Week 6: Projections in ArcGIS

Original Map Projection from Lab: GCS WGS 1984, distance between Washington D.C. and Kabul was 7,018 miles.

Equidistant Cylindrical Map, distance from Washington D.C. to Kabul, Afghanistan was 5,075 miles.


Equidistant Conic Map, distance between Washington D.C. and Kabul was 6,966 miles.


Sinusoidal Map, distance between Washington D.C. and Kabul was 8,081 miles.


Cylindrical Equal Area map, distance between Washington D.C. and Kabul was 10,135 miles.


WGS 1984 Web Mercador Map, distance between Washington D.C. and Kabul was 10,164 miles.


Mercador Map, distance between Washington D.C. and Kabul was 10,123 miles.



This exercise brings to attention how relative these maps truly are. The distance between the cities of Washington D.C. and Kabul, Afghanistan was different in every map projection, with as much of a difference as 5,000 miles. The Mercador map versus the Equidistant Cylindrical map was the most extreme example. The different shapes and views of the maps affect the distance between these two cities. These maps are more accurate towards the center of the projection, but the further away you get from the center, the maps become more distorted.
It is useful to look at the different projections to acknowledge that while they may be mostly accurate up close, like on personal GPS devices, when viewing a large area they are often unreliable. Even globes are unreliable as a perfect model of the earth because they are perfectly spherical. It is nearly impossible to produce a perfect model of the earth, but geographers use these map projections to represent our world the best way possible. Being able to look at multiple map projections allows us to get a better idea of the way the world looks. Manipulating these maps on ArcGIS makes this reality even more tangible.
The pitfalls of using these map projections is that without viewing multiple projections, one's worldview is literally distorted. The combination of these maps, though contradicting, at least show that no specific one is to be completely relied on. Each is useful for a specific point of view, but none is flawless.
The positives of these map projections is that while they're not realistic in some cases, they allow maps to be worked on with the computer, on paper, and with more detail than a huge globe. We know the earth isn't flat, but sometimes that's the best way to work with it, even if certain parts are stretched or scrunched.