Analysis of a Road Image as Seen from a Vehicle

This paper proposes a method to record three‐dimensional (3‐D) geometry of a road from a single‐eye image. Although generally it is impossible to obtain a 3‐D information from a single image of a road edge, this becomes possible by adding information of the road from its design conditions. This paper describes a method to calculate the model parameters from the edge of a traffic lane in an image of a road, after presenting a 3‐D model of a road based on its design conditions. In the proposed model it is assumed that the shapes of the center line of a road seen in horizontal and vertical planes consist of alternative straight lines and curves. The 3‐D shape of a road using this assumption can be classified into four categories. First, the parameters for a pair of parallel straight lines connected to an adjacent curve are calculated. Then the parameters of the curve connected to the straight lines are calculated. A model having such synthesized road edges was computer‐simulated, giving the maximum relative error of the parameters of 12 percent. Images of road edges photographed from a vehicle on an actual road were processed manually for comparison, giving a maximum relative error of 21 percent with reference to the design data of the road.