Heretofore, various apparatus have been proposed for recognizing lane marks that define lanes (traffic lanes) on a road, on the basis of images that are captured of areas in front of and behind a vehicle.
Japanese Patent No. 4631197 discloses an apparatus, which uses a linear equation to approximate a positional dependency of the distance between two white lines, and decides whether or not there is a branch point depending on the gradient of a straight line.
Japanese Patent No. 4162618 discloses an apparatus for formulating the position and direction of each extracted edge line using a real-number parameter composed of at least two variables, and for deciding whether or not a crossing point of two edge lines can be a branch point for a traffic lane, on the basis of whether or not a characteristic differential vector between the two edge lines, which is calculated from the real-number parameter, falls within a prescribed appropriate range.