How to convert the k1 and k2 of your paper into the radial distortion parameters of the opencv checkerboard calibration method

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The minimization is performed in the normalized parameters p1 and p2 instead of k1 and k2. But I see the k1 and k2 are different from the k1 and k2 of the opencv checkerboard calibration method. How to convert the k1 and k2 of your paper into the radial distortion parameters of the opencv checkerboard calibration method? When I multiply the k1 by the square of the focal distance, k2 multiply the square of the focal distance, the undistion is still wrong.