Hierarchical line extraction

A hierarchical line and segment extraction algorithm, based on a pyramid, is described. Initially, lines are detected in small windows using the Hough transform. The detected lines are then merged using a distance criteria thus avoiding a reaccumulation process at each level of the pyramid. The hierarchical merging process is efficiently performed on lines rather than on segments (since there are many more segments than lines). The detected lines are broken into segments, at the top of the pyramid. The proposed approach is compared to similar approaches based on hierarchical feature extraction. The authors show that their approach combines the advantages of other works and avoids their drawbacks such as quantisation effect and lack of robustness