GEO 481 Study Guide - Midterm Guide: Grs 80, Zip Code, World Geodetic System
4 Mar 2019
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Document Summary
Powerful functions help us better use geographic information. Use computer based maps rather than paper maps. Geodesy: the science of measuring the shape of the earth. When the earth is a sphere, its circumference is 40 million meters. Ellipsoid: ellipse rotated around shorter axis; clarke 1866, grs80, wgs84. Geoid: undulations of the earth at mean sea level. Datum: the combination of an ellipsoid and a number of benchmarks to approximate the surface of the earth. Benchmark: point with a precisely known relationship to the level datum of the area, typically mean sea level. Datum: the same location can be offset hundreds of meters. Prime meridian: defined by the zero meridian. Distance estimation based on latitudes and longitudes. Gcs specifies coordinates on an ellipsoidal surface. Map projection: transformation of coordinates between ellipsoid and a flat map. Equatorial: projections based on axes parallel to the earth"s rotation axis. Transverse: 90 degrees to the rotation axis.
