The ASTER Digital Elevation Model and Orthorectified Registered Radiance at the Sensor (AST14DMO) product (https://lpdaac.usgs.gov/documents/996/ASTER_Earthdata_Search_Order_Instructions.pdf) form a multi-file product. The product contains both a Digital Elevation Model (DEM) and up to 15 orthorectified images representing Visible and Near Infrared (VNIR), Shortwave Infrared (SWIR), and Thermal Infrared (TIR) data layers for each available ASTER scene, if acquired. The spatial resolution is 15 m (VNIR), 30 m (SWIR), and 90 m (TIR) with a temporal coverage of 2000 to present.For more information, see the links below:(AST14DEM) (https://doi.org/10.5067/ASTER/AST14DEM.003)(AST14OTH) (https://doi.org/10.5067/ASTER/AST14OTH.003)Improvements/Changes from Previous VersionsAs of January 2021, the LP DAAC has implemented version 3.0 of the Sensor Information Laboratory Corporation ASTER DEM/Ortho (SILCAST) software, which is used to generate the Level 2 on-demand ASTER Orthorectified and Digital Elevation Model (DEM) products (AST14). The updated software provides digital elevation extraction and orthorectification from ASTER L1B input data without needing to enter ground control points or depending on external global DEMs at 30-arc-second resolution (GTOPO30). It utilizes the ephemeris and attitude data derived from both the ASTER instrument and the Terra spacecraft platform. The outputs are geoid height-corrected and waterbodies are automatically detected in this version. Users will notice differences between AST14DEM, AST14DMO, and AST14OTH products ordered before January 2021 (generated with SILCAST V1) and those generated with the updated version of the production software (version 3.0). Differences may include slight elevation changes over different surface types, including waterbodies. Differences have also been observed over cloudy portions of ASTER scenes. Additional information on SILCAST version 3.0 can be found on the SILCAST website (http://www.silc.co.jp/en/products.html).Starting June 23, 2021, radiometric calibration coefficient Version 5 (RCC V5) will be applied to newly observed ASTER data and archived ASTER data products. Details regarding RCC V5 are described in the following journal article.Tsuchida, S., Yamamoto, H., Kouyama, T., Obata, K., Sakuma, F., Tachikawa, T., Kamei, A., Arai, K., Czapla-Myers, J.S., Biggar, S.F., and Thome, K.J., 2020, Radiometric Degradation Curves for the ASTER VNIR Processing Using Vicarious and Lunar Calibrations: Remote Sensing, v. 12, no. 3, at https://doi.org/10.3390/rs12030427.

The Polar Geospatial Center’s ArcticDEM elevation products are the result of an institutional collaboration between the U.S. National Geospatial-Intelligence Agency (NGA) and the National Science Foundation (NSF). The objective of these efforts are to automatically produce high-resolution, high-quality digital surface models (DSM) of polar regions using optical imagery, high-performance computing, and open source photogrammetry software. The result is a collection of time-dependent DSM strips and seamless terrain mosaics. ArcticDEM can be used and distributed without restriction.This Image Service drives the ArcticDEM Explorer application developed in partnership with ESRI. See the ArcticDEM v4.1 Storymap for visual examples illustrating how we built the newest mosaic layers.Key PropertiesGeographic Coverage: Arctic - land and offshore areas north of 60°N plus all of Greenland, Alaska (before June 2022), and the Kamchatka PeninsulaTemporal Coverage: 2007 – 2024Refresh Rate: YearlyProduct Type: Digital surface model, which includes surface features such as man-made structures and vegetationProduct Values: Elevation in meters above the WG84 ellipsoidSpatial Resolution: 2-meters per pixelCoordinate System: NSIDC Sea Ice Polar Stereographic North WGS84 (EPSG:3413)Data ProductsElevation products are built using the Surface Extraction from Tin-based Search-space Minimization (SETSM) and median mosaic algorithms developed by Myong-Jong Noh and Ian Howat at the Byrd Polar Research and Climate Center. Individual DEM strips are extracted from pairs of Maxar images. DEM strip dimensions will vary according to the sensor, off-nadir angle of collection, and the corresponding stereo-pair overlap. Most strips are between 16 km and 18 km in width, and 110 km and 120 km in length.DEM Tiles are compiled from multiple strips that have been co-registered, blended, and feathered to reduce edge-matching artifacts. Tile sizes are standardized at 50 km x 50 km.ApplicationsThe time-dependent nature of the strip DEM files allows users to perform change detection analysis and to compare observations of topographic data acquired in different seasons or years. The mosaic DEM tiles are assembled from multiple strip DEMs with the intention of providing a more consistent and comprehensive product over larger areas while also providing a per-pixel minimum and maximum date range to enable change detection.ArcticDEM products can be used for a variety of applications:Terrain correction for radar and optical remote sensingFusion with lidar-based systemGlacier monitoring and change measurementVegetation characterization and analysisHydrologic modellingFine-scale mapping Dynamic Renderings The default rendering is Hillshade Elevation TintedVarious pre-defined on-the-fly Raster Functions can be selected:

