GTOPO-30
is a global digital elevation model (DEM) resulting from a collaborative effort
led by the staff at the U.S. Geological Survey's
EROS Data Center in South Dakota, USA. Elevations in GTOPO-30 are
regularly spaced at 30-arc seconds (approximately 1 kilometer), and
are represented as metres above mean sea level. GTOPO-30
was developed to meet the needs of the geospatial data user community for
regional and continental scale topographic data.
The above global elevation image is an example of how the data can be used
to great effect.
Data Sources
Several different sources were combined to create the GTOPO-30 dataset, including
USGS Digital Elevation Models, Digital Chart of the World, DTED, Army maps and
national databases (see above).
NPA supply the USGS Global Digital Elevation Model (GTOPO30)
on a single CD-ROM in compressed TNTmips format for £125
(US$200). A free TNT Atlas viewer is also included, enabling
viewing and inspection of the data for those without the full
TNTmips software package. The same data in tiles are also
available as a set of 5 CD's in a 16-bit uncompressed format
for use in other image processing systems, for just £95.
The figures above indicate the areas covered by each tile
and CD-Rom.
