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magazine / so96
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September/October 1996 issue |
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Map projection explained
HOW MANY
CANADIANS know that from Winnipeg, the east/west centre
of the country, China is closer than Greece? That the shortest
air route to Rome is over Greenland? That the speediest trip
to Bombay would be over the North Pole?
On this map a straight line from Winnipeg to any other point
on the globe shows the most direct route. The length of that
route can be translated into kilometres to calculate its exact
distance. The map's projection, called azimuthal equidistant,
is used by, among others, airlines to calculate air travel distances
and earth scientists to display the felt area of an earthquake.
The resulting projection is, of course, an image with obviously
distorted shapes and sizes. Mapmakers, however, just can't avoid
the fact that whenever they try to represent a sphere on a flat
surface, something has to give. Several hundred different types
of maps have been devised since the discovery of the shape of
the Earth. Each has its own advantages and each, when misunderstood,
tells its own lies.
- Click to enlarge -
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