Hello,

someone can help me? Perhaps Nathan.

You can see below a small copy picture (because this group is not made
for picture) of the picture post on p.b.i. and called  "wine of glass".
But here the plane have a simple white pigment (no more wood image_map).
The image is only 160*120 no AA. One can see that there are no color in
the caustic! When there are no photons the shadow is really red. Now the
shadow is black: ok this is good! but the caustic are white. Why?

I used this settings:
1) in global settings

#declare phd=1;
  photons{
    gather 20, 100
    radius 0.1*phd, 2, 0.1*phd
    autostop 0
    jitter .4
    expand_thresholds 0.2, 40
  }

2) for the wine

photons {
    separation 0.02*phd
    reflection on
    refraction on
   }

3) for the glass

photons {
    separation 0.02*phd
    reflection on
    refraction on
    ignore_photons
   }

the wine is a simple absorbing media with absorbing color
<0.27,1,1>*2.5. If I change this value the caustic are still white.

Thanks

Fabian.

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Attachments:
Download 'verre_vin.jpg' (6 KB)

Preview of image 'verre_vin.jpg'

I am remembering: This is not because photon don't yet interact with media?

Thank light my thought.

Fabian.

Fabian Brau wrote:

> Hello,
>
> someone can help me? Perhaps Nathan.
>
> You can see below a small copy picture (because this group is not made
> for picture) of the picture post on p.b.i. and called  "wine of glass".
> But here the plane have a simple white pigment (no more wood image_map).
> The image is only 160*120 no AA. One can see that there are no color in
> the caustic! When there are no photons the shadow is really red. Now the
> shadow is black: ok this is good! but the caustic are white. Why?
>
> I used this settings:
> 1) in global settings
>
> #declare phd=1;
>   photons{
>     gather 20, 100
>     radius 0.1*phd, 2, 0.1*phd
>     autostop 0
>     jitter .4
>     expand_thresholds 0.2, 40
>   }
>
> 2) for the wine
>
> photons {
>     separation 0.02*phd
>     reflection on
>     refraction on
>    }
>
> 3) for the glass
>
> photons {
>     separation 0.02*phd
>     reflection on
>     refraction on
>     ignore_photons
>    }
>
> the wine is a simple absorbing media with absorbing color
> <0.27,1,1>*2.5. If I change this value the caustic are still white.
>
> Thanks
>
> Fabian.
>
>   ------------------------------------------------------------------------
>  [Image]

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Fabian Brau wrote:
> 
> I am remembering: This is not because photon don't yet interact with media?

Yes this is true.

-- 
Ken Tyler -  1100+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Fabian Brau wrote:
> 
> I am remembering: This is not because photon don't yet interact with media?
> 

True. You should tint the container object to have coloured caustics.
Also, you can use fade_distance instead of absorbing media, with little loss of
quality and considerable gain of speed.
Media is necessary only if you go for all-out realism, i.e. you want the volume
of the wine to interact with the light_source.

Margus

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Someone is working on a modification to add fade_color.  Hopefully soon I'll
have media working with photons and have fade_color added to UVPov.
Recently I got side-tracked with lots to do at work and working on lots of
fun radiosity enhancements.

Anyway, photons currently ignore all media (the code is actually there, just
commented out).  If you send me the source code, when I get a chance to get
started this will give me a scene to test things on.

-Nathan

Margus Ramst <mar### [at] peakeduee> wrote...
> Fabian Brau wrote:
> >
> > I am remembering: This is not because photon don't yet interact with
media?
> >
>
> True. You should tint the container object to have coloured caustics.
> Also, you can use fade_distance instead of absorbing media, with little
loss of
> quality and considerable gain of speed.
> Media is necessary only if you go for all-out realism, i.e. you want the
volume
> of the wine to interact with the light_source.
>
> Margus

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Nathan Kopp wrote:

> Recently I got side-tracked with lots to do at work and working on lots of
> fun radiosity enhancements.

Don't know if this will be of any use to you but take a look at the bottom
of this page: http://www.cs.unc.edu/~hoff/papers/index.html

Other goodies on that site at: http://www.cs.unc.edu/~hoff/

-- 
Ken Tyler -  1100+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Nathan Kopp <Nat### [at] Koppcom> wrote in message
news:380e8dfb@news.povray.org...
> Someone is working on a modification to add fade_color

That's me - It's finished and posted in p.b.p

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