Cartography essays

Cartography essays Cartography is described by Webster's as the art of making maps, but how is it done? A cartographer doesn't just sit down and draw a map free hand. He has to have techniques and equipment to do the job right and accurately. Maps can be made in three different ways: cylindrical projection, conic projection, and azimuthal projection. These different ways vary the quality and the accuracy of the map. No matter how a map is made it is going to have geographic grids, which help us find and describe locations. These grids are affected in different ways by each of the projection methods. Cylindrical projections are the projections of the globe onto a cylinder. The easiest way to understand cylindrical projection is to imagine a paper cylinder wrapped around an illuminated globe. The lines from the globe are then projected onto the cylinder in shadows and can be traced. When that is finished the cylinder is slit and unrolled. The problem with cylindrical projection is that there are very few lines that are free of distortion. The lines that are closest to the part of the cylinder that touched the globe are going to be more accurate, while the ones farther out are less accurate. This makes countries like Greenland look humongous on a map, while making America look smaller then actual size. Conic projections are the projections of a globe onto a cone. The best way to visualize conic projections is to imagine a paper cone with its open end resting over part of an illuminated globe. The lines are put onto the cone the same way they were put onto the cylinder in cylindrical projection. Then the cone is slit and unrolled. If the cone was directly over the north (or south) pole, the meridians are projected as strait lines radiating straight from the pole, while the parallels appear as portions of the circle. Just as in cylindrical projection, only a few lines, the lines that exist at the points where the cone touches the ...