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1204 Chapter 15: Lights and Cameras
3toN=NxNrays.
ForexamplesettingPass1Qualityto5would
generate 25 rays. This is the primary control for
“finding” small objects and thin spaces between
objects.Iftheshadowsaremissingasmallobject
in your scene, try increasing Pass 1 Quality, 1
step at a time. A ls o, if there are blotches in the
penumbra (soft area), t ry increasing this setting.
Increasing the Shadow Integrity value creates more accurate
shadow contour and detail.
Shadow Quality—Sets the total number of rays cast
in the p enumbra (soft area) region, including the
rays fired in p ass.
Theseraysareprojectedfromeverypointthatisin
the penumbra, or antialiased edge of the shadow,
to smooth it out.
Thenumberofraysisasfollows:
2=5 rays
3toN=NxN
Quality=5 would mean 25 rays. Pass 2 Quality
should always be greater than Pass 1 Quality. This
is because the s econdary rays are overlaid on top
of the first pass’s rays using the same algorithm.
Increase Pass 2 quality to fix b anding in the
penumbra, and eliminate the noise p attern from
jittering.
Increasing the Shadow Qualit y value produces a more
accurate penumbra (soft area) within the contour defined
by the Shadow Integrity value.
Sample Spread—The radius, in pixels, to blur the
antialiased edge.
Note: As this value increases, so does the quality
of the blur. However, increasing this value also
increases the likelihood of missing small objects.
To avoid this problem, increase the value of Pass 1
Quality.
Shadow B ias—The minimum distance that an
object must be from the point being shaded in
ordertocastashadow. Thispreventsblurred
shadows from affecting surfaces they shouldn’t.
Note: As you increase the blur value, you should
also increase the bias.
Jitter Amount—Adds randomness to the ray
positions. The rays are initially in a very regular
pattern, which c an show up in the blurry part
of the shadow as reg ular artifacts. Jittering will
convert these artifacts to noise, which is generally
less noticeable to the eye. Recommended values
are 0.25 to 1.0. However, very blurry shadows will
requiremorejitter.