CODEWITHSUNDEEP
c++opencvmatrixcamera
Meng
Meng

Reputation: 99

C++ Opencv Calibration of the camera with different resolution

My camera has different resolutions 1280*480 640*240 320*120

I have used the algorithm of Opencv3 to calibrate the camera with the resolution of 1280*480 and I have got the camera matrix (fx fy cx cy)and the distortion matrix (k1 k2 p1 p2 k3)for this resolution.

But now I want to use these camera matrix and distortion matrix to calibrate the camera with the resolution of 320*120. I don't know how to apply these two matrix of the resolution 1280*480 to the resolution of 320*120. PS I haven't calibrated the camera with the resolution of 320*120 directly because the image is too small and the algorithm of Opencv can't find the chessboard.

I want to know how the camera matrix (fx fy cx cy)and the distortion matrix (k1 k2 p1 p2 k3) will change if i change the resolution 1280*480 to 320*120.

The algorithm of opencv is the following one: http://docs.opencv.org/3.0-beta/doc/tutorials/calib3d/camera_calibration/camera_calibration.html

Upvotes: 5

Views: 6595

Answers (1)

KjMag
KjMag

Reputation: 2780

You don't need to change the distortion matrix. As for the camera matrix (the one containing fx, fy, cx, cy), you just need to divide them by 4 in your case. The general formula is:

fx' = (dimx' / dimx) * fx 
fy' = (dimy' / dimy) * fy

fx' is the value for your new resolution, fx is the value you already have for your original resolution, dimx' is the new resolution along the x axis, dimx is the original one. The same applies to fy.

cx and cy are calculated analogically because all these values are expressed in pixel coordinates.

As per the OpenCV docs regarding the camera matrix:

if an image from the camera is scaled by a factor, all of these parameters should be scaled (multiplied/divided, respectively) by the same factor.

Upvotes: 7

Related Questions