SRTM (Shuttle Radar Topography Mission)
The Shuttle Radar Topography Mission (SRTM) was a 10-day mission which flew on the Space Shuttle Endeavour in February 2000. It was a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA, formerly Defense Mapping Agency) that collected high-resolution topographic data for most of the land surfaces between -54 and 60 degrees latitude. Data was collected using a method called single-pass radar interferometry, with two imaging radar systems on the Shuttle separated by a 60 meter mast. This technology is based on the Spaceborne Imaging Radar - C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that was used on two previous Shuttle missions.
Although the data collection effort has been completed, the post-processing and validation necessary to produce a final gridded data set is scheduled to be complete sometime in 2004. As of June, data for North and South America, Eurasia and Africa have been made available on an FTP site (see link below) in a simple, binary "HGT" format as 2-byte integers. The final data set is to be delivered to the EROS Data Center (EDC) of the USGS for distribution, possibly in the SDTS Raster Profile format. For latitudes between -50 and 50, the grid spacing will be 1 arcsecond of latitude and longitude (about 30 meters at the equator and decreasing towards the poles). For latitudes between -54 and 50 and between 50 and 60, the grid spacing will be 1 arcsecond of latitude and 2 arcseconds of longitude. Each tile in the data set will span 5 degrees of latitude and 5 degrees of longitude. For the region between -50 and 50, each tile will then contain 18000 rows and 18000 columns. Elevations will be measured in meters relative to the WGS84 ellipsoid model.
The final data set will be distributed by the EROS Data Center (EDC) of the US Geological Survey (USGS).
Coverage includes most land surfaces between -54 and 60 degrees latitude. Within the US, the full-resolution data will be released without restrictions. Outside the US, the grid spacing will be reduced from 1 to 3 arcseconds. NIMA is expected to reformat the data into their DTED format and handle distribution to the Department of Defense.
SRTM Home: http://www.jpl.nasa.gov/srtm
Data Products: http://www.jpl.nasa.gov/srtm/dataproducts.html
Data at the USGS: http://srtm.usgs.gov
Data available for download: ftp://e0dps01u.ecs.nasa.gov/srtm
Copyright (c) 1998-2008, Rivix, LLC. All rights reserved.