a method for tracking the motion of a person &# 39 ; s face for the purpose of animating a 3 - d face model of the same or another person is disclosed . the 3 - d face model carries both the geometry and the texture characteristics of the person &# 39 ; s face . the shape of the face model is represented via a 3 - d triangular mesh , while the texture of the face model is represented via a 2 - d composite image . both the global motion and the local motion of the person &# 39 ; s face are tracked . global motion of the face involves the rotation and the translation of the face in 3 - d . local motion of the face involves the 3 - d motion of the lips , eyebrows , etc ., caused by speech and facial expressions . the 2 - d positions of salient features of the person &# 39 ; s face and / or markers placed on the person &# 39 ; s face are automatically tracked in a time - sequence of 2 - d images of the face . global and local motion of the face are separately calculated using the tracked 2 - d positions of the salient features or markers . global motion is represented in a 2 - d image by rotation and position vectors while local motion is represented by an action vector that specifies the amount of facial actions such as smiling - mouth , raised - eyebrows , etc .