State Topography Images: How to Get Source Data?
Source data for these images (and for many more areas) are available in several forms:
You can obtain the actual source data, which is a 30 arc-second (somewhat better than 1 km) topographic grid.
These data may be obtained in two formats:
-
Directly on the World Wide Web, from the Global Land One-kilometer Base Elevation (GLOBE)
Digital Elevation Model (DEM) Website. If you have fast internet access, you may prefer this method.
From the GLOBE Home Page, select Get Data,
then
- get the two premade tiles that include the Conterminous 48 States
and Hawaii (and also get the two tiles (A and D) that include data for
Alaska), or
-
interactively select your own area (which must be smaller than about 40 megabytes,
thus smaller than the Conterminous USA).
Be sure to get the associated documentation for the data, also available from the GLOBE Home Page.
-
Alternatively, you can order the CD-ROMs and documentation for yourself.
If your internet access is via a modem, or if you are a researcher wanting the
full printed documentation (which is convenient, and provides a useful discussion
of the characteristics of various DEMs), you
should consider this alternative. The link above gives information on
the contents of GLOBE. Call (303-497-6125) or email to ngdc.info@noaa.gov
for more information about ordering the GLOBE CD-ROMs.
If you are interested in additional illustrations of topography (digital images,
animations, paper maps, etc.), or additional digital data for bathymetry and surface
relief, visit the site that emphasizes this
approach to data access. Please note that there is substantial overlap of data
content between the Global Relief CD-ROM featured on this site, and TerrainBase,
linked just above. However, the presentation styles of the two CDs differ, as should
be apparent from their descriptions. Choose the one you prefer, for your intended use.
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