9

1018 G lossa ry
Subtractive opacity darkens colors behind the
material by subtracting the material’s colors from
the background colors.
If you simply want to reduce the apparent opacity
of a material, while maintaining the color values of
its diffuse (or mapped) properties, use subtractive
opacity.
See also
Additive Opacity (page 3–906)
Sunlight
The Sun is modeled as a parallel lig ht source,
which makes the incident direction of sunlight
constant over all surfaces in the scene. You can
specify the direction and intensity of the sun
directly. Alternatively, the direction and intensity
ofthesuncanbecalculatedbasedongeographical
location, time, and sky condition settings.
See also
Skylight (page 3–1012)
Sunlight and Daylight Systems (page 1–418)
Super B lack
Super Black limits the darkness of rendered
geometry. Thisoptionisusedforvideo
compositing. When compositing, you need pure
black for the background, but overlaying objects
need to be less than pure black so that you can
still see exactly where they are. Also, some v ideo
systems have problems with black that has RGB
values of 0,0,0, and consider it an "i l legal" color.
Unless you’re sure you need it, leave Super Black
tuned off in the Render S cene dia log .
ThescanlinerendererusesthevalueoftheSuper
Black preference as a threshold for the darkness
of the rendered scene. For example, if you’re
rendering a heavily shadowed object against a
black background, although the background will
be rendered as pure black, the deepest shadows on
theobjectwillbenodarkerthantheintensitylevel
specified by the Threshold spinner (default is 15).
Note: If the threshold spinner is set too high, it will
artificially raise low-blended values. This can ruin
antialiasing effects in the renderer.
Super sa mpling
Supersamplingisoneofseveralantialiasing
techniques that the s of tware performs. Textures,
shadows, highlights, and raytraced reflections
and refractions all have their own preliminary
antialiasing st rategies. Supersampling is an
optional additional step that provides a "best
guess" color for each rendered pixel. The
supersampler’s output is then passed on to the
renderer, which performs a final antialiasing pass.
See also
SuperSampling Rollout (page 2–1459)
Su ppor t Per iod
In footstep animat ion (page 3–943),theperiod
whereoneorbothofthebipedfeetareonthe
ground.
SurfaceArriveBehavior
In crowd animation (page 2–1154),theSurface
Arrive behavior is similar to the Seek behavior: it
letsyouspecifyoneormorerobjectsasastationary
or moving target for delegates. The pr incipal
difference is that you can use the A pproach settings
to specify an intermediate target. After reaching
this location, the delegates will then mak e their
final approach to the ultimate target sur face.