9

Subsur face Scattering (SSS) Materials 1583
Outside Light Persistence—
In conjunction with the
Persistence Distance, controls the percentage of
light tr ansmitted on the other side of a surface.
When set to the default of black, this control has
no effect. See the section “Adjacent Refract ive
Materials,” above. Default=black (R=G=B=0.0).
Index Of R efraction (out)—Sets the IOR on the other
sideofasurface.Whensettothedefaultofzero,
this cont rol has no effect. S ee the sect ion “Adjacent
Refractive Materials,” above. Default=0.0.
Persistence Distance—In conjunction with the
Light Persistence color, controls the percentage of
lightthatthevolumetransmits.Itisthedistance
at w hich light transmission is reduced to the
percentage specified by the Light Persistence RGB
values. Default=1.0.
If you specify an Outside Light Persistence color,
that setting also uses the Persistence Distance.
Ignore Normals—When on, the renderer does
not use normals to decide whether a light ray
is entering or leaving the object. Normally, the
material uses normals to decide w hether a ray is
entering or leaving an object. (It is entering if the
normal p oints toward the ray, leaving if the normal
points away from the ray.) This can present a
problem for rendering objects whose normals are
not unified. hen Ignore Normals is on, the material
decides whether a ray is entering or leaving the
object by counting the number of times the ray has
intersected the object . Default=off.
Opaque Alpha—When on, refracted r ays that touch
the env ironment don’t generate a transparent
alpha value. ( This is how 3ds Max usually treats
the environment.) When off, refracted rays that
touch the environment render a transparent
alpha value, which can help if you plan to use the
rendering as part of a composite. Default=off.
Phong Coefficient—When g reater than zero,
generates Phong highlights on the material. The
high lights appear in the sample s lot. In general
this value must be g reater than 10 for highlights to
be apparent. Default=0.0.
Subsur face Scattering (SSS)
Mater ials
Material Editor > Type b utton > Material/M ap Browser
> Choose SSS Fast Material (mi), SSS Fast Skin Material
(mi), S SS Fast Skin Material+Displace (m i), or SSS Physical
Material (mi), and then click OK.
Note: The SS S materials appear in the Browse r only if the
mental ray renderer is the currently ac tive renderer.
The subsurface scattering (SSS) materials a re
provided especially to model skin and other
organic materials whose appearance depends on
more than one la yer of light scattering. 3ds Max
provides four of these materials. Each material is a
top-level wrapper (a “phenomenon”) for shaders
whose controls are documented in the Standard
mental ray Shader Libraries document. Click a
link to see the mental images documentation for
the shader.
Tip: When you follow a link to the documentation
for mental images library shaders, scroll up a bit in
your browser. The links tend to go past the title
of the section, and there might be introductory
content above the link loc ation. If the link goes to
the beginning of a section, scroll down instead.
Mater ial Name mi Library Shader Name
SSS Fast Material (mi) misss_fast_simple_phen
SSS Fast Skin Material (mi) misss_ fast_skin_phen
SSS Fast Sk in
Material+Displace (mi)
misss_ fast_skin_phen_d
SSSPhysicalMaterial(mi) misss_physical
Also see Subsurface Scattering Shaders and the
topics that follow it for more general information.
See P
hysically Correct Subsurface Scattering
for background inform ation and tips ab out the
Physical material.