oa The Shuttle Radar Topography Mission–a new source of near-global digital elevation data

The Shuttle Radar Topography Mission (SRTM) has generated a homogeneous near-global digital elevation model (DEM) of the Earth using single pass radar interferometry. The crew of Space Shuttle Endeavour (STS-99) operated the modified dual antenna synthetic aperture radar systems for 11 days in February 2000. SRTM acquired both C-band and X-Band synthetic aperture radar data, collecting 3-D data using a 60-metre mast extending from the shuttle payload bay, containing additional C-band and X-band receiver antennas.

SRTM DEM data have a horizontal resolution of 1 arc second (30 m at the equator) and vertical resolution of 10 m (C-band radar). SRTM-1 (1 arc second) data are only available for US territories with subsampled SRTM-3 (3 arc second) data provided for the rest of the world. The USGS are responsible for archiving the data with 3 arc second data being made available on a continent by continent basis. So far North and South America and Eurasia have been completed and the rest of the data processing is expected to be complete by July 2004. Comparison of SRTM DEM data with older GTOPO and altimetric DEMs shows a significant improvement in resolution, similar to that achieved by ASTER. The SRTM DEM data provide a useful new resource, especially in areas where limited topographic data are available. The data are free and in a simple format.