[Radiance-general] .pic precision

[Gregory J. Ward]

>> Avoiding these variances requires turning off Monte Carlo sampling as
>> much as possible, which probably requires no diffuse interreflection
>> and only purely specular (polished) or diffuse surfaces.  I can give
>> you hints on how to do this if that is what you are after.
>
> Yes, that would be very helpful, thanks.

OK, let's start with a set of rendering (rtrace) options to use:

	-dt 0 -dj 0 -sj 0 -ab 0

This turns off direct, specular, and diffuse interreflection sampling, 
so you won't see any MC noise from those.  (Technically, the -dt 0 is 
not really necessary, as it uses a mostly deterministic algorithm, but 
I put it in there to be on the safe side.)  Next, you need to eliminate 
sources of noise in your scene.  This means sticking to simple 
materials like plastic, metal, glass, and light, and avoiding patterns 
and textures with random or complex behaviors.  Certain ones will be 
OK, but explaining which and why would take too much space, so it's 
best to ask when you need one.

That should get you started well enough.
-Greg