[wgldhexc] Map projection for interactive maps

For maps "permanently printed" on a flat sheet of paper, it's never obvious what map projection to use. What regions should have high distortion versus what other regions have low distortion?

However, for electronic interactive maps, the answer is more clear. The center of the map, corresponding to the address the user has looked up, and consequently the center of attention, should have the least distortion. Often, the user is interested in distances from the center, so choose the projection (Azimuthal Equidistant) so that straight lines from the center are geodesics and distances are true. If the user wants less distortion in a different area of the map, he or she may recenter the map, or the UI may provide a way to specify a different center of projection.

For maps which are directions (a path) between two points, display the Two-Point Equidistant Projection.

Unfortunately, the popular technique (e.g., Google Maps) of precalculated map tiles will not work, as every region looks different depending on how far it is from the center of projection. We need some powerful magic possibly involving SVG and image transformations.