I was so impressed I had to try to see if I could do something similar with Gimp:
Attachment 3442
I created a set layers of rotated thatch images, then set the layer mask for each as a bump mapped version of the heightfield with the light coming from the same direction as the thatch was rotated. I think I had the lighting elevation too low, and I only went with 45 degree rotations, cause I was just playing.
I realized afterward that I should have scaled the thatch down a bit, but I think the basics are there.
How did you blend the rotated layers to get the non-direction version?
I think this might be worth scripting...
-Rob A>