[ptx] Looking for expertise on optimizer internals

[Pablo d'Angelo]

On Mon, 26 Apr 2004, Littlefields - Rik, Janis, Kyle & Peter wrote:

> Briefly, I have working prototype code that changes the way that the 
> lmdif optimizer is called.  The original code seeks to optimize distance 
> squared, where distance is what lmdif sees.  My mods also seek to 
> optimize distance squared, but the formulation is to optimize dx^2 + 
> dy^2, where dx and dy are what lmdif sees.
> 
> The change in formulation gives lmdif better information about how to 
> change the parameters, leading to faster and more accurate convergence.
> 
> But of course there are wrinkles dealing with wraparound and near-polar 
> points, and I would like to tap into whatever other people know about 
> the optimizer, to be sure that I don't mess things up..

I think panotools uses angular differences (for normal control points), and
its probably a not good idea to split the spherical coordinates and use them
like they where normal cartesian coordinates, at least near the poles.

> If you have experience with the guts of adjust.c and are willing to 
> share it, please chime in.

Sounds very interesting. I'm still thinking about adding a (optional)
penalty for the HFOV optimisation, so that it becomes possible to optimise
it for partial panos as well.

Can you post you code, or the patches, so that we can see exactly what you
modified.

ciao
  Pablo