"scott" <sco### [at] scottcom> wrote:
> I've been re-rendering a lot of my radiosity scenes with mcpov recently,
> usually I just copy&paste in the mcpov global header code and then let it
> run overnight.  Scenes that caused hours of frustration with artifacts under
> radiostity magically rendered perfectly :-)  It's really really cool, it
> should an option in the standard POV build IMO.

I must say that I do agree with that. I'd particularly like a hybrid that does
full-fledged path tracing for diffuse or ambient-based illumination, but still
allows it to be intermixed with the classic lighting model for everything else
- if only to have a reference for radiosity...

.... which may be a valid reason for me to actually go ahead and *do* integrate
it; I can always clame it's just a debugging aid for me :P

(Indeed, I can't use mcpov as a reference because it doesn't combine with
classic lighting.)


However, we are actually talking about a whole bunch of features, which might be
integrated into POV (and make sense) all separately:

* The ability to use something like "uncached radiosity" to get artifact-free
diffuse interreflection (provided you are patient enough), either as reference
for radiosity, but also for top-quality shots when rendering time is not an
issue.

* Native support for blurred reflections (which arguably would not give much
different results nor any higher speed than the common averaged-texture
micro-/macronormals approach - except for one important detail: Standardized
easy setup of materials that use it; right now, the most convenient way to do
this would be to use some framework that provides macros for it; but there may
be various such frameworks out there, each with its own "macro syntax").

* The ability to optimize combinations of various effects that need to shoot
many rays - like focal blur + area lights + media + uncached radiosity +
diffuse reflections - by restricting each of these steps to follow only a few
randomly chosen rays (or to follow even just a single random one), and let
oversampling take care of the rest at the "root".

* Support for yet another oversampling approach besides static or adaptive
anti-aliasing and focal blur, which does not depend on a pre-set parameter, but
on the user's decision that the image is now pretty enough. Or that he made a
blunder and it's not worth wasting more rendering time on the shot.

* The ability to mark objects or regions as particularly strong sources of
diffuse illumination ("portals"; radiosity could benefit from these, too)

(Did I forget a thing here?)


Plus, there's another thing I'd like to see implemented, which even mcpov
doesn't have:

* True subsurface scattering simulation, using not any smart optimized
mathematical approximations, but simulating the path of individual photons
through the material (of course this will be awfully slow I bet, but there may
be situations where the average SSS aproximation just doesn't quite grasp some
detail (like the subtle effect of the bones in a finger); it might be of
benefit again as reference for SSS approximation, but also on top-quality shots
when rendering time is not an issue.

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