Structured light is directed across a monitored region. An image is captured of a light pattern that forms on the object as a result of the object intersecting the structured light when the object is placed at a first position in the monitored region. A geometric characteristic is identified of the image...http://www.google.com.au/patents/US20030218760?utm_source=gb-gplus-sharePatent US20030218760 - Method and apparatus for approximating depth of an object's placement onto a monitored region with applications to virtual interface devices
