Autodesk LIGHTSCAPE, Manual

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Editing Material Properties
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5.
If needed, adjust the Reflectance and Color
Bleed Scales to control the amount and color of dif-
fuse light reflected from the material into your mod-
el.
Note: If you select any of the metals templates,
Transparency and Refractive Index are deactivated.
Metals are not transparent, so the Transparency
box is not relevant. The system also automatically
approximates a metal’s refractive index based on
its color. When ray traced, a metal has colored high-
lights and reflections and a nonmetal has white
reflections.
Selecting a Template
Use templates to help you define materials with real-
istic physical properties. When you select a template,
the program displays guidelines on relevant material
properties. The valid range of values for the template
selected is highlighted in green. You can then adjust
these values within the given range to create a
specific appearance.
If you want to create a material that is not in the
Template list, select the template that most closely
resembles the material you want to create. For
example, to define acrylic you can use the glass
template. Alternatively, you can use the User
Defined template. However, this template does not
provide you with any specific guidelines so you
should be confident that you can set values that are
physically valid.
When selecting a template, make sure it represents
the surface finish of the material. For example, if
your material is a painted metal, use a paint
template. On the other hand, to simulate wood
painted with metallic paint, use the metal template.
Using Reflectance Scale
To obtain a valid radiosity solution, it is important
that the reflectance of the material be set to within
the recommended range of values for the specific
type of material being defined. Reflectance, by
default, is set either by the brightness of a texture
map (if one is used) or by the Value of the color (if a
texture map is not used). A green line on these
parameters displays the recommended range of
values. In addition, if you are outside the recom-
mended range, the Average Reflectance of the
material (displayed at the bottom of the menu) will
be displayed in red.
Sometimes, to obtain a desired effect in a rendering,
you may want a texture map or color to appear
brighter or darker in a rendering than the software
recommends. In this situation you should use the
Reflectance Scale to adjust the Average Reflectance
to be within the recommended range. The Reflec-
tance Scale allows you to keep the reflectance of a
material correct for radiosity processing (i.e.
lighting simulation and analysis) while adjusting the
appearance of a material, as necessary.
Using Color Bleed Scale
The amount of color that bleeds from a material is
defined by default from the saturation of the color or
texture map. Sometimes, you may want a material to
appear highly saturated in your final display or
rendering but you may not want to have the strong
color bleeding effect that results from such materials
in the radiosity process. In this situation, you can use
the Color Bleed Scale on the physics page to adjust
the amount of color bleeding that you will obtain
from a material. At 0% there will be no color
bleeding at all.
Average and Maximum Reflectance
The Average and Maximum reflectance relate to how
much diffuse light is reflected back into the environ-
ment from the material. To obtain a valid lighting
simulation, it is important that the reflectance is set
to be within the valid range for the type of material
being defined. Typically the reflectance is set by