An orientation sensor utilizing an inexpensive but relatively slow base
orientation sensor, augmented by capture of a video images, identifying
reference objects or regions therein, and calculating displacement of
those objects to derive supplementary orientation information. Recurrent
base orientation sensor results are used to correct drift of the video
based technique. Augmenting the slow but accurate base orientation sensor
with the consecutive images derived orientation data, provides a fast and
inexpensive orientation sensor.