Week 6, Lab 5: Projections in ArcGIS

The equator spans 360 decimal degrees in this 30 degree x 30 degree quadrangle. The northernmost and southernmost graticule lines on the map represent the North and South Poles, and the distance between the two spans 180 decimal degrees.

Standard Projection:



There are approximately 10,135.71 miles between Washington D.C. and Kabul in this 30 degree x 30 degree Standard projection.

Equal Area Map Projections:



There are approximately 6,716.8 miles between Washington D.C. and Kabul in this Equal Area: Bonne Projection.



There are approximately 8,339.5 miles between Washington D.C. and Kabul in this Equal Area: Hammer Projection.

Equidistant Map Projections:



There are approximately 10,160.7 miles between Washington D.C. and Kabul in this Equidistant: Plate Caree Projection.



There are approximately 6,984.9 miles between Washington D.C. and Kabul in this Equidistant: Conic Projection.

Conformal Map Projections:



There are approximately 10,085.9 miles between Washington D.C. and Kabul in this Conformal: Mercator Projection.



There are approximately 7,129.8 miles between Washington D.C. and Kabul in this Conformal: Gall Stereographic Projection.

Write-Up:

Map projections are extremely useful and complex. The complexities arise when trying to project a 3-dimensional surface onto a flat, 2-dimensional surface. We worked on three different types of map projections, which included: equal area, equidistant, and conformal projections. These projections minimize distortions in some of the following properties while maximizing the error in others: conformality, distance, direction, scale, and area.

The Mercator and Gall Stereographic projections are examples of conformal map projections. A conformal map projection has straight meridians and parallels that intersect at right angles. The scale is true at the equator and these types of projections are useful for marine navigation because all the straight lines are of a constant azimuth. Equal Area maps, suych as the Bonne and Hammer projections, preserve area. In other words, these projections distort the sizes of land to make each country the same size in terms of area. Finally, equidistant maps, such as the Plate Caree and Conic projections, preserve distance from a standard point or line.

These map projections are significant because they are each designed to serve different purposes and help people complete various tasks. The problem with these projections is, however, that people who are not well versed in the different types of projections may misread or misuse the projections in trying to complete certain tasks. These projections are also difficult to understand at the onset; it's difficult to grasp which maps distort what attributes, and so on.

Overall, I found this exercise extremely interesting and am interested to learn more about the uses of these different map projections. My favorite projection out of the six that I posted is the Bonne projection because the shape is the most original and the most interesting. I am still unsure about how the spherical surface of the Earth can be projected onto something like the equidistant, Conic projection, so I will need to look into that and attempt to understand it. The distances between Washington, D.C. and Kabul, Afghanistan were all different depending on which map projection was used, which highlights how different map projections can distort the size, area, and distances between different places.