Lab #5: Projections in ArcGIS

Planar Distances from Washington, D.C. and Kabul, Afghanistan via Conformal, Equal Area, and Equidistant Map Projections

Map projection is a tool in which the 3D world can be represented in the 2D form. This approach allows geographers, urban planners, architects, and other entities to analyze data in simpler terms instead of mentally figuring the 3D world. There are many different projections that can be done. The main three that we focus on are: conformal projections, equal projections, and equidistant projections. These different projections represent different data and analysis. In this lab, I analyze the planar distance from Washington, D.C. and Kabul, Afghanistan via Conformal, Equal Area, and Equidistant Map Projections. Also, with these different map projections come pitfalls and difficulties.

Conformal map projections preserve angles. This distorts the area and distance on the map. Gall’s Stereographic map projection shows that distortion slowly increases away from these latitudes. For the stereographic map projection, scales are distorted as we move away from the center and area is distorted as distance increases. The pitfalls for this particular map projection may be in the size of each country/region. Although the angle is preserved, the shape and area is further distorted, giving off an image that confuses people. One can assume that these map projections allow political parties propagandize; for example, the image of Russia as being bigger than it actually is. Another example would be Greenland’s distorted size and shape.

Equal area map projections focus on preserving the area. The angle, shape, and distance are distorted as you move from the equators and closer to the poles. These map projections are generally used for world maps and are good for regions close to the equators due to the lack of distortion there. The positive aspect of these map projections is that Greenland is not blown out of proportion in terms of shape and area.

Equidistant map projections focus on preserving the distance from certain reference points. Choosing different reference point(s) can distort the map. The Equidistant Cylindrical map projection is best used for small areas with map scales, such as city maps. It is used to simply represent minimal geographic data, making for easy index maps. The Equidistant Conic map projection is common for atlas maps of small countries. It was used in the Soviet Union to map out their territory. Equidistant map projections then are limited in the sense that particularly everything is distorted in one way or another, for example the limitation of the angles.