[ptx] autopano: first attempt at semi-automatic panorama stitching

[Pablo d'Angelo]

Hi Sebastian,

> On Sat, Dec 27, 2003 at 05:41:22PM +0100, Pablo d'Angelo wrote:
> 
> > [...]
> > when you create your rotationally invariant descriptor, by suming the
> > polar image, one looses all rotation information. Probably it would be
> > interesting to create a kind of "local" reference frame, from the center
> > to the strongest feature. This could then be used for corrospondence
> > analysis as well.
> 
> I am not sure if I understand completely what you mean with reference frame.

when you create your features, one could try to find a "feature coordinate
system", for example by introding an "artificial x axis", for example by 
using the strongest edge in the feature neighbourhood, or some other measure
that works reliably. then you have a rotation invariant feature measure,
like before, and also an estimation of the rotation.

If I remember correctly, this is also one of the interesting parts of the
SIFT features.

Your first correlation step you could use your rotation invariant, radial
sum descriptor, but additionally you have additional information that can be
exploited, like it is done with the RANSAC in Browns approach.

> > Alexandre has implemented some parts of that algorithm, but the SIFT
> > features seem to be patented (don't know where, haven't found a patent in
> > the german patent database). But since we do not really need scale
> > invariant features (I think), we could replace the SIFT feature detector
> > with something more simple.
> 
> Is there code of his implementation to review?

Alexandre hasn't posted it yet. we have to think if we want to introduce
patented algorithms into hugin. hmm maybe its ok for us germans, at least
for now ;)

ciao
  Pablo
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