Hi all,

I mostly shoot my panoramas on film and scan using two different
scanners. One of them is a Nikon LS-4000 ED film scanner which shows a
huge vertical shear (sigh). My usual workflow prior to feed hugin with
my images is to
- correct for vertical shear (9-14 pixels depending on scan
resolution/size/whatever/...weather?)
- crop all images to the same frame size and add masks to hide unwanted
parts)
- correct for vignetting

BTW the other scanner (a Hasselblad 646) introduces no shear at all, I
just need a custom made scanner specific mask to be able to scan more
that one frame in one go. (another deep sigh)

Dev's description of how to correct g and t inside hugin is accurate, I
only think that my values were actually optimized whenever I tried.
Sometimes I also try to optimize g an t inside hugin but I'd prefer an
addition in the optimizer tab that uses the two tables for 'd' and 'e'
in a more flexible way: All other tables for yaw, pitch, roll, vof, a, b
and c should be 'static' like thea are now but the following ones could
IMHO be of better use if the table header was a drop down list showing
all other available variables one could possibly want to optimize (I'm
already preparing a screenshot...)

I know this could also be done editing the script but this solution
might be faster (and also easier for less experienced users).

One more idea: how about showing the lens number in this tab's tables
for every clickable image number? This could help to better distinguish
the standard shots from those handheld nadir shots :-)

Carl

dev g wrote:
> Hello,
> 
> Scanners or scanning cameras can introduce shearing distortions to images.
> In order to correct for such shears, the panotool's imaging model can
> optimize two parameters g, shearing in the x-direction and t, shearing in
> the y-direction.
> 
> However, I have noticed that if one wants to optimize the shear parameters,
> the values returned by the optimizer are not passed to the panorama.  To
> test this, set up a .pto file with a pair of images and generate control
> points between them.  Go the optimizer tab and click the "edit script" box.
> Then you must add the shearing parameters to the list of variables you wish
> to optimize (e.g. g1, t1, g2, t2, etc.).  After pressing optimize, you'll
> find that the values of g and t don't change in the panorama.  Is there a
> reason for this?  Is this by design?
> 
> I was able to change this by adding a couple of lines to the
> GetAlignInfoVariables function in PanoToolsInterface.cpp.  This causes the
> optimized values of g and t to be passed to the panorama and display in the
> GUI.  A patch file is attached.

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