[Bf-vfx] Blender camera tracking approach

[Tom M]

On Sun, May 8, 2011 at 10:06 AM, Remo Pini <remo.pini at avexys.com> wrote:
> I kind of disagree...
>
> If you have lens distortion in you footage, this would most likely be
> bad and you would not want the final result to have that in it anymore,
> sooo....

You are thinking extreme distortion - this is about the very slight
distortion that comes from all camera lenses due to their lense shape
(as well as lense imperfections - but the imperfections are mostly
ignored by most lense solvers).

Our brains ignore the distortion but it confuses trackers since travel
in a straight line isn't straight with the distortion.

Undistorting the lense reduces the image quality because it shifts
pixel locations and thus 'blurs' pixels that the undistorted location
of a pixel will not be exactly on the pixel boundary of a previous
pixel.

Thus undistortion is only used to provide straighter lines to the tracker.

Applying the lens distortion to your rendered image is so that it's
straight lines are curved similarly to that of the original image.
Again this introduces blurring of your render if it is applied as a
post process - so either you need to render larger or do the
distortion at render time.  In practice the amount of bluring from
doing it as a post process is probably not significant enough to be
noticable in most situations.

LetterRip