MAP PROJECTION: WHAT AND WHY ?

Mathematician, Carl Friedrich Gauss proved that spherical surfaces cannot be represented as planar surface without any distortions. If we were to represent our not-so-spherical earth to a planar surface, we will have to make some compromises.  Since 1500’s cartographers have been trying to represent our earth flat and this is done by a process called Projection.

Map Projection can be defined simply as the mathematical transformations of the location in the 3-D space of earth’s surface onto the 2-D space of map sheet. Cartographers and mathematicians have created huge library of available projections, yet no projection can completely represent earth in all aspects. Certain map projections can be misleading or very helpful depending on what you are searching for. 

The four dimensions that we need to preserve to fittingly project earth on the paper are :

  • Area
  • Shape
  • Distance
  • Direction

But as we try to preserve one aspect, other gets distorted. Every projection comes with its own trade off. There are different ways to classify map projections. One simple scheme is to classify map projections according to the type of develop-able surface onto which the network of meridians and parallels is projected. Popular theoretical map use cylindrical projection for creating map. 

Mercator projection has been used for navigation purposes as it preserves shape and direction. Google maps use Mercator projection even though it distorts the area. Greenland and Africa appear of the same size even though Africa is 14 times bigger. Similarly Gall-Peters projection accurately display the area of the countries but misleads the shape.

Since the invention of GPS, traditional maps are seldom used for navigation purposes but more for imperatives and aesthetics design. 

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