Model-based vehicle detection and classification using orthographic approximations

This paper reports the current state of work to simplify our previous model-based methods for visual tracking of vehicles for use in a realtime system intended to provide continuous monitoring and classification of traffic from a fixed camera on a busy multi-lane motorway. The main constraints of the system design were: (i) all low level processing is to be carried out by low-cost auxiliary hardware; (ii) all 3-D reasoning is to be carried out automatically off-line, at set-up time. The system developed uses three main stages: (i) pose and model hypothesis using 1-D templates, (ii) hypothesis tracking, and (iii) hypothesis verification, using 2-D templates. Stages (i) and (iii) have radically different computing performance and computational costs. and need to be carefully balanced for efficiency. Together, they provide an effective way to locate, track and classify vehicles. (C) 1997 Elsevier Science B.V.