Hi, I'm not sure if this is the right place to post this question, but it
seems a little obscure for most places...

I'm trying to make a portal in a POV-Ray scene. To explain what I mean
imagine a teleport device in the middle of a room. All around it you see
the room, but where the teleport device is you look through it to another
scene entirely to say, a beach scene. It sounds odd, but I know it is
possible in other 3d formats, for instance in VRML, a realtime 3d format,
there is the ability to set up portals (not in standard VRML, but in some
extensions to the standard).

Of course I *could* composite two scenes in post-processing, but I don't
like that. It feels like cheating, and I like the idea of being able to
easily render stereo pairs where the portal has the same depth
characteristics as the world around it.

Anybody know if this can be done in POV-Ray?

Thanks in advance.

- Miriam

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Wasn't it miriam english who wrote:
>Hi, I'm not sure if this is the right place to post this question, but it
>seems a little obscure for most places...
>
>I'm trying to make a portal in a POV-Ray scene. To explain what I mean
>imagine a teleport device in the middle of a room. All around it you see
>the room, but where the teleport device is you look through it to another
>scene entirely to say, a beach scene. It sounds odd, but I know it is
>possible in other 3d formats, for instance in VRML, a realtime 3d format,
>there is the ability to set up portals (not in standard VRML, but in some
>extensions to the standard).
>
>Of course I *could* composite two scenes in post-processing, but I don't
>like that. It feels like cheating, and I like the idea of being able to
>easily render stereo pairs where the portal has the same depth
>characteristics as the world around it.
>
>Anybody know if this can be done in POV-Ray?
>
>Thanks in advance.

1. You might consider creating both scenes on the front side of the
portal and making everything in one scene have the no_image attribute
and the other scene have no_reflection. Use a mirror as the portal. The
tricky bit would be getting the shadows right. I think you might need to
have a light group for each scene to ensure that objects in one scene
don't cast shadows onto objects in the other.


2. I seem to remember an old trick whereby you could have things in one
scene bounded_by something that's the shape of your portal, and things
in the other bounded_by something with that shape differenced out of it.
You might have to rig things so that POV doesn't override your dodgy
manual bounding, and I don't have any clues about how to get the shadows
to work. It does have the advantage that you can have portals to more
than one destination in the same image, whereas all mirrors in method 1
would reflect the same stuff.


-- 
Mike Williams
Gentleman of Leisure

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On Thu,  9 Sep 2004 06:44:00 EDT, "miriam english" <mir### [at] werplenetau>
wrote:
> Anybody know if this can be done in POV-Ray?

I'm not sure that fits your needs but MegaPOV 1.1 contains camera_view pigment
type where you can apply of any camera as a pigment to anything.

A few applications of this camera_view pigment can be seen at:

http://megapov.inetart.net/demo/camera_motion.png
http://megapov.inetart.net/demo/subviews.png
http://megapov.inetart.net/demo/camera_view_desk.png

All above images were done in single render. Last one is identicall to the
sample of official POV-Ray thought used camera_view instead of a few rendering
frames and animation.

http://megapov.inetart.net

ABX

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Mike Williams wrote:
> The tricky bit would be getting the shadows right. I think you might
> need to have a light group for each scene to ensure that objects in
> one scene don't cast shadows onto objects in the other.

You can't do that with light_groups. All objects always cast shadows for all
light_sources.

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk

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I recently made an animation with a portal in it. You can see it on this
page:

http://runevision.com/3d/anims/

Since all other techniques I know of have problems, typically with shadows,
I decided to use an image_map for the portal and have the image in the
image_map be generated by a different scene (but where the camera is
synchronized in both scenes). Well, it was not a regular image_map I used,
but rather one generated by my Illusion Include File which can be found on
this page:
http://runevision.com/3d/include/

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk

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In article <mpq0k0t80tih6blf19nki3qvid0tj52dtk@4ax.com>, abx### [at] abxartpl 
says...
> On Thu,  9 Sep 2004 06:44:00 EDT, "miriam english" <mir### [at] werplenetau>
> wrote:
> > Anybody know if this can be done in POV-Ray?
> 
> I'm not sure that fits your needs but MegaPOV 1.1 contains camera_view pigment
> type where you can apply of any camera as a pigment to anything.
> 
> A few applications of this camera_view pigment can be seen at:
> 
> http://megapov.inetart.net/demo/camera_motion.png
> http://megapov.inetart.net/demo/subviews.png
> http://megapov.inetart.net/demo/camera_view_desk.png
> 
> All above images were done in single render. Last one is identicall to the
> sample of official POV-Ray thought used camera_view instead of a few rendering
> frames and animation.
> 
> http://megapov.inetart.net
> 
Interesting.. So basically it displaces the source to another point, so 
that renderings there are copied directly to the 'view' you are mapping 
it too, right? So animations would work as well, like a bird that flies 
'between' the two scenes and through the portal? (Of course that would be 
two identical birds you animate the same way, which could get 
complicated...)

