Lab 5 - Map Projections

Different map projections by type





The fact that the world is round and in a three dimensional space poses problems when converting them to a map on a two dimentional plane. Inevitably there will be distortions that may introduce errors into the data. Working through this lab allowed me to see the map projections first hand and how different they look compared to other projections. For example, the Mercator projection (3rd map layout)distorts the size of Antartica and Greenland dramatically compared to the Mollweide projection (2nd map layout)where Greenland and Antartica look much more resonable. This emphasizes the importance of using the correct map projection for the task at hand.

Since distortions occur for any projection, researchers need to use a projection that protrays the areas of interest with the least distortion. This would explain the plethora of projections available. So equal area maps would be used for reasearchers that are interested in problems involving land mass and conformal maps that preserve angles would be used for navigation.

Another dramatic different between maps is how the distance between Washington D.C. and Kabul changes. One of the more dramatic difference was the Equidistant Conic projection (1st map layout) which measured the distance between Washington D.C. and Kabul to be 4399 miles and the Plat carree projection (1st map layout) which only measures that distance to be 2341 miles. At first it was strange to me that even among equidistant projections the distance between two objects could be so different. I suppose the way the projections are created distorts the areas between two points and a straight line between those two points will have different lengths depending on the projection.

Although some map projectiosn look very different from each other, other map projections look very similar. An example are the Mollwiede and Hammer projections (1st map layout). They are both equidistant projections and they are also very similar in appearance. So researchers must always be careful when layering maps to always check the metadata to make sure all projections used are the same.