Utilizing instantaneous driving direction for enhancing lane-marking detection

Our earlier lane-marking detection method identified lane-markings appearing on an input image based on the intensity contrast between lane-markings pixels and their neighboring pixels. This detection results in outputs with nearly-zero false negatives, but with many false positives. To filter out these false positives in a principled way, we utilize the driving direction of a roadway. We do this because longitudinal lane-markings delineate the driving direction of a road and the orientations of any true, longitudinal lane-markings appearing on input images should be aligned with this direction. To approximate the driving direction of a road, we detect the vanishing point on a horizon line and draw a line to link the image coordinates of the detected vanishing point to those of the center of the image bottom. We then filter out any lane-marking blobs if their orientations are not aligned with that of the approximated driving direction. Through testing with streets and inter-city highway images, the proposed method demonstrates its effectiveness.