California, USA, 04 June 2007: The ESRI’s 90-meter resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data is now included with the latest version of ESRI Data & Maps.
The global elevation data is based primarily on SRTM 90-meter data and is intended for use in small- to medium-scale 3D and 2D visualization applications. The enhancements include filling in all data voids; mosaicking all 14,277 1-by-1 degree Digital Terrain Elevation Data (DTED) Level 1 cells into six raster datasets ; and reducing storage requirements by compressing the elevation data from 35 GB in the original DTED format to slightly more than 4 GB using JPEG 2000 compression. For void filling, ESRI chose to use a new technique known as the Delta Surface Fill (DSF) method (introduced by NGA)
The global elevation data also includes pregenerated hillshade (shaded relief) datasets of the void-filled SRTM data, as well as ocean and inland water mask datasets based on the SRTM Water Body dataset produced by NGA. The hillshades are distributed along with cloud-free 150-meter imagery.
In the polar areas not captured during the shuttle mission, ESRI has included GTOPO30 (1 km) elevation and hillshade datasets. To maintain consistency with the data provided in the SRTM coverage area, ESRI has included ocean and inland water mask datasets for the polar areas derived from the Digital Chart of the World (VMap Level 0).
The SRTM data was originally collected during the February 2000 mission of the space shuttle Endeavour using Interferometric Synthetic Aperture Radar. During the mission, data for 80 percent of the earth’s landmass was collected between 56 degrees south and 60 degrees north. The SRTM data is is available to the general public as a result of a cooperative project between the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA).
