Wide range Time of Flight camera for outdoor surveillance

This paper presents the application of the time of flight (ToF) cameras to outdoor surveillance. The applications of ToF camera were limited to its non ambiguity distance range, less than 10 meters. We present the problems and the solution for extending the distance use of ToF cameras beyond the non ambiguity range. The distance ambiguity can be solved by measuring the distance with two different frequencies. The needed contrast range of the amplitude image increases with the square of the distance. The efficient use of ToF cameras for outdoor surveillances imposes not only the increase of the illuminating power but also to increase the accuracy of the distance and amplitude images. The ambiguity of the measured distance can be effectively solved if the multiple reflections inside the camera body are reduced.