摘要 |
A head tracker system for determining a user's head orientation relative to a datum ( 22 ) comprises: a head mounting ( 2 ) for attachment to the user's head; an optical sensor ( 12 ) which in use is located in fixed relation with a known fixed point relative to the head mounting ( 2 ) and a plurality of distinguishable markings ( 18 a -18 j) each of which when in use is located in fixed relation with a respective known point which is fixed relative to the datum ( 22 ). The head tracker further comprises an optical correlator ( 26 ) for optically correlating the optical image from the optical sensor ( 12 ) with an optical image representative of at least one of said markings ( 18 a -18 j); and means ( 28 ) for determining the orientation of the head mounting using the output from the optical correlator when it detects that there is correlation between the images.
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