Why does my stereo calibration fails for extrinsics?
-
I am using the modal ai portal for calibration of onboard stereo cameras but it has failed to calibrate the extrinsics multiple times.
The board size is 6x9 with each square of 25 mm
Please open voxl-portal in a web browser to view the camera calibrator overlay stream Calibrating Left Camera Matrix [508.80440670594, 0, 308.5135447003642; 0, 505.8572996337453, 244.1641938401985; 0, 0, 1] Distortion [-0.1811268882769062; 0.07256140246308232; 0.001569367963422894; -0.001895561795494848; 0] distortion_model: plumb_bob Re-projection error reported by calibrateCamera: 0.228868 Calibration Succeded! Calibrating Right Camera Matrix [499.3757621172282, 0, 325.48861203442; 0, 497.8217173811094, 235.3877218749848; 0, 0, 1] Distortion [-0.1815603484893367; 0.06567294535447908; -0.001628603839397166; 0.001644475509575583; 0] distortion_model: plumb_bob Re-projection error reported by calibrateCamera: 0.219737 Calibration Succeded! Calibrating Extrinsics 4 frames will be processed R [0.9998749556474266, -0.01520329924164708, 0.004351179291381281; 0.01514403461767066, 0.9997962803983895, 0.01334375947938024; -0.004553162039243111, -0.01327619650779887, 0.9999015008098201] T [-0.08098804070286524; -0.000892545176548338; -0.003303076144588922] Re-projection error reported by stereoCalibrate: 0.832656 Detected horizontal stereo pair Distance between cameras: 0.0810 Extrinsics Calibration Failed exceeded allowable max reprojection error: 0.5 Saved intrinsics to: /data/modalai/opencv_stereo_intrinsics.yml Exiting Cleanly -
Can you take a picture of your setup?
Are the image sensors mounted rigidly on the same plane?
-
This post is deleted! -
@Chad-Sweet I am not sure about the plane of the camera. I am attaching some photos for your reference
https://drive.google.com/drive/folders/1nJOy9G0-hZSNSN0kZyrtJ9HcxRaZa50X?usp=share_link
-
@Chad-Sweet I am also facing the same issue, it is unclear from the documentation what is the procedure that should be followed to calibrate the extrinsics. Should the board be tilted? Should it be vertical or horizontal?
-
@afdrus have you watched the video here found at this link? https://docs.modalai.com/calibrate-cameras/#stereo-calibration-process
The angle of the PCB is not related to stereo calibration. For stereo configuration, the sensors must be rigidly mounted and coplanar. Any movement or tilt between the sensors will not work
-
@Moderator thank you for the reply, by board I meant the checkboard used for the calibration not the PCB.
However, I watched the video, but it looks old because the current extrinsics procedure is asking me to move the checkboard in 4 poses whereas the video is showing only 2 poses. How much tilt should the checkboard have during the extrinsics calibration process in order to have a low calibration error?
