8

Multi-Pass Motion Blur Parameters for Cameras 1231
Impor tant: This effect is for the default scanline
renderer. The
mental ray renderer (page 3–77) has its
own depth-of-field effect. See
Motion Blur with the
mental ray Renderer (page 3–88)
.
Tip:
To reduce the visible effect of multiple camera
passes, try setting the antialiasing filter to Blend,
withaWidthvalueintherange4.0to5.0,and
a Blend value in the neighborhood of 0.1. (You
choose the antialiasing filter and adjust its sett ings
on the
Default Scanline Renderer rollout (page
3–37)
.) Also, try reducing the Dither Strength
value,intheeffect’sPassBlendinggroup,tothe
neighborhood of 0.2.
Inter face
Note: The multi-pass motion blur parameters are
animatable.
Sampling group
Display Pas ses—When on, the rendered frame
w indow displays the multiple rendering passes.
When off, the frame window displays only the final
result. Thiscontrolhasnoeffectonpreviewing
motion blur in camera viewports. Default=on.
Total Passes—The number of passes used to
generate the effect. Increasing this value can
increase the effect’s accuracy, but at a cost of
rendering time. Default=12.
Durati on (fr ames)—The number of frames in the
animation to which the motion blur effect will be
applied. Default=1.0.
Bias—Changes the blurring so that it appears
to derive more from frames before or after the
current f r ame. Range=0.01 to 0.99. Default=0.5.
By default, the blurr i ng comes equally f rom frames
before and after the current frame; that is, a
blurred object appears at the center of the blurred
area. This is the closest to w hat an actual camera
would capture. Increasing the Bias value moves
the blurring behind the blurred object, in relation
to its direction of motion. Decreasing it moves the
blurring in front of the blurred object.
Extremevaluesmovemostoftheblurringvery
close to the blurred object, which makes it difficult
to see. For best results, use intermediate Bias
values in the range 0.25 to 0.75.
Pass Blending group
The multiple motion blur passes are blended by
dithering, which you can control by the parameters
in this group.
These controls apply only to renderings of the
motion blur effect, not to previews in viewports.
Nor mali ze Weights—Passes are blended with
random weighting to avoid artifac ts such as
streaking. When Normalize Weights is on, the
weights are norma lized, giving a smoother result.
Whenoff,theeffectisabitsharperbutusually
gr ainier. Default=on.
Dither Str ength—C ontrols how much dithering
is applied to the rendered passes. Increasing this
value increases the amount of dithering, and can