Research on vehicle speed measurement by video image based on Tsai´s two stage method

Based on the camera calibration principle of Tsai´s two stage method, a vehicle speed measurement method by video was put forward and the error analysis of camera calibration and vehicle speed measurement were carried out in this paper. Firstly, the internal and external parameters of the camera were gained based on Tsai´s two stage method. Secondly, the displacement offset of the same vehicle´s feature point in every image was extracted and converted to the world coordinate system. Lastly, instantaneous velocity of the vehicles was carried out based on the time difference between two sequential frames. Experimental result shows that the vehicle speed measurement method in this paper is not only simple and practical but also highly robust and accurate. In a word, the speed measure method can fulfill the requirements in the vehicle speed measurement system by video.