Mercator Rotator

Usually when we think of the Mercator Projection, we think of this map with the geographic North Pole at the top, Antarctica at the bottom, and the relative size of the Northern Hemisphere severely exaggerated:

Months ago, this picture appeared on a site called Apathy Sketchpad:

The map is also the Mercator Projection.  Mercator’s contribution was not in putting north at the top, but in developing a particular mathematical formula for representing the planet’s roundish surface on a flat map.  As the author of Apathy Sketchpad puts it, “the Mercator projection doesn’t need to make Africa small and Greenland big. It can do anything you want it to.”  Producing a map with Africa at the top, he explains:

In principle a Mercator projection can be continued infinitely in the vertical direction, and in this case the ‘north’ pole is in Africa, so the map would be Africa all the way up. The level of detail would, source image notwithstanding, get bigger and bigger until eventually sub-atomic particles started to appear. Theoretically, you could exploit this to produce a map where Britain opened out as Africa has at the top, and extend the map up to include a road map of England, including  a large-scale street map of Manchester, eventually opening out to provide a floor-plan of one particular building, then room, and eventually the layout of one table. This, however, seems like it would be very difficult so I haven’t bothered.

In the comments on this post, I remarked that I’d long thought someone should create a flash app called “Mercator Rotator” which would enable a user to put “north” wherever s/he liked and see the resulting Mercator map of the earth.  I have no intention to produce such an application myself, but if you, the reader, have the requisite computer savvy and some time on your hands, I recommend that you do so and let us know about it in the comments.

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2 Comments

  1. believer1

     /  January 25, 2011

    It’s amazing how different the two maps look.

  2. acilius

     /  January 26, 2011

    I agree, Believer! He has several other versions of the Mercator Projection in the same post that make me long for the Mercator Rotator app.

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