I. Introduction
Map building is a key module for autonomous mobile robots since both localization and planning usually depend on the map information of the environment [1], [2]. One typical map representation is the grid map [3], [4], in which the value of each cell represents the probability of being occupied by obstacles. However, the required memory of the grid map grows rapidly with the increase in the environmental size. Therefore, the representation of the environment by features, such as line segments, becomes a popular alternative to the grid map [6], [10], [11], [26]. Compared with the grid map, the line segment map is more compact, consuming less memory and scaling better with the environmental size. Furthermore, the line segment map does not split the environment into grids and, thus, it does not suffer from discretization problems [27].