                     SOURCES OF DIGITAL DATA 

(Information for this section is extracted from the USACERL Technical
Report "\Sources of Digital Spatial Data\," USACERL Technical Report
N-88/01/ADA189788).

As applications for GRASS have increased, the ability to develop useful,
accurate, and up-to-date \digital\ \map layers\ has become very
important.  Legal boundaries, roads, hydrography, soils, watersheds, and
elevation data are among the map layers commonly developed for GRASS
\databases\.

In this section, major sources of national and/or global \digital\
landscape data, and status, coverage and aquisition information about
those sources, are identified.  Information is provided on data: format,
scale/resolution, coverage, media, costs, and textural descriptions and
comments.

This information is needed to assess the cost and time requirements of
building a digital database for any specific geographic region.  Use of
existing digital data sources, rather than construction of new digital
data, can result in tremendous savings in both time and money.  Also,
use of standard sources insures minimum standards for accuracy and quality.

Only national sources are covered.  More sources may be available at
state agencies such as transportion, environmental, and natural resource
management departments.  Local planning offices, university geography,
urban planning, and civil engineering departments may also provide data.

Further information about specific data sources can be accessed by
selecting one of the topic areas listed below:

     \Defense Mapping Agency data\  -- DMA data
     \Earth Observation Satellite Co. data\ -- EOSAT data
     \Environmental Protection Agency data\ -- EPA data
     \National Climatic Data Center data\ -- NCDC data
     \National Cartographic Information Center data\ -- NCIC data
     \National Geophyiscal Data Center data\ -- NGDC data
     \National Geodetic Information Center data\ -- NGIC data
     \National Oceanographic Data Center data\ -- NODC data
     \National Technical Information Service data\ -- NTIS data
     \Oak Ridge National Laboratory data\ -- ORNL data
     \Soil Conservation Service data\ -- SCS data
     \Satellite pour l'Observation de la Terre data\ -- SPOT data
     \EPA STORET (Water Quality) data\ -- STORET data
     \U.S. Bureau of the Census data\ -- USBC data
     \U.S. Geological Survey-1 data\ -- USGS data
     \U.S. Geological Survey-2 data\ -- USGS data
     \U.S. Geological Survey-3 data\ -- USGS data
     \U.S. Geological Survey-4 data\ -- USGS data

     \Digital Data Cross-Reference\
     \Tabular Data Cross-Reference\

