Recommendations for taking calibration photos

Written by Alexander Velizhev

Attention! Verify your calibration pattern size. If you have entered wrong object dimentions detection will run incorrectly. It runs only with calibration patterns using odd x even (or even x odd) number of squares (i.e 5×6, 7×8, 10×7, etc).

  • The white space (marked with red on the picture below) between the outer squares and the object boundary should be at least 1 square wide, like this:


    Figure 1. Calibration pattern

  • All the squares must be clearly visible (unoccluded).

  • Use a tripod

  • Take 25 images and more

  • Use a paper size ".3" and more

  • Square size is 3-5 cm

  • The chessboard on the images must be located in the all places of the camera matrix 


    Figure 2. Point density

  • The chessboard must be plane

  • Take photos from these positions + from the top of the chessboard


    Figure 3. Camera positions

  • The tilt angle is constant (for example 45 deg)


    Figure 4. Tilt angle

  • Take photos with three camera positions


    Figure 5. Tilts of the camera

Another thing is that I actually tested only on my images, so maybe my modifications won’t help other people to do their calibration. If so – send me your image sequences, I’ll try to tune up my method to work with them also.

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