Camera parameters for ideal calibrated camera

Dear Community,

simple question: I read this documentation:

I saw the parameters that define the camera lens distortion. However I don’t get what they mean, e.g. what is “lens_circle_falloff”. I can only guess its a multiplication factor for how “ball-like” the lens is. Is there some explanation somewhere that i cant find?

And more importantly: Which parameters lead to a “calibrated” camera, i.e. no lens distotion of the image, such that straight lines in the real world will be straight lines in the image?

I would like to get RGB images like the middle one: