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Shuttle Radar Topography Mission

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Processing the SRTM data took two years to complete.

Copying the SRTM data tapes
The first activity was the copying of the flight data tapes. There are 208 C-radar data tapes containing over seven terabytes of raw data. These invaluable tapes were held at the Kennedy Space Center in climate-controlled safes. The copying was done at KSC by a team of engineers from JPL. Two copies of the tapes were made at KSC. The copies were transported to JPL, one batch at a time, for processing. The X-SAR data are being processed in Munich byDLR, the German space agency.

The SRTM processing software
The software for the Ground Data Processing System (GDPS) was under development for some time by the Algorithm Development and Verification (ADV) team. The system is broken into three parts: interferometric processor, which converts the raw radar data into a height map and radar image strips; mosaic processor, which takes the myriad of strips from all over the world and compiles a mosaic of the height and image data one continent at a time; and the verification system, which tests the mosaics for quality, producing an accuracy map. The processors operate on workstations at JPL; the next job was to install them on a set of supercomputers for systematic processing of the full SRTM data set. While this was going on, JPL released additional products to the public, as we did during the flight.

Processing the SRTM data
After the GDPS was set up and tested, systematic processing began in April 2002. The SRTM data were processed on a continent-by-continent basis, with priorities given by NGA. As the continents were finished, the data were sent to NGA for final data quality checking. After that step, copies were sent to the U.S. Geological Survey's EROS Data Center (EDC) for archive and distribution to the public. NGA will reformat the data into their own DTED format and handle archive and distribution to the Department of Defense.

Archiving the SRTM data
At the end of systematic processing, the full SRTM data set, including ancillary data, will be archived at the EROS Data Center.

Formats and distribution of the SRTM data
Distriubtion of SRTM data is through the EROS Data Center.

Data Similar to the SRTM DEMs
If you're interested in data similar to SRTM's DEMs, the USGS EROS Data Center is the place to visit. The first two data sets listed below are very similar to the resolution and quality of the full-resolution SRTM DEMs.

National Elevation Dataset (NED)
- seamless, "best available" U.S. Geological Survey elevation data
- resolution: 1 arc second (approximately 30 meters); Alaska: 2 arc seconds
- coverage: United States (including Alaska and Hawaii)
- Web site:

7.5-minute (1:24,000-scale) DEMs
- 7.5-minute tiles
- resolution: 30 meters; some at 10 meters
- coverage: conterminous United States, Hawaii, Puerto Rico

15-minute (1:63,360-scale) DEMs
- 15-minute tiles
- resolution: 2 by 3 arc seconds (approximately 60 meters)
- coverage: Alaska
- Web site:

1-degree (1:250,000-scale) DEMs
- 1-degree tiles
- resolution: 3 arc seconds (approximately 90 meters)
- coverage: United States (including Alaska and Hawaii), Puerto Rico
- Web site:

- seamless, "best available" public domain elevation data
- resolution: 30 arc seconds (approximately 1 kilometer)
- coverage: global
- Web site: