Visual information is essential in traffic: traffic lights tell us when to cross the street. Zebra crossings signalise visually street sections where car drivers have to pay special attention to pedestrians. Children are taught to look to the left and to the right before crossing the street. Motorists are aware of the problems and hazards occurring by darkness, rain, snow or fog when range of sight is decreased. A lot of accident avoidance deals with the issue to see and to be seen, e.g., the failure of motorists to detect and recognise motorcycles in traffic was regarded as the predominating cause of motorcycle accidents [1].