Do You Really Know Where You Are?
By Casey J. McLaughlin
Map projections have caused me great pain. The standard Mercator map I grew up with became standard 500 years – shapes are well represented and any line drawn on the map represents a true compass bearing. In other words, a Mercator map was incredibly useful for navigating and became the projection of choice for sea travel. Take a step back and understand that a projection is “a method by which the curved surface of the earth is portrayed on a flat surface” (ESRI GIS Dictionary). Wikipedia has a good description of map projections. Seemingly a simple concept, there are several hundred types of projections. Each has its own uses, but all flat maps contain distortion of some kind.
Greenland and Antarctica appear as huge white areas. Notice the grid cells at the top and bottom are quite long. This projection distorts area as you travel away from the equator. Would you it surprise you that in reality, Africa is 14 times larger than Greenland?! On the television series, “The West Wing” (Season 2, episode 16) character Josh Lyman asks a group of cartographers:
“Relative size is one thing, but you’re telling me Germany isn’t where we think it is?”
Dr. Fallow responds: “Nothing is where you think it is.”
Casey McLaughlin is a first generation Geospatial Enthusiast who has worked with EPA since 2003 as a contractor and now is the Regional GIS Lead. He currently holds the rank of #1 GISer in the EPA Region 7′s Environmental Services Division.
Editor's Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.