Calibration matrix - how?

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I am trying to perform measurements on a depth image, by selecting a region of interest in the RGB image. However there seem to be an offset between the RGB/depth image, not to mention there are some distortion on the depth image. I have looked into different methods for calibrating, all of which employs use of matrices. The thing is I need to identify some the intrinsic parameters, for instance focal length on both axises, fx and fy and k1, k2, k3 and p1,p2. It sees that I can't make my camera work with OpenCV (only the RGB camera), so here goes: How do I obtain the parameters required? And how do I implement them? Btw. I am using LabVIEW for measuring the depth data.