9

Rendering Algorithms Rollout (mental ray R e nderer) 117
Inter face
By default, both Ray Trace and Scanline are
enabled, which lets the mental ray renderer use
a combination of ray tracing (page 3–88) and
scanline rendering to render the scene. Scanline
renderingisusedfordirectillumination(“primary
rays”) only; ray tracing is used for indirect
illumination (caustics and global illumination) as
well as reflections, refract ions, and lens effects.
Youcandisableoneortheotheroption,butnot
both. For example, if only ray tracing is enabled
and you turn it off, 3ds Max enables scanline
rendering.
Scanline group
Enable—When on, the renderer c an u se scanline
rendering. When off, the renderer uses the
ray-tracing metho d only. Scan line rendering
is faster than ray t r acing, but cannot generate
reflections, refrac tions, shadows, depth of field, or
indirect lighting. Default=on.
Use Fast R asterizer (Ra pid M otion B lur)—When
on, uses a fast ra ster izer method to generate the
first generation of rays to trace. This can improve
rendering speed. Default=off.
This option works well with object motion blur,
andalsowithscenesthathavenomotionblur.
The following sett ings are available for the fast
rasterizer:
•
Samples per Pixel—Controls the number of
samples per pixel used by the fast rasterizer
method. More samples result in g reater
smoothness, at a cost of render time. Range=1
to 225. Default=16.
•
Shades per Pixel—Controls the approximate
number of shading cal ls per pixel. Greater
values result in more accurate renderings, at a
cost of render t ime. Range=0.1 to 10000 (ten
thousand). Default=1.0.
Note: mental ray provides a Time Samples setti ng
specifically for motion blur in the fast rasterizer.
When Use Fast Rasterizer is on, the Camera Effects
rollout >Time Samples label changes to Time
Samples (Fast Rasterizer) to indicate that this
version of Time Samples is now in effect.
Ray Tracing group
Enable—When on, mental ray uses ray tracing
to render reflections, refractions, lens effects
(motion blur and depth of field), and indirect
lighting (caustics and g lobal illumination). When
off, the renderer uses the scanline method only.
Ray t racing is slower but more accurate and more
realistic. Default=on.
You must turn on Ray Trace to render reflections,
refractions, depth of field, and indirect lighting
(caustics and g lobal i llumination).
Use A utov ol ume—When on, uses the mental ray
autovolume mode. When Autovolume is on,
you can render nested or overlapping volumes
such as the intersection of two spotlight beams.