Object-aware bundle adjustment for correcting monocular scale drift

Without knowledge of the absolute baseline between images, the scale of a map from single-camera simultaneous localization and mapping system is subject to calamitous drift over time. We describe a monocular approach that in addition to point measurements also considers object detections to resolve this scale ambiguity and drift. By placing a prior on the size of the objects, the scale estimation can be seamlessly integrated into a bundle adjustment. When object observations are available, the local scale of the map is then determined jointly with the camera pose in local adjustments. Unlike many previous visual odometry methods, our approach does not impose restrictions such as approximately constant camera height or planar roadways, and is therefore applicable to a much wider range of applications. We evaluate our approach on the KITTI dataset and show that it reduces scale drift over long-range outdoor sequences with a total length of 40 km. Qualitative evaluation is also performed on video footage from a hand-held camera.