What is Mercator?

How?

Imagine that the earth is surrounded by a cosmic toilet paper tube.  If you can do that, then it shouldn’t be a stretch to imagine a gigantic light bulb in the center of the earth.  If you were to then trace the projected image of the earth onto the toilet paper tube and unwrap it, you have a map of the earth in the glorious Mercator projection.  For further info on projections, check out this cool site.

A New Life for an Old Projection

When Google Maps and Microsoft’s Virtual Earth came out a couple of years back, I remember hearing startled rumblings from my fellow map geeks.  "Mercator!  That’s so 16th century!"  In cartographic circles Mercator has gotten a bad rap as being a has-been relic of the age of exploration and the cold war. The usefulness of Mercator has been reborn! It’s so hot right now. History Gerardus Mercator (1512 – 1594) was a Renaissance cartographer who gave us the Mercator projection.  He compiled the best maps around and created a portable book, in effect creating the first atlas (named so because he used the image of the mythical Atlas whose burden it was to carry the world on his shoulders). (source: University of Houston) The early benefit of the Mercator projection was that it maintained angles.  This meant explorers could plot a course on their map then follow the compasses -not the case for other projections around at the time. (Mercator map of Europe.  Image URL) One of today’s benefits is that Mercator does not distort shape (but it does distort size things get bigger the farther they are from the equator).  This means that if I zoom in to a building in Helsinki, it will still look like a building, not squished (it will, however be much larger than a same-sized building near the equator at the same zoom level).

 

John Nelson / IDV Solutions / john.nelson@idvsolutions.com

 

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