Distortion plot - how to use it?

[Bene]

Hi folks,

Can anyone explain me clearly what are and how to interpret the "Distortion Plot" graphics?

How can I use these results in my benefit (see attachments)?

Thanks in advance.

Regards,
B

[n@sk]

the first and third should give an indication of which parts of the frame to avoid
the assumption is that distortions are symmetrical around the principal point

the directions  of the distortion vectors in the second one should be more randomly distributed
this pattern indicates a systematic error

the last one is an estimation of the correlation between the interior orientation parameters
K4 (and perhaps K3 as well) is not required to model the radial distortion and should not be used