Hey guys, I’m doing camera calibration using Zhang's method with a checkerboard and around 30 images. The results I’m getting are pretty random. Sometimes the error is around 1.5 px, and sometimes it goes up to 3 px.
Board flatness: My calibration board is not perfectly flat; it has some small ups and downs (varied depths) across the plane. Does this small change in depth mess up the results?
Barrel distortion: On both sides of the camera near the edges, there is more barrel distortion as the R value increases. Is this why the error is high?
Reproducibility: I can't reproduce the same error even if I pick the same number of images (30). The values keep shifting.
Low image count: Sometimes, if I calibrate with very few images (like 4-5), the undistorted image looks okay in the middle, but the edges and sides get totally warped or "wobbled."
Error increases with distance: I noticed that when the checkerboard is near the camera, the error is low (around 0.5px). But as I move the board back along the axis, the error shoots up to 2.2px in a single jump. Why does the error increase so much just by moving the board further away?