Assignment 5

Mollwiede Projection (equal area)
Distance from DC to Kabul in miles:
Planar: 7,925
Geodesic: 6,934
Loxodrome: 7,925

Cylindrical Equal Area Projection
Distance from DC to Kabul in miles
Planar: 10,108
Geodesic: 6, 934
Loxodrome: 8,112

Azimuthal Equidistant Projection
Distance from DC to Kabul in miles:
Planar: 8,341 miles
Geodesic: 6,934
Loxodrome: 8,112

Sinusoidal Projection (equidistant)
Distance from DC to Kabul in miles:
Planar: 8,098
Geodesic: 6,934
Loxodrome: 8,098

Stereographic Projection (conformal)
Distance from DC to Kabul in miles:
Planar: 9,878
Geodesic: 6,934
Loxodrome: 8,112

Mercator Projection (conformal)
Distance from DC to Kabul in miles:
Planar: 10,112
Geodesic: 6,934
Loxodrome: 8,112

Map projections are a way to enable the reshaping of Earth by converting spherical coordinates (x, y, and z coordinates) to two dimensional coordinates (x, y coordinates). This process distorts either the shape, area, distance, or angle, and often some of these at once. Each projection causes different distortions of the earth, which you can see in the six projections that I have chosen. Picking the proper projection mostly has to do with the purpose of the map and the qualities that are most important to you. The three main types of maps are conformal which preserves angles, equidistant which preserves distance, and equal area which preserves the proper area. Even though there is some consistency within each general type of projection, you can see that there is still some variation in the distance between DC and Kabul on all of the maps. 

The first two projections are equal area projections. The cylindrical equal area projection preserves the area of the earth's features. A cylindrical projection refers to the way the map was created - by essentially wrapping a piece of paper around the globe. There is the least amount of distortion at the equator with growing distortion at the poles. The Mollwiede is an equal area pseudocylindrical projection which shows the equator as a horizontal line and meridians that compress near the poles. The next two maps are both equidistant projections. The Sinusoidal projection conserves the distances along the meridians and the Azimuthal equidistant conserves distances along great circles (a great circle is a full meridian circle). The last two projections are conformal projections. The Mercator projection is an old and well known conformal projection and is easy to spot because the lines of latitude and longitude intersect at 90 degree angles. Lastly, the Stereographic projection projects the shape of the earth's spree as a plane. All of these projections have pros and cons depending on the purpose of the map. 

A huge drawback to map projections is that there is a lot of distortion. As you can see the distance between Washington DC and Kabul varies greatly depending on which map you are looking at. The equidistant map projections (the Sinusoidal and the Azimuthal equidistant projections) both show that the distance is about 8,000 miles. But even between the two there is discrepancy. Other maps distort area and makes certain countries look bigger or smaller than they should. 

Although globes are the most accurate way to display the world with little error, globes are not the most practical tools for most mapping applications. Map projections have great potential depending on the purpose of your map. Map projections allow us to analyze aspects of the earth on many scales and in many different ways. The computer's ability to create thousands of projections increases the ways we can look at the world as opposed to the traditional planar, conic, and cylindrical projections that we have achieved from theoretically wrapping a piece of paper around a globe. Although we need to be careful and aware of any errors a map projection may create, map projections have a lot of potential and are an extremely important part of GIS and geography.