Camera IMU LRF calibration

Kalibr provides limited, experimental support for spatio-temporal laser range finder (LRF) calibration as detailed on in [1].

Usage

This work marks an extension to camera/IMU calibration. Accordingly, it extends the command line interface with a few LRF specific options, while all camera and IMU options remain valid. These additional options are

• --lrf-topic The topic of the ROS scan message.
• --q_bl An initial guess for the rotation from the laser into the body frame as quaternion.
• --t_bl The corresponding, relative translation.

Note that the initial guess needs to be sufficiently accurate to yield an initial point cloud that allows for identification of planes. Please consider [2] for determining an initial guess in case coarse estimates fail to produce plane detections.

The following command spells out the options used to process the example dataset:

kalibr_calibrate_imu_camera_laser --cam ../camchain-calibration_2015-10-09-10-48-02.yaml --imu ../imu_adis16448_ident.yaml --target ../april_6x6.yaml --imu-models calibrated --bag ../calibration_2015-11-05-13-39-04.bag --reprojection-sigma 0.1 --time-calibration --timeoffset-padding 0.1 --lrf-topic /scan --q_bl -0.5 0.5 -0.5  0.5 --t_bl 0. 0. 0.

Dataset

The approach uses planes present in the environment to formulate a probabilistic model of range measurements. For this method to produce correct results, please collect a dataset as described for camera/IMU calibration but additionally in an environment where preferably multiple planes unobstructed to the LRF are present.

An example dataset can be found here. Please note that this dataset was selected for its size, not because it is particularly suited for the task. In general, please prefer less cluttered environments and avoid scenarios where subtle non-planarities are present, since these may bias the estimate.

General Comments

References

Please cite the appropriate papers when using this toolbox or parts of it in an academic publication.

1. Rehder, Joern, Roland Siegwart, and Paul Furgale. "A General Approach to Spatiotemporal Calibration in Multisensor Systems." IEEE Transactions on Robotics 32.2 (2016): 383-398.
2. Zhang, Qilong, and Robert Pless. "Extrinsic calibration of a camera and laser range finder (improves camera calibration)." Intelligent Robots and Systems, 2004.(IROS 2004). Proceedings. 2004 IEEE/RSJ International Conference on. Vol. 3. IEEE, 2004.