Tips for calibrating / aligning the camera

These are the most common reasons for difficulty with camera calibration:

  • The camera doesn’t need to be on the machine for the lens calibration - It’s ONLY the lens and pattern that matter for this part, and the pattern can be scaled up.

  • If you do it on the machine, if you have a honeycomb bed, cover it (bedsheet, paper, wood, etc) - the pattern gets misinterpreted as more circles and confuses the software.

  • The printed circle pattern has to be as flat as possible . Glue it to wood or foam board so it’s flat. If it isn’t, the curvature will be considered part of your lens distortion.

  • The card should be in focus, and placed on something, not held - if it’s shaking, the image will be blurred, and that will affect calibration.

  • The calibration card should be facing directly at the camera for a fisheye lens, or perfectly flat and parallel with the lens for a non-fisheye lens.

  • The circles pattern should fill roughly 1/3rd of the view of the camera in both directions. If it’s much too small, or much too large, you won’t get good results.

These are the most common issues with camera alignment:

  • Make sure you’re using “Absolute Coords” mode when doing the alignment, or using the camera for alignment or capture.

  • Make sure the top of the material is at the same height as when you ran the camera alignment process. This would normally just be the focus height for your beam.

  • Make sure your lid always opens to the same position - if the hinges allow the lid to slide, or it doesn’t open the same height, this will cause misalignment.

  • When doing the camera alignment process, use the largest scale that fits properly on your laser. The default size is 180mm square. If you have a 500mm high laser, you can go to 250% scale with no trouble, and the larger scale will improve the accuracy of the result.

See also:

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