Abstract:
A digital raster graphic (DRG) is a scanned image of a U.S.
Geological Survey (USGS) topographic map. The scanned image includes
all map collar information. The image inside the map neatline is
georeferenced to the surface of the Earth. The DRG can be used to
collect, review, and revise other digital data especially digital
line graphs (DLG). When the DRG is
... combined with other digital
products, such as digital orthophoto quadrangles (DOQ) or digital
elevation models (DEM), the resulting image provides additional
visual information for the extraction and revision of base
cartographic information. The USGS is producing DRGs of the
1:24,000-, 1:25,000-, 1:63,360- (Alaska), 1:100,000-, and
1:250,000-scale topographic map series. 
Purpose:
The DRG is used for validating digital line graphs (DLGs) and for
DLG data collection and revision. The DRG can help assess the
completeness of digital data from other mapping agencies. It can
also be used to produce "hybrid" products. These include combined
DRGs and DOQs for revising and collecting digital data, DRGs and
DEMs for creating shaded-relief DRGs and
... combinations of DRG, DOQ,
and DLG data. Although a standard DRG is an effective mapping tool,
its full potential for digital production is realized in combination
with other digital data.
Supplemental_Information:
Digital raster graphic (DRG) data are being produced by
the U.S. Geological Survey (USGS) through an Innovative Partnership
agreement with The Land Information Technology Company Ltd. of
Aurora, CO. This series includes DRG's of USGS standard series
quadrangle maps of the United States, its Trusts, and Territories.
