Underwater Calibration Using ZED SDK Tools and Checkerboard Requirements

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Hello,

I am planning to use the ZED camera with a Jetson board as an underwater camera setup. I intend to perform underwater calibration using the calibration tools provided by the ZED SDK. Instead of using a waterproof monitor connected to the Jetson, I plan to access the Jetson via VNC to run the tools.

For the checkerboard, I am considering printing and waterproofing it myself. Could you please let me know if there’s a way to obtain a separate checkerboard image? Alternatively, if I print the checkerboard displayed in the tools directly, are there specific requirements for the checkerboard dimensions? For example, is there a minimum size for each square or the entire checkerboard?

Thank you for your assistance.

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Hi @kwonok
Welcome to the Stereolabs community.
For underwater applications, we recommend using the “standard” OpenCV calibration process: How to Calibrate your ZED camera with OpenCV - Stereolabs
When you have a calibration file you can “tell” the ZED SDK to use it instead of the default, see sl::InitParameters::optional_opencv_calibration_file.

There are not minimum or maximum sizes for squares; a bigger chessboard helps obtain more accurate calibrations.

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Thank you for your response.

I tried performing calibration using OpenCV and then used sl::InitParameters::optional_opencv_calibration_file. However, when I checked the video output, the results were not as good as when I used the ZED SDK tool. The edges of the video showed noticeable distortion.(For the calibration process, I used an A3-sized checkerboard and captured images from various angles and positions.)

Therefore, I would like to attempt calibration using the SDK tool. Could you please provide detailed instructions on how to use a printed checkerboard image with the ZED SDK tool for calibration? Alternatively, could you share how to achieve higher-quality calibration using OpenCV?

Thank you for your help.

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You cannot use a printed chessboard with the ZED Calibration Tool. It uses dynamic screen information.

The process is standard, you can find many guides on the internet: capture many images that cover the entire field of view from various distances and at different angles. If you notice distortions at the edges of the images, it indicates that you haven’t taken enough pictures of the chessboard in those areas.