Re: What is optimized FOV really?

Hello,

Quick addition and summary from my side.

1) Barrel distortion correction: panotools uses r* = a*r^4 + b*r^3 +
c*r^2 + d*r,
with r being the normalised radius. If it were not for the condition a
+b+c+d=1
this parameter d would be fully collinear with the focal length.
focal_length_panotools * d = true_focal_length

2) http://www.vision.caltech.edu/bouguetj/calib_doc/htmls/parameters.html
x_d=x_n * (1+kc(1)*r^2+kc(2)*r^4+kc(5)*r^6) +dx, dx=[...]
Looking at the distortion formulas the Bouguet model looks
mathematically
sound to me, as the parameters x_d and dx only use odd and even
powers,
respectively, of (r,x,y) polynomial expressions.
That respects the lense symmetry. Parameters a and c in panotools do
not.

3) In the xd formula 1 is equivalent to d, kc(1)=b/d, kc(2) and kc(5)
are unaccounted for. (N.B. I suggested a few times to include
a kc(2) type parameter into hugin/panotools).

4) Sheer parameters are available in panotools but are not shown
in the hugin GUI. There are two parameters, and combined with
the roll parameter I suspect that this set of three only spans
a two-dimensional configuration space, save for possibly a
higher order correction that results in non-square-like pixels.

5) Tangential distortion vectors, kc(3) and kc(4) in Bouguet,
I have not seen such in hugin/panotools.

6) Principal point cc in Bouguet are parameters e and f
in panotools, in the GUI labelled x and y.

7) Rectangular non-square pixels, Bouguet using fc(1) and fc(2),
are not there in the hugin/panotools model.

Summary: models are reasonably similar, Bouguet is more powerful,
and parameters a and c of hugin/panotools, the only ones
I cannot find a match in Bougues, have a maths symmetry issue.

Cheers
Klaus

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group.
A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ
To post to this group, send email to hugin-ptx@...
To unsubscribe from this group, send email to hugin-ptx-unsubscribe@...
For more options, visit this group at http://groups.google.com/group/hugin-ptx
-~----------~----~----~----~------~----~------~--~---