fabio schrieb:
> Hello everyone,
> I'm working on a real time approach to GI and
> I was looking for an engine able to provide the ground
> truth for my experiments.
> Essentially I have the following setting:
> 
> A "hollow" object filled with an homogeneous media
> and containing one or more solid objects.
> 
> I want a rendering accounting for:
> * single and multiple scattering
> * reflection / diffraction
> 
> I've browsed for existing engines and POV Ray seems the only
> one that should be able to do it (by photon mapping).
> 
> So my question is simply: did I get something wrong of do you foresee
> problem to do it with povray?

That depends on what exactly you intend to do.

If you're looking for some rendering engine speedy enough to use as a 
basis for "real time" rendering (whatever your definition of that may 
actually be), then POV-Ray may not be what you want.

If you're looking for a reference rendering engine to compare the output 
of some self-made software with, then POV-Ray may not be ideally suited 
either, as its roots are artwork, not physically realistic simulations, 
and even though it has grown quite good at simulating realistic 
/effects/, the relationship between POV-Ray's parameterization and the 
underlying physical parameters are often somewhat obscure.

McPOV, a patch to POV-Ray (actually a patch to MegaPOV, which in turn is 
a patched POV-Ray derivative), might be a better choice for such a 
purpose, as its monte-carlo based unbiased approach circumvents the most 
"unphysical" stuff in POV-Ray.


Another issue is the "multiple scattering"; I guess you're not talking 
about diffuse interreflection between objects here, but rather about 
media interaction, and I am sorry to say that POV-Ray only supports 
single scattering there, and this is even true for McPOV.

Depending on what type of media you're actually trying to simulate, 
POV-Ray 3.7.0's experimental subsurface scattering may be closest to 
what you want; it uses a mathematical approximation to compute both 
single and multiple scattering in highly-scattering media, based on the 
work by Jensen et al.

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