Week 6: Map Projections

Map projections aim to solve the issue of how a 3D globe can be accurately reproduced on a 2D surface. The importance of accurate cartography has prompted the creation of many types of projections, each with its own strengths and weaknesses. The maps I have created were made using six different types of map projections. In the first row, on the left, is a Mercator conformal projection, and on the right, is a WGS 1984 Web Mercator conformal projection. The maps in the second row display the Cylindrical Equal Area projection and Sinusoildal Equal Area projection on the left and right, respectively. In third row, the map on the left is a Plate Caree Equidistant projection and the map on the right is a Equidistant Cylindrical projection.

Conformal maps, by definition, have longitude and latitude lines that intersect at 90 degree angles and therefore preserve local angles. These types of maps are useful for preserving direction. However, the projection distorts distance as you move away from the equator. In the Mercator projection, the distance between Washington D.C. and Kabul, Afghanistan was measured at 16,290,029 meters. In the WGS 1984 Mercator projection, the distance was 16,155,109 meters.

The equal area projections, as the name implies, aims to preserve the relative areas of all the countries on the map. This is useful for subjects like ecology and meteorology where the area something occupies is relevant. Getting an accurate measure of area is essential to extrapolation and drawing conclusions about an affected population in the area. In the Cylindrical Equal Area projection, D.C. and Kabul are 15,985,172 meters apart. This projection also preserves direction at the cost of being stretched out lengthwise. The Sinusoidal Equal Area map shows that D.C. and Kabul are 13,230,876 meters apart. This map is distorted to preserve the spherical shape and distance of a globe, but the direction is not preserved.

The equidistant map projections are used when distances are important, such as in airline navigation. Distances are preserved in respect to a chosen reference point on the map, which is usually the equator or a longitude line. The Plate Caree Equidistant projection spaces out circles of latitude evenly along a rectangular grid. By doing so, the projection distorts area and direction. According to this projection, D.C. and Kabul are 16,367,464 meters apart. The Equidistant Cylindrical projects the globe cylindrically along a longitude line. This causes the North-South distances to be stretched and the East-West distances to be compacted. In this map, D.C. and Kabul are only 8,145,837 meters apart. Equidistant map projections are especially important for calculating trajectories and weapon ranges in the military.