Tools of the GeographerMapsA map is the fundamental tool of the geographer. With a map, one can illustrate the spatial distribution (i.e., geographic pattern) of almost any kind of phenomena. Maps provide a wealth of information. The information collected to create a map is called spatial data. Any object or characteristic that has a location can be considered spatial data. The data collected for a map can be qualitative (buildings, rivers, roads) or quantitative (elevation, air temperature, population density). There are many different kinds of maps that serve quite different purposes. Map projectionsA map projection is a method of portraying the two-dimensional curved surface of the Earth on a flat planar surface. Projections are created to preserve one or several measurements of the following qualities: Each projection handles the conversion of these metric properties from the curved surface of a globe to the flat surface of map differently. The purpose of the map is of primary importance in choosing a projection to illustrate spatial patterns of Earth phenomena. For instance, the Mercator projection was long used for navigation or maps of equatorial regions. The cylindrical Mercator projection mathematically projects the globe onto a cylinder tangent to the Equator. Large areas become distorted which increases toward away fromthe Equator. Distances are true only along the Equator, special scales are provided for other latitudes for measurement.
Figure EG.10 Cylindrical Mercator projection The Robinson projection uses tabular coordinates rather than mathematical formulas to make earth features look the "right" size and shape. A better balance of size and shape result is a more accurate picture of high-latitude lands like Russia, Soviet and Canada. Greenland is truer to size but compressed.
EG.11 Robinson projection For more on projections see: Map Projections from the United States Geological Survey.
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