Tracking camera calibration not progressing

Troi

Hello, I tried to calibrate the tracking camera using a 4x7 checkerboard with side lengths of 4 cm. I launched voxl-portal to view the camera calibration overlay. Then I placed the checkerboard in various positions and orientations within the red box overlayed on the tracking camera image. However, the calibration process does not progress. I never receive a green (overlay) box and the process remains at 0%.

What should I do to solve this issue?

Command used:
voxl-calibrate-camera tracking -f -l 0.04 -s 4x7

I followed the calibrate camera instructions from here: https://docs.modalai.com/calibrate-cameras/.

plub

@Troi same issue here but with stereo camera and command:

voxl-calibrate-camera stereo_front -s 6x9 -l 0.030

Did you resolve this?

Alex Kushleyev

@plub ,

Can you provide any more details? Are you able to start the camera calibration and view the camera images using voxl-portal ?

Are you sure that you are using a correct type of the checkerboard (correct number of corners)?

Alex

plub

@Alex-Kushleyev What do you mean by "start" the camera calibration? I've used command which i have pasted in previous post. Then i was able to see camera calibrator tool and images from stereo cameras. Red rectangles showed up but when i placed the chessboard inside them, nothings happened. I am using checkerboard recommended by you: 9x6 OpenCV chessboard. I've tried various combinations in front of the camera but calibration didn't started.

thanks for trying to help

Piotr

Alex Kushleyev

@plub , sorry for the delay. By start the calibration, I meant launch the voxl-calibrate-camera app and view the calibration stream via voxl-portal (it seems you have it working).

Is it possible for you to paste a video of a screen recording while you are doing the calibration (screen record the voxl-portal stream).

Thank you

Alex

plub

@Alex-Kushleyev Thanks. Now calibration is starting. Solution is to use 5x6 checkerboard with trimmed in half squares on edges. But even we can do full calibration, it says failed in the end. Re-projection error for stereo calibration ( standalone cameras calibrate fine ) is very high. Any solutions for this?

Alex Kushleyev

@plub , could you please clarify which cameras you are using in the stereo configuration? OV7251?

If the larger pattern was still detected by the procedure but was not accepted as a sample, this means that the pattern took up too little space of the desired area. You need to fill the desired area in each step almost completely, so that the sample is accepted.

Also, is your checkerboard printed on paper and attached to a very flat surface without wrinkles? A poor calibration pattern can lead to poor results.

Can you please post the result of the calibration? intrinsic and extrinsic parameters that are generated by the calibration procedure, even though it fails. Also please share the reprojection errors.

Alex