Personally I am for sharing information, but I think one is free to share, or not,said this, these bas-reliefs can also be done in other ways with Blender (https://blender.stackexchange.com/questions/1161/how-to-make-a-displacement-map-from-existing-3d-geometry), then use that image generated and with the Heightmap script you have a nurbs surface , using a displacement image.

an example made with a displacement map and heightmap script