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/

Post a reply to this message

"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/

Post a reply to this message

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

Post a reply to this message

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. ;)

Post a reply to this message

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

Post a reply to this message

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

Post a reply to this message

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>

Post a reply to this message

>    // replace with "rgb 1" to see effect without translucence
>    texture {pigment {color rgb 1}}
                                           ^^^^
Ahem... ;)

--
#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

Post a reply to this message

The only program that seems to implement subsurface scatering not by a
fake seems to be finalrender a new plugin renderer for 3dsmax4.2.

I felt upon the van jensen paper some time ago, I have been really
impressed with the human skin he could obtain.

If POV would implement BSSRDF model it would clearly maintain it in
the top renderers... Whisfull thinking...





"Patrick Elliott" <sel### [at] rrazcom> wrote in message
news:1104_1011391405@selliot...
> 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. ;)
>

Post a reply to this message

Claude Mench wrote:
> 
> The only program that seems to implement subsurface scatering not by a
> fake seems to be finalrender a new plugin renderer for 3dsmax4.2.
> 

It seems you have not completely understood this, 'real' subsurface
scattering with the model explained in the van Jensen paper is in fact
much more fake than participating media, of course it's much faster than
media without serious quality problems due to some neat approximations.

Christoph

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

Post a reply to this message

On Mon, 21 Jan 2002 18:38:29 +0100, Christoph Hormann <chr### [at] gmxde> wrote:
> 
> 
> Claude Mench wrote:
> > 
> > The only program that seems to implement subsurface scatering not by a
> > fake seems to be finalrender a new plugin renderer for 3dsmax4.2.
> > 
> 
> It seems you have not completely understood this, 'real' subsurface
> scattering with the model explained in the van Jensen paper is in fact
> much more fake than participating media, of course it's much faster than
> media without serious quality problems due to some neat approximations.
> 
> Christoph
> 
> -- 
> Christoph Hormann <chr### [at] gmxde>
> IsoWood include, radiosity tutorial, TransSkin and other 
> things on: http://www.schunter.etc.tu-bs.de/~chris/

That may be true, but using media requires a number of things. Like a clear 'inside'
and
'outside' for object. In some circumstances, including using meshes, the method of
employing media could be probamatic at the very least. Not to mention that there is a
major difference between adding a single keywork like 'sub_scatter .5'  and fiddling
with
media settings, which I for one don't have a clue about. I want to be able to
realistically
model a human, but would definitely prefer not to have to spend 4 times longer trying
to
learn how to do it the hard way and getting a useful set of media to produce the
desired
effect, than I would just dropping in one or two keywords. I am not that good at
either
model buidling or the complexities of things like media. Nor being somewhat lazy am I
going to spend a lot of time playing with them to figure out how they work. Also for
those
that do 'need' it, for professional work, the extra time needed to tweak media and
render
can become expensive in terms of time needed to complete a project.

I could be wrong about it not being functionally possible in a mesh though, since I am
by no means an expert. ;)

Post a reply to this message

On Mon, 21 Jan 2002 22:16:22 GMT, Patrick Elliott wrote:
> 
> That may be true, but using media requires a number of things. Like a clear 'inside'
and
> 'outside' for object. 

This is a commonly held, though erroneous, belief.


-- 
#macro R(L P)sphere{L F}cylinder{L P F}#end#macro P(V)merge{R(z+a z)R(-z a-z)R(a
-z-z-z a+z)torus{1F clipped_by{plane{a 0}}}translate V}#end#macro Z(a F T)merge{
P(z+a)P(z-a)R(-z-z-x a)pigment{rgbf 1}hollow interior{media{emission 3-T}}}#end 
Z(-x-x.2x)camera{location z*-10rotate x*90normal{bumps.02scale.05}}

Post a reply to this message

In article <slr### [at] fwicom>,
 Ron Parker <ron### [at] povrayorg> wrote:

> This is a commonly held, though erroneous, belief.

Not so erroneous, unless you're talking about media without a container. 
As I understand it, you can use it in meshes, but it uses the number of 
intersections it has encountered to decide whether or not it is inside. 
Meshes with holes or other "odd" formations will not render as expected, 
because they don't have defined boundaries for the media sampling.

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

Post a reply to this message

Christopher James Huff wrote:
> 
> Not so erroneous, unless you're talking about media without a container.
> As I understand it, you can use it in meshes, but it uses the number of
> intersections it has encountered to decide whether or not it is inside.
> Meshes with holes or other "odd" formations will not render as expected,
> because they don't have defined boundaries for the media sampling.

And 'real' subsurface scattering will have the same problems with such
meshes.  You simply can't expect 'odd' meshes to render correctly, in
addition other intrinsic problems like shadow line artefacts have their
influence too.  

Christoph

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

Post a reply to this message