Tuesday, May 10, 2011

Lab 5: Map Projections Part 2

Map projections are extremely valuable resource of geography due to it's ability to turn a 3-d object, like the earth, into a 2-d object that can be utilized for navigation and different uses for mapmaking. Typically, map projections fall into 3 categories: equal area, equidistant or conformal.

Equal-area map projections maintain the relative distance and size of the geographic features. This type of projection is ideal for accurate representation of the surface area of the countries. Equidistant projection preserve the distance between points and is proportional to the surface distance on the earth. Lastly, the conformal projections preserve angles locally, which are useful for navigation. Each of these categories have their own advantages and disadvantages.

For instance, conformal maps, like the Mercator projections, are indispensable tools for navigation and used to chart courses. Unfortunately, while conformal projections display correct angular relationships, people can develop an incorrect idea of the actual size of the countries. For example, on the mercator projection, certain countries look bigger and closer to the poles than they actually are.

Equidistant projections, like conformal projections, have their advantages and disadvantages. Because equidistant projections preserve distance at the cost of area and angles, they can only preserve distance from a central point. As a result, the more one deviates from that point, the less accurate the measurement will turn out to be.

Lastly, equal area projections are useful because they convey geographically accurate features on the map as they are in real life, which can prove to be accurate when features are changing like polar ice caps, or rivers. However, at the same time, it becomes difficult to represent all of the earth in a rectangular form, which makes it difficult to compare geographic features.



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