I ran the calibration successfully on my image, and the undistortion worked great. Now I want to do it my hand, and I seem to be off by a scaling factor.
On the first page of the Calibration tutorial:
https://docs.opencv.org/2.4/doc/tutorials/calib3d/camera_calibration/camera_calibration.html
the equation for removing radial distortion is x' = x(1+k1 r^2 + k2 r^4 + k3 r^6)
My camera matrix says that the center of my image is at (x0,y0) = (630,470)
I want to undistort a point in the picture at pixel location (70,70). So I calculate my r as:
sqrt( (630-70)^2 + (470-70)^2 ) = 688.
With my k values, I get an x' in the zillions, so clearly I need to scale my numbers before using the equation. Can someone tell me how to do this?