Specifications of Checkerboard for calibration for camera Calibration

Right now , I am calibrating a monocular camera so afterwards I can calculate distance of planar objects in the image (Z=0).

However, I'd like to know how much it is important to know the structure size. The board's squares sizes change a lot in the image based on how far you are so I am not sure if it is a robust parameter as you would always have a relative scale ?

Moreover, for my camera which will be mounted on a cieling ( around 10 meters high) , How could I estimate suitable sizes of a checkerboard and squares for accurate calibration ?

Answer 1

[Florian Morsch]

Do you use the camera calibrator app from MATLAB? This makes it easy to calibrate the camera.

The only thing you need to know of your checker board is the square size in the real world (in mm). It doesnt matter if you take a checker board picture from 1 m or 10 m distance, the real world size of the squares will always be the same, the rest is perspective of the camera.

If you have the camera mounted 10 m away from the plane you want to look at i would just make the square size bigger, in the matlab example its 29 mm, so maybe go with 50 to 100 mm for one square. Keep in mind that the checkerboard should be a odd number of width and height, and you should have at least 12 detectable points, so a board with 5x4 is your minimum borad size.