Can't wait until I am fairly sure you have a reasonably stable version 
that works with the 3.6 engine, so I can have something else I can look 
at and go, "Dang, too bad I don't have the talent to take advantage of 
that." lol

-- 
void main () {

    call functional_code()
  else
    call crash_windows();
}

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Thanks for the neat ideas Mike.

Mike Williams <nos### [at] econymdemoncouk> wrote:

> 1. You might consider creating both scenes on the front side of the
> portal and making everything in one scene have the no_image attribute
> and the other scene have no_reflection. Use a mirror as the portal. The
> tricky bit would be getting the shadows right. I think you might need to
> have a light group for each scene to ensure that objects in one scene
> don't cast shadows onto objects in the other.

This is a cool idea. I will bear it in mind for some other ideas I've had,
like a person looking into a mirror and the reflected person is subtly
different. I'd previously thought I'd have to render the picture in two
parts then join them later (clumsy!), but if I'm reading this properly your
idea means I could have the two people occupy the same space; one would be
seen and the other reflected. Unfortunately this is not suitable for my
current picture because the amount of light spilling from the object would
affect the scene before it returns from the reflecting object. But lovely
concept, thanks.


> 2. I seem to remember an old trick whereby you could have things in one
> scene bounded_by something that's the shape of your portal, and things
> in the other bounded_by something with that shape differenced out of it.
> You might have to rig things so that POV doesn't override your dodgy
> manual bounding, and I don't have any clues about how to get the shadows
> to work. It does have the advantage that you can have portals to more
> than one destination in the same image, whereas all mirrors in method 1
> would reflect the same stuff.

This sounds very promising. I'll have to look more into that. I don't
completely understand the mechanics of what you're saying, but from my
reading of it, it sounds exactly like what I want.

I'm very grateful.

Heheheh I like your tag "Gentleman of leisure".

Miriam
Non-profit human

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ABX <abx### [at] abxartpl> wrote:

> I'm not sure that fits your needs but MegaPOV 1.1 contains camera_view pigment
> type where you can apply of any camera as a pigment to anything.
>
> A few applications of this camera_view pigment can be seen at:
>
> http://megapov.inetart.net/demo/camera_motion.png
> http://megapov.inetart.net/demo/subviews.png
> http://megapov.inetart.net/demo/camera_view_desk.png
>
> All above images were done in single render. Last one is identicall to the
> sample of official POV-Ray thought used camera_view instead of a few rendering
> frames and animation.
>
> http://megapov.inetart.net

I'd previously looked at MegaPOV, but was reluctant to spend a lot of time
exploring what I'd felt might be a temporary fork in the POV-Ray project,
but looking at the features list and some of the insanely cool pictures and
concepts there I don't know if I'll be able to resist much longer. Their
undeniable usefulness mean they are almost certain to end up being
incorporated into the main POV-Ray stream.

The third of your image links is most useful for what I'm wanting to do.
Frankly the MegaPOV realisation of the desk picture positively boggles the
mind! Thanks for pointing this out to me ABX.

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"Rune" <run### [at] runevisioncom> wrote:
> I recently made an animation with a portal in it. You can see it on this
> page:
>
> http://runevision.com/3d/anims/
>
> Since all other techniques I know of have problems, typically with shadows,
> I decided to use an image_map for the portal and have the image in the
> image_map be generated by a different scene (but where the camera is
> synchronized in both scenes). Well, it was not a regular image_map I used,
> but rather one generated by my Illusion Include File which can be found on
> this page:
> http://runevision.com/3d/include/

Oh my!
This is very close to the effect I wanted. I shall be spending a while
teasing apart your illusion include to work out how you have done it. I
hope I can build on what you've done and return the favor one day. Thank
you very much Rune.

Wonderful and incredibly informative site, by the way.
I've signed up for your updates. :)

Best wishes,

- Miriam

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On Thu, 9 Sep 2004 15:11:47 -0700, Patrick Elliott <sha### [at] hotmailcom>
wrote:
> Interesting.. So basically it displaces the source to another point, so 
> that renderings there are copied directly to the 'view' you are mapping 
> it too, right?

If I understand the question right, yes.

> Can't wait until I am fairly sure you have a reasonably stable version 
> that works with the 3.6 engine

We have replaced beta relase with final 1.1 two days ago :-)

ABX

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