On importance of nose for face tracking

Human nose, while being in many cases the only facial feature clearly visible during the head motion, seems to be very undervalued in face tracking technology. This paper shows theoretically and by experiments conducted with ordinary USB cameras that, by properly defining nose as an extremum of the 3D curvature of the nose surface, nose becomes the most robust feature which can be seen for almost any position of the head and which can be tracked very precisely, even with low resolution cameras