Saturday, October 12, 2013

Don't lie to children, damn you! —with map projections

On Friday I had the honor of keynoting the North American Cartographic Information Society (NACIS) Annual Meeting. I told many silly stories to keep the audience mildly engaged because my talk was after dinner; everybody —including me— had enjoyed at least a glass of fine red wine already. The most successful anecdote went more or less like this: A few weeks ago, I went to the bookstore with my kid to buy a world map. I want him to learn some geography. To my dismay, this is the one he chose:


When my boy saw me grimacing he asked: "What's wrong?"

"I don't think that this is the map we need" I answered.

"Why not? It looks great! I didn't know that Canada was so huge."

"Well, it actually isn't!" I didn't elaborate further. What should I do? Explain to him how the Mercator projection works and why it may not be the most appropriate choice for world maps? That'd be overkill for a kid that just turned eight, wouldn't it? On a side note, even The West Wing made fun of this kind of map, comparing it to the ungraceful Gall-Peters projection. Don't miss that video clip, please.

As Mark Monmonier wrote in his classic little book, all maps lie. I'd dare to add that some of them lie more than others. The one that we found at the bookstore lies a bit first because it greatly distorts areas that are far from the Equator —it preserves angles and shapes, though. So why did the designer add this to the bottom right corner?:


Where should we assume that this scale is true? If it is along the Equator (the standard line in many cylindrical projections) it won't be true anywhere else, after all. So this is clearly a second lie. And there's a third one, which is even funnier:


When I noticed that footnote, I felt compelled to send a letter to whoever designed this thing, bluntly expressing my distress. I summarized it in this slide which, to my relief, made the audience roar with laughter:


After the presentation, a very experienced cartographer approached me to suggest: "You'd better get your son a globe." Words of wisdom!

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