BiCamSLAM: Two times mono is more than stereo

This paper is an invitation to use mono-vision techniques on stereo-vision equipped robots. By using monocular algorithms on both cameras, the advantages of mono-vision (bearing-only, with infinity range but no 3D instant information) and stereo-vision (3D information only up to a limited range) naturally add up to provide interesting possibilities, that are here developed and demonstrated using an EKF-based monocular SLAM algorithm. Mainly we obtain: a) fast 3D mapping with long term, absolute angular references; b) great landmark updating flexibility; and c) the possibility of stereo rig extrinsic self-calibration, providing a much more robust and accurate sensor. Experimental results show the pertinence of the proposed ideas, which should be easily exportable (and we encourage to do so) to other, more performing, vision-based SLAM algorithms.