Image radial distortion correction

The chessboard calibration is a computer vision task that must be approached considering some guidelines:

1. Use target printed only by laser or inkjet devices to validate and test.
2. The target should cover approximately half of the total area when seen front-parallel in the camera images.
3. The target should have a high feature count and using fine patterns is preferable, especially for cameras above 3MPx.
4. Proper mounting of calibration target and camera, having them mounted preferably vertically. Consider moving the camera instead of the target.
5. Set the camera focus on the final application condition and the lens focus should be unchanged after calibration.
6. Collect images from different areas and tilts (Fig.1), viewing the target to fully cover the image area. Include both front-parallel images, and images taken with the board tilted up to +/- 45 degrees in both horizontal and vertical directions.
7. Use good lighting, having the calibration target diffusely lit with shadows avoided.
8. At least 6 observations (images) of a calibration target are required.

Figure 1. Examples of potential target orientations