REVISED NOTES ON MAP PROJECTIONS

REVISED NOTES ON MAP PROJECTIONS - R EVISED NOTES ON MAP...

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REVISED NOTES ON MAP PROJECTIONS It is impossible to accurately represent the spherical surface of the earth on a flat piece of paper. While a globe can represent the planet accurately, a globe large enough to display most features of the earth at a usable scale would be too large to be useful, so we use maps. Also imagine peeling an orange and pressing the orange peel flat on a table - the peel would crack and break as it was flattened because it can't easily transform from a sphere to a plane. The same is true for the surface of the earth and that's why we use map projections. The term map projection can be thought of literally as a projection. If we were to place a light bulb inside a translucent globe and project the image onto a wall - we'd have a map projection. However, instead of projecting a light, cartographers use mathematical formulas to create projections. Depending on the purpose of a map, the cartographer will attempt to eliminate distortion in one or several aspects of the map. Remember that not all aspects can be accurate so the map maker must choose which distortions are less important than the others. The map maker may also choose to allow a little distortion in all four of these aspects to produce the right type of map. Conformality - the shapes of places are accurate Distance - measured distances are accurate Area/Equivalence - the areas represented on the map are proportional to their area on the earth Direction - angles of direction are portrayed accurately The Mercator projection was developed in 1569 by Gerardus Mercator as a navigation tool. Like the Peters map, the grid is rectangular and lines of latitude and longitude are all parallel. The Mercator map was designed as an aid to navigators The Mercator map has always been a poor projection for a world map yet due to its rectangular grid and shape, geographically illiterate publishers found it useful for wall maps, atlas maps, and maps in books and newspapers published by non- geographers. It became the standard map projection in the mental map of most westerners.
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This note was uploaded on 04/14/2011 for the course GUS 0821 taught by Professor Davidorgan during the Spring '11 term at Temple.

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REVISED NOTES ON MAP PROJECTIONS - R EVISED NOTES ON MAP...

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