WorldWideScience

Sample records for dem digital elevation

  1. Coastal Digital Elevation Models (DEMs)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital elevation models (DEMs) of U.S. and other coasts that typically integrate ocean bathymetry and land topography. The DEMs support NOAA's mission to understand...

  2. Digital Elevation Model (DEM) 24K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  3. Digital Elevation Models (DEMs) for the main 8 Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM)...

  4. Digital Elevation Models (DEMs) for the main 8 Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection...

  5. Digital Elevation Model (DEM), Published in 2007, City of Dubuque.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from Orthoimagery information as of 2007. Data by this publisher are often provided in State...

  6. A 30 meter Digital Elevation Model (DEM) of the San Gorgonio Pass area, Riverside County, California.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Digital Elevation Models (DEMs) are digital records of terrain elevations at regularly spaced intervals. The interval between elevations of 7.5 minute DEMs is...

  7. Digital Elevation Model (DEM), digital elevation model, Published in unknown, Louisiana State University - Louisiana Geographic Information Center.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from LIDAR information as of unknown. It is described as 'digital elevation model'. Data by...

  8. The New Global Digital Elevation Model : TanDEM-X DEM and its Final Performance

    Science.gov (United States)

    Gonzalez, Carolina; Rizzoli, Paola; Martone, Michele; Wecklich, Christopher; Borla Tridon, Daniela; Bachmann, Markus; Fritz, Thomas; Wessel, Birgit; Krieger, Gerhard; Zink, Manfred

    2017-04-01

    Digital elevation models (DEMs) have become widely used in many scientific and commercial applications and there are several local products have been developed in the last years. They provide a representation of the topographic features of the landscape. The importance of them is known and valued in every geoscience field, but they have also vast use in navigation and in other commercial areas. The main goal of the TanDEM-X (TerraSARX add-on for Digital Elevation Measurements) mission is the generation of a global DEM, homogeneous in quality with unprecedented global accuracy and resolution, which has been completed in mid-2016. For over four years, the almost identical satellites TerraSAR-X and TanDEM-X acquired single-pass interferometric SAR image pairs, from which is it possible to derive the topographic height by unwrapping the interferometric phase, unaffected by temporal decorrelation. Both satellites have been flying in close formation with a flexible geometric configuration. An optimized acquisition strategy aimed at achieving an absolute vertical accuracy much better than 10 meters and a relative vertical accuracy of 2 m and 4 m for flat and steep terrain, respectively, within a horizontal raster of 12 m x 12 m, which slightly varies depending on the geographic latitude. In this paper, we assess the performance of the global Tandem-X DEM, characterized in terms of relative and absolute vertical accuracy. The coverage statistics are also discussed in comparison to the previous almost global but with lower resolution DEM provided by the Shuttle Radar Topography Mission (SRTM). The exceptional quality of the global DEM is confirmed by the obtained results and the global TanDEM-X DEM is now ready to be distributed to the scientific and commercial community.

  9. The TanDEM-X Digital Elevation Model and Terrestrial Impact Craters

    OpenAIRE

    Gottwald, Manfred; Fritz, Thomas; Breit, Helko; Schättler, Birgit; Harris, Alan

    2014-01-01

    We use the global digital elevation model (DEM) generated in the TanDEM-X mission for mapping further confirmed terrestrial impact craters. This DEM provides the most accurate spaceborne global elevation data. It permits detailed studies of the topography of the sites of simple and complex structures with unprecedented accuracy.

  10. ElevationDEM_DEM1M2005

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM, DEMHF...

  11. ElevationDEM_DEM2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington County 2012 2.0m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  12. ElevationDEM_DEM1M2009

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM, DEMHF...

  13. ElevationDEM_DEM1M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM, DEMHF...

  14. ElevationDEM_DEM1M2007

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM, DEMHF...

  15. Digital Elevation Model (DEM), Topographic survey of Eureka Township, Published in unknown, Eureka County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from Field Survey/GPS information as of unknown. It is described as 'Topographic survey of...

  16. Digital elevation models (DEMs) of the Elwha River delta, Washington, September 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in September...

  17. A seamless, high-resolution, coastal digital elevation model (DEM) for Southern California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A seamless, three-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the...

  18. Digital elevation models (DEMs) of the Elwha River delta, Washington, May 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in May 2011....

  19. Digital elevation models (DEMs) of the Elwha River delta, Washington, August 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in August 2011....

  20. Digital Elevation Model (DEM), Published in unknown, DeKalb County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from LIDAR information as of unknown. Data by this publisher are often provided in State...

  1. A seamless, high-resolution, coastal digital elevation model (DEM) for Southern California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A seamless, three-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the...

  2. Digital elevation models (DEMs) of the Elwha River delta, Washington, July 2016

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in July 2016....

  3. Digital elevation models (DEMs) of the Elwha River delta, Washington, September 2010

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in September...

  4. Digital elevation models (DEMs) of the Elwha River delta, Washington, August 2012

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents a digital elevation model (DEM) derived from bathymetry and topography data of the Elwha River delta collected in August 2012....

  5. San Francisco Bay-Delta bathymetric/topographic digital elevation model(DEM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A high-resolution (10-meter per pixel) digital elevation model (DEM) was created for the Sacramento-San Joaquin Delta using both bathymetry and topography data. This...

  6. ElevationDEM_DEM1m

    Data.gov (United States)

    Vermont Center for Geographic Information — A "Bare Earth" Digital Elevation Model (DEM) data represents the bare ground surface without any objects like plants and buildings on it, was derived from the best...

  7. Open-Source Digital Elevation Model (DEMs) Evaluation with GPS and LiDAR Data

    Science.gov (United States)

    Khalid, N. F.; Din, A. H. M.; Omar, K. M.; Khanan, M. F. A.; Omar, A. H.; Hamid, A. I. A.; Pa'suya, M. F.

    2016-09-01

    Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) are freely available Digital Elevation Model (DEM) datasets for environmental modeling and studies. The quality of spatial resolution and vertical accuracy of the DEM data source has a great influence particularly on the accuracy specifically for inundation mapping. Most of the coastal inundation risk studies used the publicly available DEM to estimated the coastal inundation and associated damaged especially to human population based on the increment of sea level. In this study, the comparison between ground truth data from Global Positioning System (GPS) observation and DEM is done to evaluate the accuracy of each DEM. The vertical accuracy of SRTM shows better result against ASTER and GMTED10 with an RMSE of 6.054 m. On top of the accuracy, the correlation of DEM is identified with the high determination of coefficient of 0.912 for SRTM. For coastal zone area, DEMs based on airborne light detection and ranging (LiDAR) dataset was used as ground truth data relating to terrain height. In this case, the LiDAR DEM is compared against the new SRTM DEM after applying the scale factor. From the findings, the accuracy of the new DEM model from SRTM can be improved by applying scale factor. The result clearly shows that the value of RMSE exhibit slightly different when it reached 0.503 m. Hence, this new model is the most suitable and meets the accuracy requirement for coastal inundation risk assessment using open source data. The suitability of these datasets for further analysis on coastal management studies is vital to assess the potentially vulnerable areas caused by coastal inundation.

  8. The Importance of Precise Digital Elevation Models (DEM) in Modelling Floods

    Science.gov (United States)

    Demir, Gokben; Akyurek, Zuhal

    2016-04-01

    Digital elevation Models (DEM) are important inputs for topography for the accurate modelling of floodplain hydrodynamics. Floodplains have a key role as natural retarding pools which attenuate flood waves and suppress flood peaks. GPS, LIDAR and bathymetric surveys are well known surveying methods to acquire topographic data. It is not only time consuming and expensive to obtain topographic data through surveying but also sometimes impossible for remote areas. In this study it is aimed to present the importance of accurate modelling of topography for flood modelling. The flood modelling for Samsun-Terme in Blacksea region of Turkey is done. One of the DEM is obtained from the point observations retrieved from 1/5000 scaled orthophotos and 1/1000 scaled point elevation data from field surveys at x-sections. The river banks are corrected by using the orthophotos and elevation values. This DEM is named as scaled DEM. The other DEM is obtained from bathymetric surveys. 296 538 number of points and the left/right bank slopes were used to construct the DEM having 1 m spatial resolution and this DEM is named as base DEM. Two DEMs were compared by using 27 x-sections. The maximum difference at thalweg of the river bed is 2m and the minimum difference is 20 cm between two DEMs. The channel conveyance capacity in base DEM is larger than the one in scaled DEM and floodplain is modelled in detail in base DEM. MIKE21 with flexible grid is used in 2- dimensional shallow water flow modelling. The model by using two DEMs were calibrated for a flood event (July 9, 2012). The roughness is considered as the calibration parameter. From comparison of input hydrograph at the upstream of the river and output hydrograph at the downstream of the river, the attenuation is obtained as 91% and 84% for the base DEM and scaled DEM, respectively. The time lag in hydrographs does not show any difference for two DEMs and it is obtained as 3 hours. Maximum flood extents differ for the two DEMs

  9. Digtial Elevation Model (DEM) 250K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  10. Digitial Elevation Model (DEM) 100K

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital Elevation Model (DEM) is the terminology adopted by the USG to describe terrain elevation data sets in a digital raster form. The standard DEM consists of a...

  11. Digital Elevation Model (DEM), Lanai Digital Elevation Model, Published in 2005, 1:24000 (1in=2000ft) scale, U.S. Geological Survey.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Orthoimagery information as of 2005. It is...

  12. Digital Elevation Model (DEM), Oahu Digital Elevation Model, Published in 2003, 1:24000 (1in=2000ft) scale, U.S. Geological Survey.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Orthoimagery information as of 2003. It is...

  13. Digital Elevation Model (DEM), Hawaii (Big Island) Digital Elevation Model, Published in 2004, 1:24000 (1in=2000ft) scale, U.S. Geological Survey.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Orthoimagery information as of 2004. It is...

  14. Tectonic development of the Northwest Bonaparte Basin, Australia by using Digital Elevation Model (DEM)

    Science.gov (United States)

    Wahid, Ali; Salim, Ahmed Mohamed Ahmed; Ragab Gaafar, Gamal; Yusoff, AP Wan Ismail Wan

    2016-02-01

    The Bonaparte Basin consist of majorly offshore part is situated at Australia's NW continental margin, covers an area of approx. 270,000km2. Bonaparte Basin having a number of sub-basins and platform areas of Paleozoic and Mesozoic is structurally complex. This research established the geologic and geomorphologic studies using Digital Elevation Model (DEM) as a substitute approach in morphostructural analysis to unravel the geological complexities. Although DEMs have been in practice since 1990s, they still have not become common tool for mapping studies. The research work comprised of regional structural analysis with the help of integrated elevation data, satellite imageries, available open topograhic images and internal geological maps with interpreted seismic. The structural maps of the study area have been geo-referenced which further overlaid onto SRTM data and satellite images for combined interpretation which facilitate to attain Digital Elevation Model of the study area. The methodology adopts is to evaluate and redefine development of geodynamic processes involved in formation of Bonaparte Basin. The main objectives is to establish the geological histories by using digital elevation model. The research work will be useful to incorporate different tectonic events occurred at different Geological times in a digital elevation model. The integrated tectonic analysis of different digital data sets benefitted substantially from combining them into a common digital database. Whereas, the visualization software facilitates the overlay and combined interpretation of different data sets which is helpful to reveal hidden information not obvious or accessible otherwise for regional analysis.

  15. Digital Elevation Model (DEM), GRID derived from USGS .dem, Published in 2007, 1:600 (1in=50ft) scale, Shawnee County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2007. It is described as...

  16. Digital Elevation Model (DEM), 5 Meter Auto-correlated DEM, Published in 2006, 1:24000 (1in=2000ft) scale, State of Utah Automated Geographic Reference Center.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2006. It is described...

  17. Digital Elevation Model (DEM), 2 Meter LIDAR Bare Earth DEM, Published in 2006, 1:12000 (1in=1000ft) scale, State of Utah Automated Geographic Reference Center.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:12000 (1in=1000ft) scale, was produced all or in part from LIDAR information as of 2006. It is described...

  18. Digital Elevation Model (DEM), Allegany County DEM 10 ft pixel, Published in 2005, 1:1200 (1in=100ft) scale, Allegany County Government.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from LIDAR information as of 2005. It is described as...

  19. ElevationDEM_DEM3p2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Chittenden County 2004 3.2m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  20. ElevationDEM_DEM1p6M2008

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Lower 2008 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  1. ElevationDEM_DEM0p7M2013

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area: Rutland/GI Counties 2013 0.7m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  2. ElevationDEM_DEM1p6M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  3. ElevationDEM_DEM3p2M2004

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Chittenden County 2004 3.2m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  4. ElevationDEM_DEM0p7M2015

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  5. ElevationDEM_DEM1p6M2012

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  6. Digital Elevation Model (DEM), LiDAR-based Digital Elevation Model (DEM) in Esri GRID format. 5 foot resolution countywide., Published in 2010, 1:1200 (1in=100ft) scale, Brown County, WI.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from LIDAR information as of 2010. It is described as...

  7. Digital Elevation Model (DEM), Published in 1996, 1:2400 (1in=200ft) scale, Shawano County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Orthoimagery information as of 1996. Data by this...

  8. Digital Elevation Model (DEM), Published in 2007, 1:12000 (1in=1000ft) scale, Door County, Wisconsin.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:12000 (1in=1000ft) scale, was produced all or in part from LIDAR information as of 2007. Data by this...

  9. Digital Elevation Model (DEM), Published in 2005, 1:24000 (1in=2000ft) scale, Sauk County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from LIDAR information as of 2005. Data by this...

  10. Digital Elevation Model (DEM), Published in 2000, 1:7200 (1in=600ft) scale, Southern Georgia Regional Commission.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:7200 (1in=600ft) scale as of 2000. Data by this publisher are often provided in State Plane coordinate...

  11. Digital Elevation Model (DEM), Published in 2000, 1:12000 (1in=1000ft) scale, Off.of Admin - ITSD.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:12000 (1in=1000ft) scale, was produced all or in part from Other information as of 2000. Data by this...

  12. Digital Elevation Model (DEM), Published in 2004, 1:2400 (1in=200ft) scale, St. Croix County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Orthoimagery information as of 2004. Data by this...

  13. Digital Elevation Model (DEM), Published in unknown, 1:4800 (1in=400ft) scale, Stokes County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:4800 (1in=400ft) scale, was produced all or in part from LIDAR information as of unknown. Data by this...

  14. Digital Elevation Model (DEM), NED Elevation Sets for the counties we serve from USGS, Published in 1999, Prairie Land Electric COOP, Inc..

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from Not Provided information as of 1999. It is described as 'NED Elevation Sets for the...

  15. A Seamless, High-Resolution, Coastal Digital Elevation Model (DEM) for Southern California

    Science.gov (United States)

    Barnard, Patrick L.; Hoover, Daniel

    2010-01-01

    A seamless, 3-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the 20-m elevation contour. This dataset was produced to provide critical boundary conditions (bathymetry and topography) for a modeling effort designed to predict the impacts of severe winter storms on the Southern California coast (Barnard and others, 2009). The hazards model, run in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable detailed prediction of water levels, run-up, wave heights, and currents. Research-grade predictions of coastal flooding, inundation, erosion, and cliff failure are also included. The DEM was constructed to define the general shape of nearshore, beach and cliff surfaces as accurately as possible, with less emphasis on the detailed variations in elevation inland of the coast and on bathymetry inside harbors. As a result this DEM should not be used for navigation purposes.

  16. San Francisco Bay-Delta bathymetric/topographic digital elevation model (DEM)

    Science.gov (United States)

    Fregoso, Theresa; Wang, Rueen-Fang; Ateljevich, Eli; Jaffe, Bruce E.

    2017-01-01

    A high-resolution (10-meter per pixel) digital elevation model (DEM) was created for the Sacramento-San Joaquin Delta using both bathymetry and topography data. This DEM is the result of collaborative efforts of the U.S. Geological Survey (USGS) and the California Department of Water Resources (DWR). The base of the DEM is from a 10-m DEM released in 2004 and updated in 2005 (Foxgrover and others, 2005) that used Environmental Systems Research Institute (ESRI), ArcGIS Topo to Raster module to interpolate grids from single beam bathymetric surveys collected by DWR, the Army Corp of Engineers (COE), the National Oceanic and Atmospheric Administration (NOAA), and the USGS, into a continuous surface. The Topo to Raster interpolation method was specifically designed to create hydrologically correct DEMs from point, line, and polygon data (Environmental Systems Research Institute, Inc., 2015). Elevation contour lines were digitized based on the single beam point data for control of channel morphology during the interpolation process. Checks were performed to ensure that the interpolated surfaces honored the source bathymetry, and additional contours and (or) point data were added as needed to help constrain the data. The original data were collected in the tidal datum Mean Lower or Low Water (MLLW) or the National Geodetic Vertical Datum of 1929 (NGVD29). All data were converted to NGVD29.The 2005 USGS DEM was updated by DWR, first by converting the DEM to the current modern datum of North American Vertical Datum of 1988 (NAVD88) and then by following the methodology of the USGS DEM, established for the 2005 DEM (Foxgrover and others, 2005) for adding newly collected single and multibeam bathymetric data. They then included topographic data from lidar surveys, providing the first DEM that included the land/water interface (Wang and Ateljevich, 2012).The USGS further updated and expanded the DWR DEM with the inclusion of USGS interpolated sections of single beam

  17. ElevationDEM_DEMHF2M2012

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington County 2012 2.0m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  18. A time series of TanDEM-X digital elevation models to monitor a glacier surge

    Science.gov (United States)

    Wendt, Anja; Mayer, Christoph; Lambrecht, Astrid; Floricioiu, Dana

    2016-04-01

    Bivachny Glacier, a tributary of the more than 70 km long Fedchenko Glacier in the Pamir Mountains, Central Asia, is a surge-type glacier with three known surges during the 20th century. In 2011, the most recent surge started which, in contrast to the previous ones, evolved down the whole glacier and reached the confluence with Fedchenko Glacier. Spatial and temporal glacier volume changes can be derived from high-resolution digital elevation models (DEMs) based on bistatic InSAR data from the TanDEM-X mission. There are nine DEMs available between 2011 and 2015 covering the entire surge period in time steps from few months up to one year. During the surge, the glacier surface elevation increased by up to 130 m in the lower part of the glacier; and change rates of up to 0.6 m per day were observed. The surface height dataset was complemented with glacier surface velocity information from TerraSAR-X/ TanDEM-X data as well as optical Landsat imagery. While the glacier was practically stagnant in 2000 after the end of the previous surge in the 1990s, the velocity increase started in 2011 in the upper reaches of the ablation area and successively moved downwards and intensified, reaching up to 4.0 m per day. The combination of surface elevation changes and glacier velocities, both of high temporal and spatial resolution, provides the unique opportunity to describe and analyse the evolution of the surge in unprecedented detail. Especially the relation between the mobilization front and the local mass transport provides insight into the surge dynamics.

  19. Digital Elevation Model (DEM), 2005 Digtial Elevation Model, Published in 2009, 1:2400 (1in=200ft) scale, Dane County Land Information Office.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Other information as of 2009. It is described as...

  20. Revealing topographic lineaments through IHS enhancement of DEM data. [Digital Elevation Model

    Science.gov (United States)

    Murdock, Gary

    1990-01-01

    Intensity-hue-saturation (IHS) processing of slope (dip), aspect (dip direction), and elevation to reveal subtle topographic lineaments which may not be obvious in the unprocessed data are used to enhance digital elevation model (DEM) data from northwestern Nevada. This IHS method of lineament identification was applied to a mosiac of 12 square degrees using a Cray Y-MP8/864. Square arrays from 3 x 3 to 31 x 31 points were tested as well as several different slope enhancements. When relatively few points are used to fit the plane, lineaments of various lengths are observed and a mechanism for lineament classification is described. An area encompassing the gold deposits of the Carlin trend and including the Rain in the southeast to Midas in the northwest is investigated in greater detail. The orientation and density of lineaments may be determined on the gently sloping pediment surface as well as in the more steeply sloping ranges.

  1. Review of Digital Elevation Model (DEM) Based Research on China Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    Tang Guo'an; Ge Shanshan; Li Fayuan; Zhou Jieyu

    2005-01-01

    The Loess Plateau is one of the hot research areas for its specific geographical features. In resent years, with the establishment of national multi-scale DEMs and the perfection of DEM based digital terrain analysis methods, new thoughts and methodologies have been constructed for the Loess Plateau research. This paper introduces the characteristics of DEM data, analyses the development stages of DEM applied in the Loess Plateau research, and discusses its further possible research direction. More discussions are focused on slope spectrum and its concept, as well as the significance in the Loess Plateau research.

  2. Coastal Digital Elevation Models (DEMs) for tsunami hazard assessment on the French coasts

    Science.gov (United States)

    Maspataud, Aurélie; Biscara, Laurie; Hébert, Hélène; Schmitt, Thierry; Créach, Ronan

    2015-04-01

    Building precise and up-to-date coastal DEMs is a prerequisite for accurate modeling and forecasting of hydrodynamic processes at local scale. Marine flooding, originating from tsunamis, storm surges or waves, is one of them. Some high resolution DEMs are being generated for multiple coast configurations (gulf, embayment, strait, estuary, harbor approaches, low-lying areas…) along French Atlantic and Channel coasts. This work is undertaken within the framework of the TANDEM project (Tsunamis in the Atlantic and the English ChaNnel: Definition of the Effects through numerical Modeling) (2014-2017). DEMs boundaries were defined considering the vicinity of French civil nuclear facilities, site effects considerations and potential tsunamigenic sources. Those were identified from available historical observations. Seamless integrated topographic and bathymetric coastal DEMs will be used by institutions taking part in the study to simulate expected wave height at regional and local scale on the French coasts, for a set of defined scenarii. The main tasks were (1) the development of a new capacity of production of DEM, (2) aiming at the release of high resolution and precision digital field models referred to vertical reference frameworks, that require (3) horizontal and vertical datum conversions (all source elevation data need to be transformed to a common datum), on the basis of (4) the building of (national and/or local) conversion grids of datum relationships based on known measurements. Challenges in coastal DEMs development deal with good practices throughout model development that can help minimizing uncertainties. This is particularly true as scattered elevation data with variable density, from multiple sources (national hydrographic services, state and local government agencies, research organizations and private engineering companies) and from many different types (paper fieldsheets to be digitized, single beam echo sounder, multibeam sonar, airborne laser

  3. ElevationDEM_DEM0p7M2014

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Rutland/GI Counties 2013 0.7m and Digital Elevation Model (DEM) datasets of various "hydro-treatments":...

  4. ElevationDEM_DEM1p4m

    Data.gov (United States)

    Vermont Center for Geographic Information — "Bare Earth" Digital Elevation Model (DEM) data, i.e., a bare ground surface without any objects like plants and buildings on it, was derived from the best available...

  5. Application of Digital Elevation Model (DEM for description of soil microtopography changes in laboratory experiments

    Directory of Open Access Journals (Sweden)

    Stańczyk Tomasz

    2016-12-01

    Full Text Available In the study we evaluated spatial and quantitative changes in soil surface microtopography to describe water erosion process under simulated rain with use of a non-contact optical 3D scanner. The experiment was conducted in two variants: with and without drainage layer. Two clay soils collected from farmlands from the catchment of lake Zgorzała (Warsaw were investigated. Six tests of simulated rain were applied, with 55 mm·h−1. The surface roughness and microrelief were determined immediately after every 10 min of rainfall simulation by 3D scanner. The volume of surface and underground runoff as well as soil moisture were measured. The surface points coordinates obtained while scanning were interpolated using natural neighbour method and GIS software to generate Digital Elevation Models (DEM with a 0.5 mm resolution. Two DEM-derived surface roughness indices: Random Roughness (RR and Terrain Ruggedness Index (TRI were used for microrelief description. Calculated values of both roughness factors have decreased with time under the influence of rainfall in all analyzed variants. During the sprinkling the moisture of all samples had been growing rapidly from air-dry state reaching values close to the maximum water capacity (37–48% vol. in 20–30 min. Simultaneously the intensity of surface runoff was increasing and cumulative runoff value was: 17–35% for variants with drainage and 72–83% for the variants without drainage, relative to cumulative rainfall. The observed soil surface elevation changes were associated with aggregates decomposition, erosion and sedimentation, and above all, with a compaction of the soil, which was considered to be a dominant factor hindering the assessment of the erosion intensity of the of the scanned surface.

  6. High-Accuracy Tidal Flat Digital Elevation Model Construction Using TanDEM-X Science Phase Data

    Science.gov (United States)

    Lee, Seung-Kuk; Ryu, Joo-Hyung

    2017-01-01

    This study explored the feasibility of using TanDEM-X (TDX) interferometric observations of tidal flats for digital elevation model (DEM) construction. Our goal was to generate high-precision DEMs in tidal flat areas, because accurate intertidal zone data are essential for monitoring coastal environment sand erosion processes. To monitor dynamic coastal changes caused by waves, currents, and tides, very accurate DEMs with high spatial resolution are required. The bi- and monostatic modes of the TDX interferometer employed during the TDX science phase provided a great opportunity for highly accurate intertidal DEM construction using radar interferometry with no time lag (bistatic mode) or an approximately 10-s temporal baseline (monostatic mode) between the master and slave synthetic aperture radar image acquisitions. In this study, DEM construction in tidal flat areas was first optimized based on the TDX system parameters used in various TDX modes. We successfully generated intertidal zone DEMs with 57-m spatial resolutions and interferometric height accuracies better than 0.15 m for three representative tidal flats on the west coast of the Korean Peninsula. Finally, we validated these TDX DEMs against real-time kinematic-GPS measurements acquired in two tidal flat areas; the correlation coefficient was 0.97 with a root mean square error of 0.20 m.

  7. Digital Elevation Model (DEM), A 10 meter digital elevation model (DEM) is a digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals, Published in 2005, 1:24000 (1in=2000ft) scale, State of Utah Automated Geographic Reference Center.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Orthoimagery information as of 2005. It is...

  8. Digital Elevation Model (DEM), A 30 meter digital elevation model (DEM) is a digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals, Published in 2000, 1:100000 (1in=8333ft) scale, State of Utah Automated Geographic Reference Center.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:100000 (1in=8333ft) scale, was produced all or in part from Orthoimagery information as of 2000. It is...

  9. A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

    Directory of Open Access Journals (Sweden)

    A. J. Cook

    2012-10-01

    Full Text Available A high resolution surface topography Digital Elevation Model (DEM is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S, based on ASTER Global Digital Elevation Model (GDEM data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA imagery. The new DEM has a mean elevation difference of −4 m (± 25 m RMSE from ICESat (compared to −13 m mean and ±97 m RMSE for the original ASTER GDEM, and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (Digital Elevation Model (DEM), 20' Grid DEM for Iredell County provided by 2003 Floodplain Mapping Program data, Published in 2007, 1:600 (1in=50ft) scale, Iredell County GIS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2007. It is described as...

  10. Digital Elevation Model (DEM), The OSIP 2.5FT gridded DEM was derived from LiDAR, Published in 2007, 1:600 (1in=50ft) scale, Ohio Geographically Referenced Information Program (OGRIP).

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2007. It is described as...

  11. Digital Elevation Model (DEM), 5-ft dem derived from LIDAR point data. Some errors between mosaiced tile edges., Published in 2006, 1:600 (1in=50ft) scale, Lumpkin County, GA.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2006. It is described as...

  12. Digital Elevation Model (DEM), 10' DEM from LIDAR (1.2 m raw point spacing, 36.6 cm vertical accuracy, 50 cm horizontal), Published in 2008, 1:1200 (1in=100ft) scale, CITY OF PORTAGE.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from LIDAR information as of 2008. It is described as...

  13. Digital Elevation Model (DEM), DEM created from LIDAR data collected in the spring of 2009 as part of an MPO aerial/contour collection., Published in 2009, 1:600 (1in=50ft) scale, City of Bismarck.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2009. It is described as...

  14. Digital Elevation Model (DEM), Lidar data with break lines, Published in 2007, 1:2400 (1in=200ft) scale, Randolph County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from LIDAR information as of 2007. It is described as...

  15. Digital Elevation Model (DEM), Published in 2002, 1:2400 (1in=200ft) scale, Columbia County Wisconsin Land Information Department.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Orthoimagery information as of 2002. Data by this...

  16. Capturing Micro-topography of an Arctic Tundra Landscape through Digital Elevation Models (DEMs) Acquired from Various Remote Sensing Platforms

    Science.gov (United States)

    Vargas, S. A., Jr.; Tweedie, C. E.; Oberbauer, S. F.

    2013-12-01

    The need to improve the spatial and temporal scaling and extrapolation of plot level measurements of ecosystem structure and function to the landscape level has been identified as a persistent research challenge in the arctic terrestrial sciences. Although there has been a range of advances in remote sensing capabilities on satellite, fixed wing, helicopter and unmanned aerial vehicle platforms over the past decade, these present costly, logistically challenging (especially in the Arctic), technically demanding solutions for applications in an arctic environment. Here, we present a relatively low cost alternative to these platforms that uses kite aerial photography (KAP). Specifically, we demonstrate how digital elevation models (DEMs) were derived from this system for a coastal arctic landscape near Barrow, Alaska. DEMs of this area acquired from other remote sensing platforms such as Terrestrial Laser Scanning (TLS), Airborne Laser Scanning, and satellite imagery were also used in this study to determine accuracy and validity of results. DEMs interpolated using the KAP system were comparable to DEMs derived from the other platforms. For remotely sensing acre to kilometer square areas of interest, KAP has proven to be a low cost solution from which derived products that interface ground and satellite platforms can be developed by users with access to low-tech solutions and a limited knowledge of remote sensing.

  17. High-resolution digital elevation models from single-pass TanDEM-X interferometry over mountainous regions: A case study of Inylchek Glacier, Central Asia

    Science.gov (United States)

    Neelmeijer, Julia; Motagh, Mahdi; Bookhagen, Bodo

    2017-08-01

    This study demonstrates the potential of using single-pass TanDEM-X (TDX) radar imagery to analyse inter- and intra-annual glacier changes in mountainous terrain. Based on SAR images acquired in February 2012, March 2013 and November 2013 over the Inylchek Glacier, Kyrgyzstan, we discuss in detail the processing steps required to generate three reliable digital elevation models (DEMs) with a spatial resolution of 10 m that can be used for glacial mass balance studies. We describe the interferometric processing steps and the influence of a priori elevation information that is required to model long-wavelength topographic effects. We also focus on DEM alignment to allow optimal DEM comparisons and on the effects of radar signal penetration on ice and snow surface elevations. We finally compare glacier elevation changes between the three TDX DEMs and the C-band shuttle radar topography mission (SRTM) DEM from February 2000. We introduce a new approach for glacier elevation change calculations that depends on the elevation and slope of the terrain. We highlight the superior quality of the TDX DEMs compared to the SRTM DEM, describe remaining DEM uncertainties and discuss the limitations that arise due to the side-looking nature of the radar sensor.

  18. ElevationDEM_DEMHF0p7M2013

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area: Rutland/GI Counties 2013 0.7m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  19. ElevationDEM_DEMHF1p6M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  1. ElevationDEM_DEMHF1p6M2012

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  2. ElevationDEM_DEMHF1p6M2008

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Lower 2008 1.6m and Digital Elevation Model (DEM) datasets of various "hydro-treatments": DEM,...

  3. Catchment properties in the Kruger National Park derived from the new TanDEM-X Intermediate Digital Elevation Model (IDEM)

    Science.gov (United States)

    Baade, J.; Schmullius, C.

    2015-04-01

    Digital Elevation Models (DEM) represent fundamental data for a wide range of Earth surface process studies. Over the past years the German TanDEM-X mission acquired data for a new, truly global Digital Elevation Model with unpreceded geometric resolution, precision and accuracy. First processed data sets (i. e. IDEM) with a geometric resolution of 0.4 to 3 arcsec have been made available for scientific purposes. This includes four 1° x 1° tiles covering the Kruger National Park in South Africa. Here we document the results of a local scale IDEM validation exercise utilizing RTK-GNSS-based ground survey points from a dried out reservoir basin and its vicinity characterized by pristine open Savanna vegetation. Selected precursor data sets (SRTM1, SRTM90, ASTER-GDEM2) were included in the analysis and highlight the immense progress in satellite-based Earth surface surveying over the past two decades. Surprisingly, the high precision and accuracy of the IDEM data sets have only little impact on the delineation of watersheds and the calculation of catchment size. But, when it comes to the derivation of topographic catchment properties (e.g. mean slope, etc.) the high resolution of the IDEM04 is of crucial importance, if - from a geomorphologist's view - it was not for the disturbing vegetation.

  4. A simulation of wide area surveillance (WAS) systems and algorithm for digital elevation model (DEM) extraction

    Science.gov (United States)

    Cheng, Beato T.

    2010-04-01

    With the advances in focal plane, electronics and memory storage technologies, wide area and persistence surveillance capabilities have become a reality in airborne ISR. A WAS system offers many benefits in comparison with the traditional airborne image capturing systems that provide little data overlap, both in terms of space and time. Unlike a fix-mount surveillance camera, a persistence WAS system can be deployed anywhere as desired, although the platform typically has to be in motion, say circling above an area of interest. Therefore, WAS is a perfect choice for surveillance that can provide near real time capabilities such as change detection and target tracking. However, the performance of a WAS system is still limited by the available technologies: the optics that control the field-of-view, the electronics and mechanical subsystems that control the scanning, the focal plane data throughput, and the dynamics of the platform all play key roles in the success of the system. It is therefore beneficial to develop a simulated version that can capture the essence of the system, in order to help provide insights into the design of an optimized system. We describe an approach to the simulation of a generic WAS system that allows focal plane layouts, scanning patterns, flight paths and platform dynamics to be defined by a user. The system generates simulated image data of the area ground coverage from reference databases (e.g. aerial imagery, and elevation data), based on the sensor model. The simulated data provides a basis for further algorithm development, such as image stitching/mosaic, registration, and geolocation. We also discuss an algorithm to extract the terrain elevation from the simulated data, and to compare that with the original DEM data.

  5. Digital Elevation Model (DEM), Included in the USGS National Elevation Dataset at seamless.usgs.gov, Published in 2005, 1:24000 (1in=2000ft) scale, U.S. Geological Survey.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Hardcopy Maps information as of 2005. It is...

  6. Coastal Topography--Northeast Atlantic Coast, Post-Hurricane Sandy, 2012: Digital elevation model (DEM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A DEM was produced for a portion of the New York, Delaware, Maryland, Virginia, and North Carolina coastlines, post-Hurricane Sandy (Sandy was an October 2012...

  7. Arctic Digital Elevation Models (DEMs) generated by Surface Extraction from TIN-Based Searchspace Minimization (SETSM) algorithm from RPCs-based Imagery

    Science.gov (United States)

    Noh, M. J.; Howat, I. M.; Porter, C. C.; Willis, M. J.; Morin, P. J.

    2016-12-01

    The Arctic is undergoing rapid change associated with climate warming. Digital Elevation Models (DEMs) provide critical information for change measurement and infrastructure planning in this vulnerable region, yet the existing quality and coverage of DEMs in the Arctic is poor. Low contrast and repeatedly-textured surfaces, such as snow and glacial ice and mountain shadows, all common in the Arctic, challenge existing stereo-photogrammetric techniques. Submeter resolution, stereoscopic satellite imagery with high geometric and radiometric quality, and wide spatial coverage are becoming increasingly accessible to the scientific community. To utilize these imagery for extracting DEMs at a large scale over glaciated and high latitude regions we developed the Surface Extraction from TIN-based Searchspace Minimization (SETSM) algorithm. SETSM is fully automatic (i.e. no search parameter settings are needed) and uses only the satellite rational polynomial coefficients (RPCs). Using SETSM, we have generated a large number of DEMs (> 100,000 scene pair) from WorldView, GeoEye and QuickBird stereo images collected by DigitalGlobe Inc. and archived by the Polar Geospatial Center (PGC) at the University of Minnesota through an academic licensing program maintained by the US National Geospatial-Intelligence Agency (NGA). SETSM is the primary DEM generation software for the US National Science Foundation's ArcticDEM program, with the objective of generating high resolution (2-8m) topography for the entire Arctic landmass, including seamless DEM mosaics and repeat DEM strips for change detection. ArcticDEM is collaboration between multiple US universities, governmental agencies and private companies, as well as international partners assisting with quality control and registration. ArcticDEM is being produced using the petascale Blue Waters supercomputer at the National Center for Supercomputer Applications at the University of Illinois. In this paper, we introduce the SETSM

  8. Evaluating the Quality and Accuracy of TanDEM-X Digital Elevation Models at Archaeological Sites in the Cilician Plain, Turkey

    Directory of Open Access Journals (Sweden)

    Stefan Erasmi

    2014-10-01

    Full Text Available Satellite remote sensing provides a powerful instrument for mapping and monitoring traces of historical settlements and infrastructure, not only in distant areas and crisis regions. It helps archaeologists to embed their findings from field surveys into the broader context of the landscape. With the start of the TanDEM-X mission, spatially explicit 3D-information is available to researchers at an unprecedented resolution worldwide. We examined different experimental TanDEM-X digital elevation models (DEM that were processed from two different imaging modes (Stripmap/High Resolution Spotlight using the operational alternating bistatic acquisition mode. The quality and accuracy of the experimental DEM products was compared to other available DEM products and a high precision archaeological field survey. The results indicate the potential of TanDEM-X Stripmap (SM data for mapping surface elements at regional scale. For the alluvial plain of Cilicia, a suspected palaeochannel could be reconstructed. At the local scale, DEM products from TanDEM-X High Resolution Spotlight (HS mode were processed at 2 m spatial resolution using a merge of two monostatic/bistatic interferograms. The absolute and relative vertical accuracy of the outcome meet the specification of high resolution elevation data (HRE standards from the National System for Geospatial Intelligence (NSG at the HRE20 level.

  9. Digital Elevation Model (DEM), Our DEM was created by using the LiDAR data from our recent acquisition. The layer was created with the help of contour data, mass points & breaklines., Published in 2012, Not Applicable scale, Chippewa County Government.

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Digital Elevation Model (DEM) dataset current as of 2012. Our DEM was created by using the LiDAR data from our recent acquisition. The layer was created with the...

  10. Digital Elevation Model (DEM), 1.7 meter DEM in Urban Areas, 5 Meter DEM in National Forest, flown as part of the LAR-IAC project, Published in 2006, 1:600 (1in=50ft) scale, County of Los Angeles.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:600 (1in=50ft) scale, was produced all or in part from LIDAR information as of 2006. It is described as...

  11. 2009-2011 CA Coastal California TopoBathy Merged Project Digital Elevation Model (DEM)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter...

  12. 2013 NOAA Coastal California TopoBathy Merge Project Digital Elevation Model (DEM)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter...