Rendering
Description

Height EllisoidalElevation values in meters above the ellipsoid (WGS84) Height OrthometricElevation values in meters above the geoid (EGM08) Hillshade GrayHillshade image with a solar azimuth of 315 degrees and solar altitude of 45 degrees. Z-factor defaults to 4, but can be specified via the the REST API Hillshade Elevation TintedHillshade image with color tints indicating elevation values (default) Hillshade MultidirectionalHillshade image derived weighted contributions of six different directions Contour 2525-meter contour lines Contour Smoothed 2525-meter smoothed contour lines Aspect DegreesAspect in degrees Aspect MapColor representation of aspect values Slope DegreesSlope in degrees Slope MapColor representation of slope values

Additional Usage NotesWithout ground control points absolute accuracy is approximately 4 meters in horizontal and vertical planes. Uniform ground control must be applied to achieve higher accuracy.The data has not been edited to remove processing anomalies. Pits, spikes, false landforms, and other DEM anomalies may exist in this dataset. Hydrographic features have not been flattened in the DEM Strips.Optically-derived DEMs are subject to clouds, fog, shadows, and other atmospheric obstructions obscuring the ground and resulting in data gaps.The data spans multiple years and seasons.Mosaic tiles are displayed by default. Strips can be selected and displayed via image filtering.For more information on the source data and project, see the ArcticDEM website and the ArcticDEM Explorer app.

The use of high-resolution remotely sensed imagery can be an effective way to obtain quantitative measurements of rock-avalanche volumes and geometries in remote glaciated areas, both of which are important for an improved understanding of rock-avalanche characteristics and processes. We utilized the availability of high-resolution (~0.5 m) WorldView satellite stereo imagery to derive digital elevation data in a 100 km2 area around the 28 June 2016 Lamplugh rock avalanche in Glacier Bay National Park and Preserve, Alaska. We used NASA Ames Stereo Pipeline, an open-source software package available from NASA, to produce one pre- and four post-event digital elevation models (DEMs) of the area surrounding the Lamplugh rock avalanche. This data release includes five raster elevation datasets (2-m resolution) in GeoTIFF format that have been orthrectified to the Universal Transverse Mercator (UTM) coordinate system (zone 7N). Elevations are measured in reference to the World Geodetic System 1984 (WGS84) ellipsoid. Because the study area is remote and difficult to access, ground control was not available to assess the absolute accuracy of DEMs. The DEMs have not been precisely co-registered. Data contained in this release include a pre-event DEM from 15 June 2016, and post-event DEMs from 16 July 2016, 27 August 2016, 27 September 2016, and 28 September 2016. The filenames for these DEMs are 20160615_LamplughDEM.tif, 20160716_LamplughDEM.tif, 20160827_LamplughDEM.tif, 20160927_LamplughDEM.tif, and 20160928_LamplughDEM.tif, respectively. We also provide a CSV file (Lamplugh_DEM_Image_Notes.csv) that contains the acquisition date, satellite platform, image identification number, resolution, off-nadir angle, and notes on image quality for each stereo pair used to generate DEMs.

