Lab 5: Map Projections

 

Map projections are vital and prominent in the world of cartography and GIS. They are a way of transforming Earth's three-dimensional surface into a two-dimensional flat map that are most efficient for use. However, map projections are ultimately abstractions and each one creates some type of distortion to either Earth's area, distance, direction, or shape because it is not possible to accurately translate all spatial characteristics from a spherical globe to a flat surface. Some of the most common projections include conformal, equal area, and equidistant which all encompass their own  perils/potentials and advantages/disadvantages. Despite these inaccuracies, map projections all have their own significance as they enable convenient representation of the world's surface in a relatively efficient way that creates easier use and distribution among consumers.

Conformal projections, such as the Mercator and Hotine Oblique Mercator above, retain local shapes as they preserve the angles of boundaries of countries, continents, and other features. However, by maintaining angles, the actual area within certain features becomes distorted. For example, in the Mercator projection above, the recognizable shape of Greenland remains but it seems way larger than the country of Mexico, which is almost its spatial equivalent in actuality. You can see the area distortion again in the Hotine Oblique Mercator, as the island chain of Indonesia looks as large as the continent of Africa.

Equal Area projections, like the Cylindrical Equal Area and the Eckert VI projections.,  preserve the amount of space/area within map features. In both equal area projections shown above, Greenland and Mexico are projected to be about the same size, which corresponds to the actual area in reality. Also, The continent of Africa remains larger in size than the continent of South America, which again corresponds to reality. However, equal area projections distort all other properties such as shape, direction and distance. When measuring and comparing the distance between Washington D.C. and Kabul on both the Cylindrical Equal Area and Eckert VI projections, one can see the drastic difference in measurement. The distance measured between the two cities on the Cylindrical Equal Area is a little over 10,000 miles, while the distance measured between the same two cities on the Eckert VI projection is only about 7500 miles.

Equidistant map projections, like the Equidistant Conic and the Azimuthal Equidistant above, preserve the distances along designated lines and/or outward from the center. Nevertheless, this type of projection does distort area of features, as can be seen in the Azimuthal Equidistant projection where the continent of Australia looks larger than that of Africa. This type of projection also does not always show true distances between various points, which is conveyed by the different measurements of the distance between Washington D.C. and Kabul found in the Equidistant Conic (about 7000 miles) and the Azimuthal Equidistant (about 8400 miles).

In conclusion, the concept of map projection does have its various significances, perils, and potentials. Since it is impossible to accurately translate a three-dimensional Earth onto a two-dimensional flat surface, all projections will have some type of disparity and distortion in its features. Therefore, it is important to recognize that each projection is best used for specific inquiries and data to avoid false measurements and findings. Despite the inaccuracies of projections, map projections are still essential in making the spatial analysis of the Earth possible.