Geography 7 Lab 5

*Measurements will be listed as Geodesic / Loxodrome / Great Elliptic 

Lab #5

 

1) Cylindrical Equal Area (Sphere): 11,136,432 / 13,025,008 / 11,136,432

2)Cylindrical Equal Area (World): 11,159,983 / 13,055,122 / 11,159,992

As we see in these first two projections, equal area projections such as these preserve the amount of space between features on a map and preserve the size of land masses on a map. Using the graticule we can see that in both maps the area has been preserved, although some distortions do exist. For example, when comparing the distance between Washington D.C. and Kabul, Afghanistan in the two projections, we can clearly see that  distance has not been preserved. Regardless of which form of measurement you use, we can see that the second projection increased the distance between the two cities every time.

 

3) Sphere Equidistant Cylindrical: 11,136,432 / 13,025,008 / 11,136,432

4) Sphere Equidistant Conic:         11,136,432 / 13,025,008 / 11,136,432

When looking at the two projections above it is clear that equidistant projections do not preserve a maps shape or area. The continents are different shapes and sizes in the two maps. "Equidistant" projections, however, do preserve the distance between point on a map. As seen through the measurements above, the distance between Washington D.C. and Kabul, Afghanistan is the same in both maps. Although these projections look very different because one is cylindrical and one is a conic, these are both examples of equidistant projections because they preserve distance.

5) USA Contiguous Lambert Conic: 11,159,983 / 13, 055,122 / 11,159,992

6) Europe Lambert Conic:                 11,160,469 / 13,055,701 / 11,160,478

The two maps above are examples of conformal map projections, which preserve shape by keeping the angles of feature boundaries like the countries on these maps. As you can see above, the shapes of the continents in both maps is preserved, this is the objective of conformal projections. However preserving shape is not the same as preserving size, conformal maps can cause countries and other map features appear larger than their spatial equivalent, even though the country would still have the same shape. As seen in the measurements above, the different conformal projections did not distort distance. Although the measurements are not identical, the difference is very minimal.

Significance, Perils, Potential

Map projections are definitely significant because they are necessary to understand how to read a map. If you are not aware of the map projections you are using, you will not know which features of reality are being distorted and which are being preserved. Without knowledge of map projections, someone might foolishly use an equal area projection to measure distance. Their significance is also their peril. As a result of the immense impact that map projections have on the presentation of data, map projections could greatly alter reality in a map. The simple fact that every map projections distorts an aspect of reality is a peril, no matter what projection you use either distance, area, or shape will be distorted and therefore deceiving to unknowing viewers. These perils, however, are minimal and manageable when compared to the potential of map projections. The ability of map projections to express three-dimensional data on a flat surface while still preserving aspects of reality is an amazing feature. Although some may focus on the fact that every projection distorts, we cannot forget that every projections preserves. Map projections not only allow you to transfer three-dimensional data onto a flat surface, but they can also guarantee to preserve area, shape, or distance with different projections. The fact that certain projections distorts is not a problem, we simply need to inform viewers of what the map is preserving and direct viewers to focus on those aspects. Even though equidistant map projections may come in a wide variety of shapes and sizes, if viewers understand the map is preserving distance, they can will know how to interpret the map. The process of this lab has definitely showed me the importance and potential of map projections.