Implement Lens Distortion model for Zoom Lens

[engelbeck]

Everything I read on this forum implies that the implementation of "Brown's" Lens Distortion model used by Photoscan can not handle zoom lenses.  Have you tried to implement the Z-D calibration modification described in "Zoom-Dependent Camera Calibration in Digital Close-Range Photogrammetry" by C.S. Fraser and S. Al-Ajlouni out of the University of Melbourne in Australia?

[n@sk]

Instead of interpolating between "known calibration values at given zoom settings" they allow for the estimation of a separate interior orientation parameter set for each image (see calibration groups) so I am not exactly sure about what you have read about the implementation of Brown's model or how you have interpreted it.
I suppose that what has been mentioned is that it is better to estimate 8 parameters instead of 8000 so it is better to keep zoom,focus,aperture fixed.
I hope this helps

[engelbeck]

I am thinking about the calibration interpolating across zoom settings within a single calibration group.

I have not had good luck with calibration groups.  My markers are quickly overwhelmed by tie points and prove ineffective in forcing good alignment.  I agree that it is better to keep zoom, focus, aperture fixed...but that is not easy when the objects you are working with are 200+ feet across and depth of field becomes a significant issue...even with a prime lens. 

Being able to use a zoom lens would give me more flexibility keeping the near and far object details in focus...sounds like shooting at hyper-focal distances....but is not always the case.  Having the freedom to use a zoom lens tailored to each specific shot would help my photogrammetry results....but produces an image set that can't be sorted into a few calibration groups.