I'm wondering if there's a way to do this. I want an object that is itself
invisible, but will block the view of certain other objects in the scene
(only specific objects) as if it were a solid object in front of them. This
is basically so that I can overlay a pov animation onto actual recorded
video and have certain pov objects orbiting an actual physical object.

Basically, the plan was to create an object roughly in the shape of the
physical object, and have it block the orbiting objects as the pass behind
it so that when the clips were merged it would appear as though the pov
object was moving behind the real one. Is there some easy way to pull this
off?

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If I understand you correctly, you want something in your scene that 
blocks other objects, therefore only showing the background?

If you're using a solid color background, you could always use a texture 
like

texture {
	pigment { SomeColor }
	finish { ambient 1 diffuse 0 }
}

on any object. add no_shadow and no_reflection to the object, so it 
won't show in reflections and won't create any shadows.

HTH,
Florian

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This might work in some cases, but there are other where I'd like the
blocking object to only block certain other objects, while allowing others
to be seen. That is what I'm wondering about.

> If you're using a solid color background, you could always use a texture
> like
>
> texture {
> pigment { SomeColor }
> finish { ambient 1 diffuse 0 }
> }
>
> on any object. add no_shadow and no_reflection to the object, so it
> won't show in reflections and won't create any shadows.
>
> HTH,
> Florian
>

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Design a rough model of the scene with the dimensions and shapes which
are important (so that the povray-created objects can go behind them
etc). The apply the video image as an image map to the entire scene
(and with an ambient of 1) so that when viewed from the camera you
can't see any difference between the original still image and the
scene rendered with this image map.

  The additional objects will cast shadows onto this scene, which may
actually be a good thing. (However, if you want them to not to cast
shadows onto the scene, then you can probably remove them by using
light groups.)

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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Hash: SHA1

James Bulgin wrote:
| This might work in some cases, but there are other where I'd like the
| blocking object to only block certain other objects, while allowing
others
| to be seen. That is what I'm wondering about.
|
	Only way I see of doing that is to render your scene twice: once with
the method described by Florian for the object that will be blocked
and once with only the objects that must be seen. Then composite the
two and your video.

		Jerome

- --
******************************
*      Jerome M. Berger      *
* mailto:jbe### [at] ifrancecom *
*  http://jeberger.free.fr/  *
******************************
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Hmmm.... Maybe I'm missing something, but I'm not sure how I would apply an
image map to the entire scene. Do you just mean putting a image mapped plane
in front of the camera so that it takes up the entire view? Or is there
something else which I'm not aware of?

"Warp" <war### [at] tagpovrayorg> wrote in message
news:40782b12@news.povray.org...
>   Design a rough model of the scene with the dimensions and shapes which
> are important (so that the povray-created objects can go behind them
> etc). The apply the video image as an image map to the entire scene
> (and with an ambient of 1) so that when viewed from the camera you
> can't see any difference between the original still image and the
> scene rendered with this image map.
>
>   The additional objects will cast shadows onto this scene, which may
> actually be a good thing. (However, if you want them to not to cast
> shadows onto the scene, then you can probably remove them by using
> light groups.)
>
> --
> #macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb
x]
> [1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
> -1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// -
Warp -

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James Bulgin <jam### [at] nfsympaticoca> wrote:
> Hmmm.... Maybe I'm missing something, but I'm not sure how I would apply an
> image map to the entire scene. Do you just mean putting a image mapped plane
> in front of the camera so that it takes up the entire view? Or is there
> something else which I'm not aware of?

  Just compose your scene with untextured primitives, put all these
primitives into a union and texture this union with the image map
(using planar mapping oriented so that when the scene is looked from
the camera, you only see the image map as if it was put onto a plane
facing the camera; that is, when you apply the image map to the scene,
rotate the pigment so that it "faces" the camera).

  Hmm, now that I think of it... your camera angle can't be too large
or else you'll get distortions in the image when surfaces are located
at different distances from the camera... Perhaps it doesn't work directly
(unless you use an orthographic camera), but it's worth a try at least.

  I wonder if you can make a conical projection of the image map onto
the scene with some function... Probably possible.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

Post a reply to this message

Warp wrote:
>   Hmm, now that I think of it... your camera angle
> can't be too large or else you'll get distortions
> in the image when surfaces are located at different
> distances from the camera... Perhaps it doesn't work
> directly (unless you use an orthographic camera),
> but it's worth a try at least.

Won't work with perspective camera unless the camera angle is really
extremely small.

>   I wonder if you can make a conical projection of
> the image map onto the scene with some function...
> Probably possible.

Indeed it is - have a look at my Illusion Include File:
http://runevision.com/show.asp?page=include&data=illusion

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Mar 9**
POV-Ray Ring: http://webring.povray.co.uk

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Rune <run### [at] runevisioncom> wrote:
> Indeed it is - have a look at my Illusion Include File:
> http://runevision.com/show.asp?page=include&data=illusion

  Ah, that seems to be the perfect solution to the problem.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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Rune wrote:
> Warp wrote:
>>   I wonder if you can make a conical projection of
>> the image map onto the scene with some function...
>> Probably possible.
>
> Indeed it is - have a look at my Illusion Include File:
> http://runevision.com/show.asp?page=include&data=illusion

Oh! I found the music video that originally inspired me to create that
include file. It's not in a very good quality, but anyway... It's a
really cool video!
http://texasonline.free.fr/iol.ram

The video should also makes it clear why I called it an "Illusion
Include File"... :)

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Mar 9**
POV-Ray Ring: http://webring.povray.co.uk

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