Connectivity-Enforcing Hough Transform for the Robust Extraction of Line Segments

TL;DR

This paper introduces STRAIGHT, a novel Hough transform-based method that enforces connectivity during voting to robustly extract complete line segments in cluttered and challenging images.

Contribution

It incorporates connectivity into the Hough transform voting process, enabling extraction of longer, connected line segments even in complex scenarios, improving over existing methods.

Findings

Successfully extracts complete line segments in cluttered images

Outperforms existing methods in challenging scenarios

Efficient hierarchical implementation makes it practical

Abstract

Global voting schemes based on the Hough transform (HT) have been widely used to robustly detect lines in images. However, since the votes do not take line connectivity into account, these methods do not deal well with cluttered images. In opposition, the so-called local methods enforce connectivity but lack robustness to deal with challenging situations that occur in many realistic scenarios, e.g., when line segments cross or when long segments are corrupted. In this paper, we address the critical limitations of the HT as a line segment extractor by incorporating connectivity in the voting process. This is done by only accounting for the contributions of edge points lying in increasingly larger neighborhoods and whose position and directional content agree with potential line segments. As a result, our method, which we call STRAIGHT (Segment exTRAction by connectivity-enforcInG HT), extracts the longest connected segments in each location of the image, thus also integrating into the HT voting process the usually separate step of individual segment extraction. The usage of the Hough space mapping and a corresponding hierarchical implementation make our approach computationally feasible. We present experiments that illustrate, with synthetic and real images, how STRAIGHT succeeds in extracting complete segments in several situations where current methods fail.