Map Projections


A projection is a geometric means of constructing a map of a sphere (the earth for example) on a flat piece of paper. True projections are generated by imagining a point source of light shining through a transparent globe onto a flat surface. The paper may be considered as being rolled into a cylinder, giving rise to the common Mercator projection and relatives. Or it can be rolled into a cone, producing conic projection. Or it can be flat, producing an azimuthal projection. If the projection plane is located in space (for example at the position of a satellite), the map is orthographic. This latter is used by WinOrbit for the Globe Window.
Not all maps are true projections. The map used by the Map Windows is not. It is called an "equirectangular" map, since all points in the spherical coordinate system (latitude/longitude) are mapped uniformly (equally spaced) to a rectangular sheet. This is in contrast to the Mercator projection, where points near the poles project to points on the map infinitely far from the equator.