Gall’s Stereographic projects the earth onto a cylinder. Since the point of projection is not at the earth’s center, the great exaggeration of the extreme latitudes is avoided. The result is a pleasing picture of the earth with area and shape distortions reduced. The projection ‘averages’ the area distortions of conformal projections with the shape distortions of equal-area maps. This ‘compromising’ result pleases the eye but has no other strict cartographic virtue.
Van der Grinten projects the entire earth onto a circle. It assigns the greatest distortion to the areas very near the poles, leaving the rest of the earth to be viewed with minimized distortions. Usually the polar areas are cut off the map.
The Globular projection is very old and popular. It is easy to construct and gives an excellent appearance for a hemisphere; but it is not used for full world maps.
The idea of wrapping a cylinder around the world, projecting it on the surface, and then unrolling the cylinder is an ancient idea that is still used today. Variations of the Cylindrical projection are created by changing the point of projection from the center of the earth to a point off center (on the surface or outside the earth and cylinder itself). All cylindrical maps that are oriented to the equator maintain straight meridians and latitudes that intersect at right angles (as in reality). The polar areas, however, are greatly stretched in the east-west direction.
A cone can also be placed on the earth like a cap and have the earth’s image projected on it. The Conic projection is simple to construct and gives good results for the mid-latitudes. It is not suitable for equatorial or polar regions.
