GDEM

GDEM, or Global Digital Elevation Model, commonly refers to the ASTER Global Digital Elevation Model (ASTER GDEM), a global elevation dataset produced from stereo pairs of images captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA’s Terra satellite. The project was a joint effort between NASA's Jet Propulsion Laboratory and Japan’s Ministry of Economy, Trade and Industry (METI). The dataset provides elevation values on a grid with about 30-meter ground resolution and aims to cover most of the Earth’s land surface.

ASTER GDEM was released in two major versions. Version 1 was published around 2009 and compiled from a large archive of ASTER imagery spanning 1999–2008. Version 2, released in 2011, introduced improved processing and radiometric and geometric corrections, reduced artefacts, and completed coverage for regions previously with gaps. The data are distributed publicly by NASA’s Land Processes Distributed Active Archive Center (LP DAAC) and METI, and are widely used in topographic, hydrological, and geospatial analyses, as well as education and research.

Limitations and considerations include artefacts such as striping, gaps, and anomalous values, particularly along coastlines, in water bodies, or where stereo pairs are mismatched. Clouds, snow, and dense vegetation can also introduce errors. Users are advised to validate measurements against ground truth or compare with other digital elevation models, and to apply filtering or gap-filling as appropriate for their applications.

See also: Shuttle Radar Topography Mission (SRTM), AW3D.