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50 Chapter 17: Rendering
Radiosity
Modeling Global Illumination with
Radiosity
Radiosity is rendering technology that realistically
simulates the way in which lig ht interacts in an
environment.
This topic provides you with a conceptual
overview of what radiosity is and how this
global illumination technique relates to other
renderingtechniquesavailablein3dsMax. This
information will help you decide which technique
is most suitable for the visualization task you
want to perform. By more accurately simulat ing
the lighting in your scene, radiosity offers you
significant benefits over standard lights:
•ImprovedImageQuality:Theradiosity
technology of 3ds Max produces more accurate
photometric (page 3–1087) simulations of the
lighting in your scenes. Effects such as indirect
light, soft shadows, and color bleeding between
surfaces produce images of natural realism
that are not attainable with standard scanline
rendering. These images give you a better, more
predictable representation of what your designs
wi ll look like under specific lighting conditions.
• More Intuitive Lighting: In conjunction with
radiosity techniques, 3ds Max also provides
a real-world lighting interface