[Daub]

> There are relatively few situations where you have a distorted image taken with unknown lens, but where you have a regular grid of horizontal and vertical lines for the algorithm to rely on.

In visual effects distortion correction is required is required before effective camera tracking can take place. It is also required for a matte to fit the footage. In such situations, it is not unknown to be given 'mystery meat' footage which requires distortion correction. You would be surprised how many directors and DOPs take VFX voodoo for granted and would rather save five minutes on set at the cost of two days in post production.