Thanks for sharing your final recipe!

About manual CPs, you probably already do them well, but a good tip is to
put them away from each other not letting any big part of the joining parts
without any. As I said, I sometimes do only 3 between each pair and they
are put one at the top, one at the middle and the last at the bottom of the
image, whenever this is possible.

Cheers,

Carlos E G Carvalho (Cartola)
http://cartola.org/360



2012/1/30 torger <[email protected]>

> I appriciate the helpfullness, but unfortunately I cannot share the
> images since the originals are not mine.
>
> However, I worked this evening with this on a few images and tested
> several methods and have great help of your input. I get good results
> now (often subpixel fits), and consistent enough.
>
> The interesting fact is that setting a 1 - 2 degrees FOV is required
> for the best results. I've tried to let Hugin optimize it by itself
> but it rarely goes down to those low values, even when starting with
> the calculated 5.42 degrees. The fit often gets kind of ok with that
> 5.42 starting point, but not as good as it can get. I suspect that
> this is a special case occuring for this type of repro setup when
> there are just minor but still some yaw/pitch errors. Almost perfect
> perpendicular, but not 100% as a flatbed scanner, and not as large as
> hand held mosaics of walls. Seems to fall outside normal optimization
> space.
>
> I've also tested auto control points, and it works kind of ok, but
> there's always some outliers so I think I continue do them manually,
> having relatively few points and well-defined places gives me a better
> overview of stitching result I think, but I guess it is a matter of
> taste.
>
> I normally don't pre-correct lens distortion, since Hugin indeed does
> better fitting result if it can correct barrel etc itself, but in this
> special case the optimizer easily goes haywire so having close to
> perfect rectilinear input seems to work better. I've also tried to pre-
> correct roll, but it is not really worth it, that correction works
> well.
>
> This is the hugin workflow that gives me consistent results so far for
> this application:
>
> * Create new project
> * Open the 16 bit tiff images (usually four)
> * Don't use the field of view from EXIF, instead pre-set to 1 degree.
> * Make control points to connect all images
> * Make horizontal (and possibly also vertical) guides on all images
>  * You should have included film edge on all your frames and that is
>    what you use as guide
> * Now the exciting part - the optimizer tab
>  * First correct X and Y for all but one
>  * Then add roll to all and optimize again
>      * Theoretically this would yield perfect result already here,
> but as
>        said the repro setup is rarely that perfect
>  * Then add Z for all but one and yaw and pitch for all, and
> optimize
>    again
>  * Then open up GL preview, goto move/drag and select drag
>    mode "mosaic", and then drag the image into the center of the
> view,
>    close and optimize again
>       * Typically the optimizer has put the image far from center,
> and
>         moving it back into the middle again and reoptimizing can
> give
>         better result.
>   * You can try to add lens view as a final parameter but that
> usually
>     does not improve things.
> * Open up GL preview
>   * Choose rectilinear projection
>   * Mosaic-drag so the center is in the center of the image
>   * Fit/autocrop the view
> * Stitch to 16 bit tiff output, for further processing in your
>  favourite raw converter or photo editor
>
> On Jan 30, 7:08 pm, "Carlos Eduardo G. Carvalho (Cartola)"
> <[email protected]> wrote:
> > Well, I did mosaic maybe only a couple of times, but I didn't remember
> > having difficulties. I wouldn't do lens correction before hugin and I
> > wouldn't think of doing so much precise controls. Maybe with macro they
> are
> > more important, but I really don't know. Manual CP are surely not a
> > problem, just make sure you use at least 3 between each pair. Many times
> I
> > use only 3 (but to do spheric panoramas). Can't you give us an example
> > image set? Could be reduced size jpg preferably without any previous
> > processing, like that lens correction you mentioned.
> >
> > Is FoV so much important? Many times I just put a reasonable value and
> let
> > the optimizer correct this. More important is to guarantee that it won't
> > think it is a 360ยบ panorama, so I would think any kick to guarantee that
> > the total FoV is not going to get to 360 would be a good start, but
> again,
> > "guessing" here looks to me like a little loose of time if compared to
> see
> > your images to address the real problem.
> >
> > Cheers,
> >
> > Carlos E G Carvalho (Cartola)http://cartola.org/360
> >
> > 2012/1/30 torger <[email protected]>
> >
> >
> >
> >
> >
> >
> >
> > > Sorry for spamming... just came to think about FoV. Macro lenses are a
> > > bit special, fov doesn't match focal length at near limit. My 150mm
> > > macro lens from the focal length says "13.69 degrees fov". But at 1:1
> > > distance is 380mm so the fov would then be 2 * arctan(36/2 / 380) =
> > > 5.42 degrees, that is about the same as a 380mm lens. Anyway, I'll do
> > > some more experiments and report about the results.
> >
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