  13. An automated, open-source pipeline for mass production of digital elevation models (DEMs) from very-high-resolution commercial stereo satellite imagery

    Science.gov (United States)

    Shean, David E.; Alexandrov, Oleg; Moratto, Zachary M.; Smith, Benjamin E.; Joughin, Ian R.; Porter, Claire; Morin, Paul

    2016-06-01

    We adapted the automated, open source NASA Ames Stereo Pipeline (ASP) to generate digital elevation models (DEMs) and orthoimages from very-high-resolution (VHR) commercial imagery of the Earth. These modifications include support for rigorous and rational polynomial coefficient (RPC) sensor models, sensor geometry correction, bundle adjustment, point cloud co-registration, and significant improvements to the ASP code base. We outline a processing workflow for ∼0.5 m ground sample distance (GSD) DigitalGlobe WorldView-1 and WorldView-2 along-track stereo image data, with an overview of ASP capabilities, an evaluation of ASP correlator options, benchmark test results, and two case studies of DEM accuracy. Output DEM products are posted at ∼2 m with direct geolocation accuracy of computing environment. We are leveraging these resources to produce dense time series and regional mosaics for the Earth's polar regions.

  14. External Validation of the ASTER GDEM2, GMTED2010 and CGIAR-CSI- SRTM v4.1 Free Access Digital Elevation Models (DEMs in Tunisia and Algeria

    Directory of Open Access Journals (Sweden)

    Djamel Athmania

    2014-05-01

    Full Text Available Digital Elevation Models (DEMs including Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM, Shuttle Radar Topography Mission (SRTM, and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010 are freely available for nearly the entire earth’s surface. DEMs that are usually subject to errors need to be evaluated using reference elevation data of higher accuracy. This work was performed to assess the vertical accuracy of the ASTER GDEM version 2, (ASTER GDEM2, the Consultative Group on International Agriculture Research-Consortium for Spatial Information (CGIAR-CSI SRTM version 4.1 (SRTM v4.1 and the systematic subsample GMTED2010, at their original spatial resolution, using Global Navigation Satellite Systems (GNSS validation points. Two test sites, the Anaguid Saharan platform in southern Tunisia and the Tebessa basin in north eastern Algeria, were chosen for accuracy assessment of the above mentioned DEMs, based on geostatistical and statistical measurements. Within the geostatistical approach, empirical variograms of each DEM were compared with those of the GPS validation points. Statistical measures were computed from the elevation differences between the DEM pixel value and the corresponding GPS point. For each DEM, a Root Mean Square Error (RMSE was determined for model validation. In addition, statistical tools such as frequency histograms and Q-Q plots were used to evaluate error distributions in each DEM. The results indicate that the vertical accuracy of SRTM model is much higher than ASTER GDEM2 and GMTED2010 for both sites. In Anaguid test site, the vertical accuracy of SRTM is estimated 3.6 m (in terms of RMSE 5.3 m and 4.5 m for the ASTERGDEM2 and GMTED2010 DEMs, respectively. In Tebessa test site, the overall vertical accuracy shows a RMSE of 9.8 m, 8.3 m and 9.6 m for ASTER GDEM 2, SRTM and GMTED2010 DEM, respectively. This work is the first study to report the

  15. ElevationDEM_DEMHF0p7M2014

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Eastern VT 2014 0.7m and Digital Elevation Model (DEM) dataset of the following "hydro-treatment": *DEMHF....

  16. Digital Elevation Model (DEM) to Investigate the Results of Cutting%数字高程模型(DEM)成果裁切探讨

    Institute of Scientific and Technical Information of China (English)

    徐丽丽; 杨春全

    2015-01-01

    随着计算机技术及测绘产品的不断发展,数字高程模型( DEM)已成为地理信息空间系统和“数字地球”的重要组成部分。在测绘技术蓬勃发展的今天,数字高程模型( DEM)的生产已成为各生产部门较关注的问题之一,特别是近年来数字龙江地理空间框架建设一期工程对数字高程模型( DEM)产品成果的要求有很大提高,数字高程模型( DEM)成果的裁切也显得尤为重要,本文从工作中遇到的DEM成果裁切问题入手,结合笔者多年的测绘生产经验,研讨DEM成果裁切问题。%With the continuous development of computer technology and mapping products , digital elevation model ( DEM) has be-come more and more important part of spatial geographic information system and the “digital earth”.In the vigorous development of Surveying and mapping technology today , digital elevation model (DEM ) production has become one of the production department , especially in recent years , the construction of digital geo spatial framework of the Longjiang one phase of the project of digital elevation model ( DEM) product requirements are very high, the digital elevation model ( DEM) results of cutting is also very important , start-ing with the DEM results from the cutting problems encountered in the work , and combining the years of Surveying and mapping pro-duction experience ,research results of DEM cutting problem .

  17. ElevationDEM_DEM10m

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset is derived from the multi-resolution National Elevation Dataset (NED), at resolutions of both 1/3 arc-second (approx. 10 meters) and in limited areas,...

  18. Digital Elevation Model (DEM), Countywide DEMs were created from the 2004 Maryland Statewide Lidar data.A map service has been created to host this data but local copies are recommended for complex processing and analysis as this data is very large.Contact the ESRGC to obtain a copy, Published in 2004, 1:1200 (1in=100ft) scale, Eastern Shore Regional GIS Cooperative.

    Data.gov (United States)

    NSGIC Regional | GIS Inventory — Digital Elevation Model (DEM) dataset current as of 2004. Countywide DEMs were created from the 2004 Maryland Statewide Lidar data.A map service has been created to...

  19. Soil-landscape modelling using fuzzy c-means clustering of attribute data derived from a Digital Elevation Model (DEM).

    NARCIS (Netherlands)

    Bruin, de S.; Stein, A.

    1998-01-01

    This study explores the use of fuzzy c-means clustering of attribute data derived from a digital elevation model to represent transition zones in the soil-landscape. The conventional geographic model used for soil-landscape description is not able to properly deal with these. Fuzzy c-means clusterin

  20. Modeling Glacier Elevation Change from DEM Time Series

    Directory of Open Access Journals (Sweden)

    Di Wang

    2015-08-01

    Full Text Available In this study, a methodology for glacier elevation reconstruction from Digital Elevation Model (DEM time series (tDEM is described for modeling the evolution of glacier elevation and estimating related volume change, with focus on medium-resolution and noisy satellite DEMs. The method is robust with respect to outliers in individual DEM products. Fox Glacier and Franz Josef Glacier in New Zealand are used as test cases based on 31 Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER DEMs and the Shuttle Radar Topography Mission (SRTM DEM. We obtained a mean surface elevation lowering rate of −0.51 ± 0.02 m·a−1 and −0.09 ± 0.02 m·a−1 between 2000 and 2014 for Fox and Franz Josef Glacier, respectively. The specific volume difference between 2000 and 2014 was estimated as −0.77 ± 0.13 m·a−1 and −0.33 ± 0.06 m·a−1 by our tDEM method. The comparably moderate thinning rates are mainly due to volume gains after 2013 that compensate larger thinning rates earlier in the series. Terminus thickening prevailed between 2002 and 2007.

  1. Mass changes of glaciers over the Central Karakoram derived from TanDEM-X and SRTM/X-SAR Digital Elevation Models

    Science.gov (United States)

    Rankl, Melanie; Braun, Matthias

    2015-04-01

    Snow cover and glaciers in the Karakoram region are important freshwater resources for many downriver communities as they provide water for irrigation and hydro power. A better understanding of current glacier changes is hence an important baseline information. Glaciers in the Karakoram have shown stable and positive glacier mass balances during recent years as well as stable and advancing termini positions. The Karakoram is also known for a large number of surge-type glaciers. Here, we present geodetic glacier elevation and mass changes using TanDEM-X and SRTM/X-SAR Digital Elevation Models between 2000 and 2012. Based on previous glacier inventories for the Karakoram, we show elevation changes and glacier mass balances for glaciers with advancing and stable termini between 2000 and 2012 as well as surge-type glaciers separately. In order to convert volume changes to mass changes, we applied different density scenarios (i.e., constant densities for ice and snow or zonally variable densities). Our findings show average glacier thickening of +0.01 ± 0.02 m a-1 or mass gain of +0.0099 ± 2.8x10-5 Gt a-1(using a density of 850 kg m-3) between 2000 and 2012 for parts of the Central Karakoram. Surge-type glaciers and advancing glaciers indicated slight surface lowering, while the majority of the studied glaciers showed stable termini and surface thickening. Our measurements are independent from varying penetration depths of the radar signal or temporal decorrelation between image acquisitions. Both datasets were acquired in the X-band frequency under assumed similar surface conditions. The bistatic TanDEM-X mission is highly suitable for interferometric processing due to high spatial resolutions and only 3 sec time lag between TanDEM-X and TerraSAR-X overpasses. We want to stress the enormous potential of the TanDEM-X mission to estimate geodetic glacier mass balances, in particular when compared to elevation data sets acquired in a similar frequency and comparable

  2. Creating high-resolution bare-earth digital elevation models (DEMs) from stereo imagery in an area of densely vegetated deciduous forest using combinations of procedures designed for lidar point cloud filtering

    Science.gov (United States)

    DeWitt, Jessica D.; Warner, Timothy A.; Chirico, Pete; Bergstresser, Sarah

    2017-01-01

    For areas of the world that do not have access to lidar, fine-scale digital elevation models (DEMs) can be photogrammetrically created using globally available high-spatial resolution stereo satellite imagery. The resultant DEM is best termed a digital surface model (DSM) because it includes heights of surface features. In densely vegetated conditions, this inclusion can limit its usefulness in applications requiring a bare-earth DEM. This study explores the use of techniques designed for filtering lidar point clouds to mitigate the elevation artifacts caused by above ground features, within the context of a case study of Prince William Forest Park, Virginia, USA. The influences of land cover and leaf-on vs. leaf-off conditions are investigated, and the accuracy of the raw photogrammetric DSM extracted from leaf-on imagery was between that of a lidar bare-earth DEM and the Shuttle Radar Topography Mission DEM. Although the filtered leaf-on photogrammetric DEM retains some artifacts of the vegetation canopy and may not be useful for some applications, filtering procedures significantly improved the accuracy of the modeled terrain. The accuracy of the DSM extracted in leaf-off conditions was comparable in most areas to the lidar bare-earth DEM and filtering procedures resulted in accuracy comparable of that to the lidar DEM.

  3. ElevationDEM_DEM1p6M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m; Missisquoi Upper 2010 1.6m; Missisquoi Lower 2008 1.6m and Digital Elevation...

  4. ElevationDEM_DEM0p7M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m; Eastern VT 2014 0.7m and Rutland/GI Counties 2013 0.7m and Digital Elevation...

  5. Digital Elevation Model (DEM), Countywide DEMs were created from the 2004 Maryland Statewide Lidar data.A map service has been created to host this data but local copies are recommended for complex processing and analysis as this data is very large.Contact the ESRGC to obtain a copy, Published in 2004, 1:1200 (1in=100ft) scale, Eastern Shore Regional GIS Cooperative.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from LIDAR information as of 2004. It is described as...

  6. Digital elevation modelling using ASTER stereo imagery.

    Science.gov (United States)

    Forkuo, Eric Kwabena

    2010-04-01

    Digital elevation model (DEM) in recent times has become an integral part of national spatial data infrastructure of many countries world-wide due to its invaluable importance. Although DEMs are mostly generated from contours maps, stereo aerial photographs and air-borne and terrestrial laser scanning, the stereo interpretation and auto-correlation from satellite image stereo-pairs such as with SPOT, IRS, and relatively new ASTER imagery is also an effective means of producing DEM data. In this study, terrain elevation data were derived by applying photogrammetric process to ASTER stereo imagery. Also, the quality ofDEMs produced from ASTER stereo imagery was analysed by comparing it with DEM produced from topographic map at a scale of 1:50,000. While analyzing the vertical accuracy of the generated ASTER DEM, fifty ground control points were extracted from the map and overlaid on the DEM. Results indicate that a root-mean-square error in elevation of +/- 14 m was achieved with ASTER stereo image data of good quality. The horizontal accuracy obtained from the ground control points was 14.77, which is within the acceptable range of +/- 7m to +/- 25 m. The generated (15 m) DEM was compared with a 20m, 25m, and a 30 m pixel DEM to the original map. In all, the results proved that, the 15 m DEM conform to the original map DEM than the others. Overall, this analysis proves that, the generated digital terrain model, DEM is acceptable.

  7. Hanalei, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  8. Savannah, Georgia Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  9. Unalaska, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  10. Hoonah, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  11. Port Orford, Oregon Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  12. Cordova, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  13. Fort Bragg, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  14. Garibaldi, Oregon Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  15. Crescent City, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  16. Juneau, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  17. Taholah, Washington Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. San Diego, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. Chenega, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  20. Akutan, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  1. Biloxi, Mississippi Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Eureka, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  3. Mayaguez, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  4. Southeast Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  5. Atka, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Ponce, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  7. Northern Gulf Coast Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

  8. Daytona Beach, Florida Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  9. Ocean City, Maryland Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  10. Bar Harbor, Maine Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. Oahu, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  12. Panama City, Florida Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. New Orleans, Louisiana Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

  14. Mobile, Alabama Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

  15. Corpus Christi, Texas Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  16. Nantucket, Massachusetts Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  17. Fajardo, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. Monterey, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. Santa Barbara, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  20. Fort Bragg, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  1. Port Townsend, Washington Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Key West, Florida Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  3. Dutch Harbor, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  4. Portland, Maine Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  5. Nikolski, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Central Oregon Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  7. Keauhou, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  8. Kachemak Bay, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  9. Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  10. Adak, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. Chignik, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  12. Arena Cove, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. Craig, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  14. Arecibo, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  15. Virginia Beach, Virginia Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  16. Montauk, New York Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  17. Shemya, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. King Cove, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. Lahaina, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  20. Palm Beach, Florida Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  1. Eureka, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Kawaihae, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  3. Mayaguez, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  4. Hilo, Hawaii Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  5. Cordova, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Panama City, Florida Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

  7. Elfin Cove Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  8. Mariana Trench Bathymetric Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) created a bathymetric digital elevation model (DEM) for the Mariana Trench and adjacent seafloor in the Western...

  9. Central California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  10. Chignik, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. Midway Atoll Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  12. Monterey, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. Sand Point, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  14. Guayama, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  15. Galveston, Texas Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  16. Whittier, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  17. La Push, Washington Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. Elfin Cove Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  19. Yakutat, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  20. Akutan, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  1. Wake Island Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Tatitlek, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  3. Santa Monica, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  4. Midway Atoll Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  5. Sitka, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Digital Elevation Model (DEM), LiDAR acquired and processed over the entire county to support the generation of 1"=100' scale orthophotos & 2' contours. The Lidar LAS data has been classified to bare-earth as well as first-return points., Published in 2009, 1:1200 (1in=100ft) scale, Maryland National Capital Park and Planning Commission.

    Data.gov (United States)

    NSGIC Non-Profit | GIS Inventory — Digital Elevation Model (DEM) dataset current as of 2009. LiDAR acquired and processed over the entire county to support the generation of 1"=100' scale orthophotos...

  7. Digital Elevation Model (DEM), These data are a research product and not intended for use in management, regulation, litigation, or related activities. Data are in a gridded (TIFF) format with a horizontal resolution of 10 feet and a vertical resolution of 1 foot., Published in 2007, University of Connecticut.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Digital Elevation Model (DEM) dataset, was produced all or in part from LIDAR information as of 2007. It is described as 'These data are a research product and...

  8. Evaluation of Multiresolution Digital Elevation Model (DEM from Real-Time Kinematic GPS and Ancillary Data for Reservoir Storage Capacity Estimation

    Directory of Open Access Journals (Sweden)

    Yashon O. Ouma

    2016-04-01

    Full Text Available This study presents the estimation of reservoir storage capacity using multiresolution Real-Time Kinematic Global Positioning System (RTK-GPS DEM, in comparison with ASTER and contour-derived DEM. Through RMSE comparisons of the elevation point uncertainty and error analysis, the results shows that the RTK-GPS DEM gave the best results for the reservoir capacity-area power curve estimation, defined by a convex slope with an exponential deterministic relationship given by V = 0.09 × A 1.435 . The results further show the existence an empirical relationship between the reservoir volume certainty and the GPS point density d i as V e = c × d i ρ . This relationship is dependent on the reservoir terrain, slope and surface area. Validation of the results with in situ data showed the differences between the simulated and observed storage volumes was less than +10%, and using the Nash-Sutcliffe coefficient of efficiency on the storage volumes, an average efficiency of +0.7 on the monthly observed and simulated reservoir storage volume was observed.

  9. Stochastic Downscaling of Digital Elevation Models

    Science.gov (United States)

    Rasera, Luiz Gustavo; Mariethoz, Gregoire; Lane, Stuart N.

    2016-04-01

    High-resolution digital elevation models (HR-DEMs) are extremely important for the understanding of small-scale geomorphic processes in Alpine environments. In the last decade, remote sensing techniques have experienced a major technological evolution, enabling fast and precise acquisition of HR-DEMs. However, sensors designed to measure elevation data still feature different spatial resolution and coverage capabilities. Terrestrial altimetry allows the acquisition of HR-DEMs with centimeter to millimeter-level precision, but only within small spatial extents and often with dead ground problems. Conversely, satellite radiometric sensors are able to gather elevation measurements over large areas but with limited spatial resolution. In the present study, we propose an algorithm to downscale low-resolution satellite-based DEMs using topographic patterns extracted from HR-DEMs derived for example from ground-based and airborne altimetry. The method consists of a multiple-point geostatistical simulation technique able to generate high-resolution elevation data from low-resolution digital elevation models (LR-DEMs). Initially, two collocated DEMs with different spatial resolutions serve as an input to construct a database of topographic patterns, which is also used to infer the statistical relationships between the two scales. High-resolution elevation patterns are then retrieved from the database to downscale a LR-DEM through a stochastic simulation process. The output of the simulations are multiple equally probable DEMs with higher spatial resolution that also depict the large-scale geomorphic structures present in the original LR-DEM. As these multiple models reflect the uncertainty related to the downscaling, they can be employed to quantify the uncertainty of phenomena that are dependent on fine topography, such as catchment hydrological processes. The proposed methodology is illustrated for a case study in the Swiss Alps. A swissALTI3D HR-DEM (with 5 m resolution

  10. San Juan Islands, Washington Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. Minnesota Digital Elevation Model - Tiled 93 Meter Resolution

    Data.gov (United States)

    Minnesota Department of Natural Resources — Digital Elevation Model (DEM) at a resolution of 93 meters. Original data resolution was 3 arc seconds which corresponds (approximately) to a matrix of points at a...

  12. San Francisco Bay, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. San Juan, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  14. Chignik, Alaska 1 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  15. Sand Point, Alaska MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  16. Atlantic City, New Jersey Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  17. U.S. Virgin Islands Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. Myrtle Beach, South Carolina Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. South Padre Island, Texas Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  20. Morehead City, North Carolina Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  1. South Padre Island, Texas Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Cape Hatteras, North Carolina Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  3. Pago Pago, American Samoa Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  4. Port San Luis, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  5. Morehead City, North Carolina Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Prince William Sound, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  7. Port San Luis, California Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  8. Prince William Sound, Alaska Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  9. Generation of a new Greenland Ice Sheet Digital Elevation Model

    Science.gov (United States)

    Nagarajan, S.; Csatho, B. M.; Schenk, A. F.; Babonis, G. S.; Scambos, T. A.; Haran, T. M.; Kjaer, K. H.; Korsgaard, N. J.

    2011-12-01

    Currently available Digital Elevation Models(DEMs) of the Greenland Ice Sheet (GrIS) were originally derived from radar altimetry data, e.g. Bamber (Bamber et al., 2001) and later improved by photoclinometry to fill the regions between orbits (Scambos and Haran, 2002). The elevation error of these DEMs is a few meters in the higher part (above 2000 m) of the ice sheet, but it can be as much as 50-100 meters in marginal regions. The relatively low resolution and accuracy poses a problem, especially for ice sheet modeling. Although accurate elevation data have been collected by airborne and spaceborne laser altimetry (airborne: Airborne Topographic Mapper (ATM) (1993-present), Laser Vegetation Imaging Sensor(LVIS) (2007,2009 and 2011); spaceborne: Ice, Cloud, and land Elevation Satellite (ICESat) (2003-2009)) and DEMs have been derived from stereo satellite imagery (e.g., SPOT (40 m), ASTER (15 m)), a high resolution, consistent DEM of GrIS is not yet available. This is due to various problems, such as different error sources in the data and different dates of data acquisition. In order to overcome these difficulties, we generated a multi-resolution DEM of GrIS, reflecting June 2008 conditions, by fusing a photoclinometry DEM, SPOT and ASTER DEMs as well as elevations from ICESat, ATM and LVIS laser altimetry. The new multi-resolution DEM has a resolution of 40 m x 40 m in the marginal ice sheet regions and 250 m elsewhere. The ice sheet margin is mapped from SPOT and Landsat imagery and SPOT DEMs are used to cover the complex topography of ice sheet marginal regions. The accuracy of SPOT DEMs is approximately ± 6 m except in the areas covered by clouds regions, where the SPOT elevations were replaced by ASTER DEMs. The ASTER DEMs were checked and improved by the DEM derived from aerial photography from the 1980s. A new photoclinometry DEM, derived from Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery

  10. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Charleston WFO (Georgia)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  11. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Brownsville, Texas Weather Forecast Office (WFO)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  12. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: San Diego (CA) WFO

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's...

  13. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Seattle (WA) WFO - Grays Harbor County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  14. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Corpus Christi Weather Forecast Office (WFO)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  15. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Portland WFO (WA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  16. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Jacksonville WFO (Georgia)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  17. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Eureka (CA) WFO - Mendocino County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's...

  18. NOAA Coastal Services Center Coastal Inundation Digital Elevation Model: Philadelphia WFO - Pennsylvania

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Coastal Services Center's Sea Level...

  19. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Lake Charles, Texas WFO

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's...

  20. Generation of a new Greenland Ice Sheet Digital Elevation Model

    DEFF Research Database (Denmark)

    Nagarajan, Sudhagar; Csatho, Beata M; Schenk, Anton F

    Currently available Digital Elevation Models(DEMs) of the Greenland Ice Sheet (GrIS) were originally derived from radar altimetry data, e.g. Bamber (Bamber et al., 2001) and later improved by photoclinometry to fill the regions between orbits (Scambos and Haran, 2002). The elevation error...... m)), a high resolution, consistent DEM of GrIS is not yet available. This is due to various problems, such as different error sources in the data and different dates of data acquisition. In order to overcome these difficulties, we generated a multi-resolution DEM of GrIS, reflecting June 2008...... in an updated DEM. Finally, all elevations were corrected using elevation changes determined by SERAC (Surface Elevation Reconstruction And Change detection), to achieve a common reference date. Airborne laser altimetry elevations are used to evaluate the accuracy of the new GrIS DEM....

  1. Comparative study and error analysis of digital elevation model interpolations

    Institute of Scientific and Technical Information of China (English)

    CHEN Ji-long; WU Wei; LIU Hong-bin

    2008-01-01

    Researchers in P.R.China commonly create triangulate irregular networks (TINs) from contours and then convert TINs into digital elevation models (DEMs). However, the DEM produced by this method can not precisely describe and simulate key hydrological features such as rivers and drainage borders. Taking a hilly region in southwestern China as a research area and using ArcGISTM software, we analyzed the errors of different interpolations to obtain distributions of the errors and precisions of different algorithms and to provide references for DEM productions. The results show that different interpolation errors satisfy normal distributions, and large error exists near the structure line of the terrain. Furthermore, the results also show that the precision of a DEM interpolated with the Australian National University digital elevation model (ANUDEM) is higher than that interpolated with TIN. The DEM interpolated with TIN is acceptable for generating DEMs in the hilly region of southwestern China.

  2. Application of digital elevation model in delineating drainage networks

    Institute of Scientific and Technical Information of China (English)

    SUN Yan-ling; XIE De-ti; LIU Hong-bin; WEI Chao-fu

    2005-01-01

    A practical method to extract drainage network from DEM (digital elevation model) is introduced. DEM pretreatment includes depression and flat areas treatment. The flow direction of each grid cell in DEM is calculated according to the 8-direction pour point model, and then the flow accumulation grid from the flow direction grid. With the flow accumulation grid, streams are defined according to the given threshold value of flow accumulation. Taking Gufo River watershed as an example, the extraction of drainage network was done from DEM. The results are basically consistent with the digitized drainage network from the relief maps.

  3. Accuracy Assessment of Digital Elevation Models Using GPS

    Science.gov (United States)

    Farah, Ashraf; Talaat, Ashraf; Farrag, Farrag A.

    2008-01-01

    A Digital Elevation Model (DEM) is a digital representation of ground surface topography or terrain with different accuracies for different application fields. DEM have been applied to a wide range of civil engineering and military planning tasks. DEM is obtained using a number of techniques such as photogrammetry, digitizing, laser scanning, radar interferometry, classical survey and GPS techniques. This paper presents an assessment study of DEM using GPS (Stop&Go) and kinematic techniques comparing with classical survey. The results show that a DEM generated from (Stop&Go) GPS technique has the highest accuracy with a RMS error of 9.70 cm. The RMS error of DEM derived by kinematic GPS is 12.00 cm.

  4. Sensitivity of Coastal Flood Risk Assessments to Digital Elevation Models

    OpenAIRE

    Bas van de Sande; Claartje Hoyng; Joost Lansen

    2012-01-01

    Most coastal flood risk studies make use of a Digital Elevation Model (DEM) in addition to a projected flood water level in order to estimate the flood inundation and associated damages to property and livelihoods. The resolution and accuracy of a DEM are critical in a flood risk assessment, as land elevation largely determines whether a location will be flooded or will remain dry during a flood event. Especially in low lying deltaic areas, the land elevation variation is usually in the order...

  5. A methodology to generate high-resolution digital elevation model (DEM) and surface water profile for a physical model using close range photogrammetric (CRP) technique

    Science.gov (United States)

    Mali, V. K.; Kuiry, S. N.

    2015-12-01

    Comprehensive understanding of the river flow dynamics with varying topography in a real field is very intricate and difficult. Conventional experimental methods based on manual data collection are time consuming and prone to many errors. Recently, remotely sensed satellite imageries are at the best to provide necessary information for large area provided the high resolution but which are very expensive and untimely, consequently, attaining accurate river bathymetry from relatively course resolution and untimely imageries are inaccurate and impractical. Despite of that, these data are often being used to calibrate the river flow models, though these models require highly accurate morpho-dynamic data in order to predict the flow field precisely. Under this circumstance, these data could be supplemented through experimental observations in a physical model with modern techniques. This paper proposes a methodology to generate highly accurate river bathymetry and water surface (WS) profile for a physical model of river network system using CRP technique. For the task accomplishment, a number of DSLR Nikon D5300 cameras (mounted at 3.5 m above the river bed) were used to capture the images of the physical model and the flooding scenarios during the experiments. During experiment, non-specular materials were introduced at the inlet and images were taken simultaneously from different orientations and altitudes with significant overlap of 80%. Ground control points were surveyed using two ultrasonic sensors with ±0.5 mm vertical accuracy. The captured images are, then processed in PhotoScan software to generate the DEM and WS profile. The generated data were then passed through statistical analysis to identify errors. Accuracy of WS profile was limited by extent and density of non-specular powder and stereo-matching discrepancies. Furthermore, several factors of camera including orientation, illumination and altitude of camera. The CRP technique for a large scale physical

  6. A methodology to generate high-resolution digital elevation model (DEM) and surface water profile for a physical model using close range photogrammetric (CRP) technique

    Science.gov (United States)

    Méndez Incera, F. J.; Erikson, L. H.; Ruggiero, P.; Barnard, P.; Camus, P.; Rueda Zamora, A. C.

    2014-12-01

    Comprehensive understanding of the river flow dynamics with varying topography in a real field is very intricate and difficult. Conventional experimental methods based on manual data collection are time consuming and prone to many errors. Recently, remotely sensed satellite imageries are at the best to provide necessary information for large area provided the high resolution but which are very expensive and untimely, consequently, attaining accurate river bathymetry from relatively course resolution and untimely imageries are inaccurate and impractical. Despite of that, these data are often being used to calibrate the river flow models, though these models require highly accurate morpho-dynamic data in order to predict the flow field precisely. Under this circumstance, these data could be supplemented through experimental observations in a physical model with modern techniques. This paper proposes a methodology to generate highly accurate river bathymetry and water surface (WS) profile for a physical model of river network system using CRP technique. For the task accomplishment, a number of DSLR Nikon D5300 cameras (mounted at 3.5 m above the river bed) were used to capture the images of the physical model and the flooding scenarios during the experiments. During experiment, non-specular materials were introduced at the inlet and images were taken simultaneously from different orientations and altitudes with significant overlap of 80%. Ground control points were surveyed using two ultrasonic sensors with ±0.5 mm vertical accuracy. The captured images are, then processed in PhotoScan software to generate the DEM and WS profile. The generated data were then passed through statistical analysis to identify errors. Accuracy of WS profile was limited by extent and density of non-specular powder and stereo-matching discrepancies. Furthermore, several factors of camera including orientation, illumination and altitude of camera. The CRP technique for a large scale physical

  7. Visualization of a Digital Elevation Model

    OpenAIRE

    Linlin Lu; Huadong Guo

    2007-01-01

    In recent years, Geographic Information Systems (GIS) have gradually changed from using the traditional 2D map expression to 3D visualization. The combination of visual techniques and GIS is a multi discipline, leading edge field, the development of which needs advancement in many fields. This paper introduces related theories and algorithms of Digital Elevation Model (DEM) visualization. Advantages of the Triangle Irregular Network (TIN) model and data structure are illustrated. The algorith...

  8. Digital Elevation Model Mosaic of Mercury

    Science.gov (United States)

    Cook, A. C.; Watters, T. R.; Robinson, M. S.

    2001-01-01

    At CEPS (Center for Earth and Planetary Studies) work has been underway since 2000 to semi-automatically stereo match all Mariner 10 stereo pairs. The resulting matched image coordinates are converted into longitude, latitude, and height points and then combined to form a map projected Digital Elevation Model (DEM) mosaic of the planet's surface. Stereo images from Mariner 10 cover one quarter of the planet's surface, mostly in the southern hemisphere. Additional information is contained in the original extended abstract.

  9. Registering Thematic Mapper imagery to digital elevation models

    Science.gov (United States)

    Frew, J.

    1984-01-01

    The problems encountered when attempting to register Landsat Thematic Mapper (TM) data to U.S. geological survey digital elevation models (DEMs) are examined. It is shown that TM and DEM data are not available in the same map projection, necessitating geometric transformation of one of the data type, that the TM data are not accurately located in their nominal projection, and that TM data have higher resolution than most DEM data, but oversampling the DEM data to TM resolution introduces systematic noise. Further work needed in this area is discussed.

  10. Coastal DEMs with Cross-Track Interferometry

    NARCIS (Netherlands)

    Greidanus, H.S.F.; Huising, E.J.; Platschorre, Y.; Bree, R.J.P. van; Halsema, D. van; Vaessen, E.M.J.

    1999-01-01

    Digital elevation models (DEMs) are produced from airborne radar cross-track interferometric measurements. Radar DEMs recorded from perpendicular orientations are intercompared, and compared to DEMs derived from airborne laser altimetry

  11. 基于数字高程模型DEM的溃坝生命损失风险分析%The risk analysis of dam failure caused loss of life based on digital elevation model(DEM)

    Institute of Scientific and Technical Information of China (English)

    董建良

    2014-01-01

    Digital Elevation Model(DEM) as a basis for spatial data in many fields have a wide range of appli-cations.In this paper,under lack of data of Youluokou dam downstream,on actual terrain situations,the com-putational domain downstream with topographic data and ArcGIS software platform to get the required informa-tion such as ground elevation,based on the application software and River2D BREACH hydrodynamic model simulations Reservoir dam downstream flood evolution ,estimated the loss of life downstream dam reservoir us-ing the Graham method,when the preliminary draw Youluokou dam suffered 5000 year return period flood,the auxiliary dam outburst resulted in loss of life and damage to the occurrence of piping risk is intolerable.It can also make reservoir management decision-makers of the consequences of dam failure which cause flooding to be aware and do the daily flood control scheduling and preparation of contingency plans ,the maximum level of protection of the safety of the people downstream of the reservoir ,to prevent the occurrence of disasters.%数字高程模型DEM作为基础空间数据,在众多领域有着广泛的应用。本文在油罗口水库大坝缺乏下游实测地形数据资料的情形下,以地形图数据和ArcGIS软件平台获取的计算域下游所需地面高程等信息为基础,应用BREACH软件及River2D水动力学模型模拟了水库下游溃坝洪水演进,采用Graham法估算了水库下游溃坝生命损失,初步得出油罗口水库大坝遭受重现期为5000a一遇洪水时,副坝发生管涌破坏溃决导致的生命损失风险是不可容忍的。由此也可以让水库管理决策人员对水库溃坝洪水可能造成的后果做到心中有数,做好日常的防洪调度及应急预案编制工作,最大程度保障水库下游人民群众生命安全,防止灾害的发生。

  12. Digital elevation modeling via curvature interpolation for lidar data

    Science.gov (United States)

    Digital elevation model (DEM) is a three-dimensional (3D) representation of a terrain's surface - for a planet (including Earth), moon, or asteroid - created from point cloud data which measure terrain elevation. Its modeling requires surface reconstruction for the scattered data, which is an ill-p...

  13. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Mississippi WFO - Harrison, Hancock, and Jackson Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  14. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Portland (OR) WFO - Tillamook, Lincoln, and Lane Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  15. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Tampa (FL) WFO - Citrus, Hernando, Pasco, Pinellas, and Hillsborough Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  16. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Jacksonville (FL) WFO - Duval, Clay, and Nassau Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  17. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Eureka (CA) WFO - Humboldt and Del Norte Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  18. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Houston/Galveston, Texas Weather Forecast Office (WFO)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  19. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Portland (OR) WFO - Clatsop, Columbia, and Multnomah Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  20. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Tampa (FL) WFO - Manatee, Sarasota, Charlotte, and Lee Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  1. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Jacksonville (FL) WFO - St. Johns, Flagler and Putnam Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  2. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Miami (FL) WFO - Collier and Monroe (Mainland) Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  3. Ohio-drainage digital elevation model for use with Water Resources Investigations Report 03-4164

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This coverage was derived from U.S. Geological Survey National Elevation Dataset (NED) Digital Elevation Models (DEMs) for all of Ohio and portions of Indiana,...

  4. Sensitivity of Coastal Flood Risk Assessments to Digital Elevation Models

    Directory of Open Access Journals (Sweden)

    Bas van de Sande

    2012-07-01

    Full Text Available Most coastal flood risk studies make use of a Digital Elevation Model (DEM in addition to a projected flood water level in order to estimate the flood inundation and associated damages to property and livelihoods. The resolution and accuracy of a DEM are critical in a flood risk assessment, as land elevation largely determines whether a location will be flooded or will remain dry during a flood event. Especially in low lying deltaic areas, the land elevation variation is usually in the order of only a few decimeters, and an offset of various decimeters in the elevation data has a significant impact on the accuracy of the risk assessment. Publicly available DEMs are often used in studies for coastal flood risk assessments. The accuracy of these datasets is relatively low, in the order of meters, and is especially low in comparison to the level of accuracy required for a flood risk assessment in a deltaic area. For a coastal zone area in Nigeria (Lagos State an accurate LiDAR DEM dataset was adopted as ground truth concerning terrain elevation. In the case study, the LiDAR DEM was compared to various publicly available DEMs. The coastal flood risk assessment using various publicly available DEMs was compared to a flood risk assessment using LiDAR DEMs. It can be concluded that the publicly available DEMs do not meet the accuracy requirement of coastal flood risk assessments, especially in coastal and deltaic areas. For this particular case study, the publically available DEMs highly overestimated the land elevation Z-values and thereby underestimated the coastal flood risk for the Lagos State area. The findings are of interest when selecting data sets for coastal flood risk assessments in low-lying deltaic areas.

  5. EVALUATION DIGITAL ELEVATION MODEL GENERATED BY SYNTHETIC APERTURE RADAR DATA

    OpenAIRE

    Makineci, H. B.; H. Karabörk

    2016-01-01

    Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information S...

  6. Evaluating DEM conditioning techniques, elevation source data, and grid resolution for field-scale hydrological parameter extraction

    Science.gov (United States)

    Woodrow, Kathryn; Lindsay, John B.; Berg, Aaron A.

    2016-09-01

    Although digital elevation models (DEMs) prove useful for a number of hydrological applications, they are often the end result of numerous processing steps that each contains uncertainty. These uncertainties have the potential to greatly influence DEM quality and to further propagate to DEM-derived attributes including derived surface and near-surface drainage patterns. This research examines the impacts of DEM grid resolution, elevation source data, and conditioning techniques on the spatial and statistical distribution of field-scale hydrological attributes for a 12,000 ha watershed of an agricultural area within southwestern Ontario, Canada. Three conditioning techniques, including depression filling (DF), depression breaching (DB), and stream burning (SB), were examined. The catchments draining to each boundary of 7933 agricultural fields were delineated using the surface drainage patterns modeled from LiDAR data, interpolated to a 1 m, 5 m, and 10 m resolution DEMs, and from a 10 m resolution photogrammetric DEM. The results showed that variation in DEM grid resolution resulted in significant differences in the spatial and statistical distributions of contributing areas and the distributions of downslope flowpath length. Degrading the grid resolution of the LiDAR data from 1 m to 10 m resulted in a disagreement in mapped contributing areas of between 29.4% and 37.3% of the study area, depending on the DEM conditioning technique. The disagreements among the field-scale contributing areas mapped from the 10 m LiDAR DEM and photogrammetric DEM were large, with nearly half of the study area draining to alternate field boundaries. Differences in derived contributing areas and flowpaths among various conditioning techniques increased substantially at finer grid resolutions, with the largest disagreement among mapped contributing areas occurring between the 1 m resolution DB DEM and the SB DEM (37% disagreement) and the DB-DF comparison (36.5% disagreement in mapped

  7. ArcticDEM; A Publically Available, High Resolution Elevation Model of the Arctic

    Science.gov (United States)

    Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Bates, Brian; Willamson, Cathleen; Peterman, Kennith

    2016-04-01

    A Digital Elevation Model (DEM) of the Arctic is needed for a large number of reasons, including: measuring and understanding rapid, ongoing changes to the Arctic landscape resulting from climate change and human use and mitigation and adaptation planning for Arctic communities. The topography of the Arctic is more poorly mapped than most other regions of Earth due to logistical costs and the limits of satellite missions with low-latitude inclinations. A convergence of civilian, high-quality sub-meter stereo imagery; petascale computing and open source photogrammetry software has made it possible to produce a complete, very high resolution (2 to 8-meter posting), elevation model of the Arctic. A partnership between the US National Geospatial-intelligence Agency and a team led by the US National Science Foundation funded Polar Geospatial Center is using stereo imagery from DigitalGlobe's Worldview-1, 2 and 3 satellites and the Ohio State University's Surface Extraction with TIN-based Search-space Minimization (SETSM) software running on the University of Illinois's Blue Water supercomputer to address this challenge. The final product will be a seemless, 2-m posting digital surface model mosaic of the entire Arctic above 60 North including all of Alaska, Greenland and Kamchatka. We will also make available the more than 300,000 individual time-stamped DSM strip pairs that were used to assemble the mosaic. The Arctic DEM will have a vertical precision of better than 0.5m and can be used to examine changes in land surfaces such as those caused by permafrost degradation or the evolution of arctic rivers and floodplains. The data set can also be used to highlight changing geomorphology due to Earth surface mass transport processes occurring in active volcanic and glacial environments. When complete the ArcticDEM will catapult the Arctic from the worst to among the best mapped regions on Earth.

