Tim,

Global photon mapping isn't implemented in POV-Ray. I've checked in the
source and there are some blocks of codes related to "GLOBAL_PHOTONS" which
are not compiled. I guess that is because it is not flly functional or fully
debugged.

Yoursuggestion wouldn't work because it would produce specular reflections.
I actually tried something similar to what you suggest. What I need is
diffuse reflection.

Thanks for the suggestion. But I guess I'll wait for the global photons to
be fully implemented and debugged.

Black Zebra

"Tim Nikias" <tim### [at] gmxde> wrote in message
news:3e5553c6@news.povray.org...
> As I've read the other comments on this, here goes:
>
> Photon-light-mapping is used to reflect or refract light
> off of either reflecting or refracting (transparent objects
> with any ior-value, even the default), so for refraction to
> work properly with photons, the object needs to be
> transparent or filtering to let some light travel through
> the object. In order to reflect photons, the object needs
> to have reflection in the finish{} Block.
>
> In order to achieve what you want, it might be possible
> to supply two objects, one with no_image and reflection,
> the other without reflection and without no_image.
> The no_image-object will be the target for photons, but
> won't show up on the image itself, thus you're non-reflecting
> objects SEEM to reflect photons.
>
> But this might not work. Then you'd have to do two passes:
> Render the scene with photons and all objects that reflect
> photons have reflection, save the photons. The second
> pass will be to load the photons, but keep the object without
> reflection.
>
> One of these, at least the last, should work.
>
> --
> Tim Nikias
> Homepage: http://www.digitaltwilight.de/no_lights/index.html
> Email: Tim### [at] gmxde
>
> > I'm trying to code the cornell box but using Photons Mapping instead of
> > radiosity. So far, no success. I've got all my photons{} blocs in my
> > global, light and objects. The scene is very simple but all I get is
> > essentially the same render as with ray-trace only.
> >
> > Can anybody suggest something I might have missed?
> >
> > Thanks.
> >
> > Here is the scene file:
> >
> > global_settings {
> >   assumed_gamma 1.0
> >   max_trace_level 5
> >   photons {
> >     count 100000
> >     max_trace_level 9
> >   }
> > }
> >
> > #declare Finish=finish{diffuse 0.75 ambient 0}
> >
> > #declare White=texture{pigment{rgb<1,1,1>} finish{Finish}}
> > #declare Red=texture{pigment{rgb<0.57,0.025,0.025>} finish{Finish}}
> > #declare Green=texture{pigment{rgb<0.025,0.236,0.025>} finish{Finish}}
> >
> > #declare LightColor=<1,0.67,0.21>;
> >
> >
> > light_source{
> >   <27.8,54.88,27.95>
> >   color LightColor
> >   spotlight radius -90 falloff 90 tightness 1 point_at <27.8,0,27.95> //
for
> > cosine falloff
> >   photons {
> >     refraction on
> >     reflection yes
> >   }
> > }
> >
> >
> > camera{
> >   location  <27.8, 27.3,-80.0>
> >   direction <0, 0, 1>
> >   up        <0, 1, 0>
> >   right     <-1, 0, 0>
> >   angle 39.5
> > }
> >
> >
> > // ------------------------ OBJECTS ----------------------------
> >
> > // Light Patch
> > box{
> >   <21.3,54.87,33.2><34.3,54.88,22.7> no_shadow
> >   pigment{rgb<1,1,1>} finish{ambient 0.78 diffuse 1}
> >   photons {
> >     target
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> > union{
> >   // Floor
> >   triangle{<55.28, 0.0, 0.0>,<0.0, 0.0, 0.0>,<0.0, 0.0, 55.92>}
> >   triangle{<55.28, 0.0, 0.0>,<0.0, 0.0, 55.92>,<54.96, 0.0, 55.92>}
> >   // Ceiling
> >   triangle{<55.60, 54.88, 0.0>,<55.60, 54.88, 55.92>,<0.0, 54.88,
55.92>}
> >   triangle{<55.60, 54.88, 0.0>,<0.0, 54.88, 55.92>,<0.0, 54.88, 0.0>}
> >   // Back wall
> >   triangle{<0.0, 54.88, 55.92>,<55.60, 54.88, 55.92>,<54.96, 0.0,
55.92>}
> >   triangle{<0.0, 54.88, 55.92>,<54.96, 0.0, 55.92>,<0.0, 0.0, 55.92>}
> >   texture {White}
> >   split_union off
> >   photons {
> >     target 1.0
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> > union {
> >   // Right wall
> >   triangle{<0.0, 54.88, 0.0>,<0.0, 54.88, 55.92>,<0.0, 0.0, 55.92>}
> >   triangle{<0.0, 54.88, 0.0>,<0.0, 0.0, 55.92>,<0.0, 0.0, 0.0>}
> >   texture {Green}
> >   split_union off
> >   photons {
> >     target 1.0
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> > union {
> >   // Left wall
> >   triangle{<55.28, 0.0, 0.0>,<54.96, 0.0, 55.92>,<55.60, 54.88, 55.92>}
> >   triangle{<55.28, 0.0, 0.0>,<55.60, 54.88, 55.92>,<55.60, 54.88, 0.0>}
> >   texture {Red}
> >   split_union off
> >   photons {
> >     target 1.0
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> > box {
> >   // Short bloc
> >   <-8.35,0,-8.35>,<8.35,16.5,8.35>
> >   rotate <0,-17,0>
> >   translate <18.6,0,16.85>
> >   texture { White }
> >   photons {
> >     target 1.0
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> >
> > box {
> >   // Tall bloc
> >   <-8.35,0,-8.35>,<8.35,33,8.35>
> >   rotate <0,17,0>
> >   translate <36.85,0,35.15>
> >   texture { White }
> >   photons {
> >     target 1.0
> >     refraction off
> >     reflection yes
> >     collect off
> >   }
> > }
> >
> > WhiteZebra
> >
>
>

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