lmckenzie: Actually, if you read Hoppe's paper, cropping (hacking off a limb) is not a substantial enough attack on a mesh to fail recognition with their technique. They chop a model of a chocolate bunny to demonstrate this point. Adding 45% noise (which makes a mesh look like a raisin), downsampling, smoothing et al still leave behind the residual watermark. Even adding a second watermark retains the original. While the word "fractal" doesn't appear in the article, it's plain the transformation is intrinsic enough to survive the most likely attacks available to 3D mesh editing programs (which by and large do not apply complex statistical analysis techniques in their transformation algorithms). What I find fascinating is that this research began in the early 90s and this paper was presented in 1999. And still no indication of patents prohibiting CL or DAZ from implementing it. Read Hoppe's SIGGRAPH presentation; I can't follow the math but I can understand the concept and why it's robust. Basically the signature is embedded all over the mesh at multiple scales. Registration and recognition ignore reordered vertices, so both P4 casual and P4 nude heads would be recognized.