GTOPO30

Global Digital Elevation Model

GTOPO30 is a global digital elevation model produced by the U.S. Geological Survey. It can be downloaded from the WWW, and is available on 5 CD-ROMs. We have reformatted the data set to fit on a single CD, and to provide an easy to use, graphical interface to select and display data.

GTOPO30 contains 25,501 1° cells with land elevations, and would require 716 MB of storage (before considering cluster size considerations). This

• will not fit on a single disk,
• the data from southern Antarctica is grossly oversampled and simple
• the data from southern Antarctica requires a different display projection than that for the rest of the world.

This CD contains over 21,000 1° cells with land elevations, all those north of 77°S latitude. These files exactly recreate the elevation data files available from USGS, but discards other data (such as the files with data sources). This data is in MICRODEM format, and can be converted to some other formats with the DEMconverter software.

The following programs are included on the CD-ROM:

• MICRODEM, a freeware terrain viewer. This is the latest official release posted on the web page. This program is updated frequently, and you should check the web site for new versions.
• MICRODEM_DEBUG, a freeware terrain viewer. This version creates a debug log file that can be submitted to the program's author to track down problems. This program is updated frequently, and you should check the web site for new versions.

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Last revision 3/6/2000