5 Free Global DEM Data Sources Digital Elevation Models
· 1 Space Shuttle Radar Topography Mission (SRTM). NASA only needed 11 days to capture Shuttle Radar Topography Mission (SRTM) 30meter digital elevation model. Back in February 2000, the Space Shuttle Endeavour launched with the SRTM payload. Using two radar antennas and a single pass, it collected sufficient data to generate a digital elevation model using a technique known as