• Land Processes Distributed Active Archive Center:  http://edcdaac.usgs.gov/gtopo30/gtopo30.asp
    From the Land Processes Distributed Active Archive Center site, visitors can download digital elevation model (DEM) data (GTOPO30) for the entire globe. GTOPO30 data has a horizontal grid spacing of 30 arc seconds or approximately 1 kilometer.

  • Shuttle Radar Topography Mission:  http://www2.jpl.nasa.gov/srtm/
    During the 11-day Space Shuttle Endeavour mission in February, 2000, The Shuttle Radar Topography Mission (SRTM) obtained elevation data between 60 degrees latitude North and South for the entire globe. At present, project personnel are in the process of generating the most complete high-resolution (30m for the United States and 90m internationally) digital topographic database available. Unedited data for North and South America are already available. Data for other continents will follow with the finished digital data ready for distribution by 2005.