Patent ID: 7812816

Claim:
A system for generating position information related to a pointing device, the system comprising: the pointing device comprising; a reflector; and a powerless signal generator mechanism configured to generate a signal in response to a user action, wherein the signal triggers a function in a computing system; an image collection system configured to generate a first set of image data and a second set of image data, wherein the first set of image data includes a stronger indication of the reflector than the second set of image data; a processor configured to use the first set of image data and the second set of image data to generate position information related to the reflector, wherein the processor is configured to take the difference between the first set of image data and the second set of image data wherein taking the difference between the first set of image data and the second set of image data comprises taking the difference between corresponding data points of the first and second sets of image data such that most of the corresponding data points from the first and second sets of image data cancel each other out except for data points that correspond to the reflector; and a receiver configured to detect the signal from the powerless signal generator mechanism.