Cubic Lens Distortion (or undistortion as well) is well known in compositing or any VFX package. Basic Lens Distortion would usually solve the distord plate a the center, but closer you would get to the border of the picture, more the distortion will still there. The Cubic parameter let you control that.
It could also be used to give a “Chromatic Aberration” effect
This shader is based on the Algorithm shared by ssonTech website. This algorithm is used in SynthEyes (matchmove software) and is pretty simple.