Adaptive, real-time visual simultaneous localization and mapping
In this paper we present a real-time simultaneous localization and mapping system which uses a stereo camera as its only input. We combine the benefits of KLT feature tracking, which include high speed and robustness to repetitive features, with wide baseline features, which allow for feature matching after large camera motions. Updating the map of feature locations and camera poses is considerably more expensive than performing KLT tracking. For this reason we use the optical flow measured by the KLT tracker to adaptively select key frames for which we do a full map and camera pose update. In this way we limit the processing to only “interesting” parts of the video sequence. Additionally, we maintain a consistent scene scale at low cost by using a GPU implementation of multi-camera scene flow, a generalization of KLT to the motion of image features in three dimensions. The system uses multiple sub-maps; scalable, bag of features recognition and geometric verification to recover from motion estimation failure or “kidnapping”. This architecture allows the robot to grow the existing map online and in real time while storing all of the data necessary for an off-line optimization to complete loops. We demonstrate the robustness of our system in a challenging indoor environment that includes semi-reflective glass walls and people moving in the scene.