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designed to use a DLG-3 file as input will be executed
to produce a final plot of the PLSS map separate. This
program generates plotter driver instructions for a photo
graphic line plotter. The symbolization portrayed on the
plot (e.g. corner symbols, lines, dashed lines, section
numbers) will be derived from the attribute codes assigned
to the various elements—nodes, lines, areas. The result
ant photographic product is a film positive of the PLSS
which can be further enhanced with additional lettering
and symbolization. This plot, in turn, will be used to
produce a press-ready negative.
CONCLUSIONS
In reviewing the potential application of this approach we
find that about 50-70 percent of the remaining areas to be
covered by provisional maps consists of post-1910 cadastral
surveys. Even with the expected (unknown) percentage of
townships which probably do not meet National Map Accuracy
positional standards, the byproduct generated will serve
as a Field Surveys search (preliminary buildup) guide of
best-known approximations. For those corners where the
computations meet and adjust showing that positional re
quirements have been met, we need only a cursory field
check (symbolization change to "found corner") and then to
produce the provisional map separate. This procedure will
allow the USGS to meet the dual objective of producing a
DLG-3 overlay file and a provisional map separate.
REFERENCES
Fry, J. P. L., Skalet, C. D., 1982, CRAIGES (Cartographic
Reproduction And Interactive Graphics Editing System):
Users Manual, USGS Western Mapping Center, 345 Middle-
field Road, Menlo Park, California 94025.
Lowry, P. G., 1978, Program Users Guide for Unified Carto
graphic Line Graph Encoding System: USGS Office of
Cartographic Research, MS 519, USGS National Center,
Reston, Virginia 22092.
Intergraph, Inc., 1981, Intergraph Users Manual:
Huntsville, Alabama.
Thompson, M. M., 1979, Maps for America: USGPO, Washington,
D.C.
U.S. Geological Survey, 1981, NCIC User Guide, Digital
Cartographic Data Files, Digital Line Graphs for 7.5
and 15 minute Topographic Quadrangle Maps: National
Cartographic Information Center, MS 507, USGS
National Center, Reston, Virginia 22092.
