1. Introduction
Line segments are ubiquitous in human-made environments and encode the underlying scene structure in a compact way. As such, line features have been used in multiple vision tasks: 3D reconstruction and Structure-from- Motion (SfM) [17], [32], [34], Simultaneous Localization and Mapping [13], [15], [25], [37], [62], visual localization [14], tracking [38], vanishing point estimation [49], etc. Thanks to their spatial extent and presence even in textureless areas, they offer a good complement to feature points