I just wanted to now if in all the unoficial
versions of pov there could be a version that
allow me to do theses two things:


    - SubSurface scaterring. Very nice effects possible with it.
    - HDRI illumination maps.

Maybe in the next version of MegaPov....

may be a missed a functionnality already existing...


thanks.

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Claude Mench wrote:
> 
> I just wanted to now if in all the unoficial
> versions of pov there could be a version that
> allow me to do theses two things:
> 
>     - SubSurface scaterring. Very nice effects possible with it.

Try scattering media

>     - HDRI illumination maps.
> 

I don't know what 'illumination maps' are, but there is a patch for
reading HDR images:

http://martial.rameaux.free.fr/mael/MLPov.html

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3C48003F.A56E9D93@gmx.de...
>
>
> Claude Mench wrote:
> >
> > I just wanted to now if in all the unoficial
> > versions of pov there could be a version that
> > allow me to do theses two things:
> >
> >     - SubSurface scaterring. Very nice effects possible with it.
>
> Try scattering media
>

    thanks,

    Subsurface rendering is used for translucent materiel
    like wax in a candle. imagine a large diameter red candle
    with the flame  going down in the middle. From the side you
    will see a portion of the candle that is clompletely opaque
    dark red and at the upper part you will see illuminated red
    wax.

    generaly it is a way to transport light in the interior of
    objects. I thought that POVRAY medai where only used for
    athmospheric effects.

Post a reply to this message

Claude Mench wrote:
> 
> 
>     thanks,
> 
>     Subsurface rendering is used for translucent materiel
>     like wax in a candle. imagine a large diameter red candle
>     with the flame  going down in the middle. From the side you
>     will see a portion of the candle that is clompletely opaque
>     dark red and at the upper part you will see illuminated red
>     wax.
> 
>     generaly it is a way to transport light in the interior of
>     objects. I thought that POVRAY medai where only used for
>     athmospheric effects.

You will find some pretty realistic things of that kind in recent posts in
povray.binaries.images. that were all done with scattering media.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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Claude Mench wrote:
>
>     - SubSurface scaterring. Very nice effects possible with it.

It can be approximated with scattering media but it's not going
to work in every case and requires a lot of tweaking.

http://news.povray.org/search/advanced/?s=scattering&b=Search&g=povray.binaries.images&a=0&p=979742794
http://news.povray.org/povray.binaries.images/18020/
http://news.povray.org/povray.binaries.scene-files/18029/
and others.

>     - HDRI illumination maps.

If I'm not mistaken this can be done by mapping the image
to a sphere diffuse 0 ambient <high> no_shadow and using
radiosity with high sample count. There is another method
too but it may be slower than the high ambient map. If you
can point me to some maps and images rendered using them I
can test how POV3.5 handles such scenes.


_____________
Kari Kivisalo

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On Fri, 18 Jan 2002 10:25:28 +0100, "Claude Mench" <c.m### [at] adilinstrumentscom>
wrote:
> I just wanted to now if in all the unoficial
> versions of pov there could be a version that
> allow me to do theses two things:
> 
> 
>     - SubSurface scaterring. Very nice effects possible with it.

Someone else posted this link ( http://graphics.stanford.edu/~henrik/papers/bssrdf/ )
reffering to an article on this and using it to make a lot of things look more real.
It can possibly
be faked (though not in any eay fashion), but at this point I don't think it is
directly supported yet.

Someone may create a patch for it once 3.5 is completed. I hope so at least, since I
have seen
many posts on sites like www.renderosity.com and none of the programs they use seem to
support it, or at least they have never used it on any models. It would be a very nice
addition to
POV, especially for organics where realism is dependant as much on fine detail, as the
way light
normally interects with say human skin. You could probably tweak existing features all
you like
and never end up with something that is truly accurate. But then I am no where near as
good
as most of the other people that use POV all the time. ;)

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In article <3c481511@news.povray.org>,
 "Claude Mench" <c.m### [at] adilinstrumentscom> wrote:

>     generaly it is a way to transport light in the interior of
>     objects. I thought that POVRAY medai where only used for
>     athmospheric effects.

