Lab 5: Projections in ArcGIS

Two conformal map projection

   Two equidistant map projection

     Two equal area map projection

    Long time ago, people use maps to navigate (probably because people at that time did not realize the earth is round). After Columbus discovered the New World and scientists discovered the earth is round, some people started to use Globes. However, people nowadays use map again. Therefore, it is not hard to see that although only globes could preserve nearly all the properties of the real earth, map projections also own their equivalent significance. The Globe is hard to make measurement and expensive to produce, while map is portable and allow user to see the whole earth in a single map. There are three most essential properties people concern: conformal, equidistant and equal area. In this task we should pay more attention to equidistant, since the objective is to measure the distance from Washington D.C. to Kabul, Afghanistan.

   It is extremely hard to completely translate a globe to map, so, usually, map projections could only preserve one of the “essential properties” and the further from the center of the map the less accurate it could be. In this task, for example, different map projections have unique errors and diverse equidistant map projections have slight errors along with different centers and mapping strategies. Therefore one cannot view an accurate globe in a single map. Unfortunately, there is no way to map a completely accurate map according to topology, so the limited accuracy would be a huge obstacle of map projection.

   However, with the development of technology and topology, people may found more and more better map projections to adapt to objectives. Just like the development of the map technology from middle age to modern era, nowadays, people gradually accept the error contained and much more targeted maps. Conformal maps apply for navigation, equal area maps spread over land use maps and population density and equidistant map uses in distance measurement like this task. Because people could always learn from map projection choosing, gradually people could use the map projections professionally and bring map projections to a higher level geographic awareness.  

   All in all, as long as we could realize the error of map projections, these known unknowns would eventually help us understand more about geographic analysis. After the invention of map projection, the growing number of subcategories implies the prevalence of this new method of geography studying.  Undoubtedly, we will have more and more new ideas new methods to avoid errors in the future. Although it is hard to break the limitations of three properties for mapping, people’s ubiquitous map-awareness is around corner.