Fast and Accurate Extrinsic Calibration for Multiple LiDARs and Cameras

The combination of multiple sensors is becoming necessary in robotic applications as each sensor could complement the weakness of others. Determining a precise extrinsic parameter in a fast and reliable manner between multiple sensors is essential and remains challenging. In this paper, we propose a fast, accurate, and targetless extrinsic calibration method for multiple LiDARs and cameras based on adaptive voxelization. On the theory level, we incorporate the LiDAR extrinsic calibration with the bundle adjustment method. We derive the derivatives of the cost function w.r.t. the extrinsic parameter to accelerate the optimization. On the implementation level, we apply adaptive voxelization to reduce the computation time in the process of feature correspondence matching. The robustness and accuracy of our proposed method have been verified with experiments in outdoor test scenes under multiple LiDAR-camera configurations.