One Hundred Digital
Elevation Models
Illustrating Specified
Physiographic Features
The United States Geological Survey has a set of 100
topographic maps keyed to Fenneman's Physical Divisions of the
continental United States. We have compiled the digital
equivalent with the digital elevation models covering each of
those maps. Of the 100 paper maps, 86 have DEM coverage. We have
supplemented these with 23 additional maps. For each map we have
between at least 4 adjacent 1:24,000 DEMs, with a total of 799
quadrangles currently included. We have duplicate coverage for
some DEMs, with both 10 m and 30 m coverage or duplicate Level 1
and Level 2 coverage.
The following data sets are included on the CD-ROM; all are
public domain:
- ETOPO5, a low resolution global data set
of both topography and bathymetry. Elevations are about
every 10 km.
- DTED Level 0 covering about half of the
earth's land surface area. This data has been indexed and
extracted from the download files from the NIMA server.
This is not a complete set of what the NIMA server has
available, because that requires a complete
CD. This has elevations about every 1 km.
- USGS 1:250K DEM: 4 adjacent files around
Death Valley, in ".GZ" format exactly as
downloaded from the USGS server. This has elevations
about every 100 m.
- USGS 1:24K DEM "100"
DEMs showing physiographic features. These
are in Unix "TAR.GZ" exactly as downloaded from
the USGS server. The MICRODEM program can read this data
directly from the CD, and the DEMconvert
program can reformat them. These are in the two
directories "100 Maps" and "100+
maps", with subdirectories named for the primary
quadrangle or feature.When there is both Level 1 and
Level 2 coverage, the Level 1 data reside in a "Lev
1 Dups" subdirectory. There are also some DLG files
with hydrography for a few maps, in a "DLG"
directory. This has elevations every 30 m..
- A DEM, DRG, DOQ, and DLGs covering the
Hanging Rock Canyon quadrangle in eastern California.
DRGs and DOQs are not generally available on the WWW, and
this data sets shows how they can be used together.
There are index files for the DTED Level 0, USGS 1:250K and
1:24K DEMs so that they can be loaded with graphical selection on
an index file directly from MICRODEM, a freeware terrain viewer
included on the CD. Many of these files are compressed, but all
can be used directly from the CD without any additional
processing.
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Last revision 2/2/2000