Request for the units conversion of k1 and k2

[curryandklay]

Hi, @bvnayak
Thanks for your excellent program. I successfully used your code to convert from the CAHVOR camera model to the photogrammetry model. But I have some questions about the converted distortion parameters:

When I want to use the distortion parameters to correct the image, the units of mm^-2 and mm^-4 are not consistent with the units of distortion coefficients required by the correction functions provided by opencv or other software. According to my search results, the distortion coefficients are usually dimensionless.

Therefore, I am confused about the mm^-2 and mm^-4 units here, and hope that you can provide a conversion method so that these distortion coefficients can be used in the correction function of opencv.

Best regards