Hm, you're right. I somehow messed something up
with that "subtractive transparency" talk in the docs.


--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Email: Tim### [at] gmxde

>
> I think you need to go review at the behavior of filtering. It doesn't
> behave anything like you describe.
> rgbf  is the same as rgbf < 0.99, 0.99, 0.99, 0.99>, which is nearly
> perfectly transparent. This is not the problem.
>

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In article <Xns### [at] 204213191226>,
 "Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote:

> #if (UseMedia) // media - dust box
> box {
>   <-5,-1,-5>, <+5,8,+5>
>   pigment { rgbt 1 } // <---
>   interior { media {
>       samples 100
>       scattering { 1 rgb .1 extinction 0 }
>   } }  
>   hollow // <--- 
> }
> #end
> 
> Using media is ok, using photons is ok, but using them both gives problem.

Try adding a photon block with pass_through, if that doesn't work try 
making it a photon target. Or maybe the media itself is off...

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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"Tim Nikias" <tim### [at] gmxde> wrote in message
news:3e5ac0ff$1@news.povray.org...
> Hm, you're right. I somehow messed something up
> with that "subtractive transparency" talk in the docs.

I'm not sure that section of the docs is wrong, but it certainly is
misleading...

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"Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote in message
news:Xns### [at] 204213191226...
>
> Ok, and in btw - minimal scene to reproduce my problem :

Dunno if it's a bug or not, but you can fix it by making your media container a
bit taller so that the spotlight is inside it.

So, instead of:

>
> #if (UseMedia) // media - dust box
> box {
>   <-5,-1,-5>, <+5,8,+5>

try

> #if (UseMedia) // media - dust box
> box {
>   <-5,-1,-5>, <+5,9.5,+5>

... and watch those render times slow to a crawl (must be working then ;)

BTW I don't think your glass box needs the hollow keyword.

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"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3e5b49df$1@news.povray.org...
>
> Dunno if it's a bug or not, but you can fix it by making your media
container a
> bit taller so that the spotlight is inside it.

It's not a bug, what Chistopher said about adding pass_through into a
photons block within the media container is the answer. Just a thing about
how photons interact with objects. I guess the spotlight, being a source of
photons, wasn't getting into the media-filled box past that surface. Similar
to the camera being inside a nonhollow object maybe.

> BTW I don't think your glass box needs the hollow keyword.

And the photon spacing can be raised to about 0.05 I think. Also, media
method 2 helps with the render speed because it definitely is slower when it
is working as expected.

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Christopher James Huff <cja### [at] earthlinknet> wrote in news:cjameshuff-
F7D### [at] netplexaussieorg

> Try adding a photon block with pass_through, if that doesn't work try 

It didn't work, btw - is't this a bug ? 

> making it a photon target. 

Yep, that's it - adding to media container 
  photons { target }
do help.

I thing it's worthy adding to FAQ, maybe in spare time I will make a mini 
FAQ about using special futures that are hard to use like media+photons, 
etc.


-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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"Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote in message
news:Xns### [at] 204213191226...
>
> > making it a photon target.
>
> Yep, that's it - adding to media container
>   photons { target }

Not here. I don't get it showing up unless pass_through is in there.

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"Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote in message
news:Xns### [at] 204213191226...
> > making it a photon target.
>
> Yep, that's it - adding to media container
>   photons { target }
> do help.
>

Are you sure? It doesn't/didn't help on my tests here.

Post a reply to this message

"Tom Melly" <tom### [at] tomandlucouk> wrote in news:3e5b7cca@news.povray.org

>>
>> Yep, that's it - adding to media container
>>   photons { target }
>> do help.
> Are you sure? It doesn't/didn't help on my tests here.

uhm... yes, working scene source is :



#local QQ_Media=1;
camera {
  location <0,8,-9> look_at -y*6 angle 70
}
box { -10,+10 inverse hollow pigment { checker rgb .85 rgb 1 } finish { diffuse .97 }
}
plane { y,-9.99 pigment { rgb 1 } finish { diffuse .96 } }

global_settings {
 radiosity { media on }
 max_trace_level 10
 photons { 
   spacing 0.05
   media 20,2
   max_trace_level 5
 }
}

// ==  glass +normal + PHOTONS
#local Tr=+x*0;
#local P=<0,  2,0>+Tr;
#local T=<0,-10,0>+Tr;
sphere { P .1 finish { ambient 1 } pigment{rgb 1} no_shadow hollow photons {
pass_through } }
sphere { T .2                      pigment{rgb y}  }
light_source { 
  P rgb 1
  spotlight point_at T  radius 10 falloff 10+5
  media_interaction
  media_attenuation
  photons { reflection on  refraction on }
} 
box { -.7,+.7 scale <1,.2,1>
  pigment { rgbf .99 }
  finish { reflection .2 specular .9 roughness 0.02 }
  interior { ior 1.3 }
  normal { bozo scale .4 }
  translate <0,-1,0> translate Tr
  photons { refraction on  reflection off target on }
}
// --- media ---
#if (QQ_Media)
  box {
    <-11,-11,-11> <+11,+11,+11>
    pigment { rgbt 1 }
    interior {
      media {
        method 3 
        samples 5  intervals 2                
        scattering { 1 rgb .10 extinction 0.40 }
      }
    }  
    photons{ target on  } // <======
    hollow
  }  
#end






-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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"Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote in message
news:Xns### [at] 204213191226...
> "Tom Melly" <tom### [at] tomandlucouk> wrote in news:3e5b7cca@news.povray.org
>
> >> Yep, that's it - adding to media container
> >>   photons { target }
> >> do help.
> > Are you sure? It doesn't/didn't help on my tests here.
>
> uhm... yes, working scene source is :
---snipped---
> // ==  glass +normal + PHOTONS
> #local Tr=+x*0;
> #local P=<0,  2,0>+Tr;   <==<<
> #local T=<0,-10,0>+Tr;
---snipped some more---
> light_source {
>   P rgb 1
---snipped again---
> // --- media ---
> #if (QQ_Media)
>   box {
>     <-11,-11,-11> <+11,+11,+11>  <==<<

Yeah... uh...  :-)  ...only because the light source is no longer outside
the media container, as can be seen of the two lines shown arrowed, so it
doesn't need the pass_through anymore. And, having now tried your script
again I see that leaving the media's photon block out entirely actually
renders faster and is still okay I guess. From what I can tell in a small
rendering anyway.

Bob

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