A first mirror and a second mirror are disposed in such a manner that their reflective surfaces are parallel and face toward each other. A mark is drawn between the first mirror and the second mirror. An image of the reflections of the mark in the first mirror and the second mirror is captured with a...http://www.google.de/patents/US7124046?utm_source=gb-gplus-sharePatent US7124046 - Method and apparatus for calibration of camera system, and method of manufacturing camera system
