The GoalControl-4D system works with 14 high-speed cameras (7 per goal) around the pitch at the stadium roof/catwalk. The cameras are connected to a powerful image processing computer system which tracks the movement of all objects on the pitch and filters out the players, referees and all disturbing objects. The remaining object is the ball and the system knows its three dimensional x-, y- and z-position with a precision of a few millimeters in the coordinate system of the pitch. When the ball passes the goal line, the system sends a vibration- and optical signal to the officials´ watches.
