Autodesk LIGHTSCAPE, Manual

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D
Reflection Models
This appendix describes the reflection models you can use to create images
with Lightscape. To help you understand these models, it also explains how
light interacts with surfaces.
Introduction
The physical behavior of light interacting with
surfaces is approximated by a variety of reflection
models, which make different approximations and
are useful in different situations. Lightscape uses
reflection models during three processes: radiosity
computation, OpenGL rendering, and ray tracing.
The reflection model for radiosity processing is never
seen directly. It is simply used by the radiosity algo-
rithm to determine how much light is reflected from
the surfaces in the environment.
Radiosity and OpenGL use similar lighting models
and have similar restrictions.
With the ray tracer, you use two different lighting
models. One has the same set of restrictions as the
OpenGL display to allow compatibility between these
two renderers. The other has fewer restrictions and
can be used to produce highly realistic images.
Light and Materials
In Lightscape, you use a material’s color and reflec-
tance characteristics, as well as whether or not it is a
metal, to describe its scattering appearance. Setting
these properties is as important as placing the lights to
appropriately model light.
Reflection, Transmission, and
Absorption of Light
Light interacting with a material can behave in
various ways. As shown in the following illustration,