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About the SRTM Data Now that Endeavour has successfully acquired topographic data of more than 47.6 million square miles of the Earth, requests are now pouring in from all parts of the world from people wanting access to the data. The popular question seems to be - how can I get my hands on the data? In an effort to answer some of your questions regarding data issues, we've put together some details on the availability and quality of the data. The SRTM radar mapping data collected by Endeavour resides on 326 digital tapes of which copies will be made over the next few weeks. The tapes will then be flown to JPL where processing of the data will begin, an effort that will take 1 1/2 to 2 years. Image and data products will be made available to the public through the EROS Data Center http://edcdaac.usgs.gov/ for the cost of reproduction. Details concerning the distribution of the data are still being decided. The following is a summarized version of the NASA/NIMA Memorandum of Understanding for information about how the SRTM data will be archived and made available for use:
NASA/NIMA Memorandum of Understanding - It is intended that SRTM data be unclassified; however raw radar data, full-resolution terrain height data (ie. Level-2 data sets) or strip DEM with 30 meter spatial resolution for areas outside the United States will be under the control of the Department of Defense. Release of these data will be in accordance with guidelines mutually developed by NIMA and NASA. Terrain height data greater than or equal to three seconds of arc latitude and longitude (ie. Level-1 data sets) generated from SRTM will be released and distributed without restrictions. NASA may distribute full-resolution image data obtained from SRTM, which will be archived by NASA. Raw radar data, terrain height data of 1 second of arc latitude and longitude( ie. Level-2 data sets), and strip DEMs with 30 meter spatial resolution over the United States may be released and distributed without restrictions. The following Data Products are to be delivered to NIMA
Level-2 Terrain Height Data Sets The Data Sets are composed of files covering areas 5° in latitude by 5° in longitude.
Random Height Error Data Sets Each Level-2 Terrain Height Data Set will have a corresponding Random Height Error Data Set file covering the same area in latitude and longitude and with postings co-registered with the height measurements.
Strip Orthorectified Image Data Sets Each Data Set is created from the inboard antenna data for a single subswath; a single file covers an area of approximately 60 km in width by 450 to 4500 km (1 to 10 minutes) in length. (Currently, Data Sets from different datatakes or from multiple regions of the same datatake are not mosaicked before delivery to NIMA.) The samples within the Strip Orthorectified Image Data Sets are spaced at 15 meters by 15 meters and are gridded along a local radar coordinate system.
Systematic Height Error Model
Final Verification Report & Global Height Error Model The Global Height Error Model enhances the Systematic Height Error Model by estimating long-wavelength errors that cannot be determined from continental data alone. Source: SRTM Website Please contact the Editor for additional details.
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