Re: [PanoToolsNG] Re: PTGui/PTMac Lens Database?
- Hi Sacha,
I think we might have totally scared off Kristin with these tech answers
to a relatively simple question.
I hope she is not discouraged by this. Let me just say that she can use
any data of lens profiles provided with either software.
The import however has to be manually. Of course the calibration data
for the lens is only for a, b and c parameters.
Fov and d and e are determined by the crop you apply and how the
lens/sensor relation pertains to your particular combo.
D an E always varies. I haven"t seen a lens which does not shift in its
mount. For repeatable results or scripting you need a bracket or a strong
rubber strap to pull the lens into a registered position.
>Depending on the lens/cam registration, yes. If the lens is not
> Right, but I think most agree, if they use ptgui, templates are far better
> than a lens db, simply for the fact that the cropping is correct.
registered there will always be a shift you have to optimize for.
As i have said, I have yet to see a lens mount stay fixed and be
registere each and every time out of the box.
>I disagree. a b and c values of a calibration target are better than
> If you use only a lens db, and recreate the cropping, you might as well
> start from zero.to get a good stitch.
from just any subject. Often there are not enough good features to be
It is hard to tell if you are correct if the image fits and ultimately
that is the goal. However, if you take these achieved values and apply
it to a
perfect grid image to test the lens, you will see that the values are
never quite right.
Have you ever ended up with every pano from scratch with the exact same
Calibrated values in the lens database are a treasure. Especially to
correct single shots. Thats essentially what PTlens, Lensfix or Radcor
do. For each parameter you know is correct you do not have to optimize
for and dont need a cp for it.
>Its always been that way. The NPP shifts depending on aperture and angle
> The rotation for each shot with a fisheye is incredibly important.
> For instance, same lens, same camera dimensions, but the NPP is almost
> an inch different going from 72 degrees rotation to 45 degrees rotation.
of view of your segment used in the pano (i.e. Sigma 8 npp range is 13
mm from beta 0 to 90 ). That shift applies to pitched (vertical)
segments as well.
>Yes. And you can not expect correct abc lens values from that can you?
> Which also means, if you do creative composition shots, where you
> alter your
> rotations for the subjects, your stitching and optimization is going to be
> all over the place.
>Thats exactly it. Its always an approximation depending on features given.
> As is evident by my experience with hundreds of projects using a template
> and the difference in optimization when I freed it to get best parameters.