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31 Oct 2024 19:30:43 EDT (-0400)
  Photons with glass and metal (Message 1 to 5 of 5)  
From: Mienai
Subject: Photons with glass and metal
Date: 26 Jan 2005 23:40:01
Message: <web.41f870532c150b48fb8d24aa0@news.povray.org>
So I created this simple object made of both glass but for some reason I get
splotches where the glass reflects the photons onto the ground.  You can
see what I'm talking about here:
http://www.deviantart.com/deviation/14253556/

I tried halfing the spacing but that just increases the splotchyness
density.  Any ideas of how I can fix this, thanks.

My photons block:
  photons{
    spacing .025
    autostop 0
  }


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From: Jeremy M  Praay
Subject: Re: Photons with glass and metal
Date: 29 Jan 2005 18:14:03
Message: <41fc18bb@news.povray.org>
In the last image where I used photons, I used
spacing 0.003

Perhaps your spacing is simply too large.

-- 
Jeremy
www.beantoad.com
<Mienai> wrote in message 
news:web.41f870532c150b48fb8d24aa0@news.povray.org...
> So I created this simple object made of both glass but for some reason I 
> get
> splotches where the glass reflects the photons onto the ground.  You can
> see what I'm talking about here:
> http://www.deviantart.com/deviation/14253556/
>
> I tried halfing the spacing but that just increases the splotchyness
> density.  Any ideas of how I can fix this, thanks.
>
> My photons block:
>  photons{
>    spacing .025
>    autostop 0
>  }
>
>
>


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From: Slime
Subject: Re: Photons with glass and metal
Date: 29 Jan 2005 19:02:42
Message: <41fc2422$1@news.povray.org>
> So I created this simple object made of both glass but for some reason I
get
> splotches where the glass reflects the photons onto the ground.

What is the texture of the glass? What is the code for the light source? (Is
it an area light?)

It does seem a little strange and I do think you should try Jeremy's
suggestion of dropping the spacing by a lot more than you have.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Mienai
Subject: Re: Photons with glass and metal
Date: 1 Feb 2005 04:20:00
Message: <web.41ff4609df191e3ec4fb1c850@news.povray.org>
"Slime" <fak### [at] emailaddress> wrote:
> > So I created this simple object made of both glass but for some reason I
> get
> > splotches where the glass reflects the photons onto the ground.
>
> What is the texture of the glass? What is the code for the light source? (Is
> it an area light?)
>
> It does seem a little strange and I do think you should try Jeremy's
> suggestion of dropping the spacing by a lot more than you have.
>
>  - Slime
>  [ http://www.slimeland.com/ ]

So I tried dropping the spacing to .003 and while it did sharpen the
caustics and produce a 750Mb photon file, the splotchyness is still there.
It's less noticeable because it's denser but it's definitly there.
http://www.deviantart.com/view/14725048/

My glass textures are:
 material {
  texture {
   pigment {color  Col_Glass_Clear}//
   finish {F_Glass6}
  }
  interior {
   I_Glass_Exp(.5)
   fade_color Col_Green_01   //turqoise
  }
 }
with different fade_colors obviously.  My light source code is:
 light_source {
  <-8, 10, 18>*1.5
  color rgb 1.2

  area_light <2,0,0>,  <0,0,2>,  15, 15
  circular
  orient

  photons {
   reflection on
   refraction on
  }
 }
So yes it is an area light, but my photons aren't and turning that off
doesn't affect it (although it produces an interesting effect).  And just
for your knowlege the cube is a blob object with finish{Mirror} and the
floor reflectiveness doesn't affect it at all.

Tweaking around with the code it almost seems like the splotchyness is a
result of the photon and the interaction between the glass and the metal.
I render the glass sides alone and I can't find evidence of the spots and
the same if I run the cube alone (although the cubes reflected light is
kind of light to really tell).  I also find that the spacing multipier has
more affect when applied to just the glass as opposed to the cube.

Thank's for the ideas though, keep them coming.  I could post the entire
source code though if needed.


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From: carbon14
Subject: Re: Photons with glass and metal
Date: 1 Apr 2005 04:50:00
Message: <web.424d1915df191e3eed6c76f90@news.povray.org>
I had the same blotchiness in this image:

http://www.deviantart.com/deviation/3518047/


I have an opaque bowl with a very thin transparent glaze on the surface and
the photon interactions in this, and from the glass marbles caused the
fabulous texture on the bowl.

In fact the color of the bowl is a uniform gray, but the blotchiness looked
so good I didn't do anything else to it.


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