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input arguments of python's cv2.calibrateCamera

asked 2015-03-30 12:31:51 -0500

krips89 gravatar image

I get the following error when I try to calibrate camera using cv2.calibrateCamera:

rms, camera_matrix, dist_coefs, rvecs, tvecs = cv2.calibrateCamera(pts3d, pts2d, self.imgsize, None, None)
cv2.error: /home/sarkar/opencv/opencv/modules/calib3d/src/calibration.cpp:2976: error: (-210) objectPoints should contain vector of vectors of points of type Point3f in function collectCalibrationData

I initially had nx3 and nx2 array for pts3d and pts2d. I then tried to reshape pts3d and pts2d in the following form as the function takes vectors of vector point3d (and correspondingly pts2d) as input:

[1 x n x 3] and [1 x n x 2]

[k x n' x 3] and [k x n' x 3], where k is some random value

[1 x n x 1 x 3] and [1 x n x 1 x 2]

nothing works and it always gives the same error.

I saw the code sample code of cameraclibration provided which runs fine, and their input is of [k x n x 3]. I really don't know what is wrong with my implementation. Following is my code to be precise:

   #data contains [n x 5] dim array which is the hstacked arrays of pts3d and pts2d correspondences I obtained elsewhere. 
    pts3d = data[:, 0:3] #first 3 column 
    pts2d = data[:, 3:5] #next 2 column.. I checked the values are coming correctly 
    pts3d = pts3d.reshape(1,-1, 3) #Here, I have experimented by resizing with different values. 
    pts2d = pts2d.reshape(1,-1, 2)

    rms, camera_matrix, dist_coefs, rvecs, tvecs = cv2.calibrateCamera(pts3d, pts2d, self.imgsize, None, None)

the error happens at the time of the function call. It would be nice to know what can be wrong here.

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answered 2018-03-06 08:47:10 -0500

abhijit gravatar image

The Points must be of type np.float32. Also you can check out this small python API which you can use to calibrate the camera using opencv.

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Thanks, that helps.

klimenkov gravatar imageklimenkov ( 2019-04-02 10:59:24 -0500 )edit
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Asked: 2015-03-30 12:31:51 -0500

Seen: 841 times

Last updated: Mar 06 '18