"Bald Eagle" <cre### [at] netscapenet> wrote:
> I'm currently experiencing a major bottleneck in the radiosity-enabled render.
> It seems to me to be hanging up on the heightfield frame of the big round mirror
> on the left.

I am running into radiosity problems with height fields, but the problem is
severe, scene-destroying artifacts, not render times.  At this time, I haven't
been able to pinpoint exactly what triggers the problem (and therefore have not
reported it), but the presence of height fields together with reflective and/or
metallic objects in the scene seems to be a variable.

> Also, is there a _short_ concise explanation of this file that radiosity can
> generate?  If I suffer through this once, does it make subsequent renders vastly
> faster?

I can't help with the internals of the file, but it can be used with two-pass
radiosity.  The idea is that you generate the radiosity file using a simplified,
fast-rendering scene, then read it back in for the final render.  For some
scenes, these two passes combined will take less time than a one-pass render.
Your mirror sounds like a good candidate for elimination from the simplified
scene.  Jaime explains the technique at his Web site:

   http://www.ignorancia.org/en/index.php?page=Two_Pass_Radiosity

Beware of the parameters that need to be identical for both passes.  Failure to
sync them will result in an /increase/ in render time.

> pretrace_end 0.04
> count 35

These are pretty low quality settings.  But if you're satisfied with the
results, then of course you don't have to change them, especially if the scene
is getting bogged down.

> recursion_limit 3

For most scenes, recursion_limit 2 is sufficient.

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