hi,
i'm new to POV-Ray, i'd like to use POV-Ray to make an image illustrating
radiosity. As i now, it seems that POV-Ray uses photon map for radiosity
but i need a method "radiosity"- i mean: it calculates form factors,.., is
it
possible to do that in POV-Ray ?
Thank in advanced :)

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Bui Nguyen Minh wrote:
> hi,
> i'm new to POV-Ray, i'd like to use POV-Ray to make an image illustrating
> radiosity. As i now, it seems that POV-Ray uses photon map for radiosity
> but i need a method "radiosity"- i mean: it calculates form factors,.., is
> it possible to do that in POV-Ray ?

   I think you should read *ASAP* section 2.3.4 (Radiosity), and perhaps
also 2.6.3 (Photons).

--
Jaime

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Bui Nguyen Minh <bnm### [at] ifieduvn> wrote:
> hi,
> i'm new to POV-Ray, i'd like to use POV-Ray to make an image illustrating
> radiosity. As i now, it seems that POV-Ray uses photon map for radiosity
> but i need a method "radiosity"- i mean: it calculates form factors,.., is
> it
> possible to do that in POV-Ray ?

  No, povray does not use photon mapping for global illumination.
It uses a stochastic backward raytracing method first developed by
Greg Ward which is different from the photon mapping method and the
polygon algorithm generally called "radiosity".

  I guess that what you are looking for is the latter. The problem
is that that algorithm only works for polygon-based lightmapped
scenes and POV-Ray scenes are not limited to polygons but can use
all types of mathematical surfaces, thus that type of radiosity
cannot be used.

  The stochastic method used by POV-Ray is somewhat similar to
that "radiosity" algorithm, but it uses raytracing of semi-random
rays instead of scanline-rendering and can often produce visibly
different results.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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Warp <war### [at] tagpovrayorg> wrote:
> Bui Nguyen Minh <bnm### [at] ifieduvn> wrote:
> > hi,
> > i'm new to POV-Ray, i'd like to use POV-Ray to make an image illustrating
> > radiosity. As i now, it seems that POV-Ray uses photon map for radiosity
> > but i need a method "radiosity"- i mean: it calculates form factors,.., is
> > it
> > possible to do that in POV-Ray ?
>
>   No, povray does not use photon mapping for global illumination.
> It uses a stochastic backward raytracing method first developed by
> Greg Ward which is different from the photon mapping method and the
> polygon algorithm generally called "radiosity".
>
>   I guess that what you are looking for is the latter. The problem
> is that that algorithm only works for polygon-based lightmapped
> scenes and POV-Ray scenes are not limited to polygons but can use
> all types of mathematical surfaces, thus that type of radiosity
> cannot be used.
>
>   The stochastic method used by POV-Ray is somewhat similar to
> that "radiosity" algorithm, but it uses raytracing of semi-random
> rays instead of scanline-rendering and can often produce visibly
> different results.
>
> --
> #macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
> [1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
> -1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


Thank you very much for your help :)
One more question : is it possible to write a "plug-in" for povray to carry
out the latter ? if not, could you please tell me (in your opinion) what
should i do to carry out the latter? (using another render?, writing an
application?(using OpenGL?)...

Thanks again!

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Bui Nguyen Minh <bnm### [at] ifieduvn> wrote:
> One more question : is it possible to write a "plug-in" for povray to carry
> out the latter ?

  Plugin no, patch perhaps, but it would be quite limited as it would have
to be limited to meshes and bicubic patches (no other primitives could get
light from other surfaces nor affect the lighting) and it would be a
rather laborious task.

> if not, could you please tell me (in your opinion) what
> should i do to carry out the latter? (using another render?, writing an
> application?(using OpenGL?)...

  There are many free simple scanline renderers out there which
demonstrate radiosity. Try google.

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -

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