Lab 5 Projections!

Undoubtedly map projections are extremely important in not only the world of geography, but also any time maps are used. Representing the spherical earth onto a 2D plane is no simple task, and it is essential to be precise and exact in one's conversions in measurements so as to best represent the world. By allowing us to represent the Earth's surface in 2D, projections allow us to explore the world by simply looking at a map or a computer screen, both mediums which (obviously) require the world to be "flat" since these are much more portable and convenient than carrying around a globe.

What I never knew before this class was that there were so many different types of map projections with a variety of representations, some of which I find nearly unreadable (such as the equal area Bonne map I have created above). One goes about choosing a projection based upon what one wishes to accomplish: navigation, radio and seismic mapping are just a few of the things one could base their decision on. Obviously one would want to have a map best suited to one's particular needs.

For example, in conformal map projections (such as the Mercator and Gall-Stereographic I created) preserves the angles of the map, and has rhumb lines (a straight line on the projection) which show true direction, and would help a navigator see that he could reach a certain point if he keeps a constant bearing. Equidistant projections maintain the true distances from the center of the projection (such as in Plate Caree and Sinusoidal) which is great if one is interested in measuring things in relation to the center. In equal area projections, (Bonne and Molleweide), the areas of the Earth's surface are maintained at a smaller scale and not distorted.

But just are there are advantages to having these different projections to represent the maps differently, there are also disadvantages. What if one has all these options but is no expert in GIS? How does one choose which projection? As we can see, distance is most definitely not constant across all maps -- the distance measured between Washington DC and Kabul is different in every single projection, with great differences between them (even of the same projection!). So really without sure knowledge, one leaves it up to some ambiguous authority (Google maps, map quest, the USGS etc) to determine which projection you are to see. Also, without knowledge of which map is appropriate for which usage, one may not be able to determine the precise and correct measurement they are seeking.

And so, though there is some uncertainty involved and danger in choosing one projection over another without knowing potential distortions, having projections is of great use to us where GIS, maps, and GPS are all presented in 2D, and we can't all walk around with globes.