A hierarchical approach to line extraction based on the Hough transform

Abstract

An efficient method for finding straight lines in edge maps is described. The algorithm is based on a pyramid structure with each layer in the pyramid splitting the complete image into a number of subimages. At the bottom level of the pyramid short line segments are detected by applying a Hough transform to small subimages. The algorithm proceeds, bottom up, from this low level description by grouping line segments within local neighborhoods into longer lines. Line segments which have local support propagate up the hierarchy and take part in grouping at higher levels. The length of a line determines approximately the level in the pyramid to which it propagates. Hence we obtain a hierarchical description of the line segments in a scene which can be useful in matching. The algorithm has a number of advantages over previously proposed hierarchical methods for the detection of straight lines. It is quite efficient and has a particularly attractive architecture which is suitable for parallel implementation.