creates a 3D model. She wants to sell it, but she wants to be protected
against theft, so
watermarks the model. The watermarked version is perceptually identical
to the original (the watermark is invisible), although there are some tiny
is what the the model would look like if those changes were exaggerated.
BOB steals Alice's model.
his purposes, he changes the model (for instance, he adds noise to vertex
coordinates, rotates, scales & translates the model, and also simplifies
it to half the number of faces)
Alice notices that Bob is using a model suspiciously similar to hers, so
she takes Bob's model and checks if it contains her watermark:
she aligns (registers) the suspect model with her original,
she resamples it to see how much has each vertex moved from the original
to the suspect mesh,
and finally, she compares these motion vectors with the changes induced
by the watermark. Since the watermark predicted with high accuracy the
diference between Bob's model and her original, she can prove that Bob
stole her model.
Bob pays Alice a lot of money.