  8. Evaluation on the accuracy of digital elevation models

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There is a growing interest in investigating the accuracy of digital elevation model (DEM). However people usually have an unbalanced view on DEM errors. They emphasize DEM sampling errors, but ignore the impact of DEM resolution and terrain roughness on the accuracy of terrain representation. This research puts forward the concept of DEM terrain representation error (Et) and then investigates the generation, factors, measurement and simulation of DEM terrain representation errors. A multi-resolution and multi-relief comparative approach is used as the major methodology in this research. The experiment reveals a quantitative relationship between the error and the variation of resolution and terrain roughness at a global level. Root mean square error (RMS Et) is regressed against surface profile curvature (V) and DEM resolution (R) at 10 resolution levels. It is found that the RMS Et may be expressed as RMS Et = (0.0061· V+ 0.0052) . R - 0.022·V +0.2415. This result may be very useful in forecasting DEM accuracy, as well as in determining the DEM resolution related to the accuracy requirement of particular application.

  9. Elevation validation and geomorphic metric comparison with focus on ASTER GDEM2, SRTM- C, ALOS World 3D, and TanDEM-X

    Science.gov (United States)

    Purinton, Benjamin; Bookhagen, Bodo

    2017-04-01

    Geomorphologists use digital elevation models (DEMs) to quantify changes in topography - often without rigorous accuracy assessments. In this study we validate and compare elevation accuracy and derived geomorphic metrics from the current generation of satellite-derived DEMs on the southern Central Andean Plateau. The average elevation of 3.7 km, diverse topography and relief, lack of vegetation, and clear skies create ideal conditions for remote sensing in this study area. DEMs at resolutions of 5-30 m are sourced from open-access, research agreement, and commercial outlets, with a focus on the 30 m SRTM-C, 30 m ASTER GDEM2, 12 m TanDEM-X, and 5 m ALOS World 3D data. In addition to these edited products, manually generated DEMs included 10 m single-CoSSC TerraSAR-X / TanDEM-X DEMs and a 30 m stacked ASTER L1A stereopair DEM. We assessed vertical accuracy by comparing standard deviations (SD) of the DEM elevation versus 307,509 differential GPS (dGPS) measurements with employed a Fourier analysis to identify DEM frequencies and their spectral power. The optical 5 m ALOS World 3D DEM shows high-frequency noise in 2-8 pixel steps, with no corresponding landscape features in this highly diffusive, vegetation-free environment. Finally, we explore the geomorphometric potential of the higher-quality 12 m TanDEM-X DEM through a hillslope length and surface roughness assessment across steep environmental, climatic and topographic gradients in the Quebrada del Toro catchment, west of Salta, Argentina.

  10. Miami 1/3 arc-second MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. LiDAR Derived Bare Earth Digital Elevation Model: Camas National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This dataset represents the Camas National Wildlife Refuge survey area in Jefferson and Clark County, ID. This bare earth digital elevation model (DEM) represent...

  12. Tampa Bay 1/3 arc-second MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. St. Croix, U.S. Virgin Islands Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  14. Digital Elevation Model of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This product is a digital elevation model (DEM) for the Little Holland Tract in the Sacramento-San Joaquin River Delta, California based on U.S. Geological Survey...

  15. King Cove, Alaska 8 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  16. Cold Bay, Alaska 8 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  17. King Cove, Alaska 8/15 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  18. Puget Sound 1/3 arc-second MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. Central Florida 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  20. Tutuila, American Samoa 1/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  1. LiDAR Derived Bare Earth Digital Elevation Model: Camas National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This dataset represents the Camas National Wildlife Refuge survey area in Jefferson and Clark County, ID. This bare earth digital elevation model (DEM) represent the...

  2. Global Topographic 30 Arc-Second Digital Elevation Model: Released 1996

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several...

  3. Global Topographic 30 Arc-Second Digital Elevation Model: Released 1996

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several...

  4. Digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This product is a digital elevation model (DEM) for the Little Holland Tract in the Sacramento-San Joaquin River Delta, California based on U.S. Geological Survey...

  5. Digital Elevation Model of Kauai, Hawaii, Integrating Bathymetric and Topographic Datasets

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  6. Perryville and Ivanof Bay, Alaska 1/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  7. Cold Bay, Alaska 8/15 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  8. Puget Sound 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  9. Astoria, Oregon 1/3 arc-second MHW Coastal Digital Elevation Model Vers.3

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Centers for Environmental Information (NCEI) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These...

  10. Chignik, Alaska 1/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  11. King Cove, Alaska 8/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  12. St. Thomas and St. John, U.S. Virgin Islands Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  13. Quantifying Slopes with Digital Elevation Models of the Verdugo Hills, California: Effects of Resolution

    Science.gov (United States)

    Fielding, E. J.; Burbank, D. W.; Duncan, C. C.

    1996-01-01

    Quantification of surface slope angles is valuable in a wide variety of earth sciences. Slopes measured from digital elevation models (DEMs) or other topographic data sets depend strongly on the length scale or window size used in the slope calculations.

  14. An algorithm for treating flat areas and depressions in digital elevation models using linear interpolation

    Science.gov (United States)

    Digital elevation model (DEM) data are essential to hydrological applications and have been widely used to calculate a variety of useful topographic characteristics, e.g., slope, flow direction, flow accumulation area, stream channel network, topographic index, and others. Excep...

  15. Digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This product is a digital elevation model (DEM) for the Little Holland Tract in the Sacramento-San Joaquin River Delta, California based on U.S. Geological Survey...

  16. Central Florida 1/3 arc-second MHW Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  17. Tampa Bay 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  18. Miami 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  19. Digital Elevation Model of Southeast Alaska, Integrating Bathymetric and Topographic Datasets

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  20. Cold Bay, Alaska 8/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  1. Kodiak, Alaska 1/3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  2. Pembuatan Digital Elevation Model Resolusi 10m dari Peta RBI dan Survei GPS dengan Algoritma Anudem

    Directory of Open Access Journals (Sweden)

    Indarto

    2014-04-01

    Full Text Available This study proposes the generation of Digital Elevation Model (DEM with spatial resolution of 10m x 10m by re-interpolation of elevation data. Data input for this study includes: (1 digitized datum coordinate from RBI map, (2 sample points surveyed by GPS, (3 digitized contour data fromSRTM DEM and ASTER GDEM2, and (4 digitized stream-network layer from RBI. All collected data were converted to mass point coordinats. On the top of Topogrid-ArcGIS, all points data were interpolated to produce DEM. After that the produced DEM were compared and evaluated to the SRTM and ASTER DEMvisually. The result shows that produced DEM are more accurate to represent the detailed topography of the study areas.

  3. Registratiom of TM data to digital elevation models

    Science.gov (United States)

    1984-01-01

    Several problems arise when attempting to register LANDSAT thematic mapper data to U.S. B Geological Survey digital elevation models (DEMs). The TM data are currently available only in a rotated variant of the Space Oblique Mercator (SOM) map projection. Geometric transforms are thus; required to access TM data in the geodetic coordinates used by the DEMs. Due to positional errors in the TM data, these transforms require some sort of external control. The spatial resolution of TM data exceeds that of the most commonly DEM data. Oversampling DEM data to TM resolution introduces systematic noise. Common terrain processing algorithms (e.g., close computation) compound this problem by acting as high-pass filters.

  4. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Seattle (WA) WFO - Clallam, Jefferson, Kitsap, Mason, Pierce, and Thurston Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  5. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Seattle (WA) WFO - Whatcom, San Juan, Skagit, Island, Snohomish, and King Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  6. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: San Francisco Bay/Monterey (CA) WFO - Sonoma, Marin, Napa, and Solano Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  7. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: San Francisco Bay/Monterey (CA) WFO - Contra Costa, San Francisco, Alameda, San Mateo, and Santa Clara Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  8. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: San Francisco Bay/Monterey (CA) WFO - Santa Cruz and Monterey Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  9. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Los Angeles/Oxnard (CA) WFO - Los Angeles and Ventura Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  10. 2012 NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Mobile/Tallahassee (AL/FL) WFO - Wakulla (portion), Franklin (portion), Jefferson, Taylor, Dixie, and Levy Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  11. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Miami (FL) WFO - Palm Beach, Broward, Miami-Dade, and Monroe (Keys) Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  12. NTHMP DEM Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the...

  13. kawaihae_dem.grd

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to...

  14. NOAA VDatum DEM Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

  15. Assessment of Required Accuracy of Digital Elevation Data for Hydrologic Modeling

    Science.gov (United States)

    Kenward, T.; Lettenmaier, D. P.

    1997-01-01

    The effect of vertical accuracy of Digital Elevation Models (DEMs) on hydrologic models is evaluated by comparing three DEMs and resulting hydrologic model predictions applied to a 7.2 sq km USDA - ARS watershed at Mahantango Creek, PA. The high resolution (5 m) DEM was resempled to a 30 m resolution using method that constrained the spatial structure of the elevations to be comparable with the USGS and SIR-C DEMs. This resulting 30 m DEM was used as the reference product for subsequent comparisons. Spatial fields of directly derived quantities, such as elevation differences, slope, and contributing area, were compared to the reference product, as were hydrologic model output fields derived using each of the three DEMs at the common 30 m spatial resolution.

  16. Elevation in the Western United States (90 meter DEM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Elevation in the western United States obtained from the National Elevation Dataset. Data was converted from float point to integer format and resampled from 30m...

  17. Elevation in the Western United States (180 meter DEM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Elevation in the western United States obtained from the National Elevation Dataset. Data was converted from float point to integer format and resampled from 30m...

  18. Synthetic Aperture Radar Interferometry for Digital Elevation Model of Kuwait Desert - Analysis of Errors

    Science.gov (United States)

    Jassar, H. K. Al; Rao, K. S.

    2012-07-01

    Using different combinations of 29 Advanced Synthetic Aperture Radar (ASAR) images, 43 Digital Elevations Models (DEM) were generated adopting SAR Interferometry (InSAR) technique. Due to sand movement in desert terrain, there is a poor phase correlation between different SAR images. Therefore, suitable methodology for generating DEMs of Kuwait desert terrain using InSAR technique were worked out. Time series analysis was adopted to derive the best DEM out of 43 DEMs. The problems related to phase de-correlation over desert terrain are discussed. Various errors associated with the DEM generation are discussed which include atmospheric effects, penetration into soil medium, sand movement. The DEM of Shuttle Radar Topography Mission (SRTM) is used as a reference. The noise levels of DEM of SRTM are presented.

  19. A geomorphology-based approach for digital elevation model fusion - case study in Danang city, Vietnam

    Science.gov (United States)

    Tran, T. A.; Raghavan, V.; Masumoto, S.; Vinayaraj, P.; Yonezawa, G.

    2014-07-01

    Global digital elevation models (DEM) are considered a source of vital spatial information and find wide use in several applications. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global DEM (GDEM) and Shuttle Radar Topographic Mission (SRTM) DEM offer almost global coverage and provide elevation data for geospatial analysis. However, GDEM and SRTM still contain some height errors that affect the quality of elevation data significantly. This study aims to examine methods to improve the resolution as well as accuracy of available free DEMs by data fusion techniques and evaluating the results with a high-quality reference DEM. The DEM fusion method is based on the accuracy assessment of each global DEM and geomorphological characteristics of the study area. Land cover units were also considered to correct the elevation of GDEM and SRTM with respect to the bare-earth surface. The weighted averaging method was used to fuse the input DEMs based on a landform classification map. According to the landform types, the different weights were used for GDEM and SRTM. Finally, a denoising algorithm (Sun et al., 2007) was applied to filter the output-fused DEM. This fused DEM shows excellent correlation to the reference DEM, having a correlation coefficient R2 = 0.9986, and the accuracy was also improved from a root mean square error (RMSE) of 14.9 m in GDEM and 14.8 m in SRTM to 11.6 m in the fused DEM. The results of terrain-related parameters extracted from this fused DEM such as slope, curvature, terrain roughness index and normal vector of topographic surface are also very comparable to reference data.

  20. A global digital elevation model - GTOP030

    Science.gov (United States)

    1999-01-01

    GTOP030, the U.S. Geological Survey's (USGS) digital elevation model (DEM) of the Earth, provides the flrst global coverage of moderate resolution elevation data.  The original GTOP30 data set, which was developed over a 3-year period through a collaborative effort led by the USGS, was completed in 1996 at the USGS EROS Data Center in Sioux Falls, South Dakota.  The collaboration involved contributions of staffing, funding, or source data from cooperators including the National Aeronautics and Space Administration (NASA), the United Nations Environment Programme Global Resource Information Database (UNEP/GRID), the U.S. Agency for International Development (USAID), the Instituto Nacional de Estadistica Geografia e Informatica (INEGI) of Mexico, the Geographical Survey Institute (GSI) of Japan, Manaaki Whenua Landcare Research of New Zealand, and the Scientific Committee on Antarctic Research (SCAR). In 1999, work was begun on an update to the GTOP030 data set. Additional data sources are being incorporated into GTOP030 with an enhanced and improved data set planned for release in 2000.

  1. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987

    DEFF Research Database (Denmark)

    Korsgaard, Niels J.; Nuth, Christopher; Khan, Shfaqat Abbas

    2016-01-01

    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling...... and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision...

  2. Evaluation Digital Elevation Model Generated by Synthetic Aperture Radar Data

    Science.gov (United States)

    Makineci, H. B.; Karabörk, H.

    2016-06-01

    Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS). Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry) and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data) and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

  3. EVALUATION DIGITAL ELEVATION MODEL GENERATED BY SYNTHETIC APERTURE RADAR DATA

    Directory of Open Access Journals (Sweden)

    H. B. Makineci

    2016-06-01

    Full Text Available Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS. Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

  4. Assessing the quality of digital elevation models obtained from mini unmanned aerial vehicles for overland flow modelling in urban areas

    Science.gov (United States)

    Leitão, João P.; Moy de Vitry, Matthew; Scheidegger, Andreas; Rieckermann, Jörg

    2016-04-01

    Precise and detailed digital elevation models (DEMs) are essential to accurately predict overland flow in urban areas. Unfortunately, traditional sources of DEM, such as airplane light detection and ranging (lidar) DEMs and point and contour maps, remain a bottleneck for detailed and reliable overland flow models, because the resulting DEMs are too coarse to provide DEMs of sufficient detail to inform urban overland flows. Interestingly, technological developments of unmanned aerial vehicles (UAVs) suggest that they have matured enough to be a competitive alternative to satellites or airplanes. However, this has not been tested so far. In this study we therefore evaluated whether DEMs generated from UAV imagery are suitable for urban drainage overland flow modelling. Specifically, 14 UAV flights were conducted to assess the influence of four different flight parameters on the quality of generated DEMs: (i) flight altitude, (ii) image overlapping, (iii) camera pitch, and (iv) weather conditions. In addition, we compared the best-quality UAV DEM to a conventional lidar-based DEM. To evaluate both the quality of the UAV DEMs and the comparison to lidar-based DEMs, we performed regression analysis on several qualitative and quantitative metrics, such as elevation accuracy, quality of object representation (e.g. buildings, walls and trees) in the DEM, which were specifically tailored to assess overland flow modelling performance, using the flight parameters as explanatory variables. Our results suggested that, first, as expected, flight altitude influenced the DEM quality most, where lower flights produce better DEMs; in a similar fashion, overcast weather conditions are preferable, but weather conditions and other factors influence DEM quality much less. Second, we found that for urban overland flow modelling, the UAV DEMs performed competitively in comparison to a traditional lidar-based DEM. An important advantage of using UAVs to generate DEMs in urban areas is

  5. Generation of a new Greenland Ice Sheet Digital Elevation Model

    DEFF Research Database (Denmark)

    Nagarajan, Sudhagar; Csatho, Beata M; Schenk, Anton F

    and spaceborne laser altimetry (airborne: Airborne Topographic Mapper (ATM) (1993-present), Laser Vegetation Imaging Sensor(LVIS) (2007,2009 and 2011); spaceborne: Ice, Cloud, and land Elevation Satellite (ICESat) (2003-2009)) and DEMs have been derived from stereo satellite imagery (e.g., SPOT (40 m), ASTER (15...... conditions, by fusing a photoclinometry DEM, SPOT and ASTER DEMs as well as elevations from ICESat, ATM and LVIS laser altimetry. The new multi-resolution DEM has a resolution of 40 m x 40 m in the marginal ice sheet regions and 250 m elsewhere. The ice sheet margin is mapped from SPOT and Landsat imagery...... and SPOT DEMs are used to cover the complex topography of ice sheet marginal regions. The accuracy of SPOT DEMs is approximately $\\pm 6$ m except in the areas covered by clouds regions, where the SPOT elevations were replaced by ASTER DEMs. The ASTER DEMs were checked and improved by the DEM derived from...

  6. Comparison of 7.5-minute and 1-degree digital elevation models

    Science.gov (United States)

    Isaacson, Dennis L.; Ripple, William J.

    1995-01-01

    We compared two digital elevation models (DEM's) for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented.

  7. 2012 NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Mobile/Tallahassee (AL/FL) WFO - Okaloosa (portion), Walton, Bay, Gulf, Franklin (portion), and Wakulla (portion) Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  8. 2012 NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Mobile/Tallahassee (AL/FL) WFO - Mobile County in Alabama and Escambia, Santa Rosa, and Okaloosa (portion) Counties in Florida

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  9. From digital elevation model data to terrain depiction data

    Science.gov (United States)

    Helmetag, Arnd; Smietanski, Guillaume; Baumgart, Michael; Kubbat, Wolfgang

    1999-07-01

    The analysis of accidents focused our work on the avoidance of 'Controlled Flight Into Terrain' caused by insufficient situation awareness. Analysis of safety concepts led us to the design of the proposed synthetic vision system that will be described. Since most information on these 3D-Displays is shown in a graphical way, it can intuitively be seized by the pilot. One key element of SVS is terrain depiction, that is the topic of this paper. Real time terrain depiction has to face two requirements. On the one hand spatial awareness requires recognition of synthetic environment demanding characteristics. On the other hand the number of rendered polygons has to be minimized due to limitations of real time image generation performance. Visual quality can significantly be enhanced if equidistant data like Digital Elevation Model data (DEM) are vectorized. One method of data vectorization will be explained in detail and advantages will be mentioned. In Virtual Reality (VR) applications, conventional decimation software degrades the visual quality of geometry that is compensated by complex textures and lighting. Since terrain decimated with those tools looses its characteristics, and textures are not acceptable for several reasons, a terrain specific decimation has to be performed. How can a Digital Elevation Model (DEM) be decimated without decreasing the visualization value? In this paper, extraction of terrain characteristics and adapted decimation will be proposed. Steps from DEM to Terrain Depiction Data (TDD) are discussed in detail.

  10. NOAA Tsunami Inundation DEM Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  11. Vertical Accuracy Comparison of Digital Elevation Model from LIDAR and Multitemporal Satellite Imagery

    Science.gov (United States)

    Octariady, J.; Hikmat, A.; Widyaningrum, E.; Mayasari, R.; Fajari, M. K.

    2017-05-01

    Digital elevation model serves to illustrate the appearance of the earth's surface. DEM can be produced from a wide variety of data sources including from radar data, LiDAR data, and stereo satellite imagery. Making the LiDAR DEM conducted using point cloud data from LiDAR sensor. Making a DEM from stereo satellite imagery can be done using same temporal or multitemporal stereo satellite imagery. How much the accuracy of DEM generated from multitemporal stereo stellite imagery and LiDAR data is not known with certainty. The study was conducted using LiDAR DEM data and multitemporal stereo satellite imagery DEM. Multitemporal stereo satellite imagery generated semi-automatically by using 3 scene stereo satellite imagery with acquisition 2013-2014. The high value given each of DEM serve as the basis for calculating high accuracy DEM respectively. The results showed the high value differences in the fraction of the meter between LiDAR DEM and multitemporal stereo satellite imagery DEM.

  12. Assessing accuracy in varying Lidar data point densities in Digital Elevation Maps

    OpenAIRE

    Anderson, Brian C.

    2008-01-01

    This thesis discusses the production of Digital Elevation Maps (DEM) using varying density of data points from a Lidar (Laser or Light Detection And Ranging) collection. Additionally, this thesis contains information on the multiple space missions that use laser altimetry or Lidar to gather data about planet earth, the moon, asteroids, Mars and Mercury. The thesis covers the accuracy of different amounts of data used when generating a DEM in Quick Terrain Modeler software package and the ...

  13. 1-Meter Digital Elevation Model specification

    Science.gov (United States)

    Arundel, Samantha T.; Archuleta, Christy-Ann M.; Phillips, Lori A.; Roche, Brittany L.; Constance, Eric W.

    2015-10-21

    In January 2015, the U.S. Geological Survey National Geospatial Technical Operations Center began producing the 1-Meter Digital Elevation Model data product. This new product was developed to provide high resolution bare-earth digital elevation models from light detection and ranging (lidar) elevation data and other elevation data collected over the conterminous United States (lower 48 States), Hawaii, and potentially Alaska and the U.S. territories. The 1-Meter Digital Elevation Model consists of hydroflattened, topographic bare-earth raster digital elevation models, with a 1-meter x 1-meter cell size, and is available in 10,000-meter x 10,000-meter square blocks with a 6-meter overlap. This report details the specifications required for the production of the 1-Meter Digital Elevation Model.

  14. How processing digital elevation models can affect simulated water budgets.

    Science.gov (United States)

    Kuniansky, Eve L; Lowery, Mark A; Campbell, Bruce G

    2009-01-01

    For regional models, the shallow water table surface is often used as a source/sink boundary condition, as model grid scale precludes simulation of the water table aquifer. This approach is appropriate when the water table surface is relatively stationary. Since water table surface maps are not readily available, the elevation of the water table used in model cells is estimated via a two-step process. First, a regression equation is developed using existing land and water table elevations from wells in the area. This equation is then used to predict the water table surface for each model cell using land surface elevation available from digital elevation models (DEM). Two methods of processing DEM for estimating the land surface for each cell are commonly used (value nearest the cell centroid or mean value in the cell). This article demonstrates how these two methods of DEM processing can affect the simulated water budget. For the example presented, approximately 20% more total flow through the aquifer system is simulated if the centroid value rather than the mean value is used. This is due to the one-third greater average ground water gradients associated with the centroid value than the mean value. The results will vary depending on the particular model area topography and cell size. The use of the mean DEM value in each model cell will result in a more conservative water budget and is more appropriate because the model cell water table value should be representative of the entire cell area, not the centroid of the model cell.

  15. Validation of Orthorectified Interferometric Radar Imagery and Digital Elevation Models

    Science.gov (United States)

    Smith Charles M.

    2004-01-01

    This work was performed under NASA's Verification and Validation (V&V) Program as an independent check of data supplied by EarthWatch, Incorporated, through the Earth Science Enterprise Scientific Data Purchase (SDP) Program. This document serves as the basis of reporting results associated with validation of orthorectified interferometric interferometric radar imagery and digital elevation models (DEM). This validation covers all datasets provided under the first campaign (Central America & Virginia Beach) plus three earlier missions (Indonesia, Red River: and Denver) for a total of 13 missions.

  16. Calculation and Error Analysis of a Digital Elevation Model of Hofsjokull, Iceland from SAR Interferometry

    Science.gov (United States)

    Barton, Jonathan S.; Hall, Dorothy K.; Sigurosson, Oddur; Williams, Richard S., Jr.; Smith, Laurence C.; Garvin, James B.

    1999-01-01

    Two ascending European Space Agency (ESA) Earth Resources Satellites (ERS)-1/-2 tandem-mode, synthetic aperture radar (SAR) pairs are used to calculate the surface elevation of Hofsjokull, an ice cap in central Iceland. The motion component of the interferometric phase is calculated using the 30 arc-second resolution USGS GTOPO30 global digital elevation product and one of the ERS tandem pairs. The topography is then derived by subtracting the motion component from the other tandem pair. In order to assess the accuracy of the resultant digital elevation model (DEM), a geodetic airborne laser-altimetry swath is compared with the elevations derived from the interferometry. The DEM is also compared with elevations derived from a digitized topographic map of the ice cap from the University of Iceland Science Institute. Results show that low temporal correlation is a significant problem for the application of interferometry to small, low-elevation ice caps, even over a one-day repeat interval, and especially at the higher elevations. Results also show that an uncompensated error in the phase, ramping from northwest to southeast, present after tying the DEM to ground-control points, has resulted in a systematic error across the DEM.

  17. Using digital elevation models as an environmental predictor for soil clay contents

    DEFF Research Database (Denmark)

    Greve, Mogens Humlekrog; Bou Kheir, Rania; Greve, Mette Balslev

    2012-01-01

    The objective of this study was to evaluate the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) as an environmental predictor for soil clay content (SCC). It was based on the applicability of different DEMs, i.e., SRTM with 90-m resolution and airborne Light Detection...... and Ranging (LIDAR) (in 24- and 90-m resolution), using regression-tree analysis. Ten terrain parameters were generated from these DEMs. These terrain parameters were used along other environmental variables to statistically explain SCC content in Denmark. Results indicated that the SRTM tree model (T1: 90-m...

  18. Linear and nonlinear approach for DEM smoothening

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available One of the biggest problems faced while analyzing digital elevation models (DEMs, particularly DEMs that are produced using photogrammetry, is to avoid pits and peaks in DEMs. Peaks and pits, which are errors, are generated during the surface generation process. DEM smoothening is an important preprocessing step meant for removing these errors. This paper discusses two linear DEM smoothening methods, Gaussian blurring and mean smoothening, and two nonlinear DEM smoothening methods, morphological smoothening and morphological smoothening by reconstruction. The four methods are implemented on a photogrammetrically generated DEM. The drainage network of the resultant DEM is obtained using skeletonization by morphological thinning, and the fractal dimension of the extracted network is computed using the box dimension method. The fractal dimensions are then compared to study the effects of the four smoothening methods. The advantages of nonlinear DEM smoothening over linear DEM smoothening are discussed. This study is useful in landscape descriptions.

  19. RADAR INTERFEROMETRY APPLICATION FOR DIGITAL ELEVATION MODEL IN MOUNT BROMO, INDONESIA

    Directory of Open Access Journals (Sweden)

    Noorlaila Hayati

    2015-06-01

    Full Text Available This paper reviewed the result and processing of digital elevation model (DEM using L-Band ALOS PALSAR data and two-pass radar interferometry method in Bromo Mountain region. Synthetic Aperture Radar is an advanced technology that has been used to monitor deformation, land cover change, image detection and especially topographic information such as DEM.  We used two scenes of SAR imageries to generate DEM extraction which assumed there is no deformation effect between two acquisitions. We could derive topographic information using phase difference by combining two single looks complex (SLC images called focusing process. The next steps were doing interferogram generation, phase unwrapping and geocoding. DEM-InSAR was compared to SRTM 90m that there were significant elevation differences between two DEMs such as smoothing surface and detail topographic. Particularly for hilly areas, DEM-InSAR showed better quality than SRTM 90 m where the elevation could have 25.94 m maximum gap. Although the processing involved adaptive filter to amplify the phase signal, we concluded that InSAR DEM result still had error noise because of signal wavelength, incidence angle, SAR image relationship, and only using ascending orbit direction.

  20. Evaluation of digital elevation models for delineation of hydrological response units in a Himalayan watershed

    NARCIS (Netherlands)

    Saran, S.; Sterk, G.; Peters, P.D.; Dadhwal, V.K.

    2010-01-01

    This study reports results from evaluation of the quality of digital elevation model (DEM) from four sources viz. topographic map (1: 50,000), Shuttle Radar Topographic Mission (SRTM) (90 m), optical stereo pair from ASTER (15 m) and CARTOSAT (2.5 m) and their use in derivation of hydrological respo

  1. Lunar Topography and Basins Mapped Using a Clementine Stereo Digital Elevation Model

    Science.gov (United States)

    Cook, A. C.; Spudis, P. D.; Robinson, M. S.; Watters, T. R.

    2002-01-01

    Planet-wide (1 km/pixel and 5 km/pixel) Digital Elevation Models (DEM) of the Moon have been produced using Clementine UVVIS (Ultraviolet-Visible) stereo. Six new basins have been discovered, two suspected basins have been confirmed, and the dimensions of existing basins better defined. Additional information is contained in the original extended abstract.

  2. Evaluation of digital elevation models for delineation of hydrological response units in a Himalayan watershed

    NARCIS (Netherlands)

    Saran, S.; Sterk, G.; Peters, P.; Dadhwal, V.K.

    2010-01-01

    This study reports results from evaluation of the quality of digital elevation model (DEM) from four sources viz. topographic map (1:50,000), Shuttle Radar Topographic Mission (SRTM) (90 m), optical stereo pair from ASTER (15 m) and CARTOSAT (2.5 m) and their use in derivation of hydrological respon

  3. Uncertainty aspects of the digital elevation model for the Forsmark area

    Energy Technology Data Exchange (ETDEWEB)

    Stroemgren, Maarten; Brydsten, Lars (Umeaa Univ., Umeaa (Sweden))

    2009-10-15

    A digital elevation model (DEM) describes the terrain relief. A proper DEM is an important data source for many of the different site description models conducted in the Forsmark region. Input data for the Forsmark DEM is elevation data for both land and sea areas of different origin and quality. No statistical analysis of the error in the Forsmark DEM is so far carried out. However, the Forsmark DEM is part of the quality assessment of the regolith depth model for the Forsmark area since it represents the upper surface of the regolith depth model. The aim of this project was to calculate the errors in different areas in the Forsmark DEM and present them in terms of general descriptive statistics. Measurements have confirmed the knowledge that the 0.25-metre DEM produced from the laser scanning measurements in the Laxemar-Simpevarp area is of very high quality. The 0.25-metre DEM was used to calculate the errors of the 10 and 50-metre DEMs, and the errors for different sea shoreline sources. These error distributions were placed randomly among points for the same data sources in the Forsmark area and used for correction of the original elevation levels. Using the corrected input data for the 10 and 50-metre DEMs and for the sea shoreline, a new DEM was produced. All other input data remained unchanged. The error for the Forsmark DEM was calculated for areas within the data sources corrected from the 0.25-metre DEM. The 0.25-metre DEM from the Laxemar-Simpevarp area was also used for a calculation of how density of input data points used in interpolation affects quality in a 20-metre DEM. Part of the input data was removed in the sea area, new DEMs were produced and compared to the existing Forsmark DEM within the areas of the removed data, to get a measure of the error in these areas of the DEM. In areas of input data for the sea shoreline, the quality of the Forsmark DEM is high. The errors within the SKB 10-metre DEM are slightly less than within the extension

  4. Quality Assessment for the First Part of the Tandem-X Global Digital Elevation Model

    Science.gov (United States)

    Brautigam, B.; Martone, M.; Rizzoli, P.; Gonzalez, C.; Wecklich, C.; Borla Tridon, D.; Bachmann, M.; Schulze, D.; Zink, M.

    2015-04-01

    TanDEM-X is an innovative synthetic aperture radar (SAR) mission with the main goal to generate a global and homogeneous digital elevation model (DEM) of the Earth's land masses. The final DEM product will reach a new dimension of detail with respect to resolution and quality. The absolute horizontal and vertical accuracy shall each be less than 10 m in a 90% confidence interval at a pixel spacing of 12 m. The relative vertical accuracy specification for the TanDEM-X mission foresees a 90% point-to-point error of 2 m (4 m) for areas with predominant terrain slopes smaller than 20% (greater than 20%) within a 1° longitude by 1° latitude cell. The global DEM is derived from interferometric SAR acquisitions performed by two radar satellites flying in close orbit formation. Interferometric performance parameters like the coherence between the two radar images have been monitored and evaluated throughout the mission. In a further step, over 500,000 single SAR scenes are interferometrically processed, calibrated, and mosaicked into a global DEM product which will be completely available in the second half of 2016. This paper presents an up-todate quality status of the single interferometric acquisitions as well as of 50% of the final DEM. The overall DEM quality of these first products promises accuracies well within the specification, especially in terms of absolute height accuracy.

  5. Estuarine Bathymetric Digital Elevation Models (30 meter and 3 arc second resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These Bathymetric Digital Elevation Models (DEM) were generated from original point soundings collected during hydrographic surveys conducted by the National Ocean...

  6. Using Digital Elevation Models and LAHARZ to Forecast Inundation by Lahars

    Science.gov (United States)

    Schilling, S. P.; Iverson, R. M.

    2005-12-01

    LAHARZ is a statistically based method for evaluating the effects of three-dimensional topography on lahar inundation patterns. The method applies the average behavior of past lahars to forecast inundation areas and portray them on maps. LAHARZ software runs on a Geographic Information System (GIS) and requires inputs consisting of prospective lahar volumes appropriate for the size and geologic history of a given volcano, identification of lahar source areas, and a digital elevation model (DEM) of topography. When using LAHARZ, the attributes of the input DEM have a significant impact on delineation of hazard zones. During a volcano crisis, there may be no option other than to select any available DEM to construct hazard zones. Ideally, users should obtain and evaluate existing or construct new DEMs before a crisis situation. Considerations before using a DEM are its extent, resolution, projection, datum, construction method, and quality. DEMs should include the volcano edifice and its drainages, which may reach hundreds of kilometers away from the volcano. The DEM should have sufficient resolution to depict drainage shapes accurately. For example, a DEM with 1-km resolution will not portray a 500-m wide drainage accurately. Projection, datum, and algoritm used for DEM generation ensure the constructed hazard zones can be displayed accurately with other data used in hazard map preparation. Methods for checking horizontal and vertical accuracy can range from inspecting the DEM visually and comparing it with published topographic maps to visiting locations in the field visible in the DEM (e.g., road intersections or mountain peaks) and comparing coordinates with a global positioning system (GPS) at an accuracy equal to or higher than the DEM for comparison. The DEM should be hydrologically correct. It should route a hypothetical flow of water along drainage thalwegs downstream effectively. Hydrologic functions called by LAHARZ can be used to ensure continuity of flow

  7. Hydrological landscape analysis based on digital elevation data

    Science.gov (United States)

    Seibert, J.; McGlynn, B.; Grabs, T.; Jensco, K.

    2008-12-01

    Topography is a major factor controlling both hydrological and soil processes at the landscape scale. While this is well-accepted qualitatively, quantifying relationships between topography and spatial variations of hydrologically relevant variables at the landscape scale still remains a challenging research topic. In this presentation, we describe hydrological landscape analysis HLA) as a way to derive relevant topographic indicies to describe the spatial variations of hydrological variables at the landscape scale. We demonstrate our HLA approach with four high-resolution digital elevation models (DEMs) from Sweden, Switzerland and Montana (USA). To investigate scale effects HLA metrics, we compared DEMs of different resolutions. These LiDAR-derived DEMs of 3m, 10m, and 30m, resolution represent catchments of ~ 5 km2 ranging from low to high relief. A central feature of HLA is the flowpath-based analysis of topography and the separation of hillslopes, riparian areas, and the stream network. We included the following metrics: riparian area delineation, riparian buffer potential, separation of stream inflows into right and left bank components, travel time proxies based on flowpath distances and gradients to the channel, and as a hydrologic similarity to the hypsometric curve we suggest the distribution of elevations above the stream network (computed based on the location where a certain flow pathway enters the stream). Several of these indices depended clearly on DEM resolution, whereas this effect was minor for others. While the hypsometric curves all were S-shaped the 'hillslope-hypsometric curves' had the shape of a power function with exponents less than 1. In a similar way we separated flow pathway lengths and gradients between hillslopes and streams and compared a topographic travel time proxy, which was based on the integration of gradients along the flow pathways. Besides the comparison of HLA-metrics for different catchments and DEM resolutions we present

  8. Synergetic merging of Cartosat-1 and RAMP to generate improved digital elevation model of Schirmacher oasis, east Antarctica

    Science.gov (United States)

    Jawak, S. D.; Luis, A. J.

    2014-11-01

    Available digital elevation models (DEMs) of Antarctic region generated by using radar altimetry and the Antarctic digital database (ADD) indicate elevation variations of up to hundreds of meters, which necessitates the generation of local DEM and its validation by using ground reference. An enhanced digital elevation model (eDEM) of the Schirmacher oasis region, east Antarctica, is generated synergistically by using Cartosat-1 stereo pair-derived photogrammetric DEM (CartoDEM)-based point elevation dataset and multitemporal radarsat Antarctic mapping project version 2 (RAMPv2) DEM-based point elevation dataset. In this study, we analyzed suite of interpolation techniques for constructing a DEM from RAMPv2 and CartoDEM-based point elevation datasets, in order to determine the level of confidence with which the interpolation techniques can generate a better interpolated continuous surface, and eventually improves the elevation accuracy of DEM from synergistically fused RAMPv2 and CartoDEM point elevation datasets. RAMPv2 points and CartoDEM points were used as primary data for various interpolation techniques such as ordinary kriging (OK), simple kriging (SK), universal kriging (UK), disjunctive kriging (DK) techniques, inverse distance weighted (IDW), global polynomial (GP) with power 1 and 2, local polynomial (LP) and radial basis functions (RBF). Cokriging of 2 variables with second dataset was used for ordinary cokriging (OCoK), simple cokriging (SCoK), universal cokriging (UCoK) and disjunctive cokriging (DCoK). The IDW, GP, LP, RBF, and kriging methods were applied to one variable, while Cokriging experiments were employed on two variables. The experiment of dataset and its combination produced two types of point elevation map categorized as (1) one variable (RAMPv2 Point maps and CartoDEM Point maps) and (2) two variables (RAMPv2 Point maps + CartoDEM Point maps). Interpolated surfaces were evaluated with the help of differential global positioning system

  9. Assessing the quality of Digital Elevation Models obtained from mini-Unmanned Aerial Vehicles for overland flow modelling in urban areas

    Science.gov (United States)

    Leitão, J. P.; Moy de Vitry, M.; Scheidegger, A.; Rieckermann, J.

