Panorama restoration algorithms

Panorama restoration algorithms

Post by Thiadmer Riemers » Thu, 02 Oct 1997 04:00:00



Hello everyone,

What are the formulas to restore a (part of) a panoramic image as made by
QuickTime VR or Live Picture's PhotoVista. I mean, those applications warp
the input pictures to create a panorama. I wish to know how to unwarp them.

Literature references (books, articles) or toolkits are welcome as well.

Thanks in advance,
Thiadmer

* * *
Note: My E-mail address has been altered to avoid spam

 
 
 

Panorama restoration algorithms

Post by Dan Slate » Thu, 02 Oct 1997 04:00:00



> Hello everyone,

> What are the formulas to restore a (part of) a panoramic image as made by
> QuickTime VR or Live Picture's PhotoVista. I mean, those applications warp
> the input pictures to create a panorama. I wish to know how to unwarp them.

> Literature references (books, articles) or toolkits are welcome as well.

> Thanks in advance,
> Thiadmer

> * * *
> Note: My E-mail address has been altered to avoid spam

The basic mathematical concepts for panoramic / fisheye image
warping/dewarping are extensively described in cartography (map making)
books. See:

http://www.nearfield.com/spherecam/

for examples, references, etc.

Dan Slater

 
 
 

Panorama restoration algorithms

Post by Paul Gallagh » Sat, 04 Oct 1997 04:00:00



Images in Quicktime VR etc are not acutally "warped" instead they are
emulating what a Panarama camera does in real life... which is take a
vertical slit of a picture, rotate some and take some more.  this
actually avoids a lens correcting effect on the corners of a photo and
when the image is laid out; walls and things look "warped".

To un warp (simply, no great algorithms here)  start from the middle
of the image, leave that vertical line of pixels alone, then on the
way out to the edges start slowly stretching vertically each vertial
line of pixels in a geometric progressing of stretching to where the
edge of the images are maybe 1.5 longer (vertically) than the middle.
Voila, youre almost there.  Almost because you should have been doing
some horizontal stretching on your way to be precise.  The trick is to
do it fast and if you're adding hot spots, know where you are in the
warped part.
BTW, we did this on ZORK NEMESIS (game from activision) it was a lot
of fun... I proved we could do it, then we kept making it faster so we
didn't have to use QT VR or surround Video.  
Theres lots of optimizing tricks and compression issues to use it but
thats a start

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Quote:>Hello everyone,

>What are the formulas to restore a (part of) a panoramic image as made by
>QuickTime VR or Live Picture's PhotoVista. I mean, those applications warp
>the input pictures to create a panorama. I wish to know how to unwarp them.

>Literature references (books, articles) or toolkits are welcome as well.

>Thanks in advance,
>Thiadmer

>* * *
>Note: My E-mail address has been altered to avoid spam

 
 
 

Panorama restoration algorithms

Post by Thiadmer Riemers » Wed, 08 Oct 1997 04:00:00




>To un warp [...]  start from the middle of the image, leave that vertical
>line of pixels alone, then on the way out to the edges start slowly
>stretching vertically each vertial line of pixels in a geometric
>progressing of stretching [...].

Geometric progressing... along a circular or elliptical path I guess.

Quote:>[...] Almost because you should have been doing some horizontal
>stretching on your way to be precise.

Horizontal stretching at the edges? At first I guessed you would have to
stretch the center (or to compress the left and right edges). I use Live
Picture's PhotoVista (and their RealSpace screensaver) as a reference. That
software also stretches the edges. But the image looks distorted at the
edges, so I assume that they stretch too much.

Would you know about test images? Is there a set of pictures with a grid (or
similar) that I could stitch together and verify the equations?

Quote:>BTW, we did this on ZORK NEMESIS (game from activision) [...]

Yes, it is a wonderfull technique for these kinds of games.

Thank you for your very understandable explanation.
Thiadmer

* * *
Note: My E-mail address has been altered to avoid spam

 
 
 

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