Digital Terrain Model (bare earth) of parts of Maui and Molokai. Partial coverage Vexcel, Inc. LIDAR of Maui and Molokai were purchased by County of Maui to assist with three-dimensional modeling of structures in areas of higher development. 1'/px, LIDAR-derived, bare earth DEM/elevation raster of parts of Maui and Molokai – specifically, Central Molokai, Kahului, Kihei, Lahaina and Pukalani. XY units: feet, Z units: meters. Use Limitations: 1.Disclaimer - This dataset is being placed in the public domain. Any use is allowed except for re-sale. Neither Vexcel, Inc., the County of Maui, nor the State of Hawaii make any guarantees, expressed or implied, regarding its accuracy or fitness of use. Users should verify XYZ values through a licensed surveyor for any engineering application. This data should only be used as a guide, vs. a statement of fact regarding real-world conditions. 2.Vertical Datum - The originator of this LIDAR dataset, Vexcel Inc. of Boulder, Colorado referenced Z values to the North American Vertical Datum of 1988 (NAVD88). NAVD88 is not recognized as a valid vertical reference for the state of Hawaii. Currently Hawaii has no official (de jure or de facto) vertical datum, and NOAA's National Geodetic Survey (NGS) recommends that elevations be referenced to the nearest NOAA tidal gauge. A legacy LIDAR dataset produced in 2013 by the United States Army Corps of Engineers (USACE) used NAD83(PA11) as its vertical reference. In theory this approach should result in better accuracy for the Z dimension as PA11 is a Pacific plate-centric datum. In comparing flat areas containing neither structures or vegetation, it was found that the Vexcel values sit approximately 4 feet above the USACE dataset. The vertical datum issue was brought to the attention of Vexcel, Inc. Vexcel used the 2013 USACE LIDAR as vertical control to correct their LIDAR data. The (corrected) .las data is shared as it was delivered. As stated above, the use of this data transfers all risks and assumption of responsibility to the user. For more information see https://files.hawaii.gov/dbedt/op/gis/data/Maui_2019_DTM.html or contact County of Maui at GISMonitor@co.maui.hi.us or Hawaii Statewide GIS Program at gis@hawaii.gov.

The Polar Geospatial Center’s REMA elevation products are the result of an institutional collaboration between the U.S. National Geospatial-Intelligence Agency (NGA) and the National Science Foundation (NSF). The objective of these efforts are to automatically produce high-resolution, high-quality digital surface models (DSM) of polar regions using optical imagery, high-performance computing, and open source photogrammetry software. The result is a collection of time-dependent DSM strips and seamless terrain mosaics. REMA can be used and distributed without restriction.This Image Service drives the REMA Explorer application developed in partnership with ESRI. See the ArcticDEM v4.1 Storymap for visual examples illustrating how we built the newest mosaic layers.Key PropertiesGeographic Coverage: Antarctica - land and land-fast ice areas south of 60°N plus the sub-Antarctic islands off South AmericaTemporal Coverage: 2008 – 2024Refresh Rate: YearlyProduct Type: Digital surface model, which includes surface features such as man-made structures and vegetationProduct Values: Elevation in meters above the WG84 ellipsoidSpatial Resolution: 2-meters per pixelCoordinate System: Antarctic Polar Stereographic WGS84 (EPSG:3031)Data ProductsElevation products are built using the Surface Extraction from Tin-based Search-space Minimization (SETSM) and median mosaic algorithms developed by Myong-Jong Noh and Ian Howat at the Byrd Polar Research and Climate Center. Individual DEM strips are extracted from pairs of Maxar images. DEM strip dimensions will vary according to the sensor, off-nadir angle of collection, and the corresponding stereo-pair overlap. Most strips are between 16 km and 18 km in width, and 110 km and 120 km in length.DEM Tiles are compiled from multiple strips that have been co-registered, blended, and feathered to reduce edge-matching artifacts. Tile sizes are standardized at 50 km x 50 km.ApplicationsThe time-dependent nature of the strip DEM files allows users to perform change detection analysis and to compare observations of topographic data acquired in different seasons or years. The mosaic DEM tiles are assembled from multiple strip DEMs with the intention of providing a more consistent and comprehensive product over larger areas while also providing a per-pixel minimum and maximum date range to enable change detection.REMA products can be used for a variety of applications:Terrain correction for radar and optical remote sensingFusion with lidar-based systemGlacier monitoring and change measurementVegetation characterization and analysisHydrologic modellingFine-scale mapping Dynamic RenderingsThe default rendering is Hillshade Elevation TintedVarious pre-defined on-the-fly Raster Functions can be selected:

