Lab 5

In ArcGIS and Geography map projections are an important key in revealing the necessary information due to spatial limitations of representing a 3D Earth on a 2D plane. The significance of map projections is in the ability for one projection to preserve one or more geographic properties while at the same time distorting widely the other properties. When used in combination map projection provides a wealth of data that is accurately represented. The limitation of map projections brings both perils and potentials in its usability and the information it provides.

Conformal map projections preserve the angles or directions on the map but distorts true distance. In conformal maps, large objects are widely distorted as the distance increases from the equator this is why maps that utilize the conformal projection often are seen as distorting the size of Greenland in which the continent of Africa which appears smaller is on magnitude many times larger. The usefulness of Conformal and specifically Mercator projections is the ability to represent lines of distances accurately and therefore is useful in nautical maps. The Miller Cylindrical map is a modification of a conformal projection where the whole earth is presented as rectangular frames. The distortion exaggerations seen with the Conformal Mercator maps is decreased as with its usefulness in navigation.

Equidistant projections preserve distance on a standard line but distorts both the shape and direction of the map. Equidistant Conic maps utilizes two reference parallels to minimize distortion from 3D globe to a 2D plane. The distortion increases away from the standard parallels, useful for depicting the middle latitudes. Sinusoidal projection both the area and distance along the parallels are preserved but the shape and direction are greatly distorted. Equal Area projections depict the area and angle shape to true form. For example in Mollweide and Cylindrical Equal Area the importance of area representation takes form in favor of angle and shapes. The equator is represented as a straight horizontal line and in both maps the parallels start to compress near the poles. Equal area projections are generally used in map depictions of the world due to its preservation of area.

The potentials that map projection provides is the ability to depict certain geographic properties of the Earth accurately on a 2D plane. With this ability it is possible to fit 3D globes in the form of a paper map. Present day manipulations include the ability to overlay several maps on top of each other either in ArcGIS or through paper formats. The perils of map projections includes the limitation on preserving the shape of the map and attaining accurate properties. Also with the advent of ArcGIS and other mapping software the need for a pure 2D planar map has decreased as the ability to truly represent a 3D globe has become common as seen with the Google Earth Software. Map projections is more importantly still relevant in geography and society today as many industries rely on a specific projection that is common and people still see 2D representation of maps and the Earth as the default method for viewing.