1. A method of tracking a location of a face in an input image stream, said method comprising iteratively applying the steps of: (a) performing a computerized three-dimensional (3D) to two-dimensional (2D) rendering of a predefined textured 3D face model indicative of at least a portion of a face to produce a 2D rendered image including said face, the 3D-to-2D rendering being performed according to a previously predicted state vector derived from a previous tracking loop or a state vector from an initialisation step, wherein said state vector comprises the pose of said face; (b) processing said 2D rendered image to extract a series of point features from the portion of the face in said 2D rendered image; (c) localising corresponding point features in a current 2D image of said input image stream by comparing said 2D rendered image with said current 2D image; (d) deriving a new state vector from said localised point feature in the input image stream, the new state vector being indicative of a current location of said face within said input image stream.