Opencv_contrib: Omnidir stereoCalibrate Assertion failed

[kurohi]

Hi,
I have been trying to use the Omnidirectional camera model for stereo rectification, but even when just following the tutorial with the provided .xml I get a "Assertion failed".
The call that invokes this error is this one:

double rms = cv::omnidir::stereoCalibrate(objectPoints, imagePoints1, imagePoints2, imgSize1, imgSize2, K1, xi1, D1, K2, xi2, D2, rvec, tvec, rvecsL, tvecsL, flags, critia, idx);

The variables were set just like the tutorial on "modules/ccalib/tutorial/omnidir_tutorial.md" using the .xml on the "modules/ccalib/tutorial/data/" folder.
The full error message is this:

OpenCV Error: Assertion failed (!fixedSize() || ((Mat*)obj)->size.operator()() == Size(_cols, _rows)) in create, file /var/tmp/portage/media-libs/opencv-3.1.0-r4/work/opencv-3.1.0/modules/core/src/matrix.cpp, line 2232
terminate called after throwing an instance of 'cv::Exception'
  what():  /var/tmp/portage/media-libs/opencv-3.1.0-r4/work/opencv-3.1.0/modules/core/src/matrix.cpp:2232: error: (-215) !fixedSize() || ((Mat*)obj)->size.operator()() == Size(_cols, _rows) in function create

I am using the opencv-3.1.0-r4 on a Gentoo.
Any ideas how to go around this error?

[kristofvarszegi]

Hello! I'm also receiving this error. I also tried to initialize the function's arguments in many different ways.

Did you manage to solve the issue since then?

[jiuerbujie]

Hi, @kurohi and @kristofvarszegi , I am the author of omnidir calibration toolbox. It indeed a bug, change the 1309 line of omnidir.cpp to

        om.create(3, 1, CV_64F);
        T.create(3, 1, CV_64F);

will fix it.
If you have more questions, please inform me

[kurohi]

Thank you very much for the answer!

[kristofvarszegi]

Works for me as well, thank you for the fix!

[rnbguy]

I am getting the same error when trying to call calibrate() using Pything bindings.

K = np.zeros((3, 3))
D = np.zeros((4, 1))
xi = np.zeros(1)
ret = cv2.omnidir.calibrate(
        objpoints,
        imgpoints,
        shape,
        K,
        xi,
        D,
        cv2.omnidir.CALIB_FIX_SKEW,
        (cv2.TERM_CRITERIA_EPS+cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-6),
    )

[FlorianFranzen]

I am experiencing the exact same issues as @rnbdev using the python bindings of OpenCV 4.3.1:

OpenCV(3.4.1) Error: Assertion failed (!fixedSize() || ((Mat*)obj)->size.operator()() == Size(_cols, _rows)) in create, file /usr/local/src/opencv/modules/core/src/matrix_wrap.cpp, line 1240

I seems to have to do with the way the python wrapper allocates optional parameters, which is incompatible with the way the stereo calibration prepares it return values.

I hope I will find some time to investigate this issue further in the next few weeks.

@jiuerbujie: Any insight in what might cause this?

[pcp16]

Same issue as @rnbdev and @FlorianFranzen ... any solutions?

[benDavidson6]

Fourthed, same issue as others with the python binding when calibrating. @FlorianFranzen @pcp16 @rnbdev

[benDavidson6]

I had an array the wrong shape. The following works if anybody else ends up here:

    K = np.zeros((3, 3))
    D = np.zeros([1, 4])
    xi = np.zeros(1)
    calibration_flags = cv2.omnidir.CALIB_FIX_SKEW + cv2.omnidir.CALIB_USE_GUESS
    criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 1e-6)
    rms = \
        cv2.omnidir.calibrate(
            objpoints,
            imgpoints,
            gray.shape[::-1],
            K,
            xi,
            D,
            calibration_flags,
            criteria)

where objpoints is a list of numpy arrays, all with shape (1, checkboard_num, 3)

[FlorianFranzen]

@benDavidson6 You do not seem to run stereoCalibrate, so your results are irrelevant to at least this bug.

@jiuerbujie Might the patch you proposed be the reason that OpenCV now tries to resize some fixed size matrices when running the python bindings?

[patafix18]

Hi, @kurohi and @kristofvarszegi , I am the author of omnidir calibration toolbox. It indeed a bug, change the 1309 line of omnidir.cpp to

        om.create(3, 1, CV_64F);
        T.create(3, 1, CV_64F);

will fix it.
If you have more questions, please inform me

For me, i got the same issue with the OpenCV python bindings while using the calibrateStereo function. It always fails with an assertion failed and the following error message:

cv2.error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\core\src\matrix_wrap.cpp:1236: error: (-215:Assertion failed) !fixedSize() || ((Mat*)obj)->size.operator()() == Size(_cols, _rows) in function 'cv::_OutputArray::create'

@jiuerbujie, @alalek Is there any fix for this problem available? I would really appreciate that.

Best regards, Patrick