The ASTER Global Digital Elevation Model (GDEM) Version 3 (ASTGTM) provides a global digital elevation model (DEM) of land areas on Earth at a spatial resolution of 1 arc second (approximately 30 meter horizontal posting at the equator).
The development of the ASTER GDEM data products is a collaborative effort between National Aeronautics and Space Administration (NASA) and Japan’s Ministry of Economy, Trade, and Industry (METI). The ASTER GDEM data products are created by the Sensor Information Laboratory Corporation (SILC) in Tokyo.
The ASTER GDEM Version 3 data product was created from the automated processing of the entire ASTER Level 1A archive of scenes acquired between March 1, 2000, and November 30, 2013. Stereo correlation was used to produce over one million individual scene based ASTER DEMs, to which cloud masking was applied. All cloud screened DEMs and non-cloud screened DEMs were stacked. Residual bad values and outliers were removed. In areas with limited data stacking, several existing reference DEMs were used to supplement ASTER data to correct for residual anomalies. Selected data were averaged to create final pixel values before partitioning the data into 1° by 1° tiles with a one pixel overlap. To correct elevation values of water body surfaces, the ASTER Global Water Bodies Database (ASTWBD) Version 1 data product was also generated.
The geographic coverage of the ASTER GDEM extends from 83° North to 83° South. Each tile is distributed in GeoTIFF format and projected on the 1984 World Geodetic System (WGS84)/1996 Earth Gravitational Model (EGM96) geoid. Each of the 22,912 tiles in the collection contain at least 0.01% land area.
Provided in the ASTER GDEM product are layers for DEM and number of scenes (NUM). The NUM layer indicates the number of scenes that were processed for each pixel and the source of the data.
While the ASTER GDEM Version 3 data products offer substantial improvements over Version 2, users are advised that the products still may contain anomalies and artifacts that will reduce its usability for certain applications.
|File Size||~25 MB|
|Temporal Extent||2000-03-01 to 2013-11-30|
|Coordinate System||Geographic Latitude and Longitude|
|Geographic Dimensions||1 degree lat x 1 degree lon|
|Number of Science Dataset (SDS) Layers||2|
|Columns/Rows||3601 x 3601|
|Pixel Size||30 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|DEM||Digital Elevation Model||Meters||16-bit signed integer||-9999||N/A||-500 to 9000 (0 at sea level)||N/A|
|NUM¹||Number of scenes||Number||16-bit signed integer||N/A||N/A||0 to 250||N/A|
¹The contents of the NUM file indicate number of DEM tiles used and the source of the data.
|0-50||GDEM V3 (0 to 50+ scenes)¹|
|60-110||GDEM V2 (0 to 50+ scenes)¹|
|131-184||PRISM (1 to 54 scenes)|
|201-223||SRTM (1 to 23 swaths)|
|231||SRTM V3 from initial GDEM V3|
|232||SRTM V2 from initial GDEM V3|
|233||SRTM V2 from GDEM V2|
|234||SRTM with NGA fill from GDEM V2|
|241||NED from GDEM V2 (USA)|
|242||NED from initial GDEM V3 (USA)|
|243||CDED from GDEM V2 (Canada)|
|244||CDED from initial GDEM V3 (Canada)|
|245||Alaska DEM from GDEM V2|
|246||Alaska DEM from initial GDEM V3|
¹ 0 = Unspecified
List of abbreviations: PRISM = Advanced Land Observing Satellite (ALOS) Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), SRTM = Shuttle Radar Topography Mission, NGA = National Geospatial-Intelligence Agency, NED = United States Geological Survey (USGS) National Elevation Dataset, CDED = Canadian Digital Elevation Data, Alaska DEM = USGS 3D Elevation Program (3DEP) Alaska DEM
Quality information is provided in Section 7 of the User Guide.