"Harold Baize" <bai### [at] itsaucsfedu> wrote in message
news:3b291b2f$1@news.povray.org...
> Seems to me it would be the same as the physical
> camera attachment, just four mirrors at 45 degree
> angles.
>
>  |    |
>  |    |
>  \-\/-/
>    ||
>    __


    When I do that, I get a single image in the center, which
experimentation reveals is both halves joined in the middle.

    Life is hard when you don't know what you are doing.

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> > Seems to me it would be the same as the physical
> > camera attachment, just four mirrors at 45 degree
> > angles.
> >
> >  |    |
> >  |    |
> >  \-\/-/
> >    ||
> >    __
> 
> 
>     When I do that, I get a single image in the center, which
> experimentation reveals is both halves joined in the middle.
> 
>     Life is hard when you don't know what you are doing.

I messed around for a while (about a week or so on and off) trying to get 
this system to work, but got nowhere.  As far as I can tell, the problem 
is that the diagram above assumes an orthographic view.  Using an ortho 
camera, it might be possible to get it to work by tilting the two outer 
cubes so that their reflections are focused on a point in space...

But that's just speculation, and I haven't the faintest idea of how to do 
it with a perspective camera...

Bye for now,
     Jamie.

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Hmmm, so a virtual camera is different from a real
one? or is there something were missing here?
Here's an interesting idea, put transparent color
filters in front of the front mirrors and see if
the resulting image is an anaglyph! Another possibility
is that it needs a septum to keep the images seperate.

HB



> > Seems to me it would be the same as the physical
> > camera attachment, just four mirrors at 45 degree
> > angles.
> >
> >  |    |
> >  |    |
> >  \-\/-/
> >    ||
> >    __
>
>
>     When I do that, I get a single image in the center, which
> experimentation reveals is both halves joined in the middle.
>
>     Life is hard when you don't know what you are doing.
>
>
>

Post a reply to this message

"Harold Baize" <bai### [at] itsaucsfedu> wrote :
>
> Hmmm, so a virtual camera is different from a real
> one? or is there something were missing here?

    I would bet on the second. I tried orthographic to see if that fixed it
(thinking that it needed to have a little built in distance rather than a
'point' camera)... no go...

    I have a little bit of time to mess with it tonight, but I doubt that I
will figure it out...

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Why don't any one know this link?

http://sabix.etdv.ruhr-uni-bochum.de/sabpov/

If you want to render Stereo images, let me know it.

Let me also know, if ther is anyone of the theoretical stereo
camera macros is working well.

Stefan

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On Thu, 14 Jun 2001 12:42:59 -0400 Bill DeWitt wrote:

>
>    Is there a way to render stereo versions of an image in one pass? Other
>than setting up some mirrors?
>
>    I want to do an animation in stereo and I don't want to paste together
>all those images...
>

  Hi, Bill. See Glenn McCarter's "Dawn Patrol" image and text description. I
think this will do what you want.

http://www.irtc.org/stills/1998-02-28.html

-- 
Alan - ako### [at] povrayorg - a k o n g <at> p o v r a y <dot> o r g
http://www.povray.org - Home of the Persistence of Vision Ray Tracer

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Well damn, why didn't we hear about this!!
Great. Thanks for letting us know. I'd very
much like to have a copy of the program.
Any chance it could be added to MegaPOV or
POV 3.5??

Harold

"Benk" <Ste### [at] ruhr-uni-bochumde> wrote in message
news:3b299dc5$1@news.povray.org...
> Why don't any one know this link?
>
> http://sabix.etdv.ruhr-uni-bochum.de/sabpov/
>
> If you want to render Stereo images, let me know it.
>
> Let me also know, if ther is anyone of the theoretical stereo
> camera macros is working well.
>
> Stefan
>
>
>

Post a reply to this message

>>
>>  |    |
>>  |    |
>>  \-\/-/
>>    ||
>>    __
>
>
>    When I do that, I get a single image in the center, which
>experimentation reveals is both halves joined in the middle.

Ok, time for some physics...; let's just consider the right-hand image.

The ray that corresponds to the left side of the camera leaves in the +y
direction.  It reflects off the first mirror, and is now travelling <1,0>
It reflects from the second mirror, and is now travelling <0,1>.

I.e The left-hand edge of the right-hand image is the view dead ahead.

For a stereo image, if your angle of view is theta degrees, then you want
the left side of the right hand image to correspond to <0,1> rotated by
<- theta/2 degrees>.

Now consider the right side of the image.  With your mirror arrangement,
the ray leaves the camera at <sin(theta/2), cos(theta/2)>.  After the double
reflection, it'll leave the second mirror at that same angle.  So this ends
up at the right angle, although there is a bit of distortion introduced by
the fact that the right edge of the mirror is further away than the left edge.

What you want to have happen is that the mirror combo should reflect the
left-hand edge of the right-hand image to an angle of <-sin(theta/2), 
cos(theta/2)>; the right hand edge of the image to an angle of <+sin(th/2),
cos(th/2)>;  This is equivalent to the center of the right hand image 
looking dead ahead.

I.e. camera angle <+sin (theta/4), cos(theta/4)> gets reflected to <0,1>

Actually doing the math is fairly simple, but I don't happen to know what
the field of view for a standard camera is, so I can't run the numbers 
for you.

As a side note, If you use an arrangement more like:

    |
    |
/   |
||  |
| | |
|  ||
e   /

You'll have less distortion, because the difference in beam-length to the
different sides of the mirror will be less (although the total beam-length
will be longer)

Jamie

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"James Tonkin" <jrt### [at] calumcsclubuwaterlooca> wrote :
>
> Actually doing the math is fairly simple, but I don't happen to know what
> the field of view for a standard camera is, so I can't run the numbers
> for you.

    Actually just setting up the mirrors has been fairly simple. Making them
move with the camera as it pans and sweeps while keeping the mirrors pointed
at the look_at point is the hard part...

    There seems to be another problem with the point or perspective camera.
My drawing (in PBI) shows what I think is happening. I think I will end up
wanting a curved mirror or a different camera.

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in news:3b2a50bf$1@news.povray.org Bill DeWitt wrote:

>     Actually just setting up the mirrors has been fairly simple.

Havn't followed this thread, but maybe this helps:
http://www.irtc.org/stills/1998-02-28.html
The third-place picture is done using mirrors

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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