camera_calibration opens gui window but freezes

asked 2018-07-03 08:42:24 -0500

martinakos
38 ●5 ●6 ●12

I'm trying to run the camera_calibration node. I run this command:

rosrun camera_calibration cameracalibrator.py --size 8x7 --square 0.023 --approximate=0.1 --no-service-check image:=/camera/color/image_raw

I see a window opening but then it freezes indefinitely. I tried to debug cameracalibrator.py and saw that the freeze occurs at the cv2.namedWindow("display", cv2.WINDOW_NORMAL) in the run() method of DisplayThread which is created in the OpenCVCalibrationNode __init__(). I have tried to move the cv2.namedWindow somewhere else but it also freezes. In fact after trying a few times the freeze transforms into a segmentation fault when executing the cv2.namedWindow statement.

Any idea what could the problem be?

I'm running Ubuntu 16.04, ROS kinetic, opencv version is 3.3

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answered 2018-07-06 03:57:49 -0500

martinakos
38 ●5 ●6 ●12

This was an opencv library version conflict, as I suspected. I had opencv 3.4 also in a development folder. Despite camera_calibration being built with the opencv 3.3 that came with ROS kinetic installation for some reason ldd showed a dependency to a lib in opencv 3.4. I think this dependency came through a thirdparty library built with opencv 3.4 and installed in the system. Interestingly enough other opencv calls in camera_calibration worked well but only showed the problem when opening a window.

I uninstalled opencv 3.4 and rebuild a bunch of libraries with ROS's opencv 3.3 and it worked.

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answered 2018-07-03 09:13:42 -0500

pavel92

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Have you tried waiting few minutes for the window to unfreeze? I know that camera_calibration window can freeze up to 10 minutes after clicking the "calibrate" button (this is even stated in the documentation). From what I understand, in your case the gui freezes at the start?
According to the camera_calibration, there is also a camera parameter in the command:

rosrun camera_calibration cameracalibrator.py --size 8x6 --square 0.108 image:=/my_camera/image camera:=/my_camera

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yes it freezes at the start. I have waited for a long time anyway, but I think it's not related with the calibration computation. Maybe more like a library conflict.