This Global Digital Elevation Model, or GDEM, is a product of NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). The image was released on June 29, 2009, and was created by processing and stereo-correlating the 1.3 million-scene ASTER. The Global Digital Elevation Model is produced with 98-feet postings, and is formatted as 23,000 one-by-one-degree tiles.