This software is incredible. You feed it a 2D still of a face, and set paramaters like lighting etc, and the software compares it to its base model of faces and recognises the 3D geometry of that particular face.

http://www.youtube.com/watch?v=nice6NYb_WA&mode=related&search=

Its pretty amazing stuff. They use the software to make faces in pictures (or paintings) talk. And adding 3D objects into the scene like a hat which casts shaows correctly on the nose/eyes etc. They make Tom hanks fat/skinny etc. And they even chaned the gender. All based on typical calculations from human faces.