Hello, I need to create stereo images for a real-time virtual reality
project. This requires asymmetric viewing (camera is not in the center of
the image plane). The easiest solution might be if I could just specify the
world coodinates of the image plane. Has anyone had experience with this?

Thanks,
-Dave

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djzielin wrote:
> Hello, I need to create stereo images for a real-time virtual reality
> project. This requires asymmetric viewing (camera is not in the center of
> the image plane). The easiest solution might be if I could just specify the
> world coodinates of the image plane. Has anyone had experience with this?
> 
> Thanks,
> -Dave
> 
> 
Why do you need asymmetric viewing? Why don't you just use two normal 
camera's for stereo?

If you do want an offcenter image then...

Have you read the straight columns render bent thread? 10th Feb 2006

Or a simpler idea just render a wider angle image and crop it to the 
left/right hand side. (Or better yet tell pov to only render the left 
half of the image)

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"djzielin" <djz### [at] dukeedu> wrote:
> Hello, I need to create stereo images for a real-time virtual reality
> project. This requires asymmetric viewing (camera is not in the center of
> the image plane). The easiest solution might be if I could just specify the
> world coodinates of the image plane. Has anyone had experience with this?

Check out <http://www.povray.org/documentation/view/3.6.1/246/> in the
documentation. You need to set the up, right and direction vectors
accordingly. Note that POV-Ray may issue a warning when those are not
perpendicular.

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I have experimented with a stereo image, but only for a print and not in
real time. Set the camera {look at} parameter to point to the background or
most distant object, then  render two scenes, one with the camera displaced
to the left, then to the right, keeping {look at} fixed. The aim is to get
the closest object to the camera to move about 6 mm (1/4 inch) between the
two 6x4 inch prints, while the furthest object stays in place. A smaller
separation of the images gives a weaker stereo effect, while separating
them further makes viewing difficult. As to how to do it in VR, I pass...

F38

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thanks for the help. you can do 'toe in' stereo with two regular camera as
several posts have alluded to, but would leave parallax effects and not
technically be correct stereo. Here is a link describing toe in vs
asymmetric stereo.
http://astronomy.swin.edu.au/~pbourke/opengl/stereogl/

I'll probably go with the suggestion of using a larger picture than
necessary (with a normal camera at the center) and then trimming down (or
just requesting that pov render a subset). I've found another page that
concurs...
http://astronomy.swin.edu.au/~pbourke/stereographics/vpac/povray.html

It'd probably be nice to have as a feature another camera type called
"asymmetric", but since it can be faked with the 'rendering larger than you
need' technique, its not necessary.

Thanks,
-Dave

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djzielin wrote:
> thanks for the help. you can do 'toe in' stereo with two regular camera as
> several posts have alluded to, but would leave parallax effects and not
> technically be correct stereo. Here is a link describing toe in vs
> asymmetric stereo.
> http://astronomy.swin.edu.au/~pbourke/opengl/stereogl/
> 
> I'll probably go with the suggestion of using a larger picture than
> necessary (with a normal camera at the center) and then trimming down (or
> just requesting that pov render a subset). I've found another page that
> concurs...
> http://astronomy.swin.edu.au/~pbourke/stereographics/vpac/povray.html
> 
> It'd probably be nice to have as a feature another camera type called
> "asymmetric", but since it can be faked with the 'rendering larger than you
> need' technique, its not necessary.

Someone already answered that in this thread it seems: You have to set the 
three camera vectors "up", "right" and "direction" accordingly. The camera 
you want, "direction" is not perprendicular to the "up" and "right" vectors, 
and then you have exactly what you are looking for, and which does what 
cutting away part of the picture would do, too.

Looking at Paul Bourke 's page, I am not sure why he would not use this 
method, because for the perspective camera this will yield the same result. 
however, I am not sure if it is indeed trivial to compute the correct 
"direction" vector.

	Thorsten

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"djzielin" <djz### [at] dukeedu> wrote:
> ... you can do 'toe in' stereo with two regular camera as
> several posts have alluded to, but would leave parallax effects and not
> technically be correct stereo. Here is a link describing toe in vs
> asymmetric stereo.
> http://astronomy.swin.edu.au/~pbourke/opengl/stereogl/
>
Thanks for posting this link.  In all the years that I've been making
amateur stereo images (whether using a single camera to take two images, or
using a computer graphics app to create them) I've always grappled with this
idea of "toe in" vs. "asymmetric" viewing-- without knowing what it was all
about! From experience (using both techniques), I finally settled on the
latter approach, but never knew *why* it produced more pleasing results.
Now I do.

Ken

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"Kenneth" <kdw### [at] earthlinknet> wrote:
> Thanks for posting this link.  In all the years that I've been making
> amateur stereo images (whether using a single camera to take two images, or
> using a computer graphics app to create them) I've always grappled with this
> idea of "toe in" vs. "asymmetric" viewing-- without knowing what it was all
> about! From experience (using both techniques), I finally settled on the
> latter approach, but never knew *why* it produced more pleasing results.
> Now I do.
>
> Ken


edges of a shot: looks like I should have been masking the transparencies
instead.

F38

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