9

Camera Effects Rollout (mental ray Renderer) 103
Inter face
Motion Blur group
Tip: mental ray motion blur is not recommended
for use with particle systems, as this can increase
renderingtimeconsiderably.UseaParticle MBlur
map (page 2–1676) instead.
Note: Motion blur with the mental ray renderer
does not alwa ys follow curving trajectories.
Increasing the value of Motion Segments can help ,
but this works better for rotary motion than for
traveling motion.
TheToggle(lower-right)quadoftherendering
quad menu (
Ct rl +A l t +right-click) has a Motion
Blur toggle for a single, selected object. You can
turn on Motion Blur for lights and cameras:
moving lights and cameras can generate m ot ion
blur when rendered with mental ray.
Enable—When on, the mental ray renderer
calculates motion blur (page 3–89).Default=off.
Blur All Objects—Applies motion blur to all
objects, regardless of their object property setting.
Default=on.
Shutter Duration (frames)—Simulates the shutter
speed of a camera. At 0.0, there is no motion
blurring. The greater the Shutter Duration va lue,
the greater the blurring. Default=0.5.
Shutter Offset (frames)—Sets the b eginning of the
motion-blur effect relative to the current frame.
The default value, 0.0, centers the blurring around
the current frame for a photorealistic effect.
Default=–0.25.
Motion S egments—Sets the number of segments
for calculating motion blur. This control is for
animations. If motion blur appears to be tangential
to the actual motion of an object, increase the
Motion Se gments value. Larger values result in
more accurate motion blur, at a cost of rendering
time. Default=1.
Ti me Sa mples —When the scene uses motion
blur, controls the number of times the material is
shaded during each time interval (set by Camera
Effects rollout (page 3–101) >MotionBlurgroup>
Shutter). Range=0 to 100. Default=5.
By default, the material is shaded only once, and
then blurred. If the m aterial changes rapidly
during the shutter interval, it might be useful
to increase this value, in order to obtain more
accurate motion blur. Rapid changes in reflections
or refractions might require a higher Time Samples
value.
Note: When Rendering Algorithms rollout > Use
Fast Rasterizer is on, the label for this parameter
changes to Time Samples (Fast Rasterizer) to
indicate that this version of Time Samples is now
in effect. The default value for the Fast Rasterizer
version of Time Samples is 1, and the range is 1
to 128. If you change the value for either version,
the s oftware remembers the changed setting when
you switch.