[ptx] beta version available for pano12.dll with improved optimizer

[Rik Littlefield]

Terje Mathisen wrote:

>> This version does *not* include the option to optimize by rectangular 
>> coordinates, as discussed recently in this group.  More work is still 
>> needed to get that solid.
>
>
> But it should still work for a rectilinear output, otherwise it 
> wouldn't make any sense to use the straight line control points, right?

Correct.  There has been no change in what is optimized, only in exactly 
how the optimization is done.  Normal control points are optimized as 
angle on the sphere, scaled so that one unit = one pixel at pano 
center.  Horizontal, vertical, and line controls are optimized as 
rectangular pixel coordinates in the rendered image.  Errors are 
reported in the same way.

>
> I have a calibration photo (part of an office building) for my Oly 
> C8080 with a lot of horizontal and vertical lines in it.
>
> I entered a few vertical lines, a few horizontal, plus a bunch of 
> straight lines.
>
> Both the new and the old optimizer have really _big_ problems trying 
> to find a stable solution for the lens distortion parameters. (At 
> maximum wide angle this camera/lens have significant gullwing style 
> distortion, with barrel that flattens out towards pincussion nearer to 
> the corners).

What does "problems trying to find a stable solution" mean?  If the 
optimizer converges to different values depending on your initial 
estimates, then most likely there are a bunch of local minima in the 
error as a function of a/b/c.  I don't think that anything I did would 
change the optimizer behavior in that case.

>
> Should I place the photo + my current PTAsm project file on a web 
> server for download? 

Sure, I will be happy to take a look.  But do not get your hopes too 
high.  I am not expert on the PT lens model, and it sounds like the 
problem may be that the model just cannot represent this lens very 
well.  Perhaps someone else with more experience can take a look too.

--Rik