A simple camera calibration method for vehicle velocity estimation

Camera calibration is an essential step in vision-based vehicle speed measurement systems. In this paper, a simple, easy, and robust camera calibration method for vehicle speed measurement is proposed. First, the camera is installed at any position that can cover the desired traffic images. After that, an equilateral triangle is drawn on the ground within the view scene of the camera as a reference object. Then, the image of the triangle captured by the traffic camera is used to determine the camera parameters. The main advantage of our method is that it requires very little effort put into installing the camera and can be used in any road conditions. In order to prove the advantages of our method, we use the found camera parameters with the motion vectors of traffic video frames estimated by the optical flow algorithm to calculate the real moving speed of vehicles. Our experimental results have shown that the proposed method is reliable and easy to use.