[wlievens]

You mean the border between the hued territories? Roughly:

1) Randomly pick center points of territories, guarantee a minimum distance for best looks

2) Compute the Voronoi raster, i.e. for each pixel find the nearest territory center

3) Figure out which territories border which, based on the Voronoi raster

4) Compute borders for each territory by taking the midpoints of edges in the territory neighborhood graph. Use a couple special tricks for coastal territories.

5) Split up those borders into finer segments

6) Add noise to the border segments

7) Fill in the pixels according to the borders

[allenp]

Thank you so much for the detailed response!