAR Differential Interferometry (DInSAR) techniques are attractive for landslide investigations because of their capability to provide regional scale coverage and, under favourable conditions, spatially dense information on small ground surface deformations. In particular, advanced multi-temporal InSAR techniques such as Persistent Scatterer Interferometry (PSI) allow detecting and monitoring, with millimetre precision, displacements occurring on selected radar targets (PS) exhibiting coherent radar backscattering properties. PS targets correspond mainly to man-made structures or to rock outcrops, and their spatial density depends on the ground coverage, and it is maximum over urban areas. The application of multi-temporal InSAR analysis to slope instability monitoring poses challenges related to the complex kinematics of the phenomenon, as well as to the unfavourable settings of the area affected by landslides, often occurring on sites of limited extension, characterized by steep topography and variable vegetation cover. This is the case of the Daunia region, located in the Southern Italian Apennine Mountains, which is characterised by scarce urbanisation (mainly small hill-top towns) and dense vegetation cover. The SPINUA (Stable Point INterferometry over Un-urbanised Areas) PSI multi-temporal processing technique was used in the past years to detect and measure ground displacements over this region. Both C-band medium resolution SAR data from ERS-1/2 and ENVISAT ESA satellites, and X-band high resolution SAR data from the TerraSAR-X (TSX) satellite were used. Results indicate that PSI can be profitably used to investigate slope instability, mainly over the urban and peri-urban areas, and that, on these sites, TSX data result very promising for monitoring areas where ERS/ENVISAT PS density is too low. Nevertheless, the application of PSI for slope instability monitoring still remain problematic or impossible in rural and mountainous areas. This is the

  16. Organizational Attributes, Market Growth, and Product Innovation

    NARCIS (Netherlands)

    Song, Michael; Chen, Yan

    2014-01-01

    Extensive research has shown that organizational attributes affect product innovation. Extending this literature, this article delimits two general categories of organizational attributes and relates them to product innovation. Organizational attributes can be either control oriented or flexibility

  17. Organizational Attributes, Market Growth, and Product Innovation

    NARCIS (Netherlands)

    Song, Michael; Chen, Yan

    2014-01-01

    Extensive research has shown that organizational attributes affect product innovation. Extending this literature, this article delimits two general categories of organizational attributes and relates them to product innovation. Organizational attributes can be either control oriented or flexibility

  18. The Characteristics of Attributes in English

    Institute of Scientific and Technical Information of China (English)

    Deng Hui

    2008-01-01

    This essay focuses on two aspects.One is the characteristic of attribute.The other is concern with some points of using attributes in English.This understanding contributes to using attributes correctly both in written and spoken English.

  19. Optics as Scattering

    Science.gov (United States)

    di Francia, Giuliano Toraldo

    1973-01-01

    The art of deriving information about an object from the radiation it scatters was once limited to visible light. Now due to new techniques, much of the modern physical science research utilizes radiation scattering. (DF)

  20. Neutron scattering from fractals

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Freltoft, T.; Richter, D.

    1986-01-01

    The scattering formalism for fractal structures is presented. Volume fractals are exemplified by silica particle clusters formed either from colloidal suspensions or by flame hydrolysis. The determination of the fractional dimensionality through scattering experiments is reviewed, and recent small...