A distance judging system (S) includes at least two spaced apart marker devices (10) formed on a first object (12) and providing a signal (14). A viewer (A) is adapted to detect relative position of the signals (14) from the markers (10), and create an image (22) of the relative positions of the markers...http://www.google.fr/patents/US6327028?utm_source=gb-gplus-shareBrevet US6327028 - Night convoy maneuver system
