National Geospatial Intelligence Agency

The ASTER GDEM is referenced to the World Geodetic System 1984 (WGS 84) and the elevations are computed with respect to the WGS 84 EGM96 geoid. The elevation value at each pixel is the unweighted average of the accepted scenes in the stack. Ocean and sea elevations are set to 0 based on low observed radiance (DN) values and a GTOPO30 sea water ... ................
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