Ambient Occlusion
Overview
In this tutorial, you'll learn how about Ambient Occlusion settings and
how to solve common problems.
Ambient Occlusion Settings
Samples adjusts the smoothness
of the occlusion "shadow". Decreasing the samples yields a choppier,
darker shadow and takes less time. Increasing samples gives you a
smoother, lighter shadow and takes more time.
MaxDist changes how far the
shadow spreads. Increasing the Maxdist makes the shadow go farther.
Decreasing it makes the shadow shrink.
RayBias offsets the point from
where rays are cast. This is used to account for displaced surfaces,
and is also helpful in correcting the "black spots" problem. Increase
the RayBias slightly to get rid of spots.
Strength changes how dark the
shadow is. Reducing strength makes the shadow lighter, increasing it
beyond 1.0 has no effect.
The Dreaded Black Spots
Here's an example of the troll scene rendered with GlowWorm's default
AO options (which are the same as Poser's defaults). GlowWorm's
defaults are Samples 3.0, MaxDist 7.5, RayBias 0.2, Strength 1.0.
Big problems. Some models are prone towards getting spotty when AO is
involved. The troll and the temple ruins set are particularly bad, in
my experience.
I revised my settings to Samples
3.0, MaxDist 20.0, RayBias 0.8, Strength 1.0.
The new render is much better. There are a couple of spots still, but
it'd be faster to paint over those than to re-render. If they were
still a problem, you could raise the RayBias again and re-render.
I increased the MaxDist to compensate for the RayBias being higher.
This made the shadow spread further. If you wanted to get the exact
same look, you could increase the Samples to 6. Bear in mind that
raising the Samples increases the render time.
GlowWorm will store your last-used AO settings so, if you stumble upon
any favorites, they'll be saved for future use.
