New and improved site is at http://kevinwalker.info.
February 2005, and several later dates
I can't remember whether this technique was inspired by Goldsworthy's cracked mud walls. It might have instead been inspired by naturally occurring cracked mud in Utah, before I became aware of the Goldsworthy mud. In any case, the goal was to create a randomish cell decomposition with control over cell density. First I tried Voronoi cells around randomly selected points in the plane. This produced cell decompositions that were too irregular. The solution was to select the locations of the points subject to the constraint that the distance between points must be larger than some minimum distance. This makes the cells more regular, and varying the minimum distance according to the location on the image allows one to control the density of the cells and produce larger-scale patterns.