Аннотация
After decades of using only one map projection, the Polyconic, for
its mapping program, the U.S. Geological Survey (USGS) now uses several
of the more common projections for its published maps. For larger
scale maps, including topographic quadrangles and the State Base
Map Series, conformal projections such as the Transverse Mercator
and the Lambert Conformal Conic are used. Equal-area and equidistant
projections appear in the National Atlas. Other projections, such
as the Miller Cylindrical and the Van der Grinten, are chosen occasionally
for convenience, sometimes making use of existing base maps prepared
by others. Some projections treat the Earth only as a sphere, others
as either ellipsoid or sphere. The USGS has also conceived and designed
several new projections, including the Space Oblique Mercator, the
first map projection designed to permit mapping of the Earth continuously
from a satellite with low distortion. The mapping of extraterrestrial
bodies has resulted in the use of standard projections in completely
new settings. Several other projections which have not been used
by the USGS are frequently of interest to the cartographic public.
With increased computerization, it is important to realize that rectangular
coordinates for all these projections may be mathematically calculated
with formulas which would have seemed too complicated in the past,
but which now may be programmed routinely, especially if aided by
numerical examples. A discussion of appearance, usage, and history
is given together with both forward and inverse equations for each
projection involved.
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