The number of vehicles equipped with onboard video cameras is increasing especially for police cars. This additional information can be used for accident reconstruction and law enforcement. This paper presents a case where the video footage of a moving police car was used to determine the speed of an oncoming vehicle. The steps in processing the available information to calculate the speed of the oncoming vehicle are shown, tolerances and inaccuracies are discussed. The camera location in each video frame is determined using the camera calibration model in PC-Crash, where the camera parameters are calculated by specifying corresponding points in the video frames and the 3D scene. A 3D point cloud (laserscanner data) is used as scene information for the calculation presented. Once the camera location is known, the image information, like the position of a vehicle in the oncoming traffic, can be reprojected onto the 3D scene. In this way the position of a vehicle is calculated for a certain video frame or point in time. By knowing the position of a vehicle and the frame timing the velocity of that is calculated.

(EVU-members can download the full article)