SDF-SLAM: A Deep Learning Based Highly Accurate SLAM Using Monocular Camera Aiming at Indoor Map Reconstruction With Semantic and Depth Fusion

Simultaneous localization and mapping (SLAM) is considered as a key technique in augmented reality (AR), robotics and unmanned driving. In the field of SLAM, solutions based on monocular sensors have gradually become important due to their ability to recognize more environmental information with simple structures and low costs. Feature-based ORB-SLAM is popular in many applications, but it has many limitations in complex indoor scenes. Firstly, camera pose estimation based on monocular images is greatly affected by the environment; secondly, monocular images lack scale information and cannot be used to obtain image depth information; thirdly, monocular based SLAM builds a fused map of feature points that lacks semantic information, which is incomprehensible for machine. To solve the aforementioned issues, this paper proposes an SDF-SLAM model based on deep learning, which can perform camera pose estimation in a wider indoor environment and can also perform depth estimation and semantic segmentation on monocular images to obtain an understandable three-dimensional map. SDF-SLAM is tested and verified using a CPU platform and two sets of indoor scenes. The results show that the average accuracy of the predicted point cloud coordinates reaches 90%, and the average accuracy of the semantic labels reaches 67%. Moreover, compared with the state-of-the-art SLAM frameworks, such as ORB-SLAM, LSD-SLAM, and CNN-SLAM, the absolute error of the camera trajectory on indoor data with more feature points is reduced from 0.436 m, 0.495 m, and 0.243 m to 0.037 m, respectively. On indoor data with fewer feature points, they decrease from 1.826 m, 1.206 m, and 0.264 m to 0.124 m, respectively.