Margus Ramst <mar### [at] peakeduee> wrote...
> Nathan Kopp wrote:
> >
> > It's not the media.  It's the "noise3d" fix.
>
> I suspect there is something funny about media. I am working on a
cloudscape and
> switching to 0.5 immediately led to all sorts of weirdness. I'm still
> researching the matter, but here is one observation: method 3 media tends
to
> render as black if minimum samples is set to 1. Raising it usually helps,
but
> I've had to go as high as 20 to eliminate some weird banding. Method 2
media
> sometimes acts up too, but overall the behaviour seems kind of chaotic
(i.e. I
> haven't made the connection yet).
> Could it perhaps be connected to the constant media speed enhancement? How
does
> this work?

It's possible.  The speedup works like this:

If the ray in question is a shadow ray (meaning that we are only determining
how much light is blocked as the light travels through the media) and all
participating media are constant, then POV will use one interval, and one
sample using media method 1 instead of the user-selected method.  The reason
is that no other samples are needed.  A single sample will give us the
density, and we really don't care how much light is hitting the media along
the path of the ray, because we only care how much light was blocked as the
beam of light traveled along the ray.  Does that make sense?

-Nathan

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