Described are occupant positioning systems, and methods of use thereof, which combine image capture and radar or ultrasonic sensors, determine the head position and/or velocity of a vehicle occupant's head in three dimensions for use in a driver monitoring application. The driver monitoring applications may include features such as driver drowsiness estimation and indication, driver attention monitoring, driver gaze direction and driver gaze positioning, driver identification, head-up display adjustment and automatic sun blocking. These are features that can improve the operational safety of the vehicle.