    2015-06-01

    Precise and detailed Digital Elevation Models (DEMs) are essential to accurately predict overland flow in urban areas. Unfortunately, traditional sources of DEM remain a bottleneck for detailed and reliable overland flow models, because the resulting DEMs are too coarse to provide DEMs of sufficient detail to inform urban overland flows. Interestingly, technological developments of Unmanned Aerial Vehicles (UAVs) suggest that they have matured enough to be a competitive alternative to satellites or airplanes. However, this has not been tested so far. In this this study we therefore evaluated whether DEMs generated from UAV imagery are suitable for urban drainage overland flow modelling. Specifically, fourteen UAV flights were conducted to assess the influence of four different flight parameters on the quality of generated DEMs: (i) flight altitude, (ii) image overlapping, (iii) camera pitch and (iv) weather conditions. In addition, we compared the best quality UAV DEM to a conventional Light Detection and Ranging (LiDAR)-based DEM. To evaluate both the quality of the UAV DEMs and the comparison to LiDAR-based DEMs, we performed regression analysis on several qualitative and quantitative metrics, such as elevation accuracy, quality of object representation (e.g., buildings, walls and trees) in the DEM, which were specifically tailored to assess overland flow modelling performance, using the flight parameters as explanatory variables. Our results suggested that, first, as expected, flight altitude influenced the DEM quality most, where lower flights produce better DEMs; in a similar fashion, overcast weather conditions are preferable, but weather conditions and other factors influence DEM quality much less. Second, we found that for urban overland flow modelling, the UAV DEMs performed competitively in comparison to a traditional LiDAR-based DEM. An important advantage of using UAVs to generate DEMs in urban areas is their flexibility that enables more frequent

  10. VT Lidar DEM (1 meter) - 2005 - Essex

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various...

  11. VT Lidar DEM (1 meter) - 2009 - Washington

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Essex County 2005 1m and Digital Elevation Model (DEM) datasets of various...

  12. Predictive vegetation modeling for conservation: impact of error propagation from digital elevation data.

    Science.gov (United States)

    Van Niel, Kimberly P; Austin, Mike P

    2007-01-01

    The effect of digital elevation model (DEM) error on environmental variables, and subsequently on predictive habitat models, has not been explored. Based on an error analysis of a DEM, multiple error realizations of the DEM were created and used to develop both direct and indirect environmental variables for input to predictive habitat models. The study explores the effects of DEM error and the resultant uncertainty of results on typical steps in the modeling procedure for prediction of vegetation species presence/absence. Results indicate that all of these steps and results, including the statistical significance of environmental variables, shapes of species response curves in generalized additive models (GAMs), stepwise model selection, coefficients and standard errors for generalized linear models (GLMs), prediction accuracy (Cohen's kappa and AUC), and spatial extent of predictions, were greatly affected by this type of error. Error in the DEM can affect the reliability of interpretations of model results and level of accuracy in predictions, as well as the spatial extent of the predictions. We suggest that the sensitivity of DEM-derived environmental variables to error in the DEM should be considered before including them in the modeling processes.

  13. Determining the optimum cell size of digital elevation model for hydrologic application

    Indian Academy of Sciences (India)

    Arabinda Sharma; K N Tiwari; P B S Bhadoria

    2011-08-01

    Scale is one of the most important but unsolved issues in various scientific disciplines that deal with spatial data. The arbitrary choice of grid cell size for contour interpolated digital elevation models (DEM) is one of the major sources of uncertainty in the hydrologic modelling process. In this paper, an attempt was made to identify methods for determining an optimum cell size for a contour interpolated DEM in prior to hydrologic modelling. Twenty-meter interval contour lines were used to generate DEMs of five different resolutions, viz., 30, 45, 60, 75, and 90 m using TOPOGRID algorithm. The obtained DEMs were explored for their intrinsic quality using four different methods, i.e., sink analysis, fractal dimension of derived stream network, entropy measurement and semivariogram modelling. These methods were applied to determine the level artifacts (interpolation error) in DEM surface as well as derived stream network, spatial information content and spatial variability respectively. The results indicated that a 90 m cell size is sufficient to capture the terrain variability for subsequent hydrologic modelling in the study area. The significance of this research work is that it provides methods which DEM users can apply to select an appropriate DEM cell size in prior to detailed hydrologic modelling.

  14. THE SCHEME FOR THE DATABASE BUILDING AND UPDATING OF 1:10 000 DIGITAL ELEVATION MODELS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The National Bureau of Surveying and Mapping of China has planned to speed up the development of spatial data infrastructure (SDI) in the coming few years. This SDI consists of four types of digital products, i. e., digital orthophotos, digital elevation models,digital line graphs and digital raster graphs. For the DEM,a scheme for the database building and updating of 1:10 000 digital elevation models has been proposed and some experimental tests have also been accomplished. This paper describes the theoretical (and/or technical)background and reports some of the experimental results to support the scheme. Various aspects of the scheme such as accuracy, data sources, data sampling, spatial resolution, terrain modeling, data organization, etc are discussed.

  15. STATISTICAL EVALUATION OF FITTING ACCURACY OF GLOBAL AND LOCAL DIGITAL ELEVATION MODELS IN IRAN

    Directory of Open Access Journals (Sweden)

    F. Alidoost

    2013-09-01

    Full Text Available Digital Elevation Models (DEMs are one of the most important data for various applications such as hydrological studies, topography mapping and ortho image generation. There are well-known DEMs of the whole world that represent the terrain's surface at variable resolution and they are also freely available for 99% of the globe. However, it is necessary to assess the quality of the global DEMs for the regional scale applications.These models are evaluated by differencing with other reference DEMs or ground control points (GCPs in order to estimate the quality and accuracy parameters over different land cover types. In this paper, a comparison of ASTER GDEM ver2, SRTM DEM with more than 800 reference GCPs and also with a local elevation model over the area of Iran is presented. This study investigates DEM’s characteristics such as systematic error (bias, vertical accuracy and outliers for DEMs using both the usual (Mean error, Root Mean Square Error, Standard Deviation and the robust (Median, Normalized Median Absolute Deviation, Sample Quantiles descriptors. Also, the visual assessment tools are used to illustrate the quality of DEMs, such as normalized histograms and Q-Q plots. The results of the study confirmed that there is a negative elevation bias of approximately 5 meters of GDEM ver2. The measured RMSE and NMAD for elevation differences of GDEM-GCPs are 7.1 m and 3.2 m, respectively, while these values for SRTM and GCPs are 9.0 m and 4.4 m. On the other hand, in comparison with the local DEM, GDEM ver2 exhibits the RMSE of about 6.7 m, a little higher than the RMSE of SRTM (5.1 m.The results of height difference classification and other statistical analysis of GDEM ver2-local DEM and SRTM-local DEM reveal that SRTM is slightly more accurate than GDEM ver2. Accordingly, SRTM has no noticeable bias and shift from Local DEM and they have more consistency to each other, while GDEM ver2 has always a negative bias.

  16. Estimating Digital Terrain Model in forest areas from TanDEM-X and Stereo-photogrammetric technique by means of Random Volume over Ground model

    Science.gov (United States)

    Lee, S. K.; Fatoyinbo, T. E.; Lagomasino, D.; Osmanoglu, B.; Feliciano, E. A.

    2015-12-01

    The Digital Terrain Model (DTM) in forest areas is invaluable information for various environmental, hydrological and ecological studies, for example, watershed delineation, vegetation canopy height, water dynamic modeling, forest biomass and carbon estimations. There are few solutions to extract bare-earth Digital Elevation Model information. Airborne lidar systems are widely and successfully used for estimating bare-earth DEMs with centimeter-order accuracy and high spatial resolution. However, expensive cost of operation and small image coverage prevent the use of airborne lidar sensors for large- or global-scale. Although IceSAT/GLAS (Ice, Cloud, and Land Elevation Satellite/Geoscience Laser Altimeter System) lidar data sets have been available for global DTM estimate with relatively lower cost, the large footprint size of 70 m and the interval of 172 m are insufficient for various applications. In this study we propose to extract higher resolution bare-earth DEM over vegetated areas from the combination of interferometric complex coherence from single-pass TanDEM-X (TDX) data at HH polarization and Digital Surface Model (DSM) derived from high-resolution WorldView (WV) images by means of random volume over ground (RVoG) model. The RVoG model is a widely and successfully used model for polarimetric SAR interferometry (Pol-InSAR) forest canopy height inversion. The bare-earth DEM is obtained by complex volume decorrelation in the RVoG model with the DSM estimated by stereo-photogrammetric technique. Forest canopy height can be estimated by subtracting the estimated bare-earth model from the DSM. Finally, the DTM from airborne lidar system was used to validate the bare-earth DEM and forest canopy height estimates.

  17. Insights in hydrodynamics of bubbling fluidized beds at elevated pressure by DEM-CFD approach

    Institute of Scientific and Technical Information of China (English)

    Zahra Mansourpour; Sedighe Karimi; Reza Zarghami; Navid Mostoufi; Rahmat Sotudeh-Gharebagh

    2010-01-01

    A numerical simulation was conducted to study the effect of pressure on bubble dynamics in a gas-solid fluidized bed. The gas flow was modeled using the continuum theory and the solid phase, by the dis-crete element method (DEM). To validate the simulation results, calculated local pressure fluctuations were compared with corresponding experimental data of 1-mm polyethylene particles. It was shown that the model successfully predicts the hydrodynamic features of the fluidized bed as observed in the experiments. Influence of pressure on bubble rise characteristics such as bubble rise path, bubble sta-bility, average bubbles diameter and bubble velocity through the bed was investigated. The simulation results are in conformity with current hydrodynamic theories and concepts for fluidized beds at high pressures. The results show further that elevated pressure reduces bubble growth, velocity and stability and enhances bubble gyration through the bed, leading to change in bed flow structure.

  18. Estimating the rate and elevation dependence of net accretion in a freshwater tidal marsh using DEM-registered surveys

    Science.gov (United States)

    Cadol, D. D.; Elmore, A. J.; Engelhardt, K.; Sanders, G.

    2012-12-01

    Tidal freshwater marshes contribute to estuary health by filtering excess sediment and nutrients delivered from the watershed, but their extent and persistence is threatened by rising sea level. To maintain a semi-emergent position, the marsh surface must gain elevation by accreting mineral and/or organic material at a rate comparable to sea level rise. Historic records of sea level rise (SLR) are available from tide gages, but records of historic elevation change at the necessary precision are rare. Additionally, sedimentation, compaction, erosion, and the resultant net elevation gain are spatially heterogeneous across a marsh, varying with elevation, among other factors. We solve this issue at our study site by taking advantage of a 1992 total station survey of the marsh and RTK GPS surveys from 2005 and 2012, and registering them all against an airborne LiDAR derived DEM. Thus, although no points are directly reoccupied, survey vs. DEM trends can be found for each survey, and an average rate of elevation change can be calculated as a function of DEM elevation. We found rates of net elevation gain ranging spatially from 3-5 mm/yr between the years 1992-2012, similar to the historic rate of SLR at a nearby Washington, DC tide gage of 4 mm/yr over the past 28 years. Net elevation change varied as DEM elevation increased, with several local minima and maxima potentially related to variations and transitions in vegetation community. Assuming IPCC predicted sea level rise and a fixed relationship between elevation and net accretion, we then forecast marsh elevation relative to sea level and associated vegetative community changes through the 21st century using an inundation model that considers net accretion and a constant relationship between vegetation community type and elevation.

  19. Automated Quality Control for Ortholmages and DEMs

    DEFF Research Database (Denmark)

    Höhle, Joachim; Potucková, Marketa

    2005-01-01

    The checking of geometric accurancy of orthoimages and digital elevation models (DEMs) is discussed. As a reference, an existing orthoimage and a second orthoimage derived from an overlapping aerial image, are used. The proposed automated procedures for checking the orthoimages and DEMs are based...

  20. Fast Ray Tracing of Lunar Digital Elevation Models

    Science.gov (United States)

    McClanahan, Timothy P.; Evans, L. G.; Starr, R. D.; Mitrofanov, I.

    2009-01-01

    Ray-tracing (RT) of Lunar Digital Elevation Models (DEM)'s is performed to virtually derive the degree of radiation incident to terrain as a function of time, orbital and ephemeris constraints [I- 4]. This process is an integral modeling process in lunar polar research and exploration due to the present paucity of terrain information at the poles and mission planning activities for the anticipated spring 2009 launch of the Lunar Reconnaissance Orbiter (LRO). As part of the Lunar Exploration Neutron Detector (LEND) and Lunar Crater Observation and Sensing Satellite (LCROSS) preparations RI methods are used to estimate the critical conditions presented by the combined effects of high latitude, terrain and the moons low obliquity [5-7]. These factors yield low incident solar illumination and subsequently extreme thermal, and radiation conditions. The presented research uses RT methods both for radiation transport modeling in space and regolith related research as well as to derive permanently shadowed regions (PSR)'s in high latitude topographic minima, e.g craters. These regions are of scientific and human exploration interest due to the near constant low temperatures in PSRs, inferred to be < 100 K. Hydrogen is thought to have accumulated in PSR's through the combined effects of periodic cometary bombardment and/or solar wind processes, and the extreme cold which minimizes hydrogen sublimation [8-9]. RT methods are also of use in surface position optimization for future illumination dependent on surface resources e.g. power and communications equipment.

  1. Back to the Future: Have Remotely Sensed Digital Elevation Models Improved Hydrological Parameter Extraction?

    Science.gov (United States)

    Jarihani, B.

    2015-12-01

    Digital Elevation Models (DEMs) that accurately replicate both landscape form and processes are critical to support modeling of environmental processes. Pre-processing analysis of DEMs and extracting characteristics of the watershed (e.g., stream networks, catchment delineation, surface and subsurface flow paths) is essential for hydrological and geomorphic analysis and sediment transport. This study investigates the status of the current remotely-sensed DEMs in providing advanced morphometric information of drainage basins particularly in data sparse regions. Here we assess the accuracy of three available DEMs: (i) hydrologically corrected "H-DEM" of Geoscience Australia derived from the Shuttle Radar Topography Mission (SRTM) data; (ii) the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) version2 1-arc-second (~30 m) data; and (iii) the 9-arc-second national GEODATA DEM-9S ver3 from Geoscience Australia and the Australian National University. We used ESRI's geospatial data model, Arc Hydro and HEC-GeoHMS, designed for building hydrologic information systems to synthesize geospatial and temporal water resources data that support hydrologic modeling and analysis. A coastal catchment in northeast Australia was selected as the study site where very high resolution LiDAR data are available for parts of the area as reference data to assess the accuracy of other lower resolution datasets. This study provides morphometric information for drainage basins as part of the broad research on sediment flux from coastal basins to Great Barrier Reef, Australia. After applying geo-referencing and elevation corrections, stream and sub basins were delineated for each DEM. Then physical characteristics for streams (i.e., length, upstream and downstream elevation, and slope) and sub-basins (i.e., longest flow lengths, area, relief and slopes) were extracted and compared with reference datasets from LiDAR. Results showed that

  2. A new lunar digital elevation model from the Lunar Orbiter Laser Altimeter and SELENE Terrain Camera

    Science.gov (United States)

    Barker, M. K.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Haruyama, J.; Smith, D. E.

    2016-07-01

    We present an improved lunar digital elevation model (DEM) covering latitudes within ±60°, at a horizontal resolution of 512 pixels per degree (∼60 m at the equator) and a typical vertical accuracy ∼3 to 4 m. This DEM is constructed from ∼ 4.5 ×109 geodetically-accurate topographic heights from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter, to which we co-registered 43,200 stereo-derived DEMs (each 1° × 1°) from the SELENE Terrain Camera (TC) (∼1010 pixels total). After co-registration, approximately 90% of the TC DEMs show root-mean-square vertical residuals with the LOLA data of profiles (typically amounting to <10 m horizontally and <1 m vertically). By combining both co-registered datasets, we obtain a near-global DEM with high geodetic accuracy, and without the need for surface interpolation. We evaluate the resulting LOLA + TC merged DEM (designated as "SLDEM2015") with particular attention to quantifying seams and crossover errors.

  3. A New Lunar Digital Elevation Model from the Lunar Orbiter Laser Altimeter and SELENE Terrain Camera

    Science.gov (United States)

    Barker, M. K.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Haruyama, J.; Smith, D. E.

    2015-01-01

    We present an improved lunar digital elevation model (DEM) covering latitudes within +/-60 deg, at a horizontal resolution of 512 pixels per degree ( approx.60 m at the equator) and a typical vertical accuracy approx.3 to 4 m. This DEM is constructed from approx.4.5 ×10(exp 9) geodetically-accurate topographic heights from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter, to which we co-registered 43,200 stereo-derived DEMs (each 1 deg×1 deg) from the SELENE Terrain Camera (TC) ( approx.10(exp 10) pixels total). After co-registration, approximately 90% of the TC DEMs show root-mean-square vertical residuals with the LOLA data of < 5 m compared to approx.50% prior to co-registration. We use the co-registered TC data to estimate and correct orbital and pointing geolocation errors from the LOLA altimetric profiles (typically amounting to < 10 m horizontally and < 1 m vertically). By combining both co-registered datasets, we obtain a near-global DEM with high geodetic accuracy, and without the need for surface interpolation. We evaluate the resulting LOLA + TC merged DEM (designated as "SLDEM2015") with particular attention to quantifying seams and crossover errors.

  4. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978–1987

    Science.gov (United States)

    Korsgaard, Niels J.; Nuth, Christopher; Khan, Shfaqat A.; Kjeldsen, Kristian K.; Bjørk, Anders A.; Schomacker, Anders; Kjær, Kurt H.

    2016-01-01

    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978–1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps. PMID:27164457

  5. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

    Science.gov (United States)

    Korsgaard, Niels J; Nuth, Christopher; Khan, Shfaqat A; Kjeldsen, Kristian K; Bjørk, Anders A; Schomacker, Anders; Kjær, Kurt H

    2016-05-10

    Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

  6. Robust Mosaicking of Stereo Digital Elevation Models from the Ames Stereo Pipeline

    Science.gov (United States)

    Kim, Tae Min; Moratto, Zachary M.; Nefian, Ara Victor

    2010-01-01

    Robust estimation method is proposed to combine multiple observations and create consistent, accurate, dense Digital Elevation Models (DEMs) from lunar orbital imagery. The NASA Ames Intelligent Robotics Group (IRG) aims to produce higher-quality terrain reconstructions of the Moon from Apollo Metric Camera (AMC) data than is currently possible. In particular, IRG makes use of a stereo vision process, the Ames Stereo Pipeline (ASP), to automatically generate DEMs from consecutive AMC image pairs. However, the DEMs currently produced by the ASP often contain errors and inconsistencies due to image noise, shadows, etc. The proposed method addresses this problem by making use of multiple observations and by considering their goodness of fit to improve both the accuracy and robustness of the estimate. The stepwise regression method is applied to estimate the relaxed weight of each observation.

  7. Contour-based automatic crater recognition using digital elevation models from Chang'E missions

    Science.gov (United States)

    Zuo, Wei; Zhang, Zhoubin; Li, Chunlai; Wang, Rongwu; Yu, Linjie; Geng, Liang

    2016-12-01

    In order to provide fundamental information for exploration and related scientific research on the Moon and other planets, we propose a new automatic method to recognize craters on the lunar surface based on contour data extracted from a digital elevation model (DEM). Through DEM and image processing, this method can be used to reconstruct contour surfaces, extract and combine contour lines, set the characteristic parameters of crater morphology, and establish a crater pattern recognition program. The method has been tested and verified with DEM data from Chang'E-1 (CE-1) and Chang'E-2 (CE-2), showing a strong crater recognition ability with high detection rate, high robustness, and good adaptation to recognize various craters with different diameter and morphology. The method has been used to identify craters with high precision and accuracy on the Moon. The results meet requirements for supporting exploration and related scientific research for the Moon and planets.

  8. DIGITAL ELEVATION MODEL INTERPOLATION BY FUSION OF MORPHOLOGICAL RECONSTRUCTION AND DISTANCE TRANSFORMATION

    Directory of Open Access Journals (Sweden)

    J. Shen

    2017-09-01

    Full Text Available Interpolation methods have significant impacts on the accuracy of the digital elevation model (DEM from contours which are one of frequently employed data sources. In this paper, an interpolation method is presented to build DEM from contour lines by fusion/integration of morphological reconstruction and distance transformation with obstacles. Particularly, morphological reconstruction is used to get the elevation values of the higher contour lines and the lower contour lines of any a spatial point between two contour lines, and distance transformation with obstacles is used to get the geodesic distances of the spatial point to the higher contour lines and the lower contour lines respectively. At last, linear interpolation along water flow line is used to get the elevation values of the pixels to be interpolated. The experiment demonstrates that feasibility of our proposed method.

  9. High Resolution Digital Elevation Models of Pristine Explosion Craters

    Science.gov (United States)

    Farr, T. G.; Krabill, W.; Garvin, J. B.

    2004-01-01

    In order to effectively capture a realistic terrain applicable to studies of cratering processes and landing hazards on Mars, we have obtained high resolution digital elevation models of several pristine explosion craters at the Nevada Test Site. We used the Airborne Terrain Mapper (ATM), operated by NASA's Wallops Flight Facility to obtain DEMs with 1 m spacing and 10 cm vertical errors of 4 main craters and many other craters and collapse pits. The main craters that were mapped are Sedan, Scooter, Schooner, and Danny Boy. The 370 m diameter Sedan crater, located on Yucca Flat, is the largest and freshest explosion crater on Earth that was formed under conditions similar to hypervelocity impact cratering. As such, it is effectively pristine, having been formed in 1962 as a result of a controlled detonation of a 100 kiloton thermonuclear device, buried at the appropriate equivalent depth of burst required to make a simple crater. Sedan was formed in alluvium of mixed lithology and subsequently studied using a variety of field-based methods. Nearby secondary craters were also formed at the time and were also mapped by ATM. Adjacent to Sedan and also in alluvium is Scooter, about 90 m in diameter and formed by a high-explosive event. Schooner (240 m) and Danny Boy (80 m) craters were also important targets for ATM as they were excavated in hard basalt and therefore have much rougher ejecta. This will allow study of ejecta patterns in hard rock as well as engineering tests of crater and rock avoidance and rover trafficability. In addition to the high resolution DEMs, crater geometric characteristics, RMS roughness maps, and other higher-order derived data products will be generated using these data. These will provide constraints for models of landing hazards on Mars and for rover trafficability. Other planned studies will include ejecta size-frequency distribution at the resolution of the DEM and at finer resolution through air photography and field measurements

  10. The use of LIDAR as a data source for digital elevation models – a study of the relationship between the accuracy of digital elevation models and topographical attributes in northern peatlands

    Directory of Open Access Journals (Sweden)

    A. Hasan

    2011-06-01

    Full Text Available It is important to study the factors affecting estimates of wetness since wetness is crucial in climate change studies. The availability of digital elevation models (DEMs generated with high resolution data is increasing, and their use is expanding. LIDAR earth elevation data have been used to create several DEMs with different resolutions, using various interpolation parameters, in order to compare the models with collected surface data. The aim is to study the accuracy of DEMs in relation to topographical attributes such as slope and drainage area, which are normally used to estimate the wetness in terms of topographic wetness indices. Evaluation points were chosen from the high-resolution LIDAR dataset at a maximum distance of 10 mm from the cell center for each DEM resolution studied, 0.5, 1, 5, 10, 30 and 90 m. The interpolation method used was inverse distance weighting method with four search radii: 1, 2, 5 and 10 m. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. The accuracy of the estimated elevation for different slopes was tested using the DEM with 0.5 m resolution. Drainage areas were investigated at three resolutions, with coinciding evaluation points. The ability of the model to generate the drainage area at each resolution was obtained by pairwise comparison of three data subsets.

    The results show that the accuracy of the elevations obtained with the DEM model are the same for different resolutions, but vary with search radius. The accuracy of the values (NMAD of errors varies from 29.7 mm to 88.9 mm, being higher for flatter areas. It was also found that the accuracy of the drainage area is highly dependent on DEM resolution. Coarse resolution yielded larger estimates of the drainage area but lower slope values. This may lead to overestimation of wetness values when using a coarse resolution DEM.

  11. ASTER-Derived 30-Meter-Resolution Digital Elevation Models of Afghanistan

    Science.gov (United States)

    Chirico, Peter G.; Warner, Michael B.

    2007-01-01

    INTRODUCTION The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an imaging instrument aboard the Terra satellite, launched on December 19, 1999, as part of the National Aeronautics and Space Administration's (NASA) Earth Observing System (EOS). The ASTER sensor consists of three subsystems: the visible and near infrared (VNIR), the shortwave infrared (SWIR), and the thermal infrared (TIR), each with a different spatial resolution (VNIR, 15 meters; SWIR, 30 meters, TIR 90 meters). The VNIR system has the capability to generate along-track stereo images that can be used to create digital elevation models (DEMs) at 30-meter resolution. Currently, the only available DEM dataset for Afghanistan is the 90-meter-resolution Shuttle Radar Topography Mission (SRTM) data. This dataset is appropriate for macroscale DEM analysis and mapping. However, ASTER provides a low cost opportunity to generate higher resolution data. For this publication, study areas were identified around populated areas and areas where higher resolution elevation data were desired to assist in natural resource assessments. The higher resolution fidelity of these DEMs can also be used for other terrain analysis including landform classification and geologic structure analysis. For this publication, ASTER scenes were processed and mosaicked to generate 36 DEMs which were created and extracted using PCI Geomatics' OrthoEngine 3D Stereo software. The ASTER images were geographically registered to Landsat data with at least 15 accurate and well distributed ground control points with a root mean square error (RMSE) of less that one pixel (15 meters). An elevation value was then assigned to each ground control point by extracting the elevation from the 90-meter SRTM data. The 36 derived DEMs demonstrate that the software correlated on nearly flat surfaces and smooth slopes accurately. Larger errors occur in cloudy and snow-covered areas, lakes, areas with steep slopes, and

  12. Iowa Bedrock Surface Elevation

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This Digital Elevation Model (DEM) of the bedrock surface elevation in Iowa was compiled using all available data, principally information from GEOSAM, supplemented...

  13. Seasonal changes of surface velocity and elevation of Columbia Glacier, Alaska using time-series TerraSAR-X/TanDEM-X data

    Science.gov (United States)

    Vijay, Saurabh; Braun, Matthias

    2015-04-01

    Alaskan glaciers are a major contributor to global sea-level rise from glaciers and ice caps outside the polar ice sheets. Columbia Glacier is a large tidewater glacier located on the coast of south-central Alaska. The glacier has retreated ˜ 21 km and lost half of its volume during 1957-2007, more rapidly after 1980. It is now split into two branches, known as Main/East and West branch. In this study, we used time series of high-resolution TerraSAR-X/TanDEM-X stripmap satellite imagery during 2011-2014 to investigate the temporal development of glacier surface velocities, elevation and mass changes. The active SLC images of the bistatic TanDEM-X acquisitions, acquired over 11 or 22 days repeat intervals, are utilized to derive surface velocity fields using SAR intensity offset tracking. We observed a very strong seasonal variability in the surface velocities. Maximum values at the ice front reach up to 14.43 m/day in May and reduced to 2 m/day in October in the year 2012. However, at a distance of 17.5 km from the ice front, almost no seasonal variability can be observed. A significant influence in the distance to the terminus and elevation was detected. We attributed this temporal and spatial variability of surface velocity to changes in the basal hydrology and lubrification of the glacier bed. Similar fluctuations are observed in consecutive years. In a second step, we exploited TanDEM-X data by interferometrically generating time series of digital elevation models (DEMs) . For quantitative volume change estimates, we used DEMs of almost similar months of the observational years in order to minimize errors resulting from variable X-band radar penetration. The main branch gained a volume of 12.77± 2.89km^3in 2011-12, but lost -18.94± 3.21km^3in 2012-13 . A slight gain was observed with 1.05± .88km^3in 2013-14. However, the west branch gained volume only in 2011-12 and lost in the consecutive years. Moreover, the west branch retreated by ˜ 3km and lost its

  14. Error analysis in the digital elevation model of Kuwait desert derived from repeat pass synthetic aperture radar interferometry

    Science.gov (United States)

    Rao, Kota S.; Al Jassar, Hala K.

    2010-09-01

    The aim of this paper is to analyze the errors in the Digital Elevation Models (DEMs) derived through repeat pass SAR interferometry (InSAR). Out of 29 ASAR images available to us, 8 are selected for this study which has unique data set forming 7 InSAR pairs with single master image. The perpendicular component of baseline (B highmod) varies between 200 to 400 m to generate good quality DEMs. The Temporal baseline (T) varies from 35 days to 525 days to see the effect of temporal decorrelation. It is expected that all the DEMs be similar to each other spatially with in the noise limits. However, they differ very much with one another. The 7 DEMs are compared with the DEM of SRTM for the estimation of errors. The spatial and temporal distribution of errors in the DEM is analyzed by considering several case studies. Spatial and temporal variability of precipitable water vapour is analysed. Precipitable water vapour (PWV) corrections to the DEMs are implemented and found to have no significant effect. The reasons are explained. Temporal decorrelation of phases and soil moisture variations seem to have influence on the accuracy of the derived DEM. It is suggested that installing a number of corner reflectors (CRs) and the use of Permanent Scatter approach may improve the accuracy of the results in desert test sites.

  15. Obtaining digital elevation data in different terrain and physiognomy regions with spaceborne InSAR and its application analysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Synthetic Aperture Radar Interferometry (for short, InSAR) is a new kind of earth observation technology, which has obtained great development in recent ten years and has a great development potential and successful future. In this note, three typical regions with different physiognomies and terrains have been selected as study regions to extract their Digital Elevation Model (DEMs). Compared with the existing 1︰250000 DEM and by analyzing their results, we have obtained its accuracy and applicable scopes. The results show that in the region (plains, mountains or highlands) with dry surface and sparse vegetation, because of the better correlatability of images, the DEM obtained by InSAR is evidently better than the existing 1︰250000 DEM and the accuracy can reach 4-6 m; in the thick-vegetation-covering region, correlatability between images descends and the accuracy of InSAR DEM can only reach about 30 m worse than its existing 1︰250000 DEM; in the middle covering field, the accuracy of InSAR DEM with tandem images can reach about 10 m as well; yet in water space, such as lakes and rivers, InSAR DEM shows a big error since there is only quite faint signal reflected to the sensor. Then the conclusion has been got: in the west of China, where it has a lack-vegetation and dry ground, InSAR is completely feasible to be applied to such a complicated nature environment region.

  16. Levee crest elevation profiles derived from airborne lidar-based high resolution digital elevation models in south Louisiana

    Science.gov (United States)

    Palaseanu-Lovejoy, Monica; Thatcher, Cindy A.; Barras, John A.

    2014-01-01

    This study explores the feasibility of using airborne lidar surveys to construct high-resolution digital elevation models (DEMs) and develop an automated procedure to extract levee longitudinal elevation profiles for both federal levees in Atchafalaya Basin and local levees in Lafourche Parish, south Lousiana. This approach can successfully accommodate a high degree of levee sinuosity and abrupt changes in levee orientation (direction) in planar coordinates, variations in levee geometries, and differing DEM resolutions. The federal levees investigated in Atchafalaya Basin have crest elevations between 5.3 and 12 m while the local counterparts in Lafourche Parish are between 0.76 and 2.3 m. The vertical uncertainty in the elevation data is considered when assessing federal crest elevation against the U.S. Army Corps of Engineers minimum height requirements to withstand the 100-year flood. Only approximately 5% of the crest points of the two federal levees investigated in the Atchafalaya Basin region met this requirement.

  17. An assessment of TanDEM-X GlobalDEM over rural and urban areas

    Science.gov (United States)

    Koudogbo, Fifamè N.; Duro, Javier; Huber, Martin; Rudari, Roberto; Eddy, Andrew; Lucas, Richard

    2014-10-01

    Digital Elevation Model (DEM) is a key input for the development of risk management systems. Main limitation of the current available DEM is the low level of resolution. DEMs such as STRM 90m or ASTER are globally available free of charge, but offer limited use, for example, to flood modelers in most geographic areas. TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement), the first bistatic SAR can fulfil this gap. The mission objective is the generation of a consistent global digital elevation model with an unprecedented accuracy according to the HRTI-3 (High Resolution Terrain Information) specifications. The mission opens a new era in risk assessment. In the framework of ALTAMIRA INFORMATION research activities, the DIAPASON (Differential Interferometric Automated Process Applied to Survey Of Nature) processing chain has been successfully adapted to TanDEM-X CoSSC (Coregistered Slant Range Single Look Complex) data processing. In this study the capability of CoSSC data for DEM generation is investigated. Within the on-going FP7 RASOR project (Rapid Analysis and Spatialisation and Of Risk), the generated DEM are compared with Intermediate DEM derived from the TanDEM-X first global coverage. The results are presented and discussed.

  18. The influence of digital elevation model resolution on overland flow networks for modelling urban pluvial flooding.

    Science.gov (United States)

    Leitão, J P; Boonya-Aroonnet, S; Prodanović, D; Maksimović, C

    2009-01-01

    This paper presents the developments towards the next generation of overland flow modelling of urban pluvial flooding. Using a detailed analysis of the Digital Elevation Model (DEM) the developed GIS tools can automatically generate surface drainage networks which consist of temporary ponds (floodable areas) and flow paths and link them with the underground network through inlets. For different commercially-available Rainfall-Runoff simulation models, the tool will generate the overland flow network needed to model the surface runoff and pluvial flooding accurately. In this paper the emphasis is placed on a sensitivity analysis of ponds and preferential overland flow paths creation. Different DEMs for three areas were considered in order to compare the results obtained. The DEMs considered were generated using different acquisition techniques and hence represent terrain with varying levels of resolution and accuracy. The results show that DEMs can be used to generate surface flow networks reliably. As expected, the quality of the surface network generated is highly dependent on the quality and resolution of the DEMs and successful representation of buildings and streets.

  19. Contemporary ice-elevation changes on central Chilean glaciers using SRTM1 and high-resolution DEMs

    Science.gov (United States)

    Vivero, Sebastian; MacDonell, Shelley

    2016-04-01

    Glaciers located in central Chile have undergone significant retreat in recent decades. Whilst studies have evaluated area loss of several glaciers, there are no detailed studies of volume losses. This lack of information restricts not only estimations of current and future contributions to sea level rise, but also has limited the evaluation of freshwater resource availability in the region. Recently, the Chilean Water Directorate has supported the collection of field and remotely sensed data in the region which has enabled glacier changes to be evaluated in greater detail. This study aims to compare high-resolution laser scanning DEMs acquired by the Chilean Water Directorate in April 2015 with the recently released SRTM 1 arc-second DEM (˜30 m) acquired in February 2000 to calculate geodetic mass balance changes for three glaciers in a catchment in central Chile over a 15-year period. Detailed analysis of the SRTM and laser scanning DEMs, together with the glacier outlines enable the quantification of elevation and volume changes. Glacier outlines from February 2000 were obtained using the multispectral analysis of a Landsat TM image, whereas outlines from April 2015 were digitised from high resolution glacier orthophotomosaics. Additionally, we accounted for radar penetration into snow and/or ice by evaluating elevation differences between SRTM C-and X-bands, as well as mis-registration between SRTM DEM and the high-resolution DEMs. Over the period all glaciers show similar ice wastage in the order of 0.03 km3 for the debris-covered and non-covered glaciers. However, whilst on the non-covered glaciers mass loss is largely related to elevation and the addition of surface sediment, on the debris-covered glacier, losses are related to the development of thermokarst features. By analysing the DEM in conjunction with Landsat images, we have detected changes in the sediment cover of the non-covered glaciers, which is likely to change the behaviour of the surface mass

  20. Arc ASCII and GeoTiff DEMs of the North-Central California Coast (DEM_#_ASCII and DEM_#_GeoTIFF)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A seamless, 2 meter resolution digital elevation model (DEM) was constructed for the open-coast region of the San Francisco Bay Area (outside of the Golden Gate...

  1. Arc ASCII and GeoTiff DEMs of the North-Central California Coast (DEM_#_ASCII and DEM_#_GeoTIFF)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A seamless, 2 meter resolution digital elevation model (DEM) was constructed for the open-coast region of the San Francisco Bay Area (outside of the Golden Gate...

  2. Digital elevation modeling via curvature interpolation for LiDAR data

    Directory of Open Access Journals (Sweden)

    Hwamog Kim

    2016-03-01

    Full Text Available Digital elevation model (DEM is a three-dimensional (3D representation of a terrain's surface - for a planet (including Earth, moon, or asteroid - created from point cloud data which measure terrain elevation. Its modeling requires surface reconstruction for the scattered data, which is an ill-posed problem and most computational algorithms become overly expensive as the number of sample points increases. This article studies an effective partial differential equation (PDE-based algorithm, called the curvature interpolation method (CIM. The new method iteratively utilizes curvature information, estimated from an intermediate surface, to construct a reliable image surface that contains all of the data points. The CIM is applied for DEM for point cloud data acquired by light detection and ranging (LiDAR technology. It converges to a piecewise smooth image, requiring O(N operations independently of the number of sample points, where $N$ is the number of grid points.

  3. Modified method for extraction of watershed boundary with digital elevation modeling

    Institute of Scientific and Technical Information of China (English)

    WANGDian-zhong; HAOZhan-qing; XIONGZai-ping

    2004-01-01

    Boundary extraction of watershed is an important step in forest landscape research. The boundary of the upriver watershed of the Hunhe River in the sub-alpine Qingyuan County of eastern Liaoning Province, China was extracted by digital elevation modeling (DEM) data in Arclnfo8.1. Remote sensing image of the corresponding region was applied to help modify its copy according to Enhanced Thematic Mapper (ETM) image's profuse geomorphological structure information. Both the DEM-dependent boundary and modified copy were overlapped with county map and drainage network map to visually check the effects of result. Overlap of county map suggested a nice extraction of the boundary line since the two layers matched precisely,which indicated the DEM-dependent boundary by program was effective and precise. Further upload of drainage network showed discrepancies between the boundary and the drainage network. Altogether, there were three sections of the extraction result that needed to correct. Compared with this extraction boundary, the modified boundary had a better match to the drainage network as well as to the county map. Comprehensive analysis demonstrated that the program extraction has generally fine precision in position and excels the digitized result by hand. The errors of the DEM-dependant extraction are due to the fact that it is difficult for program to recognize sections of complex landform especially altered by human activities, but these errors are discernable and adjustable because the spatial resolution of ETM image is less than that of DEM. This study result proved that application of remote sensing information could help obtain better result when DEM method is used in extraction of watershed boundary.

  4. A high-fidelity multiresolution digital elevation model for Earth systems

    Science.gov (United States)

    Duan, Xinqiao; Li, Lin; Zhu, Haihong; Ying, Shen

    2017-01-01

    The impact of topography on Earth systems variability is well recognised. As numerical simulations evolved to incorporate broader scales and finer processes, accurately assimilating or transforming the topography to produce more exact land-atmosphere-ocean interactions, has proven to be quite challenging. Numerical schemes of Earth systems often use empirical parameterisation at sub-grid scale with downscaling to express topographic endogenous processes, or rely on insecure point interpolation to induce topographic forcing, which creates bias and input uncertainties. Digital elevation model (DEM) generalisation provides more sophisticated systematic topographic transformation, but existing methods are often difficult to be incorporated because of unwarranted grid quality. Meanwhile, approaches over discrete sets often employ heuristic approximation, which are generally not best performed. Based on DEM generalisation, this article proposes a high-fidelity multiresolution DEM with guaranteed grid quality for Earth systems. The generalised DEM surface is initially approximated as a triangulated irregular network (TIN) via selected feature points and possible input features. The TIN surface is then optimised through an energy-minimised centroidal Voronoi tessellation (CVT). By devising a robust discrete curvature as density function and exact geometry clipping as energy reference, the developed curvature CVT (cCVT) converges, the generalised surface evolves to a further approximation to the original DEM surface, and the points with the dual triangles become spatially equalised with the curvature distribution, exhibiting a quasi-uniform high-quality and adaptive variable resolution. The cCVT model was then evaluated on real lidar-derived DEM datasets and compared to the classical heuristic model. The experimental results show that the cCVT multiresolution model outperforms classical heuristic DEM generalisations in terms of both surface approximation precision and

  5. Comparison of Surface Flow Features from Lidar-Derived Digital Elevation Models with Historical Elevation and Hydrography Data for Minnehaha County, South Dakota

    Science.gov (United States)

    Poppenga, Sandra K.; Worstell, Bruce B.; Stoker, Jason M.; Greenlee, Susan K.

