[ptx] Re: how to improve HFOV optimization?

[Pablo d'Angelo]

Hi Rik,

On Thu, 29 Apr 2004, Littlefields - Rik, Janis, Kyle & Peter wrote:

> Pablo,
> 
> I plugged in the fov penalty that I suggested yesterday
> >    ...  scale the errors by 1.0/avgfov
> > to correct for the shrinking image size as fov gets smaller.
> 
> It seems to work fine.
> 
> Yesterday I gave this example:
> > ...single-row series ... with a [nominal] 105mm lens (fov 12.3).
> > It optimizes to average error (as reported by PTGui)
> > of 0.446 pixels.  When I force fov 10 and reoptimize,
> > the average error drops to 0.445 pixels.  At fov 5, the
> > error is 0.323 pixels.  It should be apparent why the
> > optimizer wants to push fov to zero in this case.
> 
> With the optimizer mod installed, this panorama now
> optimizes to focal length 117mm (fov 11.1)  even if
> I start from geometries optimized for focal lengths
> as far wrong as 20mm (fov 59.1) and 1000mm (fov 1.3).
> 
> Does that sound like what you wanted?

Yes, pretty much. Even better, since I would have tried to cure the symtoms
by adding an additional penalty term, instead of modifiying the old one.

I think this should be tested and then applied to the panotools
project on sourceforge.

I've one question. you scale by avgfov, I assume avgfov is the average of
the two fov's involved in the control point, right? How does it behave if
the hfov's are quite different? Shouldn't the fov of the complete pano be
used instead (but if I remember correctly, that is not easily available in
the optimisation function)?

Sorry, I'm quite busy these days so I can't comment on everything happening
here.

ciao
  Pablo