My comments, questions and enhancements

[Peter Suetterlin]

thp wrote:
> Hi Peter.
> 
> >>Another question: Can I customize the factor for focal length
> >>calculation? The calculated focal length is not correct for my
> >>camera. For a landscape image a focal length of 38,601 mm is
> >>calculated. The correct focal length would be 34 mm.  
> >>   
> >>
> >
> >Hmm, what do you call 'correct'?
> >
> The correct focal length is determined by a factor that differs from 
> camera to camera. As I understood hugin reads the (real) focal length 
> from the EXIF data, converts it to a focal length for a 35 mm film and 
> calculates the degrees of view. Is this right?

Yes, and this conversion is based on the size of the CCD chip as
compared to the standard 35mm film.
Next, the HFOV can be computed from focal length and chip size.  This
is most probably done assuming an error-free optics.  Real optics are
not error-free, and, e.g., cussion- or barrel distortion lead to a
slightly larger/smaller FOV when compared to the 'ideal' one.
So you get deviations from the straight-forward computed value, and
those are dependent on the lens setting (errors are different for
different focal lengthes, and so your correction parameter would be).

Therefore I prefer to compute the actual FOV from fitting a 360 deg
pano, as this is the important value for stitching.
Ideally you do this for all lenses / focal length settings and store
them in a library (together with the distortion parameters, of course).

  Pit