Practical GIS

Choosing the right projection

Now that we know how projections work, let's discuss how should we choose the right projection for our work. We learned before that projections distort reality, as we cannot convert an ellipsoid to a flat surface. Projections have some properties, which are shape, area, direction, distance, scale, and bearing. From these properties, a single projection can only fully preserve a few, at the expense of other properties. Based on the preserved properties, we distinguish between the following types:

• Conformal: Preserves bearings, and shapes locally (still distorts shapes, but it creates the best global approximations). Conformal maps (like Mercator) were life savers back in time, when sailors only had a compass ...