I now have a Hugin install with working Exposure optimisation;
grateful thanks to the good Mr Modes.
As I said, I took my photo with aperture priority
exposure (deliberate) and auto white balance (not deliberate).
On two of the images, I also took a second
shot with a reference card in shot.
(a home printed version of this:
http://www.pasthorizonstools.com/Credit_Card_archaeology_photography_scale_p/ccps.htm
)
To balance the whole image, I added the two
reference-included images, to the pano,
masked out the ref card in Hugin, and added
CPs to "tie" them to their cardless-versions.
I then (having made a backup) edited the reference
images in Gimp, colour correcting them using the
card.
I then (after some experimentation) learnt that I need
to both:
1) Unapply the Orientation value from the Camera in Gimp
(which applies the value at image load time)
2) Re-set the Orientation value in the saved image.
exiftool -tagsFromFile IMG_0252.JPG.orig -Orientation IMG_0252.JPG
This gives the new image the same properties as the original
as far as Hugin is concerned.
I then locked down the EV, Er Eb values for the two reference images
to be "8 1 1"; the "8" is near to the actual value, and "1 1" are clearly
the right values for an externally corrected image.
I then performed a sequence of exposure optimisations, with the two
reference images values "locked", and all others to be optimised,
and I alternated between optimising Ev and White balance.
This worked pretty well.
I then created a large image using nona on the command line. I did
not use enblend, since I have large parallax errors in some areas, and
am carefully using a controlled sequence of images to put
"whole" images over difficult joins, where possible.
(see earlier posts on parallax when capturing mosaics of maps for details).
This is really pretty good.
It shows two difficulties;
1) I was surprised that this final image is much darker than my corrected
reference image, even in the area of my reference image.
I don't understand this, and would like the overall pano to be a close
match to my corrected image.
2) In one corner of the pano the correction is both discontinuous
and the area is dark. I think this may have been caused by the shadow of the
tripod
arm on the images; this (given the mosaic capture) is NOT a constant
element in the image, and I don't have enough overlap to always mask
it out. This (I think) breaks the model/assumptions of exposure optimisation,
where
corresponding pixels should match.
Is there a way to control/manipulate/bypass/augment the exposure
optimisation to get a better result?
BugBear
--
A list of frequently asked questions is available at:
http://wiki.panotools.org/Hugin_FAQ
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