A method and system for tracking attitude of a device includes fixing a two-dimensional array of photosensors to the device and using the array to form a reference frame and a sample frame of images. The fields of view of the sample and reference frames largely overlap, so that there are common imaged...http://www.google.es/patents/US6489945?utm_source=gb-gplus-sharePatente US6489945 - Method and system for tracking attitude
