Originally Posted by

**waldronate**
There is a projection that I learned from Dave Allen that is very roughly equal-area and has simple connectivity rules: start with a square map and declare the upper-right corner to be the north pole, the lower-left corner to be the south pole, and the diagonal from upper-left to lower-right to be the equator. Connectivity is then simple (when you go off the top you come back in on the right; going off the bottom you come back in on the left) and quick to compute with no connectivity map required. I need to implement this algorithm in the various flow computations in Wilbur one of these years so that folks can do whole-world erosion and river computation.