Geography Reference
In-Depth Information
plies the coordinate values by the scale factor to obtain the scaled geo-
graphic information.
This chapter turns to location systems and coordinate systems, both of which
often involve a projection, but may be developed without any reference to
the earth's size or shape. Location systems are more likely to be locally devel-
oped ways for describing location using a grid of letters and numbers. Coor-
dinates without a reference to the earth's size and shape are a type of loca-
tion system. Coordinate systems may have a reference to the earth's size and
shape through a projection, normally described as a datum. Location sys-
tems are important because they are very common and can be used to coor-
dinate activities. Land subdivision is an important activity involving both
location systems and coordinate systems. It establishes the divisions of land
used in determining ownership. The U.S. Public Land Survey is possibly the
most widely used systematic survey for subdividing land. More common in
the rest of the world are unsystematic surveys that use metes-and-bounds
approaches to recording the boundaries of land parcels. Because of their
importance, law often specifies coordinate systems; usually these are called
national grids. In the United States, the State-Plane Coordinate System is
the best example. The newer U.S. National Grid is another example of a
Map showing counties of Minnesota before (left) and after (right) scale transfor-
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