    2009-01-01

    The U.S. Geological Survey (USGS) has taken the lead in the creation of a valuable remote sensing product by incorporating digital elevation models (DEMs) derived from Light Detection and Ranging (lidar) into the National Elevation Dataset (NED), the elevation layer of 'The National Map'. High-resolution lidar-derived DEMs provide the accuracy needed to systematically quantify and fully integrate surface flow including flow direction, flow accumulation, sinks, slope, and a dense drainage network. In 2008, 1-meter resolution lidar data were acquired in Minnehaha County, South Dakota. The acquisition was a collaborative effort between Minnehaha County, the city of Sioux Falls, and the USGS Earth Resources Observation and Science (EROS) Center. With the newly acquired lidar data, USGS scientists generated high-resolution DEMs and surface flow features. This report compares lidar-derived surface flow features in Minnehaha County to 30- and 10-meter elevation data previously incorporated in the NED and ancillary hydrography datasets. Surface flow features generated from lidar-derived DEMs are consistently integrated with elevation and are important in understanding surface-water movement to better detect surface-water runoff, flood inundation, and erosion. Many topographic and hydrologic applications will benefit from the increased availability of accurate, high-quality, and high-resolution surface-water data. The remotely sensed data provide topographic information and data integration capabilities needed for meeting current and future human and environmental needs.

  6. Statistical correction of lidar-derived digital elevation models with multispectral airborne imagery in tidal marshes

    Science.gov (United States)

    Buffington, Kevin J.; Dugger, Bruce D.; Thorne, Karen M.; Takekawa, John

    2016-01-01

    Airborne light detection and ranging (lidar) is a valuable tool for collecting large amounts of elevation data across large areas; however, the limited ability to penetrate dense vegetation with lidar hinders its usefulness for measuring tidal marsh platforms. Methods to correct lidar elevation data are available, but a reliable method that requires limited field work and maintains spatial resolution is lacking. We present a novel method, the Lidar Elevation Adjustment with NDVI (LEAN), to correct lidar digital elevation models (DEMs) with vegetation indices from readily available multispectral airborne imagery (NAIP) and RTK-GPS surveys. Using 17 study sites along the Pacific coast of the U.S., we achieved an average root mean squared error (RMSE) of 0.072 m, with a 40–75% improvement in accuracy from the lidar bare earth DEM. Results from our method compared favorably with results from three other methods (minimum-bin gridding, mean error correction, and vegetation correction factors), and a power analysis applying our extensive RTK-GPS dataset showed that on average 118 points were necessary to calibrate a site-specific correction model for tidal marshes along the Pacific coast. By using available imagery and with minimal field surveys, we showed that lidar-derived DEMs can be adjusted for greater accuracy while maintaining high (1 m) resolution.

  7. The effects of digital elevation model resolution on the calculation and predictions of topographic wetness indices.

    Energy Technology Data Exchange (ETDEWEB)

    Drover, Damion, Ryan

    2011-12-01

    One of the largest exports in the Southeast U.S. is forest products. Interest in biofuels using forest biomass has increased recently, leading to more research into better forest management BMPs. The USDA Forest Service, along with the Oak Ridge National Laboratory, University of Georgia and Oregon State University are researching the impacts of intensive forest management for biofuels on water quality and quantity at the Savannah River Site in South Carolina. Surface runoff of saturated areas, transporting excess nutrients and contaminants, is a potential water quality issue under investigation. Detailed maps of variable source areas and soil characteristics would therefore be helpful prior to treatment. The availability of remotely sensed and computed digital elevation models (DEMs) and spatial analysis tools make it easy to calculate terrain attributes. These terrain attributes can be used in models to predict saturated areas or other attributes in the landscape. With laser altimetry, an area can be flown to produce very high resolution data, and the resulting data can be resampled into any resolution of DEM desired. Additionally, there exist many maps that are in various resolutions of DEM, such as those acquired from the U.S. Geological Survey. Problems arise when using maps derived from different resolution DEMs. For example, saturated areas can be under or overestimated depending on the resolution used. The purpose of this study was to examine the effects of DEM resolution on the calculation of topographic wetness indices used to predict variable source areas of saturation, and to find the best resolutions to produce prediction maps of soil attributes like nitrogen, carbon, bulk density and soil texture for low-relief, humid-temperate forested hillslopes. Topographic wetness indices were calculated based on the derived terrain attributes, slope and specific catchment area, from five different DEM resolutions. The DEMs were resampled from LiDAR, which is a

  8. Vermont "Hydrologically Corrected" Digital Elevation Model (VTHYDRODEM)

    Data.gov (United States)

    Vermont Center for Geographic Information — VTHYDRODEM was created to produce a "hydrologically correct" DEM, compliant with the Vermont Hydrography Dataset (VHD) in support of the "flow regime" project whose...

  9. A Case Study of Using External DEM in InSAR DEM Generation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chunxia; GE Linlin; E Dongchen; CHANG Hsingchung

    2005-01-01

    Synthetic aperture radar interferometry (InSAR) has been used as an innovative technique for digital elevation model (DEM) and topographic map generation. In this paper, external DEMs are used for InSAR DEM generation to reduce the errors in data processing. The DEMs generated from repeat-pass InSAR are compared. For steep slopes and severe changes in topography, phase unwrapping quality can be improved by subtracting the phase calculated from an external DEM. It is affirmative that the absolute height accuracy of the InSAR DEM is improved by using external DEM. The data processing was undertaken without the use of ground control points and other manual operation.

  10. VT Lidar DEM (3.2 meter) - 2004 - Chittenden

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Chittenden County 2004 3.2m and Digital Elevation Model (DEM) datasets of various...

  11. VT Lidar Hydro-flattened DEM (2 meter) - 2012 - Bennington

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Bennington County 2012 2.0m and Digital Elevation Model (DEM) datasets of various...

  12. Klasifikasi Bentuk Wilayah yang Diturunkan dari Digital Elevation Models: Kasus DAS Citarum, Sub DAS Cilalawi, Jawa Barat

    Directory of Open Access Journals (Sweden)

    Salwati

    2008-05-01

    Full Text Available Application of GIS technology (Geographic Information System, that is Digital Elevation Models (DEMs for the analysis of landform or slope have been conducted in the Citarum watershed, Purwakarta West Java Province from August until November 2003. Research aim to make landform classification of DEMs use classification of ISODATA and to evaluate the quality of landform classification which alighted from DEMs. To reach the target have been made DEMs, is later then degraded to become map set of regional form. DEMS made from contour map scale 1 : 25.000 with inteval of 12.5 m use Arcview version 2.65 with resolution of 25 m, and slope classification made software of ER Mapper. Field observation conducted for validation result of classification. Result of research indicate that wave landform (slope 8-15% and hilly (slope 15-30% in sub watershed of Cilalawi is DEMs have lower level class of fact in the field. While set of regional form level of (slope 30% in sub of DAS Cilalawi have bevel class which almost is equal to fact in the field. Result of the research indicated that map of landform or alighted from slope is DEMs not entirely as according to situation in fact of the field. Interconnected the mentioned sliver with quality map of used contour. Thereby verification in field is absolutely needed.

  13. EFFECT OF DIGITAL ELEVATION MODEL RESOLUTION ON EMPIRICAL ESTIMATION OF SOIL LOSS AND SEDIMENT TRANSPORT WITH GIS

    Institute of Scientific and Technical Information of China (English)

    Simon WU; Jonathan LI; Gordon HUANG; G.M.ZENG

    2004-01-01

    The horizontal accuracy of topographic data represented by digital elevation model (DEM) resolution brings about uncertainties in landscape process modeling with raster GIS. This paper presents a study on the effect of topographic variability on cell-based empirical estimation of soil loss and sediment transport. An original DEM of 10m resolution for a case watershed was re-sampled to three realizations of higher grid sizes for a comparative examination. Equations based on the USLE are applied to the watershed to calculate soil loss from each cell and total sediment transport to streams. The study found that the calculated total soil loss from the watershed decreases with the increasing DEM resolution with a linear correlation as spatial variability is reduced by cell aggregation. The USLE topographic factors (LS) extracted from applied DEMs represent spatial variability, and determine the estimations as shown in the modeling results. The commonly used USGS 30m DEM appears to be able to reflect essential spatial variability and suitable for the empirical estimation. The appropriateness of a DEM resolution is dependent upon specific landscape characteristics, applied model and its parameterization. This work attempts to provide a general framework for the research in the DEM-based empirical modeling.

  14. Evaluation of lidar-derived DEMs through terrain analysis and field comparison

    Science.gov (United States)

    Cody P. Gillin; Scott W. Bailey; Kevin J. McGuire; Stephen P. Prisley

    2015-01-01

    Topographic analysis of watershed-scale soil and hydrological processes using digital elevation models (DEMs) is commonplace, but most studies have used DEMs of 10 m resolution or coarser. Availability of higher-resolution DEMs created from light detection and ranging (lidar) data is increasing but their suitability for such applications has received little critical...

  15. Input Data Boundary Outlines for DEMs of the North-Central California Coast (DEM_source_data.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A GIS polygon shapefile outlining the boundaries of the native input datasets used to construct a seamless, 2-meter resolution digital elevation model (DEM) was...

  16. A new seamless, high-resolution digital elevation model of the San Francisco Bay-Delta Estuary, California

    Science.gov (United States)

    Fregoso, Theresa; Wang, Rueen-Fang; Ateljevich, Eli; Jaffe, Bruce E.

    2017-06-14

    Climate change, sea-level rise, and human development have contributed to the changing geomorphology of the San Francisco Bay - Delta (Bay-Delta) Estuary system. The need to predict scenarios of change led to the development of a new seamless, high-resolution digital elevation model (DEM) of the Bay – Delta that can be used by modelers attempting to understand potential future changes to the estuary system. This report details the three phases of the creation of this DEM. The first phase took a bathymetric-only DEM created in 2005 by the U.S. Geological Survey (USGS), refined it with additional data, and identified areas that would benefit from new surveys. The second phase began a USGS collaboration with the California Department of Water Resources (DWR) that updated a 2012 DWR seamless bathymetric/topographic DEM of the Bay-Delta with input from the USGS and modifications to fit the specific needs of USGS modelers. The third phase took the work from phase 2 and expanded the coverage area in the north to include the Yolo Bypass up to the Fremont Weir, the Sacramento River up to Knights Landing, and the American River up to the Nimbus Dam, and added back in the elevations for interior islands. The constant evolution of the Bay-Delta will require continuous updates to the DEM of the Delta, and there still are areas with older data that would benefit from modern surveys. As a result, DWR plans to continue updating the DEM.

  17. Using Selective Drainage Methods to Extract Continuous Surface Flow from 1-Meter Lidar-Derived Digital Elevation Data

    Science.gov (United States)

    Poppenga, Sandra K.; Worstell, Bruce B.; Stoker, Jason M.; Greenlee, Susan K.

    2010-01-01

    Digital elevation data commonly are used to extract surface flow features. One source for high-resolution elevation data is light detection and ranging (lidar). Lidar can capture a vast amount of topographic detail because of its fine-scale ability to digitally capture the surface of the earth. Because elevation is a key factor in extracting surface flow features, high-resolution lidar-derived digital elevation models (DEMs) provide the detail needed to consistently integrate hydrography with elevation, land cover, structures, and other geospatial features. The U.S. Geological Survey has developed selective drainage methods to extract continuous surface flow from high-resolution lidar-derived digital elevation data. The lidar-derived continuous surface flow network contains valuable information for water resource management involving flood hazard mapping, flood inundation, and coastal erosion. DEMs used in hydrologic applications typically are processed to remove depressions by filling them. High-resolution DEMs derived from lidar can capture much more detail of the land surface than courser elevation data. Therefore, high-resolution DEMs contain more depressions because of obstructions such as roads, railroads, and other elevated structures. The filling of these depressions can significantly affect the DEM-derived surface flow routing and terrain characteristics in an adverse way. In this report, selective draining methods that modify the elevation surface to drain a depression through an obstruction are presented. If such obstructions are not removed from the elevation data, the filling of depressions to create continuous surface flow can cause the flow to spill over an obstruction in the wrong location. Using this modified elevation surface improves the quality of derived surface flow and retains more of the true surface characteristics by correcting large filled depressions. A reliable flow surface is necessary for deriving a consistently connected drainage

  18. The Sensitivity of a Volcanic Flow Model to Digital Elevation Models From Diverse Sources: Digitized Map Contours and Airborne Interferometric Radar

    Science.gov (United States)

    Stevens, N. F.; Manville, V.; Heron, D. W.

    2001-12-01

    A growing trend in the field of volcanic hazard assessment is the use of computer models of a variety of flows to predict potential areas of devastation. The accuracy of these computer models depends on two factors, the nature and veracity of the flow model itself, and the accuracy of the topographic data set over which it is run. All digital elevation models (DEMs) contain innate errors. The nature of these depends on the accuracy of the original measurements of the terrain, and on the method used to build the DEM. We investigate the effect that these errors have on the performance of a simple volcanic flow model designed to delineate areas at risk from lahar inundation. The volcanic flow model was run over two DEMs of southern Ruapehu volcano derived from (1) digitized 1:50,000 topographic maps, and (2) airborne C-band synthetic aperture radar interferometry obtained using the NASA AIRSAR system. On steep slopes (exceeding 4 degrees), drainage channels are more likely to be incised deeply, and flow paths predicted by the model are generally in agreement for both DEMs despite the differing nature of the source data. Over shallow slopes (approx. 4 degrees and less), where channels are less deep and are more likely to meander, problems were encountered with flow path prediction in both DEMs due to interpolation errors and forestry. The predicted lateral and longitudinal extent of deposit inundation was also sensitive to the type of DEM used, most likely in response to the differing degrees of surface texture preserved in the DEMs. A technique to refine contour-derived DEMs and reduce the error in predicted flow paths was tested to improve the reliability of the modeled flow path predictions. The suitability of forthcoming topographic measurements acquired by a single-pass space-borne instrument, the NASA Shuttle Radar Topography Mission (SRTM) are also tested.

  19. ICESat Lidar and Global Digital Elevation Models: Application to DESDynI

    Science.gov (United States)

    Carabajal, Claudia C.; Harding, David J.; Suchdeo, Vijay P.

    2010-01-01

    Geodetic control is extremely important in the production and quality control of topographic data sets, enabling elevation results to be referenced to an absolute vertical datum. Global topographic data with improved geodetic accuracy achieved using global Ground Control Point (GCP) databases enable more accurate characterization of land topography and its change related to solid Earth processes, natural hazards and climate change. The multiple-beam lidar instrument that will be part of the NASA Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) mission will provide a comprehensive, global data set that can be used for geodetic control purposes. Here we illustrate that potential using data acquired by NASA's Ice, Cloud and land Elevation Satellite (ICEsat) that has acquired single-beam, globally distributed laser altimeter profiles (+/-86deg) since February of 2003 [1, 2]. The profiles provide a consistently referenced elevation data set with unprecedented accuracy and quantified measurement errors that can be used to generate GCPs with sub-decimeter vertical accuracy and better than 10 m horizontal accuracy. Like the planned capability for DESDynI, ICESat records a waveform that is the elevation distribution of energy reflected within the laser footprint from vegetation, where present, and the ground where illuminated through gaps in any vegetation cover [3]. The waveform enables assessment of Digital Elevation Models (DEMs) with respect to the highest, centroid, and lowest elevations observed by ICESat and in some cases with respect to the ground identified beneath vegetation cover. Using the ICESat altimetry data we are developing a comprehensive database of consistent, global, geodetic ground control that will enhance the quality of a variety of regional to global DEMs. Here we illustrate the accuracy assessment of the Shuttle Radar Topography Mission (SRTM) DEM produced for Australia, documenting spatially varying elevation biases of several meters

  20. ALGORITHM FOR GENERATING DEM BASED ON CONE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Digital elevation model (DEM) has a variety of applications in GIS and CAD.It is the basic model for generating three-dimensional terrain feature.Generally speaking,there are two methods for building DEM.One is based upon the digital terrain model of discrete points,and is characterized by fast speed and low precision.The other is based upon triangular digital terrain model,and slow speed and high precision are the features of the method.Combining the advantages of the two methods,an algorithm for generating DEM with discrete points is presented in this paper.When interpolating elevation,this method can create a triangle which includes interpolating point and the elevation of the interpolating point can be obtained from the triangle.The method has the advantage of fast speed,high precision and less memory.

  1. Investigation of potential sea level rise impact on the Nile Delta, Egypt using digital elevation models.

    Science.gov (United States)

    Hasan, Emad; Khan, Sadiq Ibrahim; Hong, Yang

    2015-10-01

    In this study, the future impact of Sea Level Rise (SLR) on the Nile Delta region in Egypt is assessed by evaluating the elevations of two freely available Digital Elevation Models (DEMs): the SRTM and the ASTER-GDEM-V2. The SLR is a significant worldwide dilemma that has been triggered by recent climatic changes. In Egypt, the Nile Delta is projected to face SLR of 1 m by the end of the 21th century. In order to provide a more accurate assessment of the future SLR impact on Nile Delta's land and population, this study corrected the DEM's elevations by using linear regression model with ground elevations from GPS survey. The information for the land cover types and future population numbers were derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover and the Gridded Population of the Worlds (GPWv3) datasets respectively. The DEM's vertical accuracies were assessed using GPS measurements and the uncertainty analysis revealed that the SRTM-DEM has positive bias of 2.5 m, while the ASTER-GDEM-V2 showed a positive bias of 0.8 m. The future inundated land cover areas and the affected population were illustrated based on two SLR scenarios of 0.5 m and 1 m. The SRTM DEM data indicated that 1 m SLR will affect about 3900 km(2) of cropland, 1280 km(2) of vegetation, 205 km(2) of wetland, 146 km(2) of urban areas and cause more than 6 million people to lose their houses. The overall vulnerability assessment using ASTER-GDEM-V2 indicated that the influence of SLR will be intense and confined along the coastal areas. For instance, the data indicated that 1 m SLR will inundate about 580 Km(2) (6%) of the total land cover areas and approximately 887 thousand people will be relocated. Accordingly, the uncertainty analysis of the DEM's elevations revealed that the ASTER-GDEM-V2 dataset product was considered the best to determine the future impact of SLR on the Nile Delta region.

  2. Interpolation Routines Assessment in ALS-Derived Digital Elevation Models for Forestry Applications

    Directory of Open Access Journals (Sweden)

    Antonio Luis Montealegre

    2015-07-01

    Full Text Available Airborne Laser Scanning (ALS is capable of estimating a variety of forest parameters using different metrics extracted from the normalized heights of the point cloud using a Digital Elevation Model (DEM. In this study, six interpolation routines were tested over a range of land cover and terrain roughness in order to generate a collection of DEMs with spatial resolution of 1 and 2 m. The accuracy of the DEMs was assessed twice, first using a test sample extracted from the ALS point cloud, second using a set of 55 ground control points collected with a high precision Global Positioning System (GPS. The effects of terrain slope, land cover, ground point density and pulse penetration on the interpolation error were examined stratifying the study area with these variables. In addition, a Classification and Regression Tree (CART analysis allowed the development of a prediction uncertainty map to identify in which areas DEMs and Airborne Light Detection and Ranging (LiDAR derived products may be of low quality. The Triangulated Irregular Network (TIN to raster interpolation method produced the best result in the validation process with the training data set while the Inverse Distance Weighted (IDW routine was the best in the validation with GPS (RMSE of 2.68 cm and RMSE of 37.10 cm, respectively.

  3. Hydrologic analysis of a flood based on a new Digital Elevation Model

    Science.gov (United States)

    Nishio, M.; Mori, M.

    2015-06-01

    These The present study aims to simulate the hydrologic processes of a flood, based on a new, highly accurate Digital Elevation Model (DEM). The DEM is provided by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) of Japan, and has a spatial resolution of five meters. It was generated by the new National Project in 2012. The Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) is used to simulate the hydrologic process of a flood of the Onga River in Iizuka City, Japan. A large flood event in the typhoon season in 2003 caused serious damage around the Iizuka City area. Precise records of rainfall data from the Automated Meteorological Data Acquisition System (AMeDAS) were input into the HEC-HMS. The estimated flood area of the simulation results by HEC-HMS was identical to the observed flood area. A watershed aggregation map is also generated by HEC-HMS around the Onga River.

  4. A digital elevation model of the Greenland ice sheet and validation with airborne laser altimeter data

    Science.gov (United States)

    Bamber, Jonathan L.; Ekholm, Simon; Krabill, William B.

    1997-01-01

    A 2.5 km resolution digital elevation model (DEM) of the Greenland ice sheet was produced from the 336 days of the geodetic phase of ERS-1. During this period the altimeter was operating in ice-mode over land surfaces providing improved tracking around the margins of the ice sheet. Combined with the high density of tracks during the geodetic phase, a unique data set was available for deriving a DEM of the whole ice sheet. The errors present in the altimeter data were investigated via a comparison with airborne laser altimeter data obtained for the southern half of Greenland. Comparison with coincident satellite data showed a correlation with surface slope. An explanation for the behavior of the bias as a function of surface slope is given in terms of the pattern of surface roughness on the ice sheet.

  5. Development of an Integrated Digital Elevation Model for Safe Takeoff and Landing of the Aircraft

    Science.gov (United States)

    Ciećko, Adam; Jarmołowski, Wojciech

    2013-12-01

    The article describes preliminary results of the augmentation of Global Navigation Satellite System/Inertial Navigation System positioning (GNSS/INS) by Digital Elevation Model (DEM) based on the data from the Shuttle Radar Topography Mission (SRTM) and data from field survey. The prototype software is developed to refer the position of the aircraft to DEM and informs the user about the current relevant flight parameters. The number of the parameters may be arbitrarily increased, however, currently we investigate the altitude above the terrain and the aircraft position relative to the descent path and airfield. The study provides some information on the local SRTM accuracy in relation to the field survey of the airfield "Dajtki" - Aeroclub of Warmia and Mazury in Olsztyn.

  6. First Bistatic Spaceborne SAR Experiments with TanDEM-X

    OpenAIRE

    Rodriguez-Cassola, Marc; Prats, Pau; Schulze, Daniel; Tous-Ramon, Nuria; Steinbrecher, Ulrich; Marotti, Luca; Nanninni, Matteo; Younis, Marwan; Lopez-Dekker, Paco; Zink, Manfred; Reigber, Andreas; Krieger, Gerhard; Moreira, Alberto

    2011-01-01

    TanDEM-X is a high-resolution interferometric mission with the main goal of providing a global and unprecedentedly accurate digital elevation model (DEM) of the Earth surface by means of single-pass X-band SAR interferometry. Despite its usual quasi-monostatic configuration, TanDEM-X is the first genuinely bistatic SAR system in space. During its monostatic commissioning phase, the system has been mainly operated in pursuit monostatic mode. However, some pioneering bistat...

  7. Finding the service you need: human centered design of a Digital Interactive Social Chart in DEMentia care (DEM-DISC).

    Science.gov (United States)

    van der Roest, H G; Meiland, F J M; Haaker, T; Reitsma, E; Wils, H; Jonker, C; Dröes, R M

    2008-01-01

    Community dwelling people with dementia and their informal carers experience a lot of problems. In the course of the disease process people with dementia become more dependent on others and professional help is often necessary. Many informal carers and people with dementia experience unmet needs with regard to information on the disease and on the available care and welfare offer, therefore they tend not to utilize the broad spectrum of available care and welfare services. This can have very negative consequences like unsafe situations, social isolation of the person with dementia and overburden of informal carers with consequent increased risk of illness for them. The development of a DEMentia specific Digital Interactive Social Chart (DEM-DISC) may counteract these problems. DEM-DISC is a demand oriented website for people with dementia and their carers, which is easy, accessible and provides users with customized information on healthcare and welfare services. DEM-DISC is developed according to the human centered design principles, this means that people with dementia, informal carers and healthcare professionals were involved throughout the development process. This paper describes the development of DEM-DISC from four perspectives, a domain specific content perspective, an ICT perspective, a user perspective and an organizational perspective. The aims and most important results from each perspective will be discussed. It is concluded that the human centered design was a valuable method for the development of the DEM-DISC.

  8. Digital Elevation Models of Greenland based on combined radar and laser altimetry as well as high-resolution stereoscopic imagery

    Science.gov (United States)

    Levinsen, J. F.; Smith, B. E.; Sandberg Sorensen, L.; Khvorostovsky, K.; Simonsen, S. B.; Forsberg, R.

    2015-12-01

    A number of Digital Elevation Models (DEMs) of Greenland exist, each of which are applicable for different purposes. This study presents two such DEMs: One developed by merging contemporary radar and laser altimeter data, and one derived from high-resolution stereoscopic imagery. All products are made freely available. The former DEM covers the entire Greenland. It is specific to the year 2010, providing it with an advantage over previous models suffering from either a reduced spatial/ temporal data coverage or errors from surface elevation changes (SEC) occurring during data acquisition. Radar data are acquired with Envisat and CryoSat-2, and laser data with the Ice, Cloud, and land Elevation Satellite, the Land, Vegetation, and Ice Sensor, and the Airborne Topographic Mapper. Correcting radar data for errors from slope effects and surface penetration of the echoes, and merging these with laser data, yields a DEM capable of resolving both surface depressions as well as topographic features at higher altitudes. The spatial resolution is 2 x 2 km, making the DEM ideal for application in surface mass balance studies, SEC detection from radar altimetry, or for correcting such data for slope-induced errors. The other DEM is developed in a pilot study building the expertise to map all ice-free parts of Greenland. The work combines WorldView-2 and -3 as well as GeoEye1 imagery from 2014 and 2015 over the Disko, Narsaq, Tassilaq, and Zackenberg regions. The novelty of the work is the determination of the product specifications after elaborate discussions with interested parties from government institutions, the tourist industry, etc. Thus, a 10 m DEM, 1.5 m orthophotos, and vector maps are produced. This opens to the possibility of using orthophotos with up-to-date contour lines or for deriving updated coastlines to aid, e.g., emergency management. This allows for a product development directly in line with the needs of parties with specific interests in Greenland.

  9. Bathymetric survey and digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California

    Science.gov (United States)

    Snyder, Alexander G.; Lacy, Jessica R.; Stevens, Andrew W.; Carlson, Emily M.

    2016-06-10

    The U.S. Geological Survey conducted a bathymetric survey in Little Holland Tract, a flooded agricultural tract, in the northern Sacramento-San Joaquin Delta (the “Delta”) during the summer of 2015. The new bathymetric data were combined with existing data to generate a digital elevation model (DEM) at 1-meter resolution. Little Holland Tract (LHT) was historically diked off for agricultural uses and has been tidally inundated since an accidental levee breach in 1983. Shallow tidal regions such as LHT have the potential to improve habitat quality in the Delta. The DEM of LHT was developed to support ongoing studies of habitat quality in the area and to provide a baseline for evaluating future geomorphic change. The new data comprise 138,407 linear meters of real-time-kinematic (RTK) Global Positioning System (GPS) elevation data, including both bathymetric data collected from personal watercraft and topographic elevations collected on foot at low tide. A benchmark (LHT15_b1) was established for geodetic control of the survey. Data quality was evaluated both by comparing results among surveying platforms, which showed systematic offsets of 1.6 centimeters (cm) or less, and by error propagation, which yielded a mean vertical uncertainty of 6.7 cm. Based on the DEM and time-series measurements of water depth, the mean tidal prism of LHT was determined to be 2,826,000 cubic meters. The bathymetric data and DEM are available at http://dx.doi.org/10.5066/F7RX9954. 

  10. Development of an Antarctic digital elevation model by integrating cartographic and remotely sensed data: A geographic information system based approach

    Science.gov (United States)

    Liu, Hongxing; Jezek, Kenneth C.; Li, Biyan

    1999-10-01

    We present a high-resolution digital elevation model (DEM) of the Antarctic. It was created in a geographic information system (GIS) environment by integrating the best available topographic data from a variety of sources. Extensive GIS-based error detection and correction operations ensured that our DEM is free of gross errors. The carefully designed interpolation algorithms for different types of source data and incorporation of surface morphologic information preserved and enhanced the fine surface structures present in the source data. The effective control of adverse edge effects and the use of the Hermite blending weight function in data merging minimized the discontinuities between different types of data, leading to a seamless and topographically consistent DEM throughout the Antarctic. This new DEM provides exceptional topographical details and represents a substantial improvement in horizontal resolution and vertical accuracy over the earlier, continental-scale renditions, particularly in mountainous and coastal regions. It has a horizontal resolution of 200 m over the rugged mountains, 400 m in the coastal regions, and approximately 5 km in the interior. The vertical accuracy of the DEM is estimated at about 100-130 m over the rugged mountainous area, better than 2 m for the ice shelves, better than 15 m for the interior ice sheet, and about 35 m for the steeper ice sheet perimeter. The Antarctic DEM can be obtained from the authors.

  11. Building a 2.5D Digital Elevation Model from 2D Imagery

    Science.gov (United States)

    Padgett, Curtis W.; Ansar, Adnan I.; Brennan, Shane; Cheng, Yang; Clouse, Daniel S.; Almeida, Eduardo

    2013-01-01

    When projecting imagery into a georeferenced coordinate frame, one needs to have some model of the geographical region that is being projected to. This model can sometimes be a simple geometrical curve, such as an ellipse or even a plane. However, to obtain accurate projections, one needs to have a more sophisticated model that encodes the undulations in the terrain including things like mountains, valleys, and even manmade structures. The product that is often used for this purpose is a Digital Elevation Model (DEM). The technology presented here generates a high-quality DEM from a collection of 2D images taken from multiple viewpoints, plus pose data for each of the images and a camera model for the sensor. The technology assumes that the images are all of the same region of the environment. The pose data for each image is used as an initial estimate of the geometric relationship between the images, but the pose data is often noisy and not of sufficient quality to build a high-quality DEM. Therefore, the source imagery is passed through a feature-tracking algorithm and multi-plane-homography algorithm, which refine the geometric transforms between images. The images and their refined poses are then passed to a stereo algorithm, which generates dense 3D data for each image in the sequence. The 3D data from each image is then placed into a consistent coordinate frame and passed to a routine that divides the coordinate frame into a number of cells. The 3D points that fall into each cell are collected, and basic statistics are applied to determine the elevation of that cell. The result of this step is a DEM that is in an arbitrary coordinate frame. This DEM is then filtered and smoothed in order to remove small artifacts. The final step in the algorithm is to take the initial DEM and rotate and translate it to be in the world coordinate frame [such as UTM (Universal Transverse Mercator), MGRS (Military Grid Reference System), or geodetic] such that it can be saved in

  12. ASTER DEM performance

    Science.gov (United States)

    Fujisada, H.; Bailey, G.B.; Kelly, Glen G.; Hara, S.; Abrams, M.J.

    2005-01-01

    The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument onboard the National Aeronautics and Space Administration's Terra spacecraft has an along-track stereoscopic capability using its a near-infrared spectral band to acquire the stereo data. ASTER has two telescopes, one for nadir-viewing and another for backward-viewing, with a base-to-height ratio of 0.6. The spatial resolution is 15 m in the horizontal plane. Parameters such as the line-of-sight vectors and the pointing axis were adjusted during the initial operation period to generate Level-1 data products with a high-quality stereo system performance. The evaluation of the digital elevation model (DEM) data was carried out both by Japanese and U.S. science teams separately using different DEM generation software and reference databases. The vertical accuracy of the DEM data generated from the Level-1A data is 20 m with 95% confidence without ground control point (GCP) correction for individual scenes. Geolocation accuracy that is important for the DEM datasets is better than 50 m. This appears to be limited by the spacecraft position accuracy. In addition, a slight increase in accuracy is observed by using GCPs to generate the stereo data. ?? 2005 IEEE.

  13. A robust interpolation method for constructing digital elevation models from remote sensing data

    Science.gov (United States)

    Chen, Chuanfa; Liu, Fengying; Li, Yanyan; Yan, Changqing; Liu, Guolin

    2016-09-01

    A digital elevation model (DEM) derived from remote sensing data often suffers from outliers due to various reasons such as the physical limitation of sensors and low contrast of terrain textures. In order to reduce the effect of outliers on DEM construction, a robust algorithm of multiquadric (MQ) methodology based on M-estimators (MQ-M) was proposed. MQ-M adopts an adaptive weight function with three-parts. The weight function is null for large errors, one for small errors and quadric for others. A mathematical surface was employed to comparatively analyze the robustness of MQ-M, and its performance was compared with those of the classical MQ and a recently developed robust MQ method based on least absolute deviation (MQ-L). Numerical tests show that MQ-M is comparative to the classical MQ and superior to MQ-L when sample points follow normal and Laplace distributions, and under the presence of outliers the former is more accurate than the latter. A real-world example of DEM construction using stereo images indicates that compared with the classical interpolation methods, such as natural neighbor (NN), ordinary kriging (OK), ANUDEM, MQ-L and MQ, MQ-M has a better ability of preserving subtle terrain features. MQ-M replaces thin plate spline for reference DEM construction to assess the contribution to our recently developed multiresolution hierarchical classification method (MHC). Classifying the 15 groups of benchmark datasets provided by the ISPRS Commission demonstrates that MQ-M-based MHC is more accurate than MQ-L-based and TPS-based MHCs. MQ-M has high potential for DEM construction.

  14. Assessment of multiresolution segmentation for delimiting drumlins in digital elevation models.

    Science.gov (United States)

    Eisank, Clemens; Smith, Mike; Hillier, John

    2014-06-01

    Mapping or "delimiting" landforms is one of geomorphology's primary tools. Computer-based techniques such as land-surface segmentation allow the emulation of the process of manual landform delineation. Land-surface segmentation exhaustively subdivides a digital elevation model (DEM) into morphometrically-homogeneous irregularly-shaped regions, called terrain segments. Terrain segments can be created from various land-surface parameters (LSP) at multiple scales, and may therefore potentially correspond to the spatial extents of landforms such as drumlins. However, this depends on the segmentation algorithm, the parameterization, and the LSPs. In the present study we assess the widely used multiresolution segmentation (MRS) algorithm for its potential in providing terrain segments which delimit drumlins. Supervised testing was based on five 5-m DEMs that represented a set of 173 synthetic drumlins at random but representative positions in the same landscape. Five LSPs were tested, and four variants were computed for each LSP to assess the impact of median filtering of DEMs, and logarithmic transformation of LSPs. The testing scheme (1) employs MRS to partition each LSP exhaustively into 200 coarser scales of terrain segments by increasing the scale parameter (SP), (2) identifies the spatially best matching terrain segment for each reference drumlin, and (3) computes four segmentation accuracy metrics for quantifying the overall spatial match between drumlin segments and reference drumlins. Results of 100 tests showed that MRS tends to perform best on LSPs that are regionally derived from filtered DEMs, and then log-transformed. MRS delineated 97% of the detected drumlins at SP values between 1 and 50. Drumlin delimitation rates with values up to 50% are in line with the success of manual interpretations. Synthetic DEMs are well-suited for assessing landform quantification methods such as MRS, since subjectivity in the reference data is avoided which increases the

  15. Automated identification of stream-channel geomorphic features from high‑resolution digital elevation models in West Tennessee watersheds

    Science.gov (United States)

    Cartwright, Jennifer M.; Diehl, Timothy H.

    2017-01-17

    High-resolution digital elevation models (DEMs) derived from light detection and ranging (lidar) enable investigations of stream-channel geomorphology with much greater precision than previously possible. The U.S. Geological Survey has developed the DEM Geomorphology Toolbox, containing seven tools to automate the identification of sites of geomorphic instability that may represent sediment sources and sinks in stream-channel networks. These tools can be used to modify input DEMs on the basis of known locations of stormwater infrastructure, derive flow networks at user-specified resolutions, and identify possible sites of geomorphic instability including steep banks, abrupt changes in channel slope, or areas of rough terrain. Field verification of tool outputs identified several tool limitations but also demonstrated their overall usefulness in highlighting likely sediment sources and sinks within channel networks. In particular, spatial clusters of outputs from multiple tools can be used to prioritize field efforts to assess and restore eroding stream reaches.

  16. An evaluation of onshore digital elevation models for tsunami inundation modelling

    Science.gov (United States)

    Griffin, J.; Latief, H.; Kongko, W.; Harig, S.; Horspool, N.; Hanung, R.; Rojali, A.; Maher, N.; Fountain, L.; Fuchs, A.; Hossen, J.; Upi, S.; Dewanto, S. E.; Cummins, P. R.

    2012-12-01

    Tsunami inundation models provide fundamental information about coastal areas that may be inundated in the event of a tsunami along with additional parameters such as flow depth and velocity. This can inform disaster management activities including evacuation planning, impact and risk assessment and coastal engineering. A fundamental input to tsunami inundation models is adigital elevation model (DEM). Onshore DEMs vary widely in resolution, accuracy, availability and cost. A proper assessment of how the accuracy and resolution of DEMs translates into uncertainties in modelled inundation is needed to ensure results are appropriately interpreted and used. This assessment can in turn informdata acquisition strategies depending on the purpose of the inundation model. For example, lower accuracy elevation data may give inundation results that are sufficiently accurate to plan a community's evacuation route but not sufficient to inform engineering of a vertical evacuation shelters. A sensitivity study is undertaken to assess the utility of different available onshore digital elevation models for tsunami inundation modelling. We compare airborne interferometric synthetic aperture radar (IFSAR), ASTER and SRTM against high resolution (historical tsunami run-up data. Large vertical errors (> 10 m) and poor resolution of the coastline in the ASTER and SRTM elevation models cause modelled inundation to be much less compared with models using better data and with observations. Therefore we recommend that ASTER and SRTM should not be used for modelling tsunami inundation in order to determine tsunami extent or any other measure of onshore tsunami hazard. We suggest that for certain disaster management applications where the important factor is the extent of inundation, such as evacuation planning, airborne IFSAR provides a good compromise between cost and accuracy; however the representation of flow parameters such as depth and velocity is not sufficient to inform detailed

  17. Sensitivity of digital elevation models:The scenario from two tropical mountain river basins of the Western Ghats, India

    Institute of Scientific and Technical Information of China (English)

    Jobin Thomas; Sabu Joseph; K.P. Thrivikramji; K.S. Arunkumar

    2014-01-01

    The paper evaluates sensitivity of various spaceborne digital elevation models (DEMs), viz., Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mapping Mission (SRTM) and Global Multi-resolution Terrain Elevation Data 2010 (GMTED), in comparison with the DEM (TOPO) derived from contour data of 20 m interval of Survey of India topographic sheets of 1:50,000 scale. Several topographic attributes, such as elevation (above mean sea level), relative relief, slope, aspect, curvature, slope-length and -steepness (LS) factor, terrain ruggedness index (TRI), topo-graphic wetness index (TWI), hypsometric integral (Ihyp) and drainage network attributes (stream number and stream length) of two tropical mountain river basins, viz., Muthirapuzha River Basin and Pambar River Basin are compared to evaluate the variations. Though the basins are comparable in extent, they differ in respect of terrain characteristics and climate. The results suggest that ASTER and SRTM provide equally reliable representation of topography portrayed by TOPO and the topographic attributes extracted from the spaceborne DEMs are in agreement with those derived from TOPO. Despite the coarser resolution, SRTM shows relatively higher vertical accuracy (RMSE ¼ 23 and 20 m respectively in MRB and PRB) compared to ASTER (RMSE ¼ 33 and 24 m) and GMTED (RMSE ¼ 59 and 48 m). Vertical accuracy of all the spaceborne DEMs is influenced by relief of the terrain as well as type of vegetation. Further, GMTED shows significant deviation for most of the attributes, indicating its inability for mountain-river-basin-scale studies.

