Panorama stitchers, feathering, seaming etc..

[Bruno Postle]

On Wed 29-Oct-2003 at 01:32:45PM +0100, Kai-Uwe Behrmann wrote:
> Am 19.10.03, 21:29 +0100 schrieb Bruno Postle:
> 
> > > The basic idea is to assign a 'credibility' index to every pixel in
> > > each source photograph and use this to decide which pixels to render
> > > when seaming.
> 
> Therefore You need large overlapping areas which is not allways available
> and not necessary.

Not really, all it does is maximise the width of the feather to
match the width of the overlap.  With ptools the feather width is
fixed per panorama, which means that it may be too-small or
too-large for any pair of images.

> Interessting. Did You compute Your examples or are they handmade?

Both, the credibility map was created in the gimp with this set of
commands:

    layer -> add alpha channel
    layer -> add layer mask -> white
    set foreground: white
    set background: black
    set blend -> shapeburst (angular)
    do blend
    layer -> apply layer mask

PTStitcher is really broken with input images that have alpha
channels, so I used my slow perl tool to do the remapping.  Though I
could have re-mapped the alpha-channels separately and applied them
in the gimp.

I cobbled-together a horrible perl script that does the actual
merging:

    http://bugbear.blackfish.org.uk/~bruno/feathering/merge.pl

Though this is a mess and needs writing properly to be more generic
(it only takes two input images).

It could also be rewritten as a gimp plug-in, in fact the whole
stitching/merging/colour-correction procedure as performed by
panorama-tools could be done entirely in the gimp - since it is
nothing to do with panoramas anyway.

How about this as a tool-chain:

  - Hugin doesn't do stitching, the stitcher just spits out a series
    of png images for every layer in the output panorama (or a
    single multi-layer xcf file with individual layer masks).

  - A merge plug-in for the gimp stitches _any_ multilayer image
    using panorama-tools style feathering and colour correction.

The advantage of doing this in the gimp is that tweaks could be made
by hand before using the automated merging.

-- 
Bruno