Vehicle Speed Measurement Using Stereo Camera Pair

Abstract

We have proposed a novel method for vehicle speed estimation using a calibrated and synchronized pair of stereo cameras. In a newly proposed method, we first localize the vehicle by detecting and tracking its license plate in a series of stereo images; then, we triangulate the vehicle position along its trajectory; and finally, we compute its speed based on the trajectory and time. The experiments show that the proposed method overcomes state-of-the-art results with a mean error of approximately 0.05 km/h, a standard deviation of less than 0.20 km/h, and a maximum absolute error of less than 0.75 km/h. For the purpose of evaluation, we have recorded a dataset that contains over 600 vehicles whose trajectories were recorded and for which their ground truth speed was obtained from a pair of single beam LIDARs in optical gate configuration. Using the presented method, the speed was measured for over 99 % of the recorded vehicles. Others were rejected by the method mainly due to their short trajectories, obstructed license plates or frame errors that would adversely affect the precision of the measurement.