Lab 5: Map Projections

Map projections are crucial for geographical analysis. They allow easy interpretation of real world data by converting three dimensional information into comprehensible two dimensional models. Map projections generally fall into three categories: conformal, equal area, and equidistant. Conformal map projections conserve angles at the local level. Equal area map projections preserve the areas of geographical features, as its name suggests. Lastly, equidistant map projections preserve distances relative to the standard point of projection. All map projections distort the actual image of the map, so it is necessary to determine which projection best suits the purpose of the map. From this exercise, it is easy to see the distortions from the varying measurements of the distance between Washington, D.C. to Kabul, Afghanistan.

As stated earlier, conformal map projections conserve angles. Examples of conformal map projections include the Gall Stereographic projection and the Mercator projection. Projections such as these are useful for many purposes in real life analysis. Because angles are preserved, procedures that possibly require geometrical calculations or data angle manipulations are made easier. However, the preservation of angles results to the altering of shapes and sizes of map features. In both of my examples, you can see that the the continent of Antarctica is much larger relative to the other continents of the Earth. This exaggeration is due to the fact that it is furthest from the point of projection, and therefore holds the most distortion.

As a result, other projections are used if area is needed to be preserved. For instance, equal area projections like the Bonne projection and the Cylindrical Equal Area projection are useful for visualizing the sizes of objects relative to their surroundings. These maps can be used to compare the sizes of different continents or different oceans. However, shapes of the geographical features become altered using this type of projection. For instance, the Cylindrical Equal Area projection stretches the shapes horizontally, while the Bonne projection curves everything toward the north pole. Equal area maps projections should be avoided when an accurate representation of shapes is necessary.

For equidistant map projections, distance is preserved. This method of projection is best suited for this lab because we are measuring the distance between Washington, D.C. and Kabul, Afghanistan. Nevertheless, equidistant projections have distortions as well, especially along measurements that do not line up along the point of projection. These distortions are visible when comparing my two equidistant maps. The distances between Washington D.C. and Kabul differ rather significantly (a difference of approximately 2,000 miles) because they are projected along different lines. It is important to project the map closest to the area that you are examining to eliminate potential errors.