Countering drift in Visual Odometry for planetary rovers by registering boulders in ground and orbital images

Visual Odometry (VO) is a proven technology for planetary exploration rovers, facilitating their localization with a small error over medium-sized trajectories. However, due to VO´s incremental mode of operation, its estimation error accumulates over time, resulting in considerable drift for long trajectories. This paper proposes a global localization method that counters VO drift by matching boulders extracted from overhead and ground images and using them periodically to relocalize the rover and refine VO estimates. The performance of the proposed method is evaluated with the aid of overhead imagery of different resolutions. Experimental results demonstrate that a very terse representation, consisting of approximate boulder locations only, suffices for significantly improving the accuracy of VO over long traverses.