Lab 5: Map projections

Map projections derived from an attempt to transform a 3D spherical model of the earth onto a 2D plane. Needless to say, transforming all the points of a sphere results in compromising accurate images and characteristics. The six maps depicted in this blog entry are examples of conformal, equidistant, and equal area map projections. Each projection has individual nuances and characteristics due to their distortions in area size, shape, distance, and coordinates. Nevertheless, there are practical reasons and applications for the use of each projection. For example, the mercator projection is useful for navigation due to constant angles throughout the entire map. The three different map types are all developed from a different surface shape and hold different properties. The equidistant map projections were developed from cylinder and sphere surfaces, and thus conserve distance. The equal area projections conserve accurate area size of objects being mapped. In regards to the conformal map projections, they are developed from a cylindrical surface and contain an accurate coordinate system.

Map distortions, and their inconsistent effects on distances, reflect the need to understand the significance of each type of projection. The recorded distance for each projection, between Washington, D.C., and Kabul, Afghanistan, varied greatly. The three projections (conformal, equidistant, and equal area) all have particular advantages and pitfalls. For instance, conformal maps preserve longitudinal and latitudinal gridlines, which intersect right angles, as evident in the Mercator and northpole stereographic. The Mercator projection is the most common type of projection used in mapping because it preserves the size, coordinates and shapes. Equal area maps preserve area; the whole of the equal area map has the same equivalent area as the Earth as a whole, as depicted in the Mollweide projection. Equidistant maps show true distances along certain designated lines or from the center to other points. However, the relationship between points further away from the center, or point to people, do not convey an accurate relationship.

Nevertheless, we must cognizant of how each map projection portrays yet manipulates points and coordinates. For example, although conformal maps are very good at preserving angles between gridlines, these types of maps distort the sizes of areas. Equal area maps also have disadvantages despite ability to preserve area: they do not preserve gridline angles, nor do they sustain accurate area. A disadvantage of equidistant map is that these types of maps do not offer true distances while preserving equal areas. Though these distortions occur, understanding how to create and differentiate the disadvantages and advantages of each projection allows us to optimize the functionality of each type.