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90 Chapter 17: Rendering
Motion blur added to rendering of an animated wheel as it
speeds up and rolls fo rward
To render motion blur w ith the mental ray
renderer, you must turn on ray tracing (the Ray
Trace parameter) on the Render Scene dialog >
Renderer panel > Rendering Algorithms rollout
(page 3–116).
The mental ray renderer uses a Shutter parameter
to control motion blur. This simulates the shutter
speed of a camera. At 0.0, there is no mot ion
blurring.At1.0,themaximumamountofmotion
blurring occurs. Values between zero and one
adjusttheamountofmotionblur.Thecloserto
1.0, the greater the blurring.
Youturnonmotionblurandadjustshutterspeed
on the Render Scene Dialog > Renderer panel >
Camera Effects rollout (page 3–101).
If you render using shadow maps (page 3–1011),
then by default mental ray applies motion blur
totheseaswell. SeetheRenderScenedialog>
Renderer panel > Shadows & Displacement rollout
(page 3–114).
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.
Depth of Field with the mental ray
R enderer
Depth of field is a way to enhance the realism of
a rendering by simulating the way a real-world
camera works. With a broad depth of field, all or
nearly all of a scene is in focus. With a narrow
depth of field, only objects within a cert a in
distance from the camera are in focus.
Scene rendered using no dep th of field
All apples are equally in focus.
Same scene using depth of field to control focus
The middle apple is clearer than the other two.