Zed2i underwater calibration by using ROS camera_calibration package

lyehan · January 29, 2024, 9:30am

Hi,
I’m using ZED 2i camera underwater for 3D reconstruction, but I had some questions with using ros camera_calibration package.
I want to obtain the rectified underwater stereo images ,but the old calibration parameters didn’t work,so I use ros camera_calibration package to recalibrate in underwater environment. Then , i found that the parameters underwater and parameters in the air are quite different . I want to apply the new parameters to get rectified underwater stereo images from the topic “~/stereo/image_rect_color” published by ZED node. Can somebody tell me how to do that?
Thanks

Myzhar · January 29, 2024, 10:50am

Hi @lyehan
please follow this guide

lyehan · January 29, 2024, 11:11am

thanks,but i want to integrate zed2i with RVIZ. Actually, I want to use the parameters calibrated underwater to obtain the rectified stereo image directly from ros or zed sdk. How should zed sdk read this YAML file calibrated by OpenCV . in addition , i found the configure file in /usr/local/zed/tools/settings/, do I need to use the calibration results to change the parameters here?

Myzhar · January 29, 2024, 11:14am

The ZED SDK can open the OpenCV calibration file natively: optional_opencv_calibration_file

lyehan · January 29, 2024, 11:20am

After ZED SDK reads this OpenCV calibration file, I can use zed.retrieveImage(image, VIEW::LEFT); or start the ZED node to publish the rectified image, right?

Myzhar · January 29, 2024, 11:27am

Yes, that’s correct.

The feature is natively available with the ROS 2 Wrapper:

github.com

stereolabs/zed-ros2-wrapper/blob/master/zed_wrapper/config/common.yaml#L27


      
              svo_loop: false # Enable loop mode when using an SVO as input source
              svo_realtime: true # if true the SVO will be played trying to respect the original framerate eventually skipping frames, otherwise every frame will be processed respecting the `pub_frame_rate` setting
              camera_timeout_sec: 5
              camera_max_reconnect: 5
              camera_flip: false
              serial_number: 0 # usually overwritten by launch file
              pub_resolution: 'CUSTOM' # The resolution used for output. 'NATIVE' to use the same `general.grab_resolution` - `CUSTOM` to apply the `general.pub_downscale_factor` downscale factory to reduce bandwidth in transmission
              pub_downscale_factor: 2.0 # rescale factor used to rescale image before publishing when 'pub_resolution' is 'CUSTOM'
              pub_frame_rate: 15.0 # frequency of publishing of visual images and depth images
              gpu_id: -1
              optional_opencv_calibration_file: '' # Optional path where the ZED SDK can find a file containing the calibration information of the camera computed by OpenCV. Read the ZED SDK documentation for more information: https://www.stereolabs.com/docs/api/structsl_1_1InitParameters.html#a9eab2753374ef3baec1d31960859ba19 
              region_of_interest: '[]' # A polygon defining the ROI where the ZED SDK perform the processing ignoring the rest. Coordinates must be normalized to '1.0' to be resolution independent.
              #region_of_interest: '[[0.25,0.33],[0.75,0.33],[0.75,0.5],[0.5,0.75],[0.25,0.5]]' # A polygon defining the ROI where the ZED SDK perform the processing ignoring the rest. Coordinates must be normalized to '1.0' to be resolution independent.
              #region_of_interest: '[[0.25,0.25],[0.75,0.25],[0.75,0.75],[0.25,0.75]]' # A polygon defining the ROI where the ZED SDK perform the processing ignoring the rest. Coordinates must be normalized to '1.0' to be resolution independent.
              #region_of_interest: '[[0.5,0.25],[0.75,0.5],[0.5,0.75],[0.25,0.5]]' # A polygon defining the ROI where the ZED SDK perform the processing ignoring the rest. Coordinates must be normalized to '1.0' to be resolution independent.
          
          video:
              brightness: 4 # [DYNAMIC] Not available for ZED X/ZED X Mini
              contrast: 4 # [DYNAMIC] Not available for ZED X/ZED X Mini
              hue: 0 # [DYNAMIC] Not available for ZED X/ZED X Mini
              saturation: 4 # [DYNAMIC]

You can add it to the ROS 1 Wrapper by manually modifying the source code.

lyehan · January 29, 2024, 11:29am

thank you! I will try