Co-ordinate mapping and analysis of vehicle trajectory for anomaly detection

Behavioral information can be inferred from the trajectory of a rigid object. We propose a method to detect anomalies in the approach of a vehicle by observing the patterns in its velocity and describe methods for more effective analysis of the velocity trajectory. First we define a hypothetical co-ordinate system in which the axes are specified with respect to the road and distances are true ground measurements. In this co-ordinate system the (axial) velocity is a one dimensional quantity. We estimate the "normal" trends in the velocities by activity path modeling after scaling the velocities by the vehicle's average speed. We detect an anomaly if a vehicle's velocity does not fall in the available path models. Finally, we use the shape of the trajectory to determine turns and other significant maneuvers. We also detect an anomaly if a vehicle's velocity falls in a path model which is inconsistent with the shape of its trajectory. We observe that our proposed co-ordinate system also improves trajectory shape analysis by suppressing false turns.