Media is just a general "volumetric" effect, it is useful for anything 
that depends on light scattering/absorption/emission in a  3D volume 
instead of a surface. I have done experiments with candles before, using 
media to get a translucent effect.
Here, try this quick-n-dirty scene...it isn't perfect, but demonstrates 
the translucence. Real wax would have some surface characteristics like 
highlights, and I don't know the typical iors of waxes, but that isn't 
too critical since it is nearly opaque.

#include "colors.inc"

#version 3.5;

global_settings {assumed_gamma 1}

#default {finish {ambient 0}}

#declare CamLoc = <0, 3.5,-8>;

camera {
    location CamLoc
    up y*image_height/image_width right x
    angle 35
    look_at <0, 0, 0>
}

light_source {CamLoc color White*0.05}

box {<-100, 0,-100>, < 100, 0, 100>
    texture {pigment {checker color Black, color White}}
}

light_source {< 0, 3.2, 0> color White
    fade_power 2
    fade_distance 2.5
    looks_like {
        sphere {< 0, 0, 0>, 0.2
            texture {
                pigment {color rgb < 1, 0.9, 0.75>}
                finish {ambient 1}
            }
            scale < 1, 2, 1>
        }
    }
}


difference {
    merge {
        cylinder {< 0, 0, 0>, < 0, 1, 0>, 1}
        sphere {< 0, 0, 0>, 1 scale < 1, 2, 1> translate y*1}
    }
    sphere {y*3, 0.5}
    
    // replace with "rgb 1" to see effect without translucence
    texture {pigment {color rgb 1}}
    hollow
    interior {
        ior 1.5
        media {
            scattering {1, color < 1, 0.15, 0.15>*3 extinction 0}
            absorption color rgb < 0.8, 1, 1>*6
            
            method 3 intervals 3 samples 5
        }
    }
}

-- 
 -- 
Christopher James Huff <chr### [at] maccom>

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Also have a look at http://news.povray.org/povray.binaries.images/19254/
Code here: http://news.povray.org/povray.binaries.scene-files/19278/

--
#local j=text{ttf"arial""JRG".2,0}#local J=0;#while(J<10)#local R=0;#while
(R<2)#local G=0;#while(G<1)#if(inside(j<R,G.1>))object{j scale.025translate
<R-1G-J/20J/-40+2>pigment{rgb<9J>}}#debug"O"#else#debug" "#end#local G=G+
.025;#end#local R=R+.05;#debug"\n"#end#local J=J+1;#end// JRG

Home: http://digilander.iol.it/jrgpov  //New: Kitchen scene WIP

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Nice effect. You forgot the filtering, but otherwise looks good. I will try it with
my candle shape when I have some time.

--
#local j=text{ttf"arial""JRG".2,0}#local J=0;#while(J<10)#local R=0;#while
(R<2)#local G=0;#while(G<1)#if(inside(j<R,G.1>))object{j scale.025translate
<R-1G-J/20J/-40+2>pigment{rgb<9J>}}#debug"O"#else#debug" "#end#local G=G+
.025;#end#local R=R+.05;#debug"\n"#end#local J=J+1;#end// JRG

Home: http://digilander.iol.it/jrgpov  //New: Kitchen scene WIP

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In article <3c49ca75@news.povray.org>, "JRG" <jrg### [at] hotmailcom> 
wrote:

> Nice effect. You forgot the filtering, but otherwise looks good.

I didn't forget any filtering...

I very rarely use partially transparent textures. If I want something 
transparent or translucent, I use "rgbf 1" and use media (absorbing for 
clear objects, absorbing and scattering for translucent ones) or 
fade_color to color it. This gives the most realistic results: thin 
parts are nearly colorless. It is how things work in reality...a colored 
block of glass isn't a colored, infinitely thin surface that transmits 
light the same no matter how much glass it passes through.

-- 
 -- 
Christopher James Huff <chr### [at] maccom>

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