I. Introduction
Visual SLAM (V-SLAM) is one of enabling technologies for autonomous systems such as self-driving cars, unmanned aerial vehicles and space robots. While most V-SLAM solutions rely on point features due to their simplicity, line features commonly seen in man-made environments are less sensitive to lighting variation and position ambiguity and have been only used in recent work [2]–[8]. In principle, the combination of point and line features would provide more geometric constraints about the structure of the environment than either one, which motivates us to design robust V-SLAM with point and line features.