Charles nous apporta ses lumieres en ce 2007/09/09 09:12:
> Hello,
> 
> I've made some progress:
> 
> http://www.turingbirds.com/personal/random/wax_trial_2_render.png
> http://www.turingbirds.com/personal/random/wax_trial_2.pov
> 
> However, despite the end of the cylinder being inside the box, it is not
> getting "blurry", just darker. It looks like povray is treating the
> scattering media as a single entity, rather than a near-infinite number of
> particles which it's supposed to represent. Kasuga_Kyousuke on povray irc
> advised me that radiosity will not fix this scene, because of the same
> reason: looking at the media as a single entity. Does anyone know of a way
> to make this work?
> 
> Thanks,
> Charles
> 
> PS. Intended result: candle wax with black bead embedded
> (http://www.turingbirds.com/personal/random/wax.png)
> PS2. adding absorption does not work; it only makes everything evenly darker
> 
> 
The media will not change the effective direction of a ray shot from the camera. 
To do that, the generaly accepted way is to use normals, or actual surface 
bending using an isosurface.
You can add something like a "micro-normal" like:

normal{granite scale 0.001}

you may even scale smaller like 0.00001 or even less.
Works best when using anti-aliasing.
You can also use bluring using the average pettern:
#local R = seed(0);
normal{average{average_map{#local S = 20;//adjust S to change the
//quality of the bluring
#while(S) [1 normal granite scale 0.01 translate<rand(R),rand(R),rand(R)>*0.01]
#local S=S-1;
#end
}}}

-- 
Alain
-------------------------------------------------
Do you want to know who you are? Don't ask. Act! Action will delineate and
define you.
Thomas Jefferson

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Charles nous apporta ses lumieres en ce 2007/09/09 09:12:
> Hello,
> 
> I've made some progress:
> 
> http://www.turingbirds.com/personal/random/wax_trial_2_render.png
> http://www.turingbirds.com/personal/random/wax_trial_2.pov
> 
> However, despite the end of the cylinder being inside the box, it is not
> getting "blurry", just darker. It looks like povray is treating the
> scattering media as a single entity, rather than a near-infinite number of
> particles which it's supposed to represent. Kasuga_Kyousuke on povray irc
> advised me that radiosity will not fix this scene, because of the same
> reason: looking at the media as a single entity. Does anyone know of a way
> to make this work?
> 
> Thanks,
> Charles
> 
> PS. Intended result: candle wax with black bead embedded
> (http://www.turingbirds.com/personal/random/wax.png)
> PS2. adding absorption does not work; it only makes everything evenly darker
> 
> 
You use:
     media {
       intervals 10
        samples 1,1
        scattering  {5, 2 eccentricity 0.0}
     }
With the default sampling method used (methode 3, adaptive), it's prety slow.
If you remove "intervals 10" and replace samples 1,1 by samples 20, you will 
gain on quality AND speed.
Method 3 require at least 3 samples and works best with only 1 intervals. You 
may supply a second samples value but it will be ignored.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you prefer bald romatic partners, 
because they're easier to model.
John VanSickle

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Hi everyone,

Thanks for your help, but it turns out that POVRay just cannot do this.
Radiosity is too much of a simplification. I downloaded the Kerkythea
renderer which supports path tracing, and got it to work in about 5
minutes.

Kind regards,
Charles

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