Semantic Topological Descriptor for Loop Closure Detection within 3D Point Clouds In Outdoor Environment

Loop closure detection has the potential to correct the drift of trajectories and build a global consistent map in LiDAR SLAM, however it remains a challenging problem in outdoor environment due to the sparsity of 3D point clouds data, large-scale scenes and moving objects. Inspired by the way humans perceive the environment through recognizing objects and identifying their relations, this paper presents a novel descriptor that contains semantic and topological information for loop closure detection. Unlike most existing methods that extract features from the raw point clouds or use all semantic objects, we directly discard point clouds representing pedestrians and vehicles after semantic segmentation. Then, we propose a semantic topological graph representation from the remaining point clouds and convert this graph into a descriptor. Additionally, we propose a two-stage algorithm for matching descriptors to efficiently determine the loop. Our method has been extensively evaluated using the KITTI dataset and outperforms state-of-the-art methods, especially in the challenging situations such as viewpoint changes and dynamic scenes.