Rendering
Description

Height EllisoidalElevation values in meters above the ellipsoid (WGS84) Height OrthometricElevation values in meters above the geoid (EGM08) Hillshade GrayHillshade image with a solar azimuth of 315 degrees and solar altitude of 45 degrees. Z-factor defaults to 4, but can be specified via the the REST API Hillshade Elevation TintedHillshade image with color tints indicating elevation values (default) Hillshade MultidirectionalHillshade image derived weighted contributions of six different directions Contour 2525-meter contour lines Contour Smoothed 2525-meter smoothed contour lines Aspect DegreesAspect in degrees Aspect MapColor representation of aspect values Slope DegreesSlope in degrees Slope MapColor representation of slope values

Additional Usage NotesWithout ground control points absolute accuracy is approximately 4 meters in horizontal and vertical planes. Uniform ground control must be applied to achieve higher accuracy.The data has not been edited to remove processing anomalies. Pits, spikes, false landforms, and other DEM anomalies may exist in this dataset. Hydrographic features have not been flattened in the DEM Strips.Optically-derived DEMs are subject to clouds, fog, shadows, and other atmospheric obstructions obscuring the ground and resulting in data gaps.The data spans multiple years and seasons.Mosaic tiles are displayed by default. Strips can be selected and displayed via image filtering.For more information on the source data and project, see the REMA website and the REMA Explorer app.

Digital Terrain Model (bare earth) of parts of Maui and Molokai. Partial coverage Vexcel, Inc. LIDAR of Maui and Molokai were purchased by County of Maui to assist with three-dimensional modeling of structures in areas of higher development. 1'/px, LIDAR-derived, bare earth DEM/elevation raster of parts of Maui and Molokai – specifically, Central Molokai, Kahului, Kihei, Lahaina and Pukalani. XY units: feet, Z units: meters. Use Limitations: 1.Disclaimer - This dataset is being placed in the public domain. Any use is allowed except for re-sale. Neither Vexcel, Inc., the County of Maui, nor the State of Hawaii make any guarantees, expressed or implied, regarding its accuracy or fitness of use. Users should verify XYZ values through a licensed surveyor for any engineering application. This data should only be used as a guide, vs. a statement of fact regarding real-world conditions. 2.Vertical Datum - The originator of this LIDAR dataset, Vexcel Inc. of Boulder, Colorado referenced Z values to the North American Vertical Datum of 1988 (NAVD88). NAVD88 is not recognized as a valid vertical reference for the state of Hawaii. Currently Hawaii has no official (de jure or de facto) vertical datum, and NOAA's National Geodetic Survey (NGS) recommends that elevations be referenced to the nearest NOAA tidal gauge. A legacy LIDAR dataset produced in 2013 by the United States Army Corps of Engineers (USACE) used NAD83(PA11) as its vertical reference. In theory this approach should result in better accuracy for the Z dimension as PA11 is a Pacific plate-centric datum. In comparing flat areas containing neither structures or vegetation, it was found that the Vexcel values sit approximately 4 feet above the USACE dataset. The vertical datum issue was brought to the attention of Vexcel, Inc. Vexcel used the 2013 USACE LIDAR as vertical control to correct their LIDAR data. The (corrected) .las data is shared as it was delivered. As stated above, the use of this data transfers all risks and assumption of responsibility to the user. For more information see https://files.hawaii.gov/dbedt/op/gis/data/Maui_2019_DTM.html or contact County of Maui at GISMonitor@co.maui.hi.us or Hawaii Statewide GIS Program at gis@hawaii.gov.