Distance from Kabul to Washington, D.C.: 6,972.48 miles
Distance: 5,065.05 Miles
Distance: 10,115.52 Miles
Projection: Sinusoidal (Equal Area)
Distance: 8059.66 Miles
Projection: Mercator (conformal)
Distance: 6,934.47 miles
Distance: 7,156.45
Different map projections use different ways of projecting the three dimensional world onto a two dimensional surface. Because of this, every form of map projection is distorted in some way. Equidistant maps are maps where all points on the map are the same distance from the middle of the projection. Equal area maps are maps that maintain relative sizes. Conformal maps are maps that maintain angular relationships and accurate shapes over small areas. Different types of maps are useful for different purposes. Equidistant maps and conformal maps are used for navigation, while equal area maps are used for mapping distributions. In addition, a cylinder, cone, or plane may be used to translate the three dimensional sphere onto a two dimensional surface. This is done by using a shape that can be flattened out.
As shown by the maps above, different map projections account for the same distance differently. The distance from Washington, D.C. to Kabul, Afghanistan varies depending on what projection is used. The purpose of the projection must be considered when deciding which projection is most useful. For example, the equidistant conic projection is best used for navigation, because distances are equal. However, it provides very little detail, so it would potentially be more useful for flight path navigation versus navigating a very specific area. The equidistant cylindrical map preserves also preserves distance but looks completely different than the conic version. Shape and area are presented differently, and areas that are larger are not necessarily shown true to size. It is also interesting to note that the distances vary even for two equidistant maps.
The cylindrical equal area map preserves area but distance and shape are distorted, and it is clear that european region is distorted in terms of shape. The sinusoidal equal area map shows the entire globe and is better for representing information on a larger scale. The conformal maps presented look similar, and the distance from Washington D.C. and Kabul on these two maps are very close.
Having different ways of projecting the 3D world onto a 2D surface is useful for different mapping purposes. However, it is problematic because someone who uses a map may be misinformed if they are not aware of the projection they are using. In addition, it creates confusion as to what is the "real" distance, shape, or area.
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