Camera Rig Extrinsic Calibration Using a Motion Capture System

Abstract

During the development and testing phases of ego-motion estimation algorithms for robotics applications, such as Visual Odometry (VO) or visual SLAM, a ground truth trajectory is needed in order to evaluate their performances. Nowadays motion capture systems can reach millimetric accuracy thus they are a practical and accurate solution to give camera referencing trajectory during the acquisitions of datasets and evaluation benchmarks. In practice, it is particularly difficult to make the tracked frame coincident with the camera optical frame, thus a calibration procedure is needed to estimate this transformation and achieve the millimetric accuracy required for robotic exploration missions, like scientific site mapping, or satellite relative navigation. In this work we present a calibration procedure to estimate the transformation between the reference frame tracked by a motion capture system and the optical reference frame of a stereo camera. Moreover, we perform an uncertainty analysis of the adopted method and thanks to the experimental set-up we show its ability to reach a millimeter accuracy.