Autodesk LIGHTSCAPE, Manual

Page: 113 / 362

Using the Materials Table
105
❚❘❘
is true for apparently clear glass because glass always
has impurities in it. The impurities cause the glass to
absorb some light as it passes through the glass.
For example, a particular type of glass may have a
transmissivity of 85%, meaning that 85% of the light
passes through the glass. In this case, you should set
the reflectance (Value) of the glass to 85% (.85) and
its transparency to 100%.
Note: When blending is enabled in the Display
options, transparent materials are blended with
those behind them, giving a transparent effect. As
a result, transparent surfaces may be invisible. To
display the surfaces as opaque, regardless of their
transparency, disable blending. The most accurate
representation of transparency will be calculated
when you use ray trace rendering. To toggle
blending on or off, choose Display | Blending, or
click the Blending button
on the Display
toolbar.
Shininess
Shininess affects the appearance of specular reflec-
tions seen in a material. If a surface is shiny,
reflections are well defined. If a surface is not shiny,
reflections are blurry.
If you ray trace a perfectly shiny material, you get a
clear image from a reflection seen through the mate-
rial. You also get sharper highlights. For more
information, see Chapter 14, “Rendering.”
As a material becomes less shiny, reflections and
highlights seen in the material become less well
defined.
Shininess alone is not sufficient to produce specular
reflections and highlights for a surface. The refrac-
tive index must also be considered.
Refractive Index
The refractive index determines the behavior of light
at the interface between two surfaces (usually a
material and air).
This will affect how shiny a material appears or, in
the case of transparent materials such as water or
glass, the amount of distortion that occurs at the
interface.
For non-transparent materials, the higher the refrac-
tive index, the more light is reflected from the
material and the material appears shinier. A refrac-
tive index of 1.0 means that all light is transmitted
into the material. In this case, even if the material is
defined to be perfectly shiny, the surface appears
perfectly diffuse.
Using the Materials Table
All materials available in your scene are listed in the
Materials table, including materials that you have
not applied to a surface.
To display the Materials table:
Click the Materials table button on the Tables
toolbar, or choose Edit | Tables | Materials.
Note: If the Tables toolbar is not displayed, choose
Tools | Toolbars, and select Tables from the Tool-
bars dialog that appears.
Materials table button