lidar_camera_calibrator is a semi-automatic, high-precision, feature-based camera and LIDAR extrinsic calibration tool. In general, feature-based calibration methods often require some manual intervention, such as manually selecting feature points, using a calibration board with a fixed pattern, etc., resulting in a low degree of automation in this method. The lidar_camera_calibrator can semi-automatically calibrate high-precision extrinsic parameters and provide an interactive Qt interface with less manual intervention.
Hope it helps you.
Qt 5 (system)
Eigen 3 (3.3+)
# ceres dependencies $ sudo apt-get install liblapack-dev libsuitesparse-dev libcxsparse3 libgflags-dev libgoogle-glog-dev libgtest-dev
# g2o dependencies $ sudo apt-get install qt5-qmake qt5-default libqglviewer-dev-qt5 libsuitesparse-dev libcxsparse3 libcholmod3
$ mkdir -p ws_calibrator/src && cd ws_calibrator $ git clone REPOSITORY_GIT_LINK src/lidar_camera_calibrator $ catkin_make
a. Prepare the Data
Calibration board: rectangular board(It is recommended to be about 1m*1m）
If there is a AprilTag marker like
data/data-simon the calibration board, the image features can be automatically extracted.
Create calibration data
We provide a script to get soft-synced LiDAR and camera data to calibrate.
Modify the topic names of Point cloud and image in the
get_sync_data.launch, and press the
spacebutton in the terminal to save current synchronized data.
$ roslaunch lidar_camera_calibrator get_sync_data.launch
Prepare the config.json
Create a config.json and modify corresponding parameters in config.json according to
Parameter Description in config.json
"cam": # Camera internal parameters "lidar_pose":"descend" # "descend" means the LiDAR is placed upright relative to the camera and "ascend" means the LiDAR is placed upside-down relative to the camera. "pc": "PerspectiveParams": # perspective of pcl_viewer "filter": # The following parameters represent an annular sector area, and the points inside the area will be used to extract the board point cloud. "angle_start": # the starting angle "angle_size": # the angle range "min_distance": # the inside radius "max_distance": # the outer radius "ceil_gap": # the distance to the highest point of the point cloud "floor_gap": # the distance to the lowest point of the point cloud "min_distance_threshold": # the upper limit of min_distance "max_distance_threshold": # the upper limit of max_distance "max_ceil_gap": # the upper limit of ceil_gap "max_floor_gap": # the upper limit of floor_gap "plane": # parameters of extracting the board point cloud "size": # the number of sides of the calibratoin board "tag_size": # the length, width and height of the calibration board "tf": # the calibrated extrinsic parameters, which need to be saved by 'save result'
input_pathin the launch file to the absolute path of the prepared calibration data, then calibrate it according to the above tutorial.
$ roslaunch lidar_camera_calibrator calibrate.launch
Adjust the parameters in pointcloud control until the appropriate calibration board point cloud appears on the right, and then click
extract. If the correct feature is extracted in the point cloud, click
next pose, otherwise click
If the calibration board is with AprilTag, the image control part will automatically extract the corner points. If the detection is wrong or the calibration board is without AprilTag, you need to click
start selectionand then select the four corner points in the image sequentially, and finally click
Repeat steps 2 and 3 until each pair of data is processed. Finally, click
calibrate, and you can see the output of extrinsic parameters in the terminal. The calibration result can be evaluated qualitatively through
previous pose, and the extrinsic parameter can be saved to config.json with
We have tested this tool on real and simulated Velodyne-16 and normal cameras, and test data is provided under the
# Calibration using a calibration board with AprilTag(Simulation) roslaunch lidar_camera_calibrator calibrate.launch # Calibration using a calibration board without AprilTag(Real) roslaunch lidar_camera_calibrator calibrate.launch input_path:=`rospack find lidar_camera_calibrator`/data/data-hitsz
lidar_camera_calibrator is released under GPL-3.0 License.
In this project, the image feature extraction part refers to AprilTag, the point cloud feature extraction refers to the work of Jiunn-Kai Huang, and the Qt interface and framework parts refer to plycal.
Many thanks for their work.