Rivix.com: GLSDEM

GLSDEM (Global Land Survey Digital Elevation Model)

Description

The Global Land Survey Digital Elevation Model (GLSDEM) is a collection of DEM tiles compiled by NASA and the USGS in support of the GeoCover project. It was compiled from several other DEM sources including NED, CDED, DTED, GTOPO30 and SRTM to provide near-global coverage. GLSDEM consists of two sets of tiles. One set uses Geographic coordinates, 3-arcsecond grid spacing and 1-degree by 1-degree tiles. The other set uses the WRS-2 tiling system, which uses the UTM projection. The WRS-2 tiles span 185 km x 185 km and have a grid spacing of 90 meters.

Grid Information

Coord. System:	Geographic decimal degrees, fixed-angle OR UTM, meters, fixed-length
Cell Size:	Geographic: 3 arcseconds (1/1200 of a degree) OR UTM: 90 meters (UTM)
Tile Dimensions:	Geographic: 1201 columns x 1201 rows (latitudes between -60 and 90) UTM: variable (e.g. 3327 columns x 3575 rows) (latitudes between -60 and 90)
Tile Span:	Geographic: 1 degrees x 1 degree (latitudes between -60 and 90) UTM (WRS-2): 185 km x 185 km (latitudes between -60 and 90)
Data Type:	2-byte integer, signed
Horizontal Datum:	WGS 84
Vertical Datum:	mean sea level, EGM96 geoid
Vertical Units:	meters
Nodata Value:	-32768 (WRS-2). Ocean cells have elevation 0 but negative values (e.g. -1, -3) can also occur in the ocean.
Formats:	GeoTIFF Format

How to Import

Choose Import DEM → GeoTIFF from the File menu and then select the file, which will usually have the filename extension "*.tif".

Data Source

EROS Data Center (EDC) of the US Geological Survey (USGS) of the US Department of the Interior

Data Availability

GLSDEM tiles may be obtained from EROS Data Center, USGS, or GLCF (Global Land Cover Facility). GLSDEM is only available as individual tiles; their is no global mosaic. Filenames for the Geographic tiles are based on the lat and lon of the southwest corner of the tile, e.g. "GLSDEM_n025_e000". The WRS-2 edition of the DEM (UTM tiles) is only available from GLCF.

Web Sites

GLCF main page: http://www.landcover.org

GLSDEM page: http://glcf.umd.edu/data/glsdem/