9

940 Glossary
two methods of pixel averaging. Only one can be
activ e at a time.
Both metho ds require approximately t he same
rendering time. Summed-area filtering generally
yields superior results but requires much more
memory. Pyramidal filtering require s the program
to allocate memory equal to approximately
133% of the s ize of the bitmap. By comparison,
summed-area filtering requires the program to
allocate approximately 400% of the size of the
bitmap.
Use summed-area filtering only for smaller
bitmaps, and avoid using any more such bitmaps
in a scene than necessary.
Pyramidal filtering is quite adequate for most
purposes. However, b ecause it applies filtering as a
funct ion of distance, irregular antialiasing mig ht
occur on detailed texture maps that are applied
to a plane receding into the distance. The effect
of pyramidal filtering on extreme perspectives
such as this is even more noticeable in animations,
where portions of the texture map appear to
"sw im." If this occurs, turn on summed-area
filtering for the m aterial.
Note: To control whether or not a background
image is affected by the renderer’s antialiasing
filter , choose Customize > Preferences > Rendering
(page 3–826) andthenturnonFilterBackground
in the Background Antialiasing group.
Filtering (Character Animation)
Filtering is the ac tion of using selected data, rather
than all data.
In the Motion Mixer (page 2–604),youusethe
trackgroup (page 3–1024) filter to select the biped
parts that w ill be affected by motion clips and
transitionsontrackswithinthetrackgroup.See
Filtering Mixer Tracks (page 2–612).
Filtering is also a motion-capture technique (page
2–1059).Motion-captureandmarkerdata
typically have keys at every frame. Filtering
motion-capture data reduces the number of keys,
making the job of altering or personalizing the
motion data simpler. Other filtering options
include footstep extraction, applying the skeletal
structure stored in the motion-capture file to the
biped, looping the data, importing a portion of the
motion capture file, and selecting tracks to load.
See Filtering Motion-Capture and Marker Data
(page 2–1061).
Final Ga ther ing (mental r ay
R enderer )
Final gathering is an optional, additional step to
calculating global illumination (page 3–93).Using
a photon map to calculate global illumination can
cause rendering artifacts such as dark corners and
low-frequency variations in the lighting. You can
reduce or eliminate these artifacts by turning on
final gathering, which increases the number of rays
used to calculate global illumination.
Scene rendered with global illumination but no final gather