PanoTools NG:
Re: Sigma 8 F3.5 and its sharpness
John Houghton 2007-May-16 10:46:45
--- In #removed#, "Roger D. Williams" <roger@...>
wrote:
>
> On panoramas made from hand-held shots and to a lesser extent from a
> camera on a unipod, there are up to six degrees of freedom for the
> relative camera movements between shots. Since it would take at
> least two points to define each degree of freedom, that makes at
> least 12 points at each seam as an absolute mininum. In view of the
> warping that is also going on, I would have thought double that to
> be no more than a safe minimum.
Roger, I don't mind at all you putting forward a differing point of
view. A lot depends on the subject of the panorama. In the great
outdoors, you usually have some features a relatively long way away.
Any positioning errors of the camera are of little consequence. If
you move the camera up by an inch, it will have no material effect on
the imaging of the distant features. If you have managed to evaluate
some good lens parameters in a calibration exercise, the image
warping will be taken care of, though the lens fov and shift
parameters should be optimized. When the images are remapped onto
the spherical stitching surface, in principle only two points per
seam are enough to align the images, but the alignment is only going
to be good for the remote parts of the images.
In practice, more than 2 points per seam are desirable. One has to
treat each panorama according to circumstances and I wouldn't rule
anything out. It's the final result that matters.
John
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