[ptx] panosifter problems & questions

[Bruno Postle]

On Tue 17-Feb-2004 at 12:51:06PM +0100, Terje Mathisen wrote:
> 
> What's slightly more interesting is the fact that due to 
> barrel/pincussion distortion, a lens will have an effective FOV which 
> depends on the amount of overlap between images, and not only the 
> current focal length!

Yep, panorama-tools locks the a,b,c distortion to the narrowest
dimension of the photo, so a 1600x1200 photo will have a circle of
zero distortion at a radius of 600 from the centre.

This means that landscape photos always have the same vertical FOV
regardless of the a,b,c parameters, but horizontal FOV is variable
and depends on the lens settings as well as aspect ratio.

The reverse is true for portrait photos.

Horizontal field of view is a very ugly measure of a lens, though
I don't know of a better system.

-- 
Bruno