Monday, November 8, 2010

Lab 5: Projections

The following images are represented in Equal Area, Equidistant, and Conformal projections. I have given two examples of each type of projection along with labeling the two cities Washington, D.C. and Kabul, the distance between, and I have given some comments regarding the projections toward the bottom.

Equal Area



Map projections allow us to view the earth in many ways. Since the earth is a three dimensional shape it makes converting it to a computer or drawing slightly difficult. The easiest way of displaying this data is to put it into a two dimensional surface or shape. This is very useful because it provides different perspectives of the same data, which could lead to many different conclusions. There are positives and negatives towards map projections. As a result of not being able to easily represent the earth fully in a three-dimensional shape, each compares different variables and unfortunately distorts distance, shape, or area (however, many researchers have agreed on the Mercator projection showing the best results).

In map projections that distort area, such as sinusoidal projects, the area of the map north to south and east to west has the same area. When compared to the conventional two-dimensional map, the area is adversely different. The sinusoidal projection allows the grid to be equal area so, if one were to look at Greenland, it seems as if it is as long as North America. The cylindrical equal area projection takes the two-dimensional map and wraps it around a theoretical cylinder. This is helpful when the projection is concerned with the middle near the equator but towards the north and south, the projection follows the cylinder rather than a sphere. This map projection is very close to what the projection would be like on a simple two-dimensional plane. The distortion of area is something that needs to be noted otherwise it can cause one's conclusions to become inaccurate if this is not taken into account.

This is similar to equidistant projections because in those projections the distance is not changed but the area and shape is distorted. This is an interesting way to look at the earth, but one must not overlook that the measurements between two points are not the same distance. The equidistant conic projections offers an interesting outlook of the earth. In this projection the earth is viewed from the northern or southern pole and then squashed onto a two-dimensional surface. The equidistant cylindrical projection shows the earth represented by a two dimensional shape in the form of a cylinder, but unlike the cylindrical equal area projection, it also preserves distance. Since these map projections have equal area, it changes the 'actual' area of the real land mass.

In conformal projections like Mercator projections keep angles preserved while distorting shape and area. This is one of the most used projections because it can represent lines constantly as straight line segments. It maintains angles, Greenland again is displayed with having more land mass than South America. The gall stereographic projection does not preserve distances or area. This type of projection takes the spherical world and projects it onto a circular plane. There is much potential, but at the same time many perils when comparing and analyzing the accuracy and significance of map projections, but the only way to fully visualize the world is to see it through all types of map projections. If one were to over look variables that are not maintained in certain map projections, then results could turn for the worst. One has to exercise utmost caution and question the validity and accuracy of a projection when working with them.

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