All lens have some distortion no matter how big or small, so you should correct for lens distortion by calibrating a camera in terms of software. Especially, this technique is used for robotics and the distortion effects so much while a robot is mapping some obstacles using a camera as their eyes. Today, I am showing how to calibrate a ZED stereo camera for your project.
Environments & Equipments
- Ubuntu 16.04
- ROS Kinetic
- ZED SDK 2.8
- CUDA 10.0
- ZED Camera
I assume that you already have these environments and equipment to calibrate a ZED stereo camera. Please go to these links above, and set up correctly.
How to make a catkin workplace for ZED
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source /opt/ros/kinetic/setup.bash mkdir -p ~/catkin_zed/src cd ~/catkin_ws/ catkin_make source devel/setup.bash cd src git clone https://github.com/stereolabs/zed-ros-wrapper.git cd .. catkin_make |
Compiling
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rosdep install camera_calibration rosmake camera_calibration |
Calibration
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roslaunch zed_wrapper zed.launch |
Open another tab on terminal
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rosrun camera_calibration cameracalibrator.py --size 6x4 --square 0.035 --no-service-check right:=/zed/zed_node/right_raw/image_raw_color left:=/zed/zed_node/left_raw/image_raw_color right_camera:=/zed/zed_node/right left_camera:=/zed/zed_node/left |
For the calibration, I used calibration checkboard (6×4, square size 35mm). When you use another checkboard, you will just change the command after –size and –square.
Important!!!
Do NOT forget the command of
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--no-service-check |
The driver does not support set_camera_info service. Without this command, you might have got this error message after rosrun.
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('Waiting for service', '/zed/zed_node/left/set_camera_info', '...') Service not found ('Waiting for service', '/zed/zed_node/right/set_camera_info', '...') Service not found Segmentation fault (core dumped) |
There are active topics while roslaunch zed_wrapper zed.launch
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/diagnostics /rosout /rosout_agg /tf /tf_static /zed/joint_states /zed/zed_node/confidence/camera_info /zed/zed_node/confidence/confidence_image /zed/zed_node/confidence/confidence_image/compressed /zed/zed_node/confidence/confidence_image/compressed/parameter_descriptions /zed/zed_node/confidence/confidence_image/compressed/parameter_updates /zed/zed_node/confidence/confidence_image/compressedDepth /zed/zed_node/confidence/confidence_image/compressedDepth/parameter_descriptions /zed/zed_node/confidence/confidence_image/compressedDepth/parameter_updates /zed/zed_node/confidence/confidence_image/theora /zed/zed_node/confidence/confidence_image/theora/parameter_descriptions /zed/zed_node/confidence/confidence_image/theora/parameter_updates /zed/zed_node/confidence/confidence_map /zed/zed_node/depth/camera_info /zed/zed_node/depth/depth_registered /zed/zed_node/depth/depth_registered/compressed /zed/zed_node/depth/depth_registered/compressed/parameter_descriptions 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/zed/zed_node/stereo/image_rect_color/compressedDepth/parameter_updates /zed/zed_node/stereo/image_rect_color/theora /zed/zed_node/stereo/image_rect_color/theora/parameter_descriptions /zed/zed_node/stereo/image_rect_color/theora/parameter_updates /zed/zed_node/stereo_raw/image_raw_color /zed/zed_node/stereo_raw/image_raw_color/compressed /zed/zed_node/stereo_raw/image_raw_color/compressed/parameter_descriptions /zed/zed_node/stereo_raw/image_raw_color/compressed/parameter_updates /zed/zed_node/stereo_raw/image_raw_color/compressedDepth /zed/zed_node/stereo_raw/image_raw_color/compressedDepth/parameter_descriptions /zed/zed_node/stereo_raw/image_raw_color/compressedDepth/parameter_updates /zed/zed_node/stereo_raw/image_raw_color/theora /zed/zed_node/stereo_raw/image_raw_color/theora/parameter_descriptions /zed/zed_node/stereo_raw/image_raw_color/theora/parameter_updates |
Calibration Result
Done!