9
1472 Chapter 16: Material Editor, Materials, and Maps
Inter face
Advanced Transparency group
These controls affect the opacity falloff (page
3–984) of a transparent material.
Note: For the Translucent shader (page 2–1484),
these controls do not appear. They are replaced
by the Translucency controls (page 2–1491) on the
Basic Parameters rollout.
Fa lloff—Chooseswhetherfalloffisinorout,and
how great it is.
•
In—Increases transparency toward the inside of
the object, as in a glass bottle.
•
Out—Increases transparency toward the outside
of the object, as in a cloud of smoke.
Amt (Amount)—Specifies the amount of
transparency at the outside or inside extreme.
Ty pe—These controls choose how transparency
is applied.
• Filter (page 3–939) computes a filter color that
it multiplies by the color behind the transparent
surface. Click the color s watch to change the
filter color. Click the button to assign a map to
the filter color component.
The filter, or transmissive color, is the
color transmitted through transparent or
semi-transparent materials such as g lass. You
can use the filter color with volumetric lighting
to create effects such as colored light through
astained-glasswindow. Ray-traced shadows
(page 3–1000) c ast by t ransparent objects are
tinted with the filter color.
A shadow ’s color is changed with a red filter color.
• Subtractive (page 3–1017) subtracts from the
color b ehind the tr ansparent surface.
• Additive (page 3–906) adds to the color behind
the t ransparent surface.
Index of R efraction—Sets the index of refraction
(IOR) used by refraction maps and raytracing.
The IOR controls how severely the material
refractstransmittedlight. Leftat1.0,theIOR
of air, the object behind t he tr ansparent object
does not distort. At 1.5 the object behind distorts
greatly, like a g lass marble. At an IOR slight ly less
than 1.0, the object reflects along its e dges, like a
bubble seen from under water. Default=1.0.
Common IORs (assuming the camera is in air or a
vacuum) are:
Material IOR Value
Vacuum
1.0 (exactly)
Air
1.0003
Water
1.333
Glass 1.5 (clear glass) to 1.7
Diamond
2.417
In the ph ysical world, the IOR results from the
relative speeds of light through the transparent