There is a great deal to be learned from this map exercise. As we can see above, there are incredible differences between the map projections shown above, only six of MANY types of projections. The projections vary in distance, in shape, and in orientation, and these distortions can change our perception of the world around us. Equal area projections preserve area, while equidistant projections preserve distance, and conformal projections preserve angles (orientation). The map projection that a geographer ultimately chooses to use depends upon the use of the map and the message being conveyed in that map. Our lab exercise only further emphasizes that point and shows the importance of choosing ones setting's correctly.
Conformal projections (the first set of maps) preserve angles, but there is significant distortion along the poles. For example, in the Mercator projection, Antartica is approximately the same size of all the other continents combined. While the angles remain accurate, shape and size are lost. While we are quite used to seeing conformal projections, especially the Gall Stereographic, there are some great distortions. Again, the difficulty of translating form from a 3D object to a 2D surface is emphasized.
Equal area projections (shown in the second set of maps) preserve area. However, distance, shape, and direction are quite distorted. In the Hammer-Aitoff Equal Area, the size/area of Greenland and Antartica appear to be less distorted than in the Conformal projections above, but the shape appears grossly distorted. This is even more apparent in the Cylindrical Equal Area projection, where Antartica is stretched incredibly.
Equidistant projections (the third set of maps), preserve distance from a certain reference point or reference points. In the Sinusoidal projection, the shapes near the center are somewhat accurate, but as the lines converge at the pole, the shapes of continents become distorted. In the Cylindrical Equidistant projection, the area of the countries is distorted, as is visibly evident from Africa's compression. Equidistant maps can either preserve area or shapes, but not at the same time. Although we were required to do two maps per type of projection, it would have been interesting to see even more to assess how the distortions are changed and how each can lead to a different visual language when discussing certain areas of the world. There are many types of projections possible in ArcMap, but choosing the correct one will help both the creator and the users of the map and can help advance the information and visual impact of the map itself.
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