clipka <ano### [at] anonymousorg> wrote:
> 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.

Thanks for the informative reply. Yes, I'm looking for a physically based
rendering engine to compare the results of a approximation technique of mine.
So the time needed for rendering is not an issue for me, I can wait.

I would also need diffuse inter-reflection but media interaction is dominant,
so it would also be useful just that.

From your answers (I also thank Alain for the reply) it seems I should look
for some alternative (I'll check McPOV out before).

One last thing. Do you have any advise for a physically based rendering engine
that I could use ?

Thanks again,
Fabio


>
>
> 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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