We have a large bed machine (1390x2500) and like to use the camera functions. Using an 8 MP camera suspended above the bed, focused in to the point we only see the bed. Now, when trying to focus/configure the camera for Lightburn, we surely can’t use the test page that prints out (the dots). How do we go about doing this? I haven’t seen any kind of write-up to accomplish what I want.
Thanks for any help!
Brian
What’s the complication preventing you from using the calibration pattern? Are you saying because the print is too small? If so then just print the pattern full page. Make sure that it’s still in the same aspect ratio and none of the pattern is cropped.
The Dot pattern is for fish-eye correction in the field of view of the camera. You can do this outside the machine with extra light to get the pattern to take.
Once you have success with this, you can put your camera back and close the lid and work on the straight line part of the image calibration. The 4 targets remap the linear / triangular change to the point of view of the camera in software.
I’ve got a 1600x1000 bed here, but yours is a monster! You would benefit from 16MP resolution, well, the highest you can get. You’ve got 3.475 million sq mm there, so even if you had “perfect use” of 16MP, that’s only around 0.5mm resolution.
The polka dot sheet seems to be OK now. They had some bugs with high res cameras with the 16:9 aspect ratio, but ok now. I’m within a couple mm.
I do recommend the 16MP fixed-focus Arducam with a “2.8-12” varifocal lens (requires M12 locking ring). The stock lens didn’t calibrate correctly in LB for me. It calibrated, but unwarped poorly with regions of large errors.
What we want to do is get the field of view to match the bed as close as possible. Otherwise, you can easily lose half your pixel count in the margins.
The 16:9 aspect ratio is a very close match to 2500:1390. And then you zoom in the varifocal to just enough to cover the sides and nothing else.