Real-time monocular ranging by Bayesian triangulation

A method for estimating the range between moving vehicles by using a monocular camera is proposed. Although most conventional methods use vertical triangulation, the proposed method uses both vertical and horizontal triangulation, which reduces errors due to vehicle´s own pitching in the far distance. Unknown vehicle width is estimated by measuring three ranging parameters associated with an image captured by the camera, and the following distance is then computed by horizontal triangulation. Both vehicle width and following distance are dynamically updated during the vehicle-tracking process by single filtering. The proposed method runs in real time and can produce highly accurate estimation of following distance. The key contribution of this study is the coupled estimation of unknown vehicle width and following distance by sequential Bayesian estimation.