Rivix.com: GTOPO30 Elevation Data

GTOPO30 Elevation Data

Description

GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arcseconds (about 1 kilometer at the equator). GTOPO30 was developed through a collaborative effort led by staff at the USGS EROS Data Center. NASA and several other organizations around the world contributed to the project, which was completed in late 1996. The data set provides complete global coverage divided into 33 tiles. Ocean pixels are flagged with a nodata value of -9999.

For latitudes between -60 and 90 degrees there are 27 tiles, each spanning 50 degrees of latitude (6000 rows) and 40 degrees of longitude (4800 columns). Latitudes between -90 and -60 correspond to Antarctica, which is covered by 6 tiles, each spanning 30 degrees of latitude (3600 rows) and 60 degrees of longitude (7200 columns). The data for Antarctica is also available in a polar stereographic projection consisting of a single tile that has 5400 columns and 5400 rows and a grid spacing of 1000 meters. Elevation data for all tiles is stored as signed 2-byte integers in flat binary (row major, no header) files with the MSB (most significant byte first) byte order and units of meters above mean sea level. Georeferencing information is in a separate ASCII header (HDR) file. The reference ellipsoid/datum is WGS84.

The GLOBE data set offers similar coverage but differs in several respects.

Data Source

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

Data Availability

All of the tiles can be previewed and downloaded free of charge from EROS Data Center, from the web site listed below. The product is also available on 5 CD-ROMs.

Web Sites

Download page: http://edc.usgs.gov/products/elevation/gtopo30/gtopo30.html

Document page: http://edc.usgs.gov/products/elevation/gtopo30/README.html