Map projection plays a very significant role in geospatial information systems. Being as the world is generally shaped like a sphere, excluding protrusions and its slightly ellipsoidal shape, projecting the 3D world onto a 2D map can be a difficult process. As there is no way to flatten the Earth onto a map without distortion, there are no map projections that preserve distance, area and direction. We must rely on many different map projections to be used for their specific purposes. In the following paragraphs I will discuss the three factors that projections are created around.
The first type of map discussed is a conformal map. Conformal maps preserve angles. Conformal maps are great for navigation as they will not distort the angle (direction) in which one is trying to go. Many conformal maps however do no preserve distance and area. The first conformal map projection I used for the project was the Mercator. In this projection I found the distance from Washington DC to Kabul Afghanistan to be 10112 miles. In actuality this distance is 6930 miles. Likewise the Gall Stereographic projection, which is also conformal, read a distance of 7109 miles between the two points. Despite giving completely different distances, these are still accurate and useful maps just not for the purpose of measuring distance.
The second type of map discussed is equal area. Equal area maps as the name suggests preserve the area of features on maps. These maps are useful for many statistics such as population per square mile or the size of a country. I used a Mollweide map projection to get the distance from Washington DC to Kabul Afghanistan and got 7870 miles between the two points. Likewise with the Sinusoidal projection I received a distance of 8098 miles. Neither of these are correct as they are not made for measuring distance.
The third type of map projection is equidistance. As the name would suggest this preserves the distance between two features. These maps are great for finding the length of a trip or calculating the length of a flight and the fuel needed for the plane. For these I used the equidistant conic map projection and the equidistant cylindrical map projection. The equidistant conic map gave me a distance of 6964 miles between the two cities. This is very close to the actual distance, if not spot on. The equidistant cylindrical map projection on the other hand baffled me as it gave me a distance of 5067 miles. I am not sure if this is not an equidistant map as would be suggested by its name or if there was an error somewhere.
Thanks,
-Vinnie
Nice job.
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