Some articles on markerless:

Facial Expression Capture - Technologies - Markerless
... Markerless technologies use the features of the face such as nostrils, the corners of the lips and eyes, and wrinkles and then track them ... The technology for markerless face tracking is related to that in a Facial recognition system, since a facial recognition system can potentially be applied sequentially to each frame of video, resulting in ... Markerless face tracking has progressed to commercial systems such as image-metrics, Dynamixyz and has been applied in movies such as The Matrix sequels and The Curious Case of Benjamin Button ...