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Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition by Michael D. Kennedy

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A Second Fundamental Way of Defining Location

As discussed in detail earlier, a location on the surface of the Earth may be referenced in a spherical coordinates system by a ray, emanating from the center of the Earth, defined by an angle of latitude measured from the equator and an angle of longitude, measured from the prime meridian. This method is “perfect” in that no error is introduced by the system itself; our accuracy is limited only by our ability to measure. Latitude and longitude descriptions may be applied anywhere on Earth. (I also discussed earlier how these two angles may be converted into myriad other pairs of coordinates through processes of projection.)

A large part of the Earth that is most interesting to us consists of human-made infrastructure. Almost always, such infrastructure includes streets and buildings. Further, the most usual way to describe a location in such areas is with a street address. Such an address is a text string: a sequence of letters, numbers, and other characters.

Outside of all addresses being text strings, addresses appear in a wide variety of formats. Some examples:15

26376 Alpine Lane, Twin Peaks, CA 92391, USA
76-20 34th Avenue, Jackson Heights, Queens, NY 11372, USA
305 W 100 S, Salt Lake City, UT 84119, USA
N84W 16301 W Donald Ave, St Charles, IL 60175, USA
Rua Aurora 735 01209001 Sao Paula, Brazil
Wendenstrasse 403, 20537 Hamburg, Germany

Such addresses are usually quite precise—locating a structure to within several meters, ...

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