Projections and Coordinate Systems[1]

The world is not the flat, paper roadmap you might use to navigate with in your car. The earth is spherical, and there are actually several approaches to approximate the earth's shape and provide a system for identifying a position on the earth's surface. The earth's shape actually resembles an ellipsoid, as it revolves easterly on its axis, creating centrifugal force and causing a flattening at the North and South Poles and a bulge at the equator.

The ellipsoid is only a mathematical approximation of the earth, and there are several different models to provide a frame of reference for calculating coordinates on the earth's surface, each designed to closely fit the earth's surface in a particular geographical ...

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