  18. 2010 bathymetric survey and digital elevation model of Corte Madera Bay, California

    Science.gov (United States)

    Foxgrover, Amy C.; Finlayson, David P.; Jaffe, Bruce E.; Takekawa, John Y.; Thorne, Karen M.; Spragens, Kyle A.

    2011-01-01

    A high-resolution bathymetric survey of Corte Madera Bay, California, was collected in early 2010 in support of a collaborative research project initiated by the San Francisco Bay Conservation and Development Commission and funded by the U.S. Environmental Protection Agency. The primary objective of the Innovative Wetland Adaptation in the Lower Corte Madera Creek Watershed Project is to develop shoreline adaptation strategies to future sea-level rise based upon sound science. Fundamental to this research was the development of an of an up-to-date, high-resolution digital elevation model (DEM) extending from the subtidal environment through the surrounding intertidal marsh. We provide bathymetric data collected by the U.S. Geological Survey and have merged the bathymetry with a 1-m resolution aerial lidar data set that was collected by the National Oceanic and Atmospheric Administration during the same time period to create a seamless, high-resolution DEM of Corte Madera Bay and the surrounding topography. The bathymetric and DEM surfaces are provided at both 1 m and 10 m resolutions formatted as both X, Y, Z text files and ESRI Arc ASCII files, which are accompanied by Federal Geographic Data Committee compliant metadata.

  19. Forest operations planning by using RTK-GPS based digital elevation model

    Directory of Open Access Journals (Sweden)

    Neşe Gülci

    2015-07-01

    Full Text Available Having large proportion of forests in mountainous terrain in Turkey, the logging methods that not only minimize operational costs but also minimize environmental damages should be determined in forest operations planning. In a case where necessary logging equipment and machines are available, ground slope is the most important factor in determining the logging method. For this reason, accurate, up to date, and precise ground slope data is very crucial in the success of forest operations planning. In recent years, high-resolution Digital Elevation Models (DEM can be generated for forested areas by using Real Time Kinematic (RTK GPS method and these DEMs can be used to develop precise slope maps. In this study, high-resolution DEM was developed by RTK-GPS method to generate precise slope map in a sample area. Then, the slope map was classified into slope classes specified by IUFRO in order to assist forest operations planning. According to the results, logging methods that are suitable for very steep and steep terrain conditions (i.e. skyline logging, cable pulling, and chute systems should be preferred in 48.1% of the study area. It was also found that logging methods that are suitable for terrain with medium slope (i.e. skidding and cable pulling and gentle slope (i.e. skidding and mobile winch should be preferred in 34.1% and 17.8% of the study area, respectively.

  20. Parallel Priority-Flood depression filling for trillion cell digital elevation models on desktops or clusters

    Science.gov (United States)

    Barnes, Richard

    2016-11-01

    Algorithms for extracting hydrologic features and properties from digital elevation models (DEMs) are challenged by large datasets, which often cannot fit within a computer's RAM. Depression filling is an important preconditioning step to many of these algorithms. Here, I present a new, linearly scaling algorithm which parallelizes the Priority-Flood depression-filling algorithm by subdividing a DEM into tiles. Using a single-producer, multi-consumer design, the new algorithm works equally well on one core, multiple cores, or multiple machines and can take advantage of large memories or cope with small ones. Unlike previous algorithms, the new algorithm guarantees a fixed number of memory access and communication events per subdivision of the DEM. In comparison testing, this results in the new algorithm running generally faster while using fewer resources than previous algorithms. For moderately sized tiles, the algorithm exhibits ∼60% strong and weak scaling efficiencies up to 48 cores, and linear time scaling across datasets ranging over three orders of magnitude. The largest dataset on which I run the algorithm has 2 trillion (2×1012) cells. With 48 cores, processing required 4.8 h wall-time (9.3 compute-days). This test is three orders of magnitude larger than any previously performed in the literature. Complete, well-commented source code and correctness tests are available for download from a repository.

  1. Lunar digital elevation model and elevation distribution model based on Chang’E-1 LAM data

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    More than 8.2 million effective data samples were obtained by the Chang’E-1 Laser Altimeter (LAM).In order to produce a global topographic model of the moon with improved accuracy,a hierarchical many-knot spline method was proposed in this paper.This algorithm makes use of a hierarchy of control lattices to approximate or interpolate the LAM data.Based on the proposed algorithm,a 0.0625°×0.0625° grid of global lunar DEM was obtained and it was compared with ULCN2005,CLTMs01 and Kaguya models,respectively.At the same time,this paper explored the elevation distribution law and established the elevation distribution model.It is shown that the global lunar and nearside elevation distribution is positively skewed and leptokurtic normal distribution,and the farside elevation distribution is a positively skewed and platykurtic normal distribution.

  2. The geometric signature: Quantifying landslide-terrain types from digital elevation models

    Science.gov (United States)

    Pike, R.J.

    1988-01-01

    Topography of various types and scales can be fingerprinted by computer analysis of altitude matrices (digital elevation models, or DEMs). The critical analytic tool is the geometric signature, a set of measures that describes topographic form well enough to distinguish among geomorphically disparate landscapes. Different surficial processes create topography with diagnostic forms that are recognizable in the field. The geometric signature abstracts those forms from contour maps or their DEMs and expresses them numerically. This multivariate characterization enables once-in-tractable problems to be addressed. The measures that constitute a geometric signature express different but complementary attributes of topographic form. Most parameters used here are statistical estimates of central tendency and dispersion for five major categories of terrain geometry; altitude, altitude variance spectrum, slope between slope reversals, and slope and its curvature at fixed slope lengths. As an experimental application of geometric signatures, two mapped terrain types associated with different processes of shallow landsliding in Marin County, California, were distinguished consistently by a 17-variable description of topography from 21??21 DEMs (30-m grid spacing). The small matrix is a statistical window that can be used to scan large DEMs by computer, thus potentially automating the mapping of contrasting terrain types. The two types in Marin County host either (1) slow slides: earth flows and slump-earth flows, or (2) rapid flows: debris avalanches and debris flows. The signature approach should adapt to terrain taxonomy and mapping in other areas, where conditions differ from those in Central California. ?? 1988 International Association for Mathematical Geology.

  3. Effect of DEM Source and Resolution on Extracting River Network and Watershed within Multi-Lake Area in Tibet

    Science.gov (United States)

    Li, Yang; Li, Gang; Lin, Hui

    2014-11-01

    DEM defines drainage structures and basin through conducting overland flow simulation. Two matured DEM Sources are SRTM DEM (Shuttle Radar Topographic Mission) and ASTER GDEM (Advanced Space borne Thermal Emission and Reflection Radiometer Global Digital Elevation Model); The accuracy of hydrological characters that derived from DEM decreased from high resolution to coarse resolution and appeared to be different in different data source (Vaze,Teng, & Spencer, 2010).

  4. Gradient based filtering of digital elevation models

    DEFF Research Database (Denmark)

    Knudsen, Thomas; Andersen, Rune Carbuhn

    We present a filtering method for digital terrain models (DTMs). The method is based on mathematical morphological filtering within gradient (slope) defined domains. The intention with the filtering procedure is to improbé the cartographic quality of height contours generated from a DTM based on ...... in the landscape are washed out and misrepresented....

  5. Gradient based filtering of digital elevation models

    DEFF Research Database (Denmark)

    Knudsen, Thomas; Andersen, Rune Carbuhn

    We present a filtering method for digital terrain models (DTMs). The method is based on mathematical morphological filtering within gradient (slope) defined domains. The intention with the filtering procedure is to improbé the cartographic quality of height contours generated from a DTM based...

  6. A Combined SRTM Digital Elevation Model for Zanjan State of Iran Based on the Corrective Surface Idea

    Science.gov (United States)

    Kiamehr, Ramin

    2016-04-01

    One arc-second high resolution version of the SRTM model recently published for the Iran by the US Geological Survey database. Digital Elevation Models (DEM) is widely used in different disciplines and applications by geoscientist. It is an essential data in geoid computation procedure, e.g., to determine the topographic, downward continuation (DWC) and atmospheric corrections. Also, it can be used in road location and design in civil engineering and hydrological analysis. However, a DEM is only a model of the elevation surface and it is subject to errors. The most important parts of errors could be comes from the bias in height datum. On the other hand, the accuracy of DEM is usually published in global sense and it is important to have estimation about the accuracy in the area of interest before using of it. One of the best methods to have a reasonable indication about the accuracy of DEM is obtained from the comparison of their height versus the precise national GPS/levelling data. It can be done by the determination of the Root-Mean-Square (RMS) of fitting between the DEM and leveling heights. The errors in the DEM can be approximated by different kinds of functions in order to fit the DEMs to a set of GPS/levelling data using the least squares adjustment. In the current study, several models ranging from a simple linear regression to seven parameter similarity transformation model are used in fitting procedure. However, the seven parameter model gives the best fitting with minimum standard division in all selected DEMs in the study area. Based on the 35 precise GPS/levelling data we obtain a RMS of 7 parameter fitting for SRTM DEM 5.5 m, The corrective surface model in generated based on the transformation parameters and included to the original SRTM model. The result of fitting in combined model is estimated again by independent GPS/leveling data. The result shows great improvement in absolute accuracy of the model with the standard deviation of 3.4 meter.

  7. Cascading water underneath Wilkes Land, East Antarctic Ice Sheet, observed using altimetry and digital elevation models

    Directory of Open Access Journals (Sweden)

    T. Flament

    2013-03-01

    Full Text Available We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyze the event, we combined altimetry data from several sources and bedrock data. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM derived from ASTER and SPOT5 stereo-imagery. With 5.2 ± 0.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry and the SPOT5 DEM indicate that the discharge lasted approximately 2 yr. A 13-m uplift of the surface, corresponding to a refilling of about 0.64 ± 0.32 km3, was observed between the end of the discharge in October 2008 and February 2012. Using Envisat radar altimetry, with its high 35-day temporal resolution, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream. In particular, a transient temporal signal can be detected within the theoretical 500-km long flow paths computed with the BEDMAP2 data set. The volume of water traveling in this wave is in agreement with the volume that drained from Lake CookE2. These observations contribute to a better understanding of the water transport beneath the East Antarctic ice sheet.

  8. Using Digital Elevation Model to Improve Soil pH Prediction in an Alpine Doline

    Institute of Scientific and Technical Information of China (English)

    G. BUTTAFU0C; R. COMOLLI; A. CASTRIGNAN(O)

    2011-01-01

    Among spatial interpolation techniques, geostatistics is generally preferred because it takes into account the spatial correlation between neighbouring observations in order to predict attribute values at unsampled locations. A doline of approximately 15 000 m2 at 1900 m above sea level (North Italy) was selected as the study area to estimate a digital elevation model (DEM) using geostatistics,to provide a realistic distribution of the errors and to demonstrate whether using widely available secondary data provided more accurate estimates of soil pH than those obtained by univariate kriging. Elevation was measured at 467 randomly distributed points that were converted into a regular DEM using ordinary kriging. Further. 110 pits were located using spatial simulated annealing (SSA) method. The interpolation techniques were multi-linear regression analysis (MLR), ordinary kriging (OK), regression kriging (RK), knging with external drift (KED) and multi-collocated ordinary cokriging (CKmc). A cross-validation test was used to assess the prediction performances of the different algorithms and then evaluate which methods performed best. RK and KED yielded better results than the more complex CKmc and OK. The choice of the most appropriate interpolation method accounting for redundant auxiliary information was strongly conditioned by site specific situations.

  9. Wavelet based analysis of TanDEM-X and LiDAR DEMs across a tropical vegetation heterogeneity gradient driven by fire disturbance in Indonesia

    NARCIS (Netherlands)

    Grandi, De Elsa Carla; Mitchard, Edward; Hoekman, Dirk

    2016-01-01

    Three-dimensional information provided by TanDEM-X interferometric phase and airborne Light Detection and Ranging (LiDAR) Digital ElevationModels (DEMs) were used to detect differences in vegetation heterogeneity through a disturbance gradient in Indonesia. The range of vegetation types developed

  10. VT Lidar Hydro-flattened DEM (1.6 meter) - 2008 - West Franklin

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Missisquoi Lower 2008 1.6m and Digital Elevation Model (DEM) datasets of various...

  11. VT Lidar Hydro-flattened DEM (1.6 meter) - 2010 - East Franklin/West Orleans

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and Digital Elevation Model (DEM) datasets of various...

  12. VT Lidar Hydro-flattened DEM (0.7 meter) - 2014 - Chittenden, Lamoille, Orleans, & Washington Counties

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Eastern VT 2014 0.7m and Digital Elevation Model (DEM) dataset of the following...

  13. VT Lidar Hydro-flattened DEM (0.7 meter) - 2015 - Windham County

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Windham County 2015 0.7m and Digital Elevation Model (DEM) dataset of the following...

  14. VT Lidar Hydro-flattened DEM (1.6 meter) - 2012 - Addison

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Addison County 2012 1.6m and Digital Elevation Model (DEM) datasets of various...

  15. Landscape unit based digital elevation model development for the freshwater wetlands within the Arthur C. Marshall Loxahatchee National Wildlife Refuge, Southeastern Florida

    Science.gov (United States)

    Xie, Zhixiao; Liu, Zhongwei; Jones, John W.; Higer, Aaron L.; Telis, Pamela A.

    2011-01-01

    The hydrologic regime is a critical limiting factor in the delicate ecosystem of the greater Everglades freshwater wetlands in south Florida that has been severely altered by management activities in the past several decades. "Getting the water right" is regarded as the key to successful restoration of this unique wetland ecosystem. An essential component to represent and model its hydrologic regime, specifically water depth, is an accurate ground Digital Elevation Model (DEM). The Everglades Depth Estimation Network (EDEN) supplies important hydrologic data, and its products (including a ground DEM) have been well received by scientists and resource managers involved in Everglades restoration. This study improves the EDEN DEMs of the Loxahatchee National Wildlife Refuge, also known as Water Conservation Area 1 (WCA1), by adopting a landscape unit (LU) based interpolation approach. The study first filtered the input elevation data based on newly available vegetation data, and then created a separate geostatistical model (universal kriging) for each LU. The resultant DEMs have encouraging cross-validation and validation results, especially since the validation is based on an independent elevation dataset (derived by subtracting water depth measurements from EDEN water surface elevations). The DEM product of this study will directly benefit hydrologic and ecological studies as well as restoration efforts. The study will also be valuable for a broad range of wetland studies.

  16. A quality control system for digital elevation data

    Science.gov (United States)

    Knudsen, Thomas; Kokkendorf, Simon; Flatman, Andrew; Nielsen, Thorbjørn; Rosenkranz, Brigitte; Keller, Kristian

    2015-04-01

    In connection with the introduction of a new version of the Danish national coverage Digital Elevation Model (DK-DEM), the Danish Geodata Agency has developed a comprehensive quality control (QC) and metadata production (MP) system for LiDAR point cloud data. The architecture of the system reflects its origin in a national mapping organization where raw data deliveries are typically outsourced to external suppliers. It also reflects a design decision of aiming at, whenever conceivable, doing full spatial coverage tests, rather than scattered sample checks. Hence, the QC procedure is split in two phases: A reception phase and an acceptance phase. The primary aim of the reception phase is to do a quick assessment of things that can typically go wrong, and which are relatively simple to check: Data coverage, data density, strip adjustment. If a data delivery passes the reception phase, the QC continues with the acceptance phase, which checks five different aspects of the point cloud data: Vertical accuracy Vertical precision Horizontal accuracy Horizontal precision Point classification correctness The vertical descriptors are comparatively simple to measure: The vertical accuracy is checked by direct comparison with previously surveyed patches. The vertical precision is derived from the observed variance on well defined flat surface patches. These patches are automatically derived from the road centerlines registered in FOT, the official Danish map data base. The horizontal descriptors are less straightforward to measure, since potential reference material for direct comparison is typically expected to be less accurate than the LiDAR data. The solution selected is to compare photogrammetrically derived roof centerlines from FOT with LiDAR derived roof centerlines. These are constructed by taking the 3D Hough transform of a point cloud patch defined by the photogrammetrical roof polygon. The LiDAR derived roof centerline is then the intersection line of the two primary

  17. Semi-automated identification and extraction of geomorphological features using digital elevation data

    NARCIS (Netherlands)

    Seijmonsbergen, A.C.; Hengl, T.; Anders, N.S.; Smith, M.J.; Paron, P.; Griffiths, J.S.

    2011-01-01

    Geomorphological maps that are automatically extracted from digital elevation data are gradually replacing classical geomorphological maps. Commonly, digital mapping projects are based upon statistical techniques, object-based protocols or both. In addition to digital elevation data, expert knowledg

  18. What if the Earth is Not Flat? Cross-Scale Analysis of Sub-Pixel Variations in Digital Elevation Models

    Science.gov (United States)

    Ghandehari, M.; P Buttenfield, B.; J Q Farmer, C.

    2016-12-01

    Digital terrain models guide scientists and planners in multiple ways and have fundamental impacts on society, safety and resource management. Terrain is currently modeled in a grid of pixels, assuming that elevation values are constant within any single pixel of a Digital Elevation Model (DEM) (`rigid pixel' paradigm). The assumption of rigid pixels generates basic spatial measurements that are in fact imprecise. In truth, terrain can bend, twist and undulate within each pixel, more similar to a continuous and flexible fabric. For localized areas or for very small pixel sizes, the amount of imprecision is insignificant, but can increase with larger pixel size and/or across regional or global expanses, as in the case with models of climate change, sea level rise, and other modeling applications, where pixels can span dozens to hundreds of kilometers. This research examines the sensitivity of surface adjustment to a progression of spatial resolutions (10, 30, 100, and 1000 meter DEMs), validating sub-pixel variations that can be directly measured from finer resolution LiDAR data. Tests will interpolate the elevation of 1,000 georeferenced random points using different methods (weighted average, as well as bi-linear, bi-quadratic, and bi-cubic polynomial fitting) and different contiguity configurations (incorporating first and second order neighbors), and conflate each resolution against a finer resolution LiDAR data benchmark. Additional tests will compute Root Mean Square Error (RMSE) between DEM and LiDAR to assess differences in various methods and resolutions. The paper will present results of the benchmark comparison for a number of study areas characterized by varying degrees of terrain roughness, along with guidelines for determining what terrain conditions and spatial resolutions dramatically modify elevation estimates, and which elevation estimation method(s) are more reliable for particular terrain conditions and particular pixel sizes.

  19. Vegetation Cover Mapping Based on Remote Sensing and Digital Elevation Model Data

    Science.gov (United States)

    Korets, M. A.; Ryzhkova, V. A.; Danilova, I. V.; Prokushkin, A. S.

    2016-06-01

    An algorithm of forest cover mapping based on combined GIS-based analysis of multi-band satellite imagery, digital elevation model, and ground truth data was developed. Using the classification principles and an approach of Russian forest scientist Kolesnikov, maps of forest types and forest growing conditions (FGC) were build. The first map is based on RS-composite classification, while the second map is constructed on the basis of DEM-composite classification. The spatial combination of this two layers were also used for extrapolation and mapping of ecosystem carbon stock values (kgC/m2). The proposed approach was applied for the test site area (~3600 km2), located in the Northern Siberia boreal forests of Evenkia near Tura settlement.

  20. Digital elevation model and satellite images an assessment of soil erosion potential in the Pcinja catchment

    Directory of Open Access Journals (Sweden)

    Milevski Ivica

    2007-01-01

    Full Text Available Pcinja is large left tributary of Vardar River (135 km long, 2877,3 km2 catchment’s area, which drainages surface waters from northeastern Macedonia, and small part of southeastern Serbia. Because of suitable physical-geographic factors (geology, terrain morphology, climate, hydrology, vegetation coverage, soil composition, and high human impact, some parts of the catchment’s suffer significant erosion process. For this reason, it is necessary to research properly spatial distribution of erosion, then influence of physical and anthropogenic factors for the intensity of soil erosion, related erosion landforms (with morphology, genesis, evolution, soil erosion protection etc.. Earlier researches in the area have been performed generally with combination of cartographic and classic field analysis. But in last decades, there are new possibilities available like satellite images and digital elevation models. In this work has been presented the methodology of utilization of satellite images and DEM for erosion research, with analysis and comparisons of outcome data.

  1. An approach of crater automatic recognition based on contour digital elevation model from Chang'E Missions

    Science.gov (United States)

    Zuo, W.; Li, C.; Zhang, Z.; Li, H.; Feng, J.

    2015-12-01

    In order to provide fundamental information for exploration and related scientific research on the Moon and other planets, we propose a new automatic method to recognize craters on the lunar surface based on contour data extracted from a digital elevation model (DEM). First, we mapped 16-bits DEM to 256 gray scales for data compression, then for the purposes of better visualization, the grayscale is converted into RGB image. After that, a median filter is applied twice to DEM for data optimization, which produced smooth, continuous outlines for subsequent construction of contour plane. Considering the fact that the morphology of crater on contour plane can be approximately expressed as an ellipse or circle, we extract the outer boundaries of contour plane with the same color(gray value) as targets for further identification though a 8- neighborhood counterclockwise searching method. Then, A library of training samples is constructed based on above targets calculated from some sample DEM data, from which real crater targets are labeled as positive samples manually, and non-crater objects are labeled as negative ones. Some morphological feathers are calculated for all these samples, which are major axis (L), circumference(C), area inside the boundary(S), and radius of the largest inscribed circle(R). We use R/L, R/S, C/L, C/S, R/C, S/L as the key factors for identifying craters, and apply Fisher discrimination method on the sample library to calculate the weight of each factor and determine the discrimination formula, which is then applied to DEM data for identifying lunar craters. The method has been tested and verified with DEM data from CE-1 and CE-2, showing strong recognition ability and robustness and is applicable for the recognition of craters with various diameters and significant morphological differences, making fast and accurate automatic crater recognition possible.

  2. Evaluating the impact of lower resolutions of digital elevation model on rainfall-runoff modeling for ungauged catchments.

    Science.gov (United States)

    Ghumman, Abul Razzaq; Al-Salamah, Ibrahim Saleh; AlSaleem, Saleem Saleh; Haider, Husnain

    2017-02-01

    Geomorphological instantaneous unit hydrograph (GIUH) usually uses geomorphologic parameters of catchment estimated from digital elevation model (DEM) for rainfall-runoff modeling of ungauged watersheds with limited data. Higher resolutions (e.g., 5 or 10 m) of DEM play an important role in the accuracy of rainfall-runoff models; however, such resolutions are expansive to obtain and require much greater efforts and time for preparation of inputs. In this research, a modeling framework is developed to evaluate the impact of lower resolutions (i.e., 30 and 90 m) of DEM on the accuracy of Clark GIUH model. Observed rainfall-runoff data of a 202-km(2) catchment in a semiarid region was used to develop direct runoff hydrographs for nine rainfall events. Geographical information system was used to process both the DEMs. Model accuracy and errors were estimated by comparing the model results with the observed data. The study found (i) high model efficiencies greater than 90% for both the resolutions, and (ii) that the efficiency of Clark GIUH model does not significantly increase by enhancing the resolution of the DEM from 90 to 30 m. Thus, it is feasible to use lower resolutions (i.e., 90 m) of DEM in the estimation of peak runoff in ungauged catchments with relatively less efforts. Through sensitivity analysis (Monte Carlo simulations), the kinematic wave parameter and stream length ratio are found to be the most significant parameters in velocity and peak flow estimations, respectively; thus, they need to be carefully estimated for calculation of direct runoff in ungauged watersheds using Clark GIUH model.

  3. A comparative analysis of different DEM interpolation methods

    Directory of Open Access Journals (Sweden)

    P.V. Arun

    2013-12-01

    Full Text Available Visualization of geospatial entities generally entails Digital Elevation Models (DEMs that are interpolated to establish three dimensional co-ordinates for the entire terrain. The accuracy of generated terrain model depends on the interpolation mechanism adopted and hence it is needed to investigate the comparative performance of different approaches in this context. General interpolation techniques namely Inverse Distance Weighted, kriging, ANUDEM, Nearest Neighbor, and Spline approaches have been compared. Differential ground field survey has been conducted to generate reference DEM as well as specific set of test points for comparative evaluation. We have also investigated the suitability of Shuttle Radar Topographic Mapper Digital Elevation Mapper for Indian terrain by comparing it with the Survey of India (SOI Digital Elevation Model (DEM. Contours were generated at different intervals for comparative analysis and found SRTM as more suitable. The terrain sensitivity of various methods has also been analyzed with reference to the study area.

  4. A Brief Study of Digital Elevation Model%浅谈对数字高程模型的几点认识

    Institute of Scientific and Technical Information of China (English)

    赵博

    2012-01-01

    简要介绍了数字高程模型(DEM),结合实际阐述了DEM的采集方法、误差来源、质检方法,以及如何通过上述过程,使数字高程模型达到更高的精度要求。%This paper briefly introduces digital elevation model(DEM),and describes collection methods,error sources and quality control of DEM and the way to improve DEM accuracy using the above methods in the light of production practice.

  5. Optimization of computer-based technology of creating large reservoir's Digital Elevation Models

    Science.gov (United States)

    Shikunova, Ekaterina; Pavlovsky, Andrew; Zemlyanov, Igor; Gorelits, Olga

    2010-05-01

    Using Digital Elevation Model of bottom and coastal zone for large-scale anthropogenic water reservoirs is very important for sustainable water management in actual conditions of Global Climate Change. DEM is unified monitoring base for different types of reservoirs in varied types of ecosystems in various environmental and economical conditions. It may be used for getting current morphometric characteristics, pollution and biodiversity analysis, monitoring bottom relief changing and making management decisions. In 2008-2009 State Oceanography Institute (SOI) carried out the DEMs for reservoirs of Volga river system. In 2008 in SOI was created DEM of Uglichsky reservoir, which is typical Russian reservoir. Methodology and computer-based technology were developed and evaluated. In 2009 in SOI were created DEMs of Gorkovsky, Volgogradsky and six reservoirs of Moscow region. Such result was achieved by optimization of DEM's creating process. Initially we used complex of GIS programs, which include GIS Map-2008 Panorama, ArcMap v.9.3.1, ArcView v.3.2a, Golden Surfer v.8, Global Mapper v.10. The input data are bathymetric survey data, large-scale maps (scale 1:10 000, 1:25 000) and remote sensing data of high resolution. Office analysis consists of several main milestones. 1. Vectorization of coastline and relief data from maps and remote sensing data using GIS Map-2008 by Panorama; ArcView v.3.2a. 2. Maps data elaboration with using bathymetric survey data. Because some maps are longstanding it is necessary to renew them. 3. Creating point's array including all data from maps, RSD and bathymetric survey. 4. Separation small calculation zones including four survey cross-sections. 5. Determine of anisotropy parameters, which depend on channel orientation. 6. Create shapes for clipping of correct grid zones. Each shape includes 2 cross-sections. Milestones 2-6 realize in ArcView v.3.2a. 7. Creating grid's array using Golden Surfer v.8 for each zone by interpolation method

  6. The National Map seamless digital elevation model specifications

    Science.gov (United States)

    Archuleta, Christy-Ann M.; Constance, Eric W.; Arundel, Samantha T.; Lowe, Amanda J.; Mantey, Kimberly S.; Phillips, Lori A.

    2017-08-02

    This specification documents the requirements and standards used to produce the seamless elevation layers for The National Map of the United States. Seamless elevation data are available for the conterminous United States, Hawaii, Alaska, and the U.S. territories, in three different resolutions—1/3-arc-second, 1-arc-second, and 2-arc-second. These specifications include requirements and standards information about source data requirements, spatial reference system, distribution tiling schemes, horizontal resolution, vertical accuracy, digital elevation model surface treatment, georeferencing, data source and tile dates, distribution and supporting file formats, void areas, metadata, spatial metadata, and quality assurance and control.

  7. Problems and Solutions for InSAR Digital Elevation Model Generation of Mountainous Terrain

    Science.gov (United States)

    Eineder, M.

    2004-06-01

    During the last decade, the techniques to generate digital elevation models (DEM) from SAR interferometry have been demonstrated and refined to a quasi-operational status using data from the ERS tandem mission. With this experience and an improved single-pass system concept, data from the Shuttle Radar Topography Mission (SRTM) acquired in 2000 have been used to produce a global DEM with unprecedented quality. However, under the extreme viewing conditions in mountainous terrain both ERS and SRTM suffer from or even fail due to the radar specific layover and shadow effect that leaves significant areas uncovered and poses severe problems to phase unwrapping. The paper quantifies the areas leading to layover and shadow, and shows innovative ways to overcome shadow and improve phase unwrapping in general. The paper is organized in three major sections. Firstly, the problem to map slopes is addressed in a simplified statistical way. Strategies to optimize the incidence angle for single and multiple observations are proposed. Secondly, a new algorithm is presented that makes the best from shadow by actively using it to help phase unwrapping. Thirdly, an outlook on the use of deltak interferometry for phase unwrapping is given. The paper aims to improve the understanding of the mapping geometry of radar systems and the data currently available and to improve the concepts of future systems and missions.

  8. A marked point process of rectangles and segments for automatic analysis of digital elevation models.

    Science.gov (United States)

    Ortner, Mathias; Descombe, Xavier; Zerubia, Josiane

    2008-01-01

    This work presents a framework for automatic feature extraction from images using stochastic geometry. Features in images are modeled as realizations of a spatial point process of geometrical shapes. This framework allows the incorporation of a priori knowledge on the spatial repartition of features. More specifically, we present a model based on the superposition of a process of segments and a process of rectangles. The former is dedicated to the detection of linear networks of discontinuities, while the latter aims at segmenting homogeneous areas. An energy is defined, favoring connections of segments, alignments of rectangles, as well as a relevant interaction between both types of objects. The estimation is performed by minimizing the energy using a simulated annealing algorithm. The proposed model is applied to the analysis of Digital Elevation Models (DEMs). These images are raster data representing the altimetry of a dense urban area. We present results on real data provided by the IGN (French National Geographic Institute) consisting in low quality DEMs of various types.

  9. ASTER Global Digital Elevation Model Version 2 - summary of validation results

    Science.gov (United States)

    Tachikawa, Tetushi; Kaku, Manabu; Iwasaki, Akira; Gesch, Dean B.; Oimoen, Michael J.; Zhang, Z.; Danielson, Jeffrey J.; Krieger, Tabatha; Curtis, Bill; Haase, Jeff; Abrams, Michael; Carabajal, C.; Meyer, Dave

    2011-01-01

    On June 29, 2009, NASA and the Ministry of Economy, Trade and Industry (METI) of Japan released a Global Digital Elevation Model (GDEM) to users worldwide at no charge as a contribution to the Global Earth Observing System of Systems (GEOSS). This “version 1” ASTER GDEM (GDEM1) was compiled from over 1.2 million scenebased DEMs covering land surfaces between 83°N and 83°S latitudes. A joint U.S.-Japan validation team assessed the accuracy of the GDEM1, augmented by a team of 20 cooperators. The GDEM1 was found to have an overall accuracy of around 20 meters at the 95% confidence level. The team also noted several artifacts associated with poor stereo coverage at high latitudes, cloud contamination, water masking issues and the stacking process used to produce the GDEM1 from individual scene-based DEMs (ASTER GDEM Validation Team, 2009). Two independent horizontal resolution studies estimated the effective spatial resolution of the GDEM1 to be on the order of 120 meters.

  10. DEM error retrieval by analyzing time series of differential interferograms

    OpenAIRE

    Bombrun, Lionel; Gay, Michel; Trouvé, Emmanuel; Vasile, Gabriel; Mars, Jerome,

    2009-01-01

    International audience; 2-pass Differential Synthetic Aperture Radar Interferometry (D-InSAR) processing have been successfully used by the scientific community to derive velocity fields. Nevertheless, a precise Digital Elevation Model (DEM) is necessary to remove the topographic component from the interferograms. This letter presents a novel method to detect and retrieve DEM errors by analyzing time series of differential interferograms. The principle of the method is based on the comparison...

  11. Accuracy of Cartosat-1 DEM and its derived attribute at multiple scale representation

    Indian Academy of Sciences (India)

    Samadrita Mukherjee; Sandip Mukherjee; A Bhardwaj; Anirban Mukhopadhyay; R D Garg; S Hazra

    2015-04-01

    Digital Elevation Model (DEM) provides basic information about terrain relief and is used for morphological characterisation, hydrological modelling and infrastructural studies. This paper investigates the accuracy of DEM and its derived attributes in multiple scales. This study was carried out for a part of Shiwalik Himalaya using Cartosat-1 stereo pair data. DEM at various cell sizes were generated and information content was compared using mean elevation, variance and entropy statistics. Various post-spacing DEMs were validated to understand variation in vertical accuracy along different scales. The vertical accuracy (3.14–7.24 m) is affected in larger spacing DEM and elevation is underestimated. Slope of terrain also has similar impacts. The DEM and slope accuracy are also affected by the terrain roughness while assessing coarser grid size.

  12. Design flood of ungauged basins based on DEM

    Institute of Scientific and Technical Information of China (English)

    Zhang Ting; Feng Ping

    2012-01-01

    In this paper, the northern mountainous area of Fuzhou City which is an ungauged basin has been taken for example to discuss the method of design flood calculation by means of combining the DEM (digital elevation model) and the Xin' anjiang Model ( three components ). The problem of estimating the parameters of the runoff model has been solved by using the parameters of the reference station. In the conflux calculation, the isochrones are obtained by DEM which helps to avoid the cumbersome work of drawing them on the map. With the establishment of the digital elevation model throughout the country, it is practically significant to use it in the hydrological estimation.

  13. Bermuda 1 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 1 arc-second Bermuda DEM will be used to support NOAA's tsunami forecast system and for tsunami inundation modeling. This DEM encompasses the islands of Bermuda...

  14. U.S. Virgin Islands Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 1 arc-second Virgin Islands DEM will be used to support NOAA's tsunami forecast system and for tsunami inundation modeling. This DEM encompasses the Virgin...

  15. British Columbia 3 arc-second Bathymetric Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 3 arc-second British Columbia DEM will be used to support NOAA's tsunami forecast system and for tsunami inundation modeling. This DEM covers the coastal area...

  16. Bermuda 3 arc-second Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 3 arc-second Bermuda DEM will be used to support NOAA's tsunami forecast system and for tsunami inundation modeling. This DEM encompasses the islands of Bermuda...

  17. Implications of different digital elevation models and preprocessing techniques to delineate debris flow inundation hazard zones in El Salvador

    Science.gov (United States)

    Anderson, E. R.; Griffin, R.; Irwin, D.

    2013-12-01

    Heavy rains and steep, volcanic slopes in El Salvador cause numerous landslides every year, posing a persistent threat to the population, economy and environment. Although potential debris inundation hazard zones have been delineated using digital elevation models (DEMs), some disparities exist between the simulated zones and actual affected areas. Moreover, these hazard zones have only been identified for volcanic lahars and not the shallow landslides that occur nearly every year. This is despite the availability of tools to delineate a variety of landslide types (e.g., the USGS-developed LAHARZ software). Limitations in DEM spatial resolution, age of the data, and hydrological preprocessing techniques can contribute to inaccurate hazard zone definitions. This study investigates the impacts of using different elevation models and pit filling techniques in the final debris hazard zone delineations, in an effort to determine which combination of methods most closely agrees with observed landslide events. In particular, a national DEM digitized from topographic sheets from the 1970s and 1980s provide an elevation product at a 10 meter resolution. Both natural and anthropogenic modifications of the terrain limit the accuracy of current landslide hazard assessments derived from this source. Global products from the Shuttle Radar Topography Mission (SRTM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM) offer more recent data but at the cost of spatial resolution. New data derived from the NASA Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) in 2013 provides the opportunity to update hazard zones at a higher spatial resolution (approximately 6 meters). Hydrological filling of sinks or pits for current hazard zone simulation has previously been achieved through ArcInfo spatial analyst. Such hydrological processing typically only fills pits and can lead to drastic modifications of original elevation values

  18. Minnesota Digital Elevation Model - Tiled 30 Meter Resolution

    Data.gov (United States)

    Minnesota Department of Natural Resources — This 30 Meter DEM is a copy of the USGS 1:24,000 scale Level 2 DEMs for the State. There are three quadrangles known be be Level 1 DEM data: Town Line Lake (q1925),...

  19. VT Lidar Hydro-flattened DEM (0.7 meter) - 2013 - Rutland/West Washington/Grand Isle

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area: Rutland/GI Counties 2013 0.7m and Digital Elevation Model (DEM) datasets of various...

  20. Priority-flood: An optimal depression-filling and watershed-labeling algorithm for digital elevation models

    Science.gov (United States)

    Barnes, Richard; Lehman, Clarence; Mulla, David

    2014-01-01

    Depressions (or pits) are areas within a digital elevation model that are surrounded by higher terrain, with no outlet to lower areas. Filling them so they are level, as fluid would fill them if the terrain was impermeable, is often necessary in preprocessing DEMs. The depression-filling algorithm presented here - called Priority-Flood - unifies and improves the work of a number of previous authors who have published similar algorithms. The algorithm operates by flooding DEMs inwards from their edges using a priority queue to determine the next cell to be flooded. The resultant DEM has no depressions or digital dams: every cell is guaranteed to drain. The algorithm is optimal for both integer and floating-point data, working in O(n) and O(n log2 n) time, respectively. It is shown that by using a plain queue to fill depressions once they have been found, an O(m log2 m) time-complexity can be achieved, where m does not exceed the number of cells n. This is the lowest time complexity of any known floating-point depression-filling algorithm. In testing, this improved variation of the algorithm performed up to 37% faster than the original. Additionally, a parallel version of an older, but widely used, depression-filling algorithm required six parallel processors to achieve a run-time on par with what the newer algorithm's improved variation took on a single processor. The Priority-Flood Algorithm is simple to understand and implement: the included pseudocode is only 20 lines and the included C++ reference implementation is under a hundred lines. The algorithm can work on irregular meshes as well as 4-, 6-, 8-, and n-connected grids. It can also be adapted to label watersheds and determine flow directions through either incremental elevation changes or depression carving. In the case of incremental elevation changes, the algorithm includes safety checks not present in prior works.

  1. The use of LIDAR as a potential data source for the creation of digital elevation models and estimation of wetness in northern peat lands

    Science.gov (United States)

    Hasan, Abdulghani; Pilesjö, Petter; Person, Andreas; Roulet, Nigel

    2010-05-01

    The main objective of this study is to investigate the potential of using high resolution LIDAR data for the creation of accurate digital elevation models covering peat lands. The secondary aim is to get an indication of the possibility to use these digital elevation models for estimations of wetness in peat lands areas. The scale problem, i.e. the spatial resolution of the DEM, will be discussed for both objectives. Our hypothesis is that very accurate digital elevation models can be created, that these, by applying an appropriate algorithm reflect wetness in a good way, and that the estimated wetness values are highly dependant on resolution. In DEMs creation, three different interpolation methods are used with four different search radius and six selected cell resolution. We create new MATLAB code program to have full control on the interpolation process. One of the big challenges is how to deal with the huge number of data points. Processing such with computational complexity On2 was very slow. Adding a spatial index key (morton value) speed up the searching process and makes the search in nlog2n time. The new code was successful to deal with the huge number of data with a reasonable time. An important outcome from this study is the statistical comparison between different DEMs.

  2. 数字高程模型信息提取与数字水文模型研究进展%A Review of the Digital Elevation Model Extraction and Digital Hydrological Modeling

    Institute of Scientific and Technical Information of China (English)

    任立良; 刘新仁

    2000-01-01

    In this paper, the methodology of drainage network extraction from grid-based the digital elevation model (DEM) is reviewed. Then the current situation of application of information extracted from a DEM data in the field of hydrology and water resources are remarked. It is shown that the digital model plays a great role in data mining in hydrology and water resources. Water-related data measured at gauged stations could be assimilated to areal information over a catchment by the digital model, so as to serve for all trades and professions of national economy. Finally the position and the perspective of the digital hydrology (DH)in digital earth are discussed. The DH is an important component of digital earth. It needs further research.%回顾了数字高程模型(DEM)数据的信息提取方法,阐述了由DEM提取的信息在水文水资源领域应用的现状,探讨了数字模型在水文科学中的作用和数字水文在数字地球所处的地位及应用前景。

  3. Orthographic terrain views using data derived from digital elevation models

    Science.gov (United States)

    Dubayah, R. O.; Dozier, J.

    1986-01-01

    A fast algorithm for producing three-dimensional orthographic terrain views uses digital elevation data and co-registered imagery. These views are created using projective geometry and are designed for display on high-resolution raster graphics devices. The algorithm's effectiveness is achieved by (1) the implementation of two efficient gray-level interpolation routines that offer the user a choice between speed and smoothness, and (2) a unique visible surface determination procedure based on horizon angles derived from the elevation data set.

  4. Suitability of digital elevation models generated by uav photogrammetry for slope stability assessment (case study of landslide in Svätý Anton, Slovakia

    Directory of Open Access Journals (Sweden)

    Rusnák Miloš

    2016-12-01

    Full Text Available Assessing the accuracy of photogrammetrically-derived digital elevation models (DEMs from UAV is essential in many geoscience disciplines. The suitability of different DEM devised for slope stability assessment was evaluated in the example of the landslide in Svätý Anton village in Slovakia. Aerial data was acquired during a one-day field campaign in autumn 2014. The point cloud from 218 images (54,607,748 points was manually classified into 7 different classes for filtering vegetation cover and buildings. Assessment of vertical differences between the UAV derived elevation model and real terrain surface was based on comparison of control points targeted by GPS (337 points and unclassified and ground classified point cloud for raster elevation models with 1, 5, 10, 20 and 50 cm pixel resolution.

  5. Shaded Relief of Minnesota Elevation - Color

    Data.gov (United States)

    Minnesota Department of Natural Resources — This file is a product of a shaded relief process on the 30 meter resolution Digital Elevation Model data (dem30im3). This image was created using a custom AML...

  6. Shaded Relief of Minnesota Elevation - Black & White

    Data.gov (United States)

    Minnesota Department of Natural Resources — This file is a product of a shaded relief process on the 30 meter resolution Digital Elevation Model data (dem30im3). This image was created using a custom AML...

  7. A computationally efficient depression-filling algorithm for digital elevation models, applied to proglacial lake drainage

    Science.gov (United States)

    Berends, Constantijn J.; van de Wal, Roderik S. W.

    2016-12-01

    Many processes govern the deglaciation of ice sheets. One of the processes that is usually ignored is the calving of ice in lakes that temporarily surround the ice sheet. In order to capture this process a "flood-fill algorithm" is needed. Here we present and evaluate several optimizations to a standard flood-fill algorithm in terms of computational efficiency. As an example, we determine the land-ocean mask for a 1 km resolution digital elevation model (DEM) of North America and Greenland, a geographical area of roughly 7000 by 5000 km (roughly 35 million elements), about half of which is covered by ocean. Determining the land-ocean mask with our improved flood-fill algorithm reduces computation time by 90 % relative to using a standard stack-based flood-fill algorithm. This implies that it is now feasible to include the calving of ice in lakes as a dynamical process inside an ice-sheet model. We demonstrate this by using bedrock elevation, ice thickness and geoid perturbation fields from the output of a coupled ice-sheet-sea-level equation model at 30 000 years before present and determine the extent of Lake Agassiz, using both the standard and improved versions of the flood-fill algorithm. We show that several optimizations to the flood-fill algorithm used for filling a depression up to a water level, which is not defined beforehand, decrease the computation time by up to 99 %. The resulting reduction in computation time allows determination of the extent and volume of depressions in a DEM over large geographical grids or repeatedly over long periods of time, where computation time might otherwise be a limiting factor. The algorithm can be used for all glaciological and hydrological models, which need to trace the evolution over time of lakes or drainage basins in general.

  8. An efficient assignment of drainage direction over flat surfaces in raster digital elevation models

    Science.gov (United States)

    Barnes, Richard; Lehman, Clarence; Mulla, David

    2014-01-01

    In processing raster digital elevation models (DEMs) it is often necessary to assign drainage directions over flats-that is, over regions with no local elevation gradient. This paper presents an approach to drainage direction assignment which is not restricted by a flat's shape, number of outlets, or surrounding topography. Flow is modeled by superimposing a gradient away from higher terrain with a gradient towards lower terrain resulting in a drainage field exhibiting flow convergence, an improvement over methods which produce regions of parallel flow. This approach builds on previous work by Garbrecht and Martz (1997), but presents several important improvements. The improved algorithm guarantees that flats are only resolved if they have outlets. The algorithm does not require iterative application; a single pass is sufficient to resolve all flats. The algorithm presents a clear strategy for identifying flats and their boundaries. The algorithm is not susceptible to loss of floating-point precision. Furthermore, the algorithm is efficient, operating in O(N) time whereas the older algorithm operates in O(N) time. In testing, the improved algorithm ran 6.5 times faster than the old for a 100×100 cell flat and 69 times faster for a 700×700 cell flat. In tests on actual DEMs, the improved algorithm finished its processing 38-110 times sooner while running on a single processor than a parallel implementation of the old algorithm did while running on 16 processors. The improved algorithm is an optimal, accurate, easy-to-implement drop-in replacement for the original. Pseudocode is provided in the paper and working source code is provided in the Supplemental Materials.

  9. Quantification of soil losses from tourist trails - use of Digital Elevation Models

    Science.gov (United States)

    Tomczyk, Aleksandra

    2010-05-01

    Tourism impacts in protected mountain areas are one of the main concerns for land managers. Impact to environment is most visible at locations of highly concentrated activities like tourist trails, campsites etc. The main indicators of the tourist trail degradation are: vegetation loss (trampling of vegetation cover), change of vegetation type and composition, widening of the trails, muddiness and soil erosion. The last one is especially significant, since it can cause serious transformation of the land surface. Such undesirable changes cannot be repaired without high-cost management activities, and, in some cases they can made the trails difficult and unsafe to use. Scientific understanding of soil erosion related to human impact can be useful for more effective management of the natural protected areas. The aim of this study was to use of digital elevation models (DEMs) to precisely quantify of soil losses from tourist trails. In the study precise elevation data were gathered in several test fields of 4 by 5 m spatial dimension. Measurements were taken in 13 test fields, located in two protected natural areas in south Poland: Gorce National Park and Popradzki Landscape Park. The measuring places were located on trails characterized by different slope, type of vegetation and type of use. Each test field was established by four special marks, firmly dug into the ground. Elevation data were measured with the electronic total station. Irregular elevation points were surveying with essential elements of surrounding terrain surface being included. Moreover, surveys in fixed profile lines were done. For each test field a set of 30 measurements in control points has been collected and these data provide the base for verification of digital elevation models. Average density of the surveying was 70 points per square meter (1000 - 1500 elevation points per each test fields). Surveys in each test field were carried out in August and September of 2008, June 2009 and August

  10. Digital Elevation Model Creation Using SfM on High-Altitude Snow-Covered Surfaces at Summit, Greenland

    Science.gov (United States)

    Millstein, J. D.; Hawley, R. L.

    2015-12-01

    Structure from Motion (SfM) provides a means through which a digital elevation model (DEM) can be constructed with data acquired at a relatively low cost when compared to other current alternatives. Using an Unmanned Aerial Vehicle (UAV), a large area can be efficiently covered at high spatial resolution to quantify regional topography. Structure from Motion applied to photogrammetric techniques from a UAV has proven to be a successful tool, but challenges to UAV-based SfM include high-altitude locations with few distinctive surface features and minor textural differences. In June 2015, we piloted a small UAV (Quest) in order to conduct a topographical survey of Summit Camp, Greenland using SfM. Summit Camp sits at a surface elevation of 3200 meters above sea level, and occupies a snow-covered surface. The flat, very uniform terrain proved to be a challenge when flying the UAV and processing imagery using SfM techniques. In this presentation we discuss the issues both with operating a UAV instrument platform at high-altitude in the polar regions and interpreting the resulting DEM from a snow-covered region. The final DEM of Summit Camp covers a large portion of the surface area directly impacted by camp activities. In particular, volume calculations of drifting snow gauge an estimate of the equipment hours that will be required to clear and unearth structures. Investigation of surface roughness at multiple length scales can similarly provide insight on the accuracy of the DEM when observing texturally uniform surfaces.

  11. A Global Corrected SRTM DEM Product Over Vegetated Areas Using LiDAR Data

    Science.gov (United States)

    Zhao, X.; Guo, Q.; Su, Y.; Hu, T.

    2016-12-01

    The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) is one of the most complete and frequently used global-scale DEM products in various applications. However, previous studies have shown that the SRTM DEM is systematically higher than the actual land surface in vegetated mountain areas. The objective of this study is to propose a procedure to calibrate the SRTM DEM over global vegetated mountain areas. To address this, we firstly collected airborne LiDAR data over 200,000 km2 globally used as ground truth data to analyze the uncertainty of the SRTM DEM. The Geoscience Laser Altimeter System (GLAS)/ICESat (Ice, Cloud, and land Elevation Satellite) data were used as complementary data in areas lack of airborne LiDAR data. Secondly, we modelled the SRTM DEM error for each vegetation type using regression methods. Tree height, canopy cover, and terrain slope were used as dependent variables to model the SRTM DEM error. Finally, these regression models were used to estimate the SRTM DEM error in vegetated mountain areas without LiDAR data coverage, and therefore correct the SRTM DEM. Our results show that the new corrected SRTM DEM can significantly reduce the systematic bias of the SRTM DEM in vegetated mountain areas.

  12. High-resolution digital elevation dataset for Newberry Volcano and vicinity, Oregon, based on lidar survey of August-September, 2010 and bathymetric survey of June, 2001

    Science.gov (United States)

    Bard, Joseph A.; Ramsey, David W.

    2016-01-01

    Newberry Volcano, one of the largest Quaternary volcanoes in the conterminous United States, is a broad shield-shaped volcano measuring 60 km north-south by 30 km east-west with a maximum elevation of more than 2 km above sea level. It is the product of deposits from thousands of eruptions, including at least 25 in (approximately) the last 12,000 years (the Holocene Epoch). Newberry Volcano has erupted as recently as 1,300 years ago, but isotopic ages indicate that the volcano began its growth as early as 0.6 million years ago. Such a long eruptive history together with recent activity suggests that Newberry Volcano is likely to erupt in the future. This DEM (digital elevation model) of Newberry Volcano contributes to natural hazard monitoring efforts, the study of regional geology, volcanic landforms, and landscape modification during and after future volcanic eruptions, both at Newberry Volcano or elsewhere globally. In collaboration with the USGS, the Oregon Department of Geology and Mineral Industries-led Oregon Lidar Consortium contracted Watershed Sciences to collect 500 square miles of high-precision airborne lidar (Light Detection and Ranging) data. These data provide a digital map of the ground surface beneath forest cover. The lidar-derived DEM is amended to include bathymetric surveys of East Lake and Paulina Lake. The bathymetric surveys were performed in June, 2001 by Bob Reynolds of Central Oregon Community College, Bend, Oregon. The bathymetry is mosaicked into the DEM in place of the lidar derived lake surfaces. This release is comprised of a DEM dataset accompanied by a hillshade raster, each divided into eighteen tiles. Each tile’s bounding rectangle is identical to the extent of the USGS 7.5 minute topographic quadrangles covering the same area. The names of the DEM tiles are eleven characters long (e.g., dem_xxxxxx) with the prefix, "dem", indicating the file is a DEM and the last seven characters corresponding to the map reference code of the

  13. NOAA orthorectified Digital Elevation Model (DEM) image tiles, Bombay Hook, Delaware, 2011 (NODC Accession 0112173)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Bombay Hook Project covers 177 square kilometers of the Bombay Hook National Wildlife Refuge and surrounding areas in Kent County, Delaware. The Dewberry...

  14. Evaluating the Effects of Reductions in LiDAR Data on the Visual and Statistical Characteristics of the Created Digital Elevation Models

    Science.gov (United States)

    Asal, F. F.

    2016-06-01

    With continuous developments in LiDAR technologies high point cloud densities have been attainable but accompanied by challenges for processing big volumes of data. Reductions in high point cloud densities are expected to lower data acquisition and data processing costs; however this could affect the characteristics of the generated Digital Elevation Models (DEMs). This research aimed to evaluate the effects of reductions in airborne LiDAR point cloud data densities on the visual and statistical characteristics of the generated DEMs. DEMs have been created from a dataset which constitutes last returns of raw LiDAR data that was acquired at bare lands for Gilmer County, USA between March and April 2004, where qualitative and quantitative testing analyses have been performed. Visual analysis has shown that the DEM can withstand a considerable degree of quality with reduced densities down to 0.128 pts/m2 (47 % of the data remaining), however degradations in the DEM visual characteristics appeared in coarser tones and rougher textures have occurred with more reductions. Additionally, the statistical analysis has indicated that the standard deviations of the DEM elevations have decreased by only 22 % of the total decrease with data density reductions down to 0.101 pts/m2 (37 % of the data remaining) while greater rate of decreasing in the standard deviations has occurred with more reductions referring to greater rate of surface smoothing and elevation approximating. Furthermore, the accuracy analysis testing has given that the DEM accuracy has degraded by only 4.83 % of the total degradations with data density reductions down to 0.128 pts/m2, however great deteriorations in the DEM accuracy have occurred with more data reductions. Finally, it is recommended that LiDAR data can withstand point density reductions down to 0.128 pts/m2 (about 50 % of the data) without big deteriorations in the visual and statistical characteristics of the generated DEMs.

  15. Digital terrain modeling with the Chebyshev polynomials

    CERN Document Server

    Florinsky, I V

    2015-01-01

    Mathematical problems of digital terrain analysis include interpolation of digital elevation models (DEMs), DEM generalization and denoising, and computation of morphometric variables by calculation of partial derivatives of elevation. Traditionally, these procedures are based on numerical treatments of two-variable discrete functions of elevation. We developed a spectral analytical method and algorithm based on high-order orthogonal expansions using the Chebyshev polynomials of the first kind with the subsequent Fejer summation. The method and algorithm are intended for DEM analytical treatment, such as, DEM global approximation, denoising, and generalization as well as computation of morphometric variables by analytical calculation of partial derivatives. To test the method and algorithm, we used a DEM of the Northern Andes including 230,880 points (the elevation matrix 480 $\\times$ 481). DEMs were reconstructed with 480, 240, 120, 60, and 30 expansion coefficients. The first and second partial derivatives ...

  16. Anisotropic Third-Order Regularization for Sparse Digital Elevation Models

    KAUST Repository

    Lellmann, Jan

    2013-01-01

    We consider the problem of interpolating a surface based on sparse data such as individual points or level lines. We derive interpolators satisfying a list of desirable properties with an emphasis on preserving the geometry and characteristic features of the contours while ensuring smoothness across level lines. We propose an anisotropic third-order model and an efficient method to adaptively estimate both the surface and the anisotropy. Our experiments show that the approach outperforms AMLE and higher-order total variation methods qualitatively and quantitatively on real-world digital elevation data. © 2013 Springer-Verlag.

  17. Impacts of DEM uncertainties on critical source areas identification for non-point source pollution control based on SWAT model

    Science.gov (United States)

    Xu, Fei; Dong, Guangxia; Wang, Qingrui; Liu, Lumeng; Yu, Wenwen; Men, Cong; Liu, Ruimin

    2016-09-01

    The impacts of different digital elevation model (DEM) resolutions, sources and resampling techniques on nutrient simulations using the Soil and Water Assessment Tool (SWAT) model have not been well studied. The objective of this study was to evaluate the sensitivities of DEM resolutions (from 30 m to 1000 m), sources (ASTER GDEM2, SRTM and Topo-DEM) and resampling techniques (nearest neighbor, bilinear interpolation, cubic convolution and majority) to identification of non-point source (NPS) critical source area (CSA) based on nutrient loads using the SWAT model. The Xiangxi River, one of the main tributaries of Three Gorges Reservoir in China, was selected as the study area. The following findings were obtained: (1) Elevation and slope extracted from the DEMs were more sensitive to DEM resolution changes. Compared with the results of the 30 m DEM, 1000 m DEM underestimated the elevation and slope by 104 m and 41.57°, respectively; (2) The numbers of subwatersheds and hydrologic response units (HRUs) were considerably influenced by DEM resolutions, but the total nitrogen (TN) and total phosphorus (TP) loads of each subwatershed showed higher correlations with different DEM sources; (3) DEM resolutions and sources had larger effects on CSAs identifications, while TN and TP CSAs showed different response to DEM uncertainties. TN CSAs were more sensitive to resolution changes, exhibiting six distribution patterns at all DEM resolutions. TP CSAs were sensitive to source and resampling technique changes, exhibiting three distribution patterns for DEM sources and two distribution patterns for DEM resampling techniques. DEM resolutions and sources are the two most sensitive SWAT model DEM parameters that must be considered when nutrient CSAs are identified.

  18. Incorporating DEM uncertainty in coastal inundation mapping.

    Directory of Open Access Journals (Sweden)

    Javier X Leon

    Full Text Available Coastal managers require reliable spatial data on the extent and timing of potential coastal inundation, particularly in a changing climate. Most sea level rise (SLR vulnerability assessments are undertaken using the easily implemented bathtub approach, where areas adjacent to the sea and below a given elevation are mapped using a deterministic line dividing potentially inundated from dry areas. This method only requires elevation data usually in the form of a digital elevation model (DEM. However, inherent errors in the DEM and spatial analysis of the bathtub model propagate into the inundation mapping. The aim of this study was to assess the impacts of spatially variable and spatially correlated elevation errors in high-spatial resolution DEMs for mapping coastal inundation. Elevation errors were best modelled using regression-kriging. This geostatistical model takes the spatial correlation in elevation errors into account, which has a significant impact on analyses that include spatial interactions, such as inundation modelling. The spatial variability of elevation errors was partially explained by land cover and terrain variables. Elevation errors were simulated using sequential Gaussian simulation, a Monte Carlo probabilistic approach. 1,000 error simulations were added to the original DEM and reclassified using a hydrologically correct bathtub method. The probability of inundation to a scenario combining a 1 in 100 year storm event over a 1 m SLR was calculated by counting the proportion of times from the 1,000 simulations that a location was inundated. This probabilistic approach can be used in a risk-aversive decision making process by planning for scenarios with different probabilities of occurrence. For example, results showed that when considering a 1% probability exceedance, the inundated area was approximately 11% larger than mapped using the deterministic bathtub approach. The probabilistic approach provides visually intuitive maps

  19. Karst Depression Detection Using ASTER, ALOS/PRISM and SRTM-Derived Digital Elevation Models in the Bambuí Group, Brazil

    Directory of Open Access Journals (Sweden)

    Osmar Abílio de Carvalho

    2013-12-01

    Full Text Available Remote sensing has been used in karst studies to identify limestone terrain, describe exokarst features, analyze karst depressions, and detect geological structures important to karst development. The aim of this work is to investigate the use of ASTER-, SRTM- and ALOS/PRISM-derived digital elevation models (DEMs to detect and quantify natural karst depressions along the São Francisco River near Barreiras city, northeast Brazil. The study area is a karst landscape characterized by karst depressions (dolines, closed depressions in limestone, many of which contain standing water connected with the ground-water table. The base of dolines is typically sealed with an impermeable clay layer covered by standing water or herbaceous vegetation. We identify dolines by combining the extraction of sink depth from DEMs, morphometric analysis using GIS, and visual interpretation. Our methodology is a semi-automatic approach involving several steps: (a DEM acquisition; (b sink-depth calculation using the difference between the raw DEM and the corresponding DEM with sinks filled; and (c elimination of falsely identified karst depressions using morphometric attributes. The advantages and limitations of the applied methodology using different DEMs are examined by comparison with a sinkhole map generated from traditional geomorphological investigations based on visual interpretation of the high-resolution remote sensing images and field surveys. The threshold values of the depth, area size and circularity index appropriate for distinguishing dolines were identified from the maximum overall accuracy obtained by comparison with a true doline map. Our results indicate that the best performance of the proposed methodology for meso-scale karst feature detection was using ALOS/PRISM data with a threshold depth > 2 m; areas > 13,125 m2 and circularity indexes > 0.3 (overall accuracy of 0.53. The overall correct identification of around half of the true dolines suggests

  20. Method for Measuring the Information Content of Terrain from Digital Elevation Models

    Directory of Open Access Journals (Sweden)

    Lujin Hu

    2015-10-01

    Full Text Available As digital terrain models are indispensable for visualizing and modeling geographic processes, terrain information content is useful for terrain generalization and representation. For terrain generalization, if the terrain information is considered, the generalized terrain may be of higher fidelity. In other words, the richer the terrain information at the terrain surface, the smaller the degree of terrain simplification. Terrain information content is also important for evaluating the quality of the rendered terrain, e.g., the rendered web terrain tile service in Google Maps (Google Inc., Mountain View, CA, USA. However, a unified definition and measures for terrain information content have not been established. Therefore, in this paper, a definition and measures for terrain information content from Digital Elevation Model (DEM, i.e., a digital model or 3D representation of a terrain’s surface data are proposed and are based on the theory of map information content, remote sensing image information content and other geospatial information content. The information entropy was taken as the information measuring method for the terrain information content. Two experiments were carried out to verify the measurement methods of the terrain information content. One is the analysis of terrain information content in different geomorphic types, and the results showed that the more complex the geomorphic type, the richer the terrain information content. The other is the analysis of terrain information content with different resolutions, and the results showed that the finer the resolution, the richer the terrain information. Both experiments verified the reliability of the measurements of the terrain information content proposed in this paper.

  1. Mapping debris-flow hazard in Honolulu using a DEM

    Science.gov (United States)

    Ellen, Stephen D.; Mark, Robert K.; ,

    1993-01-01

    A method for mapping hazard posed by debris flows has been developed and applied to an area near Honolulu, Hawaii. The method uses studies of past debris flows to characterize sites of initiation, volume at initiation, and volume-change behavior during flow. Digital simulations of debris flows based on these characteristics are then routed through a digital elevation model (DEM) to estimate degree of hazard over the area.

  2. VALIDATION OF THE ASTER GLOBAL DIGITAL ELEVATION MODEL VERSION 2 OVER THE CONTERMINOUS UNITED STATES

    Directory of Open Access Journals (Sweden)

    D. Gesch

    2012-07-01

    Full Text Available The ASTER Global Digital Elevation Model Version 2 (GDEM v2 was evaluated over the conterminous United States in a manner similar to the validation conducted for the original GDEM Version 1 (v1 in 2009. The absolute vertical accuracy of GDEM v2 was calculated by comparison with more than 18,000 independent reference geodetic ground control points from the National Geodetic Survey. The root mean square error (RMSE measured for GDEM v2 is 8.68 meters. This compares with the RMSE of 9.34 meters for GDEM v1. Another important descriptor of vertical accuracy is the mean error, or bias, which indicates if a DEM has an overall vertical offset from true ground level. The GDEM v2 mean error of –0.20 meters is a significant improvement over the GDEM v1 mean error of –3.69 meters. The absolute vertical accuracy assessment results, both mean error and RMSE, were segmented by land cover to examine the effects of cover types on measured errors. The GDEM v2 mean errors by land cover class verify that the presence of aboveground features (tree canopies and built structures cause a positive elevation bias, as would be expected for an imaging system like ASTER. In open ground classes (little or no vegetation with significant aboveground height, GDEM v2 exhibits a negative bias on the order of 1 meter. GDEM v2 was also evaluated by differencing with the Shuttle Radar Topography Mission (SRTM dataset. In many forested areas, GDEM v2 has elevations that are higher in the canopy than SRTM.

  3. Decadal region-wide and glacier-wide mass balances derived from multi-temporal ASTER satellite digital elevation models. Validation over the Mont-Blanc area

    Science.gov (United States)

    Berthier, Etienne; Cabot, Vincent; Vincent, Christian; Six, Delphine

    2016-06-01

    Since 2000, a vast archive of stereo-images has been built by the Advanced Spaceborne Thermal Emission and Reflection (ASTER) satellite. Several studies already extracted glacier mass balances from multi-temporal ASTER digital elevation models (DEMs) but they lacked accurate independent data for validation. Here, we apply a linear regression to a time series of 3D-coregistered ASTER DEMs to estimate the rate of surface elevation changes (dh/dtASTER) and geodetic mass balances of Mont-Blanc glaciers (155 km²) between 2000 and 2014. Validation using field and spaceborne geodetic measurements reveals large errors at the individual pixel level (> 1 m a-1) and an accuracy of 0.2-0.3 m a-1 for dh/dtASTER averaged over areas larger than 1 km². For all Mont-Blanc glaciers, the ASTER region-wide mass balance (-1.05±0.37 m water equivalent (w.e.) a-1) agrees remarkably with the one measured using Spot5 and Pléiades DEMs (-1.06±0.23 m w.e. a-1) over their common 2003-2012 period. This multi-temporal ASTER DEM strategy leads to smaller errors than the simple differencing of two ASTER DEMs. By extrapolating dh/dtASTER to mid-February 2000, we infer a mean penetration depth of about 9±3 m for the C-band Shuttle Radar Topographic Mission (SRTM) radar signal, with a strong altitudinal dependency (range 0-12 m). This methodology thus reveals the regional pattern of glacier surface elevation changes and improves our knowledge of the penetration of the radar signal into snow and ice.

  4. Decadal region-wide and glacier-wide mass balances derived from multi-temporal ASTER satellite digital elevation models. Validation over the Mont-Blanc area

    Directory of Open Access Journals (Sweden)

    Etienne eBerthier

    2016-06-01

    Full Text Available Since 2000, a vast archive of stereo-images has been built by the Advanced Spaceborne Thermal Emission and Reflection (ASTER satellite. Several studies already extracted glacier mass balances from multi-temporal ASTER digital elevation models (DEMs but they lacked accurate independent data for validation. Here, we apply a linear regression to a time series of 3D-coregistered ASTER DEMs to estimate the rate of surface elevation changes (dh/dtASTER and geodetic mass balances of Mont-Blanc glaciers (155 km² between 2000 and 2014. Validation using field and spaceborne geodetic measurements reveals large errors at the individual pixel level (> 1 m a-1 and an accuracy of 0.2-0.3 m a-1 for dh/dtASTER averaged over areas larger than 1 km². For all Mont-Blanc glaciers, the ASTER region-wide mass balance (-1.05±0.37 m water equivalent (w.e. a-1 agrees remarkably with the one measured using Spot5 and Pléiades DEMs (-1.06±0.23 m w.e. a-1 over their common 2003-2012 period. This multi-temporal ASTER DEM strategy leads to smaller errors than the simple differencing of two ASTER DEMs. By extrapolating dh/dtASTER to mid-February 2000, we infer a mean penetration depth of about 9±3 m for the C-band Shuttle Radar Topographic Mission (SRTM radar signal, with a strong altitudinal dependency (range 0-12 m. This methodology thus reveals the regional pattern of glacier surface elevation changes and improves our knowledge of the penetration of the radar signal into snow and ice.

  5. DEM generated from InSAR in mountainous terrain and its accuracy analysis

    Science.gov (United States)

    Hu, Hongbing; Zhan, Yulan

    2011-02-01

    Digital Elevation Model (DEM) derived from survey data is accurate but it is very expensive and time-consuming. In recent years, remote sensing techniques including Synthetic Apenture Radar Interferometry (InSAR) had been developed as a powerful method to derive high precision DEM, especially in mountainous or deep forest areas. The purpose of this paper is to illustrate the principle of InSAR and show the result of a case study in Gejiu city, Yunnan province, China. The accuracy of DEM derived from InSAR (abbreviation as InSAR-DEM) is also evaluated by comparing it with DEM generated from topographic map at the scale of 1:50000 (abbreviation as TOP-DEM). The result shows that: (1)The general precision of the whole selected area acquired by subtracting InSAR-DEM from TOP-DEM is that the maximum, the minimum, the RMSE, and the mean of difference of the two DEMs are 203m, -188m, 26.9m and 5.7m respectively. (2)The topographic trend represented by the two DEMs is coincident, even though TOP-DEM is finer than InSAR-DEM, especial at the valley. (3) Contour maps with the interval of 100m and 50m converted from InSAR-DEM and TOP-DEM respectively show accordant relief trend. Contour from TOP-DEM is smoother than that of from InSAR-DEM, while Contour from InSAR-DEM has more islands than that of from TOP-DEM.(4) Coherence has great influence on the precision of InSAR-DEM, the precision of low-coherence area approaches 100 m while that of high-coherence area can up to m level. (5) The relief trend of 6 profiles represented by InSAR-DEM and TOP-DEM is accordant with tiny difference in partial minutiae. InSAR-DEM displays hypsographies at relative flat areas including surface of water, which reflects the influence of flat earth on InSAR to a certain extent.

  6. Effects of lidar point density on bare earth extraction and DEM creation

    Science.gov (United States)

    Puetz, Angela M.; Olsen, R. Chris; Anderson, Brian

    2009-05-01

    Data density has a crucial impact on the accuracy of Digital Elevation Models (DEMs). In this study, DEMs were created from a high point-density LIDAR dataset using the bare earth extraction module in Quick Terrain Modeler. Lower point-density LIDAR collects were simulated by randomly selecting points from the original dataset at a series of decreasing percentages. The DEMs created from the lower resolution datasets are compared to the original DEM. Results show a decrease in DEM accuracy as the resolution of the LIDAR dataset is reduced. Some analysis is made of the types of errors encountered in the lower resolution DEMs. It is also noted that the percentage of points classified as bare earth decreases as the resolution of the LIDAR dataset is reduced.

  7. A new kinematic approach for the Danakil block using a Digital Elevation Model representation

    Science.gov (United States)

    Collet, B.; Taud, H.; Parrot, J. F.; Bonavia, F.; Chorowicz, J.

    2000-01-01

    Data from the literature are integrated in a regional Digital Elevation Model (DEM) in order to analyse the motion of the Danakil block with regard to the Arabian and Somalian plates. The application of the poles and angles of rotation taken from the literature, induces a superposition of the Danakil block on the Arabian plate, and the formation of a gap in the Afar region. The determination of new poles of rotation using a best-fitting procedure allows one to avoid these drawbacks. In all cases, calculations are carried out keeping the Nubian plate stationary. The present approach shows that the Danakil block is an independent entity and is not related to the Nubian and Arabian plates. Between the Oligocene and the Miocene, it has been submitted to a N20°E sinistral strike-slip motion anterior to the rotation itself that was started in the middle Miocene. This rotation is directed by a mechanical couple due to the combination of the Red Sea and North Afar extensions.

  8. The Need of Nested Grids for Aerial and Satellite Images and Digital Elevation Models

    Science.gov (United States)

    Villa, G.; Mas, S.; Fernández-Villarino, X.; Martínez-Luceño, J.; Ojeda, J. C.; Pérez-Martín, B.; Tejeiro, J. A.; García-González, C.; López-Romero, E.; Soteres, C.

    2016-06-01

    Usual workflows for production, archiving, dissemination and use of Earth observation images (both aerial and from remote sensing satellites) pose big interoperability problems, as for example: non-alignment of pixels at the different levels of the pyramids that makes it impossible to overlay, compare and mosaic different orthoimages, without resampling them and the need to apply multiple resamplings and compression-decompression cycles. These problems cause great inefficiencies in production, dissemination through web services and processing in "Big Data" environments. Most of them can be avoided, or at least greatly reduced, with the use of a common "nested grid" for mutiresolution production, archiving, dissemination and exploitation of orthoimagery, digital elevation models and other raster data. "Nested grids" are space allocation schemas that organize image footprints, pixel sizes and pixel positions at all pyramid levels, in order to achieve coherent and consistent multiresolution coverage of a whole working area. A "nested grid" must be complemented by an appropriate "tiling schema", ideally based on the "quad-tree" concept. In the last years a "de facto standard" grid and Tiling Schema has emerged and has been adopted by virtually all major geospatial data providers. It has also been adopted by OGC in its "WMTS Simple Profile" standard. In this paper we explain how the adequate use of this tiling schema as common nested grid for orthoimagery, DEMs and other types of raster data constitutes the most practical solution to most of the interoperability problems of these types of data.

  9. A semi-automated tool for reducing the creation of false closed depressions from a filled LIDAR-derived digital elevation model

    Science.gov (United States)

    Waller, John S.; Doctor, Daniel H.; Terziotti, Silvia

    2015-01-01

    Closed depressions on the land surface can be identified by ‘filling’ a digital elevation model (DEM) and subtracting the filled model from the original DEM. However, automated methods suffer from artificial ‘dams’ where surface streams cross under bridges and through culverts. Removal of these false depressions from an elevation model is difficult due to the lack of bridge and culvert inventories; thus, another method is needed to breach these artificial dams. Here, we present a semi-automated workflow and toolbox to remove falsely detected closed depressions created by artificial dams in a DEM. The approach finds the intersections between transportation routes (e.g., roads) and streams, and then lowers the elevation surface across the roads to stream level allowing flow to be routed under the road. Once the surface is corrected to match the approximate location of the National Hydrologic Dataset stream lines, the procedure is repeated with sequentially smaller flow accumulation thresholds in order to generate stream lines with less contributing area within the watershed. Through multiple iterations, artificial depressions that may arise due to ephemeral flow paths can also be removed. Preliminary results reveal that this new technique provides significant improvements for flow routing across a DEM and minimizes artifacts within the elevation surface. Slight changes in the stream flow lines generally improve the quality of flow routes; however some artificial dams may persist. Problematic areas include extensive road ditches, particularly along divided highways, and where surface flow crosses beneath road intersections. Limitations do exist, and the results partially depend on the quality of data being input. Of 166 manually identified culverts from a previous study by Doctor and Young in 2013, 125 are within 25 m of culverts identified by this tool. After three iterations, 1,735 culverts were identified and cataloged. The result is a reconditioned

  10. Countrywide digital elevation models for the Islamic Republic of Mauritania—SRTM and ASTER (phase V, deliverable 65): Chapter F in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    Science.gov (United States)

    Lee, Gregory K.

    2015-01-01

    A digital elevation model (DEM) of the entire country of the Islamic Republic of Mauritania was produced using Shuttle Radar Topography Mission (SRTM) data as required for deliverable 65 of the contract. In addition, because of significant recent advancements of availability, seamlessness, and validity of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global elevation data, the U.S. Geological Survey (USGS) extended its efforts to include a higher resolution countrywide ASTER DEM as value added to the required Deliverable 63, which was limited to five areas within the country. Both SRTM and ASTER countrywide DEMs have been provided in ERDAS Imagine (.img) format that is also directly compatible with ESRI ArcMap, ArcGIS Explorer, and other GIS applications.

  11. PREPARATION OF THE DIGITAL ELEVATION MODEL FOR ORTHOPHOTO CR PRODUCTION

    Directory of Open Access Journals (Sweden)

    Z. Švec

    2016-06-01

    Full Text Available The Orthophoto CR is produced in co-operation with the Land Survey Office and the Military Geographical and Hydrometeorological Office. The product serves to ensure a defence of the state, integrated crisis management, civilian tasks in support of the state administration and the local self-government of the Czech Republic as well. It covers the whole area of the Republic and for ensuring its up-to-datedness is reproduced in the biennial period. As the project is countrywide, it keeps the project within the same parameters in urban and rural areas as well. Due to economic reasons it can´t be produced as a true ortophoto because it requires large side and forward overlaps of the aerial photographs and a preparation of the digital surface model instead of the digital terrain model. Use of DTM without some objects of DSM for orthogonalization purposes cause undesirable image deformations in the Orthophoto. There are a few data sets available for forming a suitable elevation model. The principal source should represent DTMs made from data acquired by the airborne laser scanning of the entire area of the Czech Republic that was carried out in the years 2009-2013, the DMR4G in the grid form and the DMR5G in TIN form respectively. It can be replenished by some vector objects (bridges, dams, etc. taken from the geographic base data of the Czech Republic or obtained by new stereo plotting. It has to be taken into account that the option of applying DSM made from image correlation is also available. The article focuses on the possibilities of DTM supplement for ortogonalization. It looks back to the recent transition from grid to hybrid elevation models, problems that occurred, its solution and getting some practical remarks. Afterwards it assesses the current state and deals with the options for updating the model. Some accuracy analysis are included.

  12. Preparation of the Digital Elevation Model for Orthophoto CR Production

    Science.gov (United States)

    Švec, Z.; Pavelka, K.

    2016-06-01

    The Orthophoto CR is produced in co-operation with the Land Survey Office and the Military Geographical and Hydrometeorological Office. The product serves to ensure a defence of the state, integrated crisis management, civilian tasks in support of the state administration and the local self-government of the Czech Republic as well. It covers the whole area of the Republic and for ensuring its up-to-datedness is reproduced in the biennial period. As the project is countrywide, it keeps the project within the same parameters in urban and rural areas as well. Due to economic reasons it cańt be produced as a true ortophoto because it requires large side and forward overlaps of the aerial photographs and a preparation of the digital surface model instead of the digital terrain model. Use of DTM without some objects of DSM for orthogonalization purposes cause undesirable image deformations in the Orthophoto. There are a few data sets available for forming a suitable elevation model. The principal source should represent DTMs made from data acquired by the airborne laser scanning of the entire area of the Czech Republic that was carried out in the years 2009-2013, the DMR4G in the grid form and the DMR5G in TIN form respectively. It can be replenished by some vector objects (bridges, dams, etc.) taken from the geographic base data of the Czech Republic or obtained by new stereo plotting. It has to be taken into account that the option of applying DSM made from image correlation is also available. The article focuses on the possibilities of DTM supplement for ortogonalization. It looks back to the recent transition from grid to hybrid elevation models, problems that occurred, its solution and getting some practical remarks. Afterwards it assesses the current state and deals with the options for updating the model. Some accuracy analysis are included.

  13. A COM-based Framework for Management,Analysis and Visualization of Large Scope Digital Elevation Models

    Institute of Scientific and Technical Information of China (English)

    WANG Yongjun; GONG Jianya

    2003-01-01

    This paper presents a component object model (COM) based framework for managing, analyzing and visualizing massive multi-scale digital elevation models (DEMs). The framework consists of a data management component (DMC), which is based on RDBMS/ORDBMS, a data analysis component (DAC) and a data render component (DRC). DMC can manage massive multi-scale data expressed at various reference frames within a pyramid database and can support fast access to data at variable resolution. DAC integrates many useful applied analytic functions whose resuits can be overlaid with the 3D scene rendered by DRC. DRC provides viewdependent data paging with the support of the underlying DMC and organizes the potential visible data at different levels into rendering.

  14. Improving maps of ice-sheet surface elevation change using combined laser altimeter and stereoscopic elevation model data

    DEFF Research Database (Denmark)

    Fredenslund Levinsen, Joanna; Howat, I. M.; Tscherning, C. C.

    2013-01-01

    laser altimeters have relatively low errors but are spatially limited to the ground tracks, while DEMs have larger errors but provide spatially continuous surfaces. The principle of our method is to fit the DEM surface to the altimeter point clouds in time and space to minimize the DEM errors and use......We combine the complementary characteristics of laser altimeter data and stereoscopic digital elevation models (DEMs) to construct high-resolution (_100 m) maps of surface elevations and elevation changes over rapidly changing outlet glaciers in Greenland. Measurements from spaceborne and airborne...... that surface to extrapolate elevations away from altimeter flight lines. This reduces the DEM registration errors and fills the gap between the altimeter paths. We use data from ICESat and ATM as well as SPOT 5 DEMs from 2007 and 2008 and apply them to the outlet glaciers Jakobshavn Isbræ (JI...

  15. High-resolution DEM Effects on Geophysical Flow Models

    Science.gov (United States)

    Williams, M. R.; Bursik, M. I.; Stefanescu, R. E. R.; Patra, A. K.

    2014-12-01

    Geophysical mass flow models are numerical models that approximate pyroclastic flow events and can be used to assess the volcanic hazards certain areas may face. One such model, TITAN2D, approximates granular-flow physics based on a depth-averaged analytical model using inputs of basal and internal friction, material volume at a coordinate point, and a GIS in the form of a digital elevation model (DEM). The volume of modeled material propagates over the DEM in a way that is governed by the slope and curvature of the DEM surface and the basal and internal friction angles. Results from TITAN2D are highly dependent upon the inputs to the model. Here we focus on a single input: the DEM, which can vary in resolution. High resolution DEMs are advantageous in that they contain more surface details than lower-resolution models, presumably allowing modeled flows to propagate in a way more true to the real surface. However, very high resolution DEMs can create undesirable artifacts in the slope and curvature that corrupt flow calculations. With high-resolution DEMs becoming more widely available and preferable for use, determining the point at which high resolution data is less advantageous compared to lower resolution data becomes important. We find that in cases of high resolution, integer-valued DEMs, very high-resolution is detrimental to good model outputs when moderate-to-low (<10-15°) slope angles are involved. At these slope angles, multiple adjacent DEM cell elevation values are equal due to the need for the DEM to approximate the low slope with a limited set of integer values for elevation. The first derivative of the elevation surface thus becomes zero. In these cases, flow propagation is inhibited by these spurious zero-slope conditions. Here we present evidence for this "terracing effect" from 1) a mathematically defined simulated elevation model, to demonstrate the terracing effects of integer valued data, and 2) a real-world DEM where terracing must be

  16. Hydro-flattened Elevation Area Outlines for DEMs of the North-Central California Coast (Hydro_flattened_water.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A GIS polygon shapefile outlining the extent of small lakes or ponds within the terrain that were assigned a hydo-flattened elevation during lidar post-processing....

  17. Hydro-flattened Elevation Area Outlines for DEMs of the North-Central California Coast (Hydro_flattened_water.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A GIS polygon shapefile outlining the extent of small lakes or ponds within the terrain that were assigned a hydo-flattened elevation during lidar post-processing....

  18. Improved estimation of flood parameters by combining space based SAR data with very high resolution digital elevation data

    Directory of Open Access Journals (Sweden)

    H. Zwenzner

    2009-05-01

    Full Text Available Severe flood events turned out to be the most devastating catastrophes for Europe's population, economy and environment during the past decades. The total loss caused by the August 2002 flood is estimated to be 10 billion Euros for Germany alone. Due to their capability to present a synoptic view of the spatial extent of floods, remote sensing technology, and especially synthetic aperture radar (SAR systems, have been successfully applied for flood mapping and monitoring applications. However, the quality and accuracy of the flood masks and derived flood parameters always depends on the scale and the geometric precision of the original data as well as on the classification accuracy of the derived data products. The incorporation of auxiliary information such as elevation data can help to improve the plausibility and reliability of the derived flood masks as well as higher level products. This paper presents methods to improve the matching of flood masks with very high resolution digital elevation models as derived from LiDAR measurements for example. In the following, a cross section approach is presented that allows the dynamic fitting of the position of flood mask profiles according to the underlying terrain information from the DEM. This approach is tested in two study areas, using different input data sets. The first test area is part of the Elbe River (Germany where flood masks derived from Radarsat-1 and IKONOS during the 2002 flood are used in combination with a LiDAR DEM of 1 m spatial resolution. The other test data set is located on the River Severn (UK and flood masks derived from the TerraSAR-X satellite and aerial photos acquired during the 2007 flood are used in combination with a LiDAR DEM of 2 m pixel spacing. By means of these two examples the performance of the matching technique and the scaling effects are analysed and discussed. Furthermore, the systematic flood mapping capability of the different imaging systems are

  19. Geomorphic Map of Worcester County, Maryland, Interpreted from a LIDAR-Based, Digital Elevation Model

    Science.gov (United States)

    Newell, Wayne L.; Clark, Inga

    2008-01-01

    A recently compiled mosaic of a LIDAR-based digital elevation model (DEM) is presented with geomorphic analysis of new macro-topographic details. The geologic framework of the surficial and near surface late Cenozoic deposits of the central uplands, Pocomoke River valley, and the Atlantic Coast includes Cenozoic to recent sediments from fluvial, estuarine, and littoral depositional environments. Extensive Pleistocene (cold climate) sandy dune fields are deposited over much of the terraced landscape. The macro details from the LIDAR image reveal 2 meter-scale resolution of details of the shapes of individual dunes, and fields of translocated sand sheets. Most terrace surfaces are overprinted with circular to elliptical rimmed basins that represent complex histories of ephemeral ponds that were formed, drained, and overprinted by younger basins. The terrains of composite ephemeral ponds and the dune fields are inter-shingled at their margins indicating contemporaneous erosion, deposition, and re-arrangement and possible internal deformation of the surficial deposits. The aggregate of these landform details and their deposits are interpreted as the products of arid, cold climate processes that were common to the mid-Atlantic region during the Last Glacial Maximum. In the Pocomoke valley and its larger tributaries, erosional remnants of sandy flood plains with anastomosing channels indicate the dynamics of former hydrology and sediment load of the watershed that prevailed at the end of the Pleistocene. As the climate warmed and precipitation increased during the transition from late Pleistocene to Holocene, dune fields were stabilized by vegetation, and the stream discharge increased. The increased discharge and greater local relief of streams graded to lower sea levels stimulated down cutting and created the deeply incised valleys out onto the continental shelf. These incised valleys have been filling with fluvial to intertidal deposits that record the rising sea

  20. Shuttle radar DEM hydrological correction for erosion modelling in small catchments

    Science.gov (United States)

    Jarihani, Ben; Sidle, Roy; Bartley, Rebecca

    2016-04-01

    Digital Elevation Models (DEMs) that accurately replicate both landscape form and processes are critical to support modelling of environmental processes. Catchment and hillslope scale runoff and sediment processes (i.e., patterns of overland flow, infiltration, subsurface stormflow and erosion) are all topographically mediated. In remote and data-scarce regions, high resolution DEMs (LiDAR) are often not available, and moderate to course resolution digital elevation models (e.g., SRTM) have difficulty replicating detailed hydrological patterns, especially in relatively flat landscapes. Several surface reconditioning algorithms (e.g., Smoothing) and "Stream burning" techniques (e.g., Agree or ANUDEM), in conjunction with representation of the known stream networks, have been used to improve DEM performance in replicating known hydrology. Detailed stream network data are not available at regional and national scales, but can be derived at local scales from remotely-sensed data. This research explores the implication of high resolution stream network data derived from Google Earth images for DEM hydrological correction, instead of using course resolution stream networks derived from topographic maps. The accuracy of implemented method in producing hydrological-efficient DEMs were assessed by comparing the hydrological parameters derived from modified DEMs and limited high-resolution airborne LiDAR DEMs. The degree of modification is dominated by the method used and availability of the stream network data. Although stream burning techniques improve DEMs hydrologically, these techniques alter DEM characteristics that may affect catchment boundaries, stream position and length, as well as secondary terrain derivatives (e.g., slope, aspect). Modification of a DEM to better reflect known hydrology can be useful, however, knowledge of the magnitude and spatial pattern of the changes are required before using a DEM for subsequent analyses.

  1. Modelling groundwater discharge areas using only digital elevation models as input data

    Energy Technology Data Exchange (ETDEWEB)

    Brydsten, Lars [Umeaa Univ. (Sweden). Dept. of Biology and Environmental Science

    2006-10-15

    Advanced geohydrological models require data on topography, soil distribution in three dimensions, vegetation, land use, bedrock fracture zones. To model present geohydrological conditions, these factors can be gathered with different techniques. If a future geohydrological condition is modelled in an area with positive shore displacement (say 5,000 or 10,000 years), some of these factors can be difficult to measure. This could include the development of wetlands and the filling of lakes. If the goal of the model is to predict distribution of groundwater recharge and discharge areas in the landscape, the most important factor is topography. The question is how much can topography alone explain the distribution of geohydrological objects in the landscape. A simplified description of the distribution of geohydrological objects in the landscape is that groundwater recharge areas occur at local elevation curvatures and discharge occurs in lakes, brooks, and low situated slopes. Areas in-between these make up discharge areas during wet periods and recharge areas during dry periods. A model that could predict this pattern only using topography data needs to be able to predict high ridges and future lakes and brooks. This study uses GIS software with four different functions using digital elevation models as input data, geomorphometrical parameters to predict landscape ridges, basin fill for predicting lakes, flow accumulations for predicting future waterways, and topographical wetness indexes for dividing in-between areas based on degree of wetness. An area between the village of and Forsmarks' Nuclear Power Plant has been used to calibrate the model. The area is within the SKB 10-metre Elevation Model (DEM) and has a high-resolution orienteering map for wetlands. Wetlands are assumed to be groundwater discharge areas. Five hundred points were randomly distributed across the wetlands. These are potential discharge points. Model parameters were chosen with the

  2. Methods for calculating glacier area and length in a mountainous area based on remote-sensing data and a digital elevation model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In a mountainous region, the glacier area and length extracted form the satellite imagery data is the projected area and length of the land surface, which can’t be representative of the reality; there are always some errors. In this paper, the methods of calculating glacier area and length calculation were put forward based on satellite imagery data and a digital elevation model (DEM). The pure pixels and the mixed pixels were extracted based on the linear spectral un-mixing approach, the slop of the pixels was calculated based on the DEM, then the area calculation method was presented. The projection length was obtained from the satellite imagery data, and the elevation differences was calculated from the DEM. The length calculation method was presented based on the Pythagorean theorem. For a glacier in the study area of western Qilian Mountain, northwestern China, the projected area and length were 140.93 km2 and 30.82 km, respectively. This compares with the results calculated by the methods in this paper, which were 155.16 km2 and 32.11 km respectively, a relative error of the projected area and length extracted from the LandSat Thematic Mapper (TM) image directly reach to -9.2 percent and -4.0 percent, respectively. The calculation method is more in accord with the practicality and can provide reference for some other object’s area and length monitoring in a mountainous region.

  3. 3D Color Digital Elevation Map of AFM Sample

    Science.gov (United States)

    2008-01-01

    This color image is a three dimensional (3D) view of a digital elevation map of a sample collected by NASA's Phoenix Mars Lander's Atomic Force Microscope (AFM). The image shows four round pits, only 5 microns in depth, that were micromachined into the silicon substrate, which is the background plane shown in red. This image has been processed to reflect the levelness of the substrate. A Martian particle only one micrometer, or one millionth of a meter, across is held in the upper left pit. The rounded particle shown at the highest magnification ever seen from another world is a particle of the dust that cloaks Mars. Such dust particles color the Martian sky pink, feed storms that regularly envelop the planet and produce Mars' distinctive red soil. The particle was part of a sample informally called 'Sorceress' delivered to the AFM on the 38th Martian day, or sol, of the mission (July 2, 2008). The AFM is part of Phoenix's microscopic station called MECA, or the Microscopy, Electrochemistry, and Conductivity Analyzer. The AFM was developed by a Swiss-led consortium, with Imperial College London producing the silicon substrate that holds sampled particles. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  4. Uncertainty of soil erosion modelling using open source high resolution and aggregated DEMs

    Directory of Open Access Journals (Sweden)

    Arun Mondal

    2017-05-01

    Full Text Available Digital Elevation Model (DEM is one of the important parameters for soil erosion assessment. Notable uncertainties are observed in this study while using three high resolution open source DEMs. The Revised Universal Soil Loss Equation (RUSLE model has been applied to analysis the assessment of soil erosion uncertainty using open source DEMs (SRTM, ASTER and CARTOSAT and their increasing grid space (pixel size from the actual. The study area is a part of the Narmada river basin in Madhya Pradesh state, which is located in the central part of India and the area covered 20,558 km2. The actual resolution of DEMs is 30 m and their increasing grid spaces are taken as 90, 150, 210, 270 and 330 m for this study. Vertical accuracy of DEMs has been assessed using actual heights of the sample points that have been taken considering planimetric survey based map (toposheet. Elevations of DEMs are converted to the same vertical datum from WGS 84 to MSL (Mean Sea Level, before the accuracy assessment and modelling. Results indicate that the accuracy of the SRTM DEM with the RMSE of 13.31, 14.51, and 18.19 m in 30, 150 and 330 m resolution respectively, is better than the ASTER and the CARTOSAT DEMs. When the grid space of the DEMs increases, the accuracy of the elevation and calculated soil erosion decreases. This study presents a potential uncertainty introduced by open source high resolution DEMs in the accuracy of the soil erosion assessment models. The research provides an analysis of errors in selecting DEMs using the original and increased grid space for soil erosion modelling.

  5. Submarine Melting of Icebergs from Repeat High-Resolution Digital Elevation Models

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; Straneo, F.; Cenedese, C.

    2014-12-01

    Icebergs calved from tidewater glaciers act as distributed freshwater sources as they transit through fjords to the surrounding ocean basins. Glacier discharge estimates provide a crude approximation of the total iceberg discharge on inter-annual timescales, but the liquid freshwater flux from icebergs in glacial fjords is largely unknown. Here we use repeat high-resolution digital elevation models (DEMs) to derive meltwater fluxes for 18 icebergs in Sermilik Fjord, East Greenland, during the 2011-2013 boreal summers, and for 33 comparably-sized icebergs in Ilulissat Fjord, West Greenland, during March-April 2011 and July 2012. We find that iceberg melt rates for Sermilik Fjord are in good agreement with simulated melt rates along the vertical terminus of Helheim Glacier in winter, i.e. when melting at the glacier front is not enhanced by subglacial discharge, providing an independent validation of our technique. Variations in meltwater fluxes from icebergs are primarily related to differences in the submerged area of individual icebergs, which is consistent with theory. The stratification of water masses in fjords has a noticeable effect on summertime-derived melt estimates, with lower melt rates (and meltwater fluxes) observed in the relatively cold and fresh Polar Water layer and higher melt rates in the underlying warmer and more saline Atlantic Water layer. The meltwater flux dependence on submerged area, particularly within the deeper Atlantic Water layer, suggests that changes in the characteristics of icebergs (size/shape/keel-depth) calved from a tidewater glacier will alter the magnitude and distribution of meltwater fluxes within the fjord, which may in turn influence fjord circulation and the heat content delivered to the glacier terminus.

  6. Automated identification of potential snow avalanche release areas based on digital elevation models

    Directory of Open Access Journals (Sweden)

    Y. Bühler

    2013-05-01

    Full Text Available The identification of snow avalanche release areas is a very difficult task. The release mechanism of snow avalanches depends on many different terrain, meteorological, snowpack and triggering parameters and their interactions, which are very difficult to assess. In many alpine regions such as the Indian Himalaya, nearly no information on avalanche release areas exists mainly due to the very rough and poorly accessible terrain, the vast size of the region and the lack of avalanche records. However avalanche release information is urgently required for numerical simulation of avalanche events to plan mitigation measures, for hazard mapping and to secure important roads. The Rohtang tunnel access road near Manali, Himachal Pradesh, India, is such an example. By far the most reliable way to identify avalanche release areas is using historic avalanche records and field investigations accomplished by avalanche experts in the formation zones. But both methods are not feasible for this area due to the rough terrain, its vast extent and lack of time. Therefore, we develop an operational, easy-to-use automated potential release area (PRA detection tool in Python/ArcGIS which uses high spatial resolution digital elevation models (DEMs and forest cover information derived from airborne remote sensing instruments as input. Such instruments can acquire spatially continuous data even over inaccessible terrain and cover large areas. We validate our tool using a database of historic avalanches acquired over 56 yr in the neighborhood of Davos, Switzerland, and apply this method for the avalanche tracks along the Rohtang tunnel access road. This tool, used by avalanche experts, delivers valuable input to identify focus areas for more-detailed investigations on avalanche release areas in remote regions such as the Indian Himalaya and is a precondition for large-scale avalanche hazard mapping.

  7. THE NEED OF NESTED GRIDS FOR AERIAL AND SATELLITE IMAGES AND DIGITAL ELEVATION MODELS

    Directory of Open Access Journals (Sweden)

    G. Villa

    2016-06-01

    Full Text Available Usual workflows for production, archiving, dissemination and use of Earth observation images (both aerial and from remote sensing satellites pose big interoperability problems, as for example: non-alignment of pixels at the different levels of the pyramids that makes it impossible to overlay, compare and mosaic different orthoimages, without resampling them and the need to apply multiple resamplings and compression-decompression cycles. These problems cause great inefficiencies in production, dissemination through web services and processing in “Big Data” environments. Most of them can be avoided, or at least greatly reduced, with the use of a common “nested grid” for mutiresolution production, archiving, dissemination and exploitation of orthoimagery, digital elevation models and other raster data. “Nested grids” are space allocation schemas that organize image footprints, pixel sizes and pixel positions at all pyramid levels, in order to achieve coherent and consistent multiresolution coverage of a whole working area. A “nested grid” must be complemented by an appropriate “tiling schema”, ideally based on the “quad-tree” concept. In the last years a “de facto standard” grid and Tiling Schema has emerged and has been adopted by virtually all major geospatial data providers. It has also been adopted by OGC in its “WMTS Simple Profile” standard. In this paper we explain how the adequate use of this tiling schema as common nested grid for orthoimagery, DEMs and other types of raster data constitutes the most practical solution to most of the interoperability problems of these types of data.

  8. VALIDATION OF THE ASTER GLOBAL DIGITAL ELEVATION MODEL VERSION 3 OVER THE CONTERMINOUS UNITED STATES

    Directory of Open Access Journals (Sweden)

    D. Gesch

    2016-06-01

    Full Text Available The ASTER Global Digital Elevation Model Version 3 (GDEM v3 was evaluated over the conterminous United States in a manner similar to the validation conducted for the original GDEM Version 1 (v1 in 2009 and GDEM Version 2 (v2 in 2011. The absolute vertical accuracy of GDEM v3 was calculated by comparison with more than 23,000 independent reference geodetic ground control points from the U.S. National Geodetic Survey. The root mean square error (RMSE measured for GDEM v3 is 8.52 meters. This compares with the RMSE of 8.68 meters for GDEM v2. Another important descriptor of vertical accuracy is the mean error, or bias, which indicates if a DEM has an overall vertical offset from true ground level. The GDEM v3 mean error of −1.20 meters reflects an overall negative bias in GDEM v3. The absolute vertical accuracy assessment results, both mean error and RMSE, were segmented by land cover type to provide insight into how GDEM v3 performs in various land surface conditions. While the RMSE varies little across cover types (6.92 to 9.25 meters, the mean error (bias does appear to be affected by land cover type, ranging from −2.99 to +4.16 meters across 14 land cover classes. These results indicate that in areas where built or natural aboveground features are present, GDEM v3 is measuring elevations above the ground level, a condition noted in assessments of previous GDEM versions (v1 and v2 and an expected condition given the type of stereo-optical image data collected by ASTER. GDEM v3 was also evaluated by differencing with the Shuttle Radar Topography Mission (SRTM dataset. In many forested areas, GDEM v3 has elevations that are higher in the canopy than SRTM. The overall validation effort also included an evaluation of the GDEM v3 water mask. In general, the number of distinct water polygons in GDEM v3 is much lower than the number in a reference land cover dataset, but the total areas compare much more closely.

  9. Validation of the ASTER Global Digital Elevation Model version 3 over the conterminous United States

    Science.gov (United States)

    Gesch, Dean B.; Oimoen, Michael J.; Danielson, Jeffrey J.; Meyer, David

    2016-01-01

    The ASTER Global Digital Elevation Model Version 3 (GDEM v3) was evaluated over the conterminous United States in a manner similar to the validation conducted for the original GDEM Version 1 (v1) in 2009 and GDEM Version 2 (v2) in 2011. The absolute vertical accuracy of GDEM v3 was calculated by comparison with more than 23,000 independent reference geodetic ground control points from the U.S. National Geodetic Survey. The root mean square error (RMSE) measured for GDEM v3 is 8.52 meters. This compares with the RMSE of 8.68 meters for GDEM v2. Another important descriptor of vertical accuracy is the mean error, or bias, which indicates if a DEM has an overall vertical offset from true ground level. The GDEM v3 mean error of −1.20 meters reflects an overall negative bias in GDEM v3. The absolute vertical accuracy assessment results, both mean error and RMSE, were segmented by land cover type to provide insight into how GDEM v3 performs in various land surface conditions. While the RMSE varies little across cover types (6.92 to 9.25 meters), the mean error (bias) does appear to be affected by land cover type, ranging from −2.99 to +4.16 meters across 14 land cover classes. These results indicate that in areas where built or natural aboveground features are present, GDEM v3 is measuring elevations above the ground level, a condition noted in assessments of previous GDEM versions (v1 and v2) and an expected condition given the type of stereo-optical image data collected by ASTER. GDEM v3 was also evaluated by differencing with the Shuttle Radar Topography Mission (SRTM) dataset. In many forested areas, GDEM v3 has elevations that are higher in the canopy than SRTM. The overall validation effort also included an evaluation of the GDEM v3 water mask. In general, the number of distinct water polygons in GDEM v3 is much lower than the number in a reference land cover dataset, but the total areas compare much more closely.

  10. Validation of the Aster Global Digital Elevation Model Version 3 Over the Conterminous United States

    Science.gov (United States)

    Gesch, D.; Oimoen, M.; Danielson, J.; Meyer, D.

    2016-06-01

    The ASTER Global Digital Elevation Model Version 3 (GDEM v3) was evaluated over the conterminous United States in a manner similar to the validation conducted for the original GDEM Version 1 (v1) in 2009 and GDEM Version 2 (v2) in 2011. The absolute vertical accuracy of GDEM v3 was calculated by comparison with more than 23,000 independent reference geodetic ground control points from the U.S. National Geodetic Survey. The root mean square error (RMSE) measured for GDEM v3 is 8.52 meters. This compares with the RMSE of 8.68 meters for GDEM v2. Another important descriptor of vertical accuracy is the mean error, or bias, which indicates if a DEM has an overall vertical offset from true ground level. The GDEM v3 mean error of -1.20 meters reflects an overall negative bias in GDEM v3. The absolute vertical accuracy assessment results, both mean error and RMSE, were segmented by land cover type to provide insight into how GDEM v3 performs in various land surface conditions. While the RMSE varies little across cover types (6.92 to 9.25 meters), the mean error (bias) does appear to be affected by land cover type, ranging from -2.99 to +4.16 meters across 14 land cover classes. These results indicate that in areas where built or natural aboveground features are present, GDEM v3 is measuring elevations above the ground level, a condition noted in assessments of previous GDEM versions (v1 and v2) and an expected condition given the type of stereo-optical image data collected by ASTER. GDEM v3 was also evaluated by differencing with the Shuttle Radar Topography Mission (SRTM) dataset. In many forested areas, GDEM v3 has elevations that are higher in the canopy than SRTM. The overall validation effort also included an evaluation of the GDEM v3 water mask. In general, the number of distinct water polygons in GDEM v3 is much lower than the number in a reference land cover dataset, but the total areas compare much more closely.

  11. High-resolution digital elevation model of Mount St. Helens crater and upper North Fork Toutle River basin, Washington, based on an airborne lidar survey of September 2009

    Science.gov (United States)

    Mosbrucker, Adam

    2014-01-01

    The lateral blast, debris avalanche, and lahars of the May 18th, 1980, eruption of Mount St. Helens, Washington, dramatically altered the surrounding landscape. Lava domes were extruded during the subsequent eruptive periods of 1980–1986 and 2004–2008. More than three decades after the emplacement of the 1980 debris avalanche, high sediment production persists in the North Fork Toutle River basin, which drains the northern flank of the volcano. Because this sediment increases the risk of flooding to downstream communities on the Toutle and Cowlitz Rivers, the U.S. Army Corps of Engineers (USACE), under the direction of Congress to maintain an authorized level of flood protection, built a sediment retention structure on the North Fork Toutle River in 1989 to help reduce this risk and to prevent sediment from clogging the shipping channel of the Columbia River. From September 16–20, 2009, Watershed Sciences, Inc., under contract to USACE, collected high-precision airborne lidar (light detection and ranging) data that cover 214 square kilometers (83 square miles) of Mount St. Helens and the upper North Fork Toutle River basin from the sediment retention structure to the volcano's crater. These data provide a digital dataset of the ground surface, including beneath forest cover. Such remotely sensed data can be used to develop sediment budgets and models of sediment erosion, transport, and deposition. The U.S. Geological Survey (USGS) used these lidar data to develop digital elevation models (DEMs) of the study area. DEMs are fundamental to monitoring natural hazards and studying volcanic landforms, fluvial and glacial geomorphology, and surface geology. Watershed Sciences, Inc., provided files in the LASer (LAS) format containing laser returns that had been filtered, classified, and georeferenced. The USGS produced a hydro-flattened DEM from ground-classified points at Castle, Coldwater, and Spirit Lakes. Final results averaged about five laser last

  12. High-resolution digital elevation model of lower Cowlitz and Toutle Rivers, adjacent to Mount St. Helens, Washington, based on an airborne lidar survey of October 2007

    Science.gov (United States)

    Mosbrucker, Adam

    2015-01-01

    The lateral blast, debris avalanche, and lahars of the May 18th, 1980, eruption of Mount St. Helens, Washington, dramatically altered the surrounding landscape. Lava domes were extruded during the subsequent eruptive periods of 1980–1986 and 2004–2008. More than three decades after the emplacement of the 1980 debris avalanche, high sediment production persists in the Toutle River basin, which drains the northern and western flanks of the volcano. Because this sediment increases the risk of flooding to downstream communities on the Toutle and lower Cowlitz Rivers, the U.S. Army Corps of Engineers (USACE), under the direction of Congress to maintain an authorized level of flood protection, continues to monitor and mitigate excess sediment in North and South Fork Toutle River basins to help reduce this risk and to prevent sediment from clogging the shipping channel of the Columbia River. From October 22–27, 2007, Watershed Sciences, Inc., under contract to USACE, collected high-precision airborne lidar (light detection and ranging) data that cover 273 square kilometers (105 square miles) of lower Cowlitz and Toutle River tributaries from the Columbia River at Kelso, Washington, to upper North Fork Toutle River (below the volcano's edifice), including lower South Fork Toutle River. These data provide a digital dataset of the ground surface, including beneath forest cover. Such remotely sensed data can be used to develop sediment budgets and models of sediment erosion, transport, and deposition. The U.S. Geological Survey (USGS) used these lidar data to develop digital elevation models (DEMs) of the study area. DEMs are fundamental to monitoring natural hazards and studying volcanic landforms, fluvial and glacial geomorphology, and surface geology. Watershed Sciences, Inc., provided files in the LASer (LAS) format containing laser returns that had been filtered, classified, and georeferenced. The USGS produced a hydro-flattened DEM from ground-classified points at

  13. 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...

  14. Global Maps from Interferometeric TanDEM-X Data: Applications and Potentials

    Science.gov (United States)

    Rizzoli, Paola; Martone, Michele; Brautigam, Benjamin; Zink, Manfred

    2015-05-01

    TanDEM-X is a spaceborne Synthetic Aperture Radar (SAR) mission, whose goal is the generation of a global Digital Elevation Model (DEM) with unprecedented accuracy, by using interferometric SAR (InSAR) techniques (InSAR). TanDEM-X offers a huge global data set of bistatic InSAR acquisitions, each of them supplemented by quick look images of different SAR quantities, such as amplitude, coherence, and DEM. Global quick look mosaics of the interferometric coherence and of the relative height error can be considered for mission performance monitoring and acquisition strategy optimization. The aim of this paper is to present the use of such mosaics within the TanDEM-X mission and to show their potentials for future scientific applications for example in the fields of glaciology and forestry.

  15. Evaluating the influence of spatial resolutions of DEM on watershed runoff and sediment yield using SWAT

    Indian Academy of Sciences (India)

    A Sivasena Reddy; M Janga Reddy

    2015-10-01

    Digital elevation model (DEM) of a watershed forms key basis for hydrologic modelling and its resolution plays a key role in accurate prediction of various hydrological processes. This study appraises the effect of different DEMs with varied spatial resolutions (namely TOPO 20 m, CARTO 30 m, ASTER 30 m, SRTM 90 m, GEO-AUS 500 m and USGS 1000 m) on hydrological response of watershed using Soil and Water Assessment Tool (SWAT) and applied for a case study of Kaddam watershed in India for estimating runoff and sediment yield. From the results of case study, it was observed that reach lengths, reach slopes, minimum and maximum elevations, sub-watershed areas, land use mapping areas within the sub-watershed and number of HRUs varied substantially due to DEM resolutions, and consequently resulted in a considerable variability in estimated daily runoff and sediment yields. It was also observed that, daily runoff values have increased (decreased) on low (high) rainy days respectively with coarser resolution of DEM. The daily sediment yield values from each sub-watershed decreased with coarser resolution of the DEM. The study found that the performance of SWAT model prediction was not influenced much for finer resolution DEMs up to 90 m for estimation of runoff, but it certainly influenced the estimation of sediment yields. The DEMs of TOPO 20 m and CARTO 30 m provided better estimates of sub-watershed areas, runoff and sediment yield values over other DEMs.

  16. Avaliação de modelos digitais de elevação para aplicação em um mapeamento digital de solos Evaluation of digital elevation models for application in a digital soil mapping

    Directory of Open Access Journals (Sweden)

    César S. Chagas

    2010-02-01

    Full Text Available No Brasil, normalmente os modelos digitais de elevação (MDEs são produzidos pelos próprios usuários e pouca atenção tem sido dada às suas limitações, como fonte de informação espacial. Este estudo propôs avaliar diferentes MDEs para subsidiar a escolha do modelo apropriado para derivar atributos topográficos utilizados em um mapeamento digital de solos, por redes neurais artificiais. A avaliação constou da determinação da raiz quadrada do erro médio quadrático da elevação (RMSE; análise das depressões espúrias; comparação entre drenagem mapeada e drenagem numérica, curvas de nível derivadas e curvas de nível originais, e análise das bacias de contribuição derivadas. Os resultados obtidos demonstraram que apenas o RMSE não foi suficiente para avaliar a qualidade desses modelos. O MDE, derivado de curvas de nível (CARTA, obtido com a utilização do módulo TOPOGRID apresentou qualidade superior aos MDEs derivados de sensores remotos (ASTER e SRTM. A análise qualitativa também identificou que o MDE CARTA é superior aos demais, pois estes apresentaram grande quantidade de erros que podem comprometer o estabelecimento das relações entre atributos do terreno e as condições locais de solos.In Brazil, the digital elevation models (DEMs are usually produced by users themselves and little attention has been given to their limitations as source of spatial information. The objective of this study was to evaluate different DEMs to help in choosing an appropriate model to derive topographical attributes used in a digital soil mapping based on a neural networks approach. The evaluation consisted of the following analysis: determination of root mean square error (RMSE of elevation; analysis of the spurious depressions; comparison between mapped drainage and numeric drainage and between derived contour lines and original contour lines; and analysis of the derived contribution basins. The results demonstrated that RMSE

  17. Generation of Statewide DEMs and Orthoimages – Guidelines and Methodology

    Directory of Open Access Journals (Sweden)

    Giribabu Dandabathula

    2015-06-01

    Full Text Available Cartosat-1 is a global, high resolution stereographic imaging mission to support enhanced applications in several areas of terrain mapping, natural resources management, disaster management, infrastructure and development planning. A collaborative project of generating statewide Digital Elevation Model (DEMs and mosaic of Ortho-image for all the states and union territories in India has completed under the project namely Space based Information Support for Decentralized Planning (SIS-DP using Photogrammetric techniques with Cartosat-1 stereo data.  Approximately 11000 stereo pairs of Cartosat-1 data were used in this process. Photogrammetric blocks for each state were processed using existing reference tiles and accordingly ortho-images were generated. The paper outlines the methodology for generating state-wide Digital Elevation Models (DEMs and ortho-images. The guidelines that govern the quality of the output were discussed. Dissemination mechanism via public accessible web platform was described.

  18. The Black Top Hat function applied to a DEM: A tool to estimate recent incision in a mountainous watershed (Estibère Watershed, Central Pyrenees)

    Science.gov (United States)

    Rodriguez, Felipe; Maire, Eric; Courjault-Radé, Pierre; Darrozes, José

    2002-03-01

    The Top Hat Transform function is a grey-level image analysis tool that allows extracting peaks and valleys in a non-uniform background. This function can be applied onto a grey-level Digital Elevation Model (DEM). It is herein applied to quantify the volume of recent incised material in a mountainous Pyrenean watershed. Grey-level Closing operation applied to the Present-Day DEM gives a new image called ``paleo'' DEM. The Black Top Hat function consists in the subtraction of the ``paleo'' DEM with the Present-Day DEM. It gives a new DEM representing all valleys whose sizes range between the size of the structuring element and the null value as no threshold is used. The calculation of the incised volume is directly derived from the subtraction between the two DEM's. The geological significance of the quantitative results is discussed.

  19. DEM Resolution Impact on the Estimation of the Physical Characteristics of Watersheds by Using SWAT

    Directory of Open Access Journals (Sweden)

    Waranyu Buakhao

    2016-01-01

    Full Text Available A digital elevation model (DEM is an important spatial input for automatic extraction of topographic parameters for the soil and water assessment tool (SWAT. The objective of this study was to investigate the impact of DEM resolution (from 5 to 90 m on the delineation process of a SWAT model with two types of watershed characteristics (flat area and mountain area and three sizes of watershed area (about 20,000, 200,000, and 1,500,000 hectares. The results showed that the total lengths of the streamline, main channel slope, watershed area, and area slope were significantly different when using the DEM datasets to delineate. Delineation using the SRTM DEM (90 m, ASTER DEM (30 m, and LDD DEM (5 m for all watershed characteristics showed that the watershed sizes and shapes obtained were only slightly different, whereas the area slopes obtained were significantly different. The total lengths of the generated streams increased when the resolution of the DEM used was higher. The stream slopes obtained using the small area sizes were insignificant, whereas the slopes obtained using the large area sizes were significantly different. This suggests that water resource model users should use the ASTER DEM as opposed to a finer resolution DEM for model input to save time for the model calibration and validation.

  20. An efficient method for applying a differential equation to deriving the spatial distribution of specific catchment area from gridded digital elevation models

    Science.gov (United States)

    Qin, Cheng-Zhi; Ai, Bei-Bei; Zhu, A.-Xing; Liu, Jun-Zhi

    2017-03-01

    Deriving the spatial distribution of specific catchment area (SCA) from a gridded digital elevation model (DEM) is one of the most important issues in digital terrain analysis. Conventional methods usually estimate SCA for each cell using a flow direction algorithm, but the results obtained are often unsatisfactory. Recently, Gallant and Hutchinson (2011, Water Resources Research, 47(5), W05535) proposed a differential equation which quantifies the change of SCA along a slope line, and thus the numerical solution of SCA at any point on a surface can be calculated accurately by integrating the differential equation. However, obtaining the numerical SCA solution based on this differential equation is so computationally intensive that it is too time-consuming to use it to derive the overall SCA spatial distribution from a gridded DEM. In this study, we developed a parallel algorithm based on OpenMP to make the numerical SCA solution based on Gallant and Hutchinson (2011)'s differential equation practical to derive the spatial distribution of SCA from a gridded DEM. Experiments based on two artificial surfaces with theoretical SCA and a more complex real terrain surface demonstrated that the proposed parallel algorithm obtained satisfactory acceleration performance and a much lower error than the MFD-md algorithm, which is a representative of conventional grid-based flow direction algorithms. Due to the speedup effects of the proposed parallel algorithm, we analyzed the effects of the DEM grid size and integration step length on the numerical SCA solution in detailed experiments. The experimental results suggested that the proposed algorithm performed best normally at the resolution of 5 m. A step ratio of 0.5 is suitable in applications of the proposed parallel algorithm.