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

[Yili Zhao]

ED wrote:
>but do you think that it will work well for 8mm fisheye lens,
>or even just very wide angle lenses?
maybe for 8mm full circular lens, if we remap it to equirectangular
format, constructing the spherical panorama becomes a pure translation
problem.You can see this process from: 
http://www.path.unimelb.edu.au/~bernardk/tutorials/360/background/process.html
Thus phase correlation and klt can be used. Other wide angle
images also need to be remapped before correlation search.

Pablo wrote:
>For a real autopano, a different approach is needed. especially the phase
>correlation needs to be replaced by something else, that is aware of the
>projections were are using. 
but, "The stitcher uses a correlation-based image registration algorithm to
match and blend adjacent pictures." (excerpt from QuickTime VR - An Image-Based
approach to Virtual Environment Navigation). If we have warped each input image,
constructing the panorama becomes a pure translation problem. I also guess that
the correlation-based image registration algorithm used by QTVR is phase correlation.

I think phase correlation can be only used to constructing single row panos.
For multiply row panos, three parameters (yaw, pitch and roll) method should be used.  
It seems that pt's algorithm falls into this category. For more information about
3 parameters model, maybe you should refer to this paper: "Creating Full View Panoramic
Image Mosaics and Environment Maps", and this paper has some more interesting things.

Happy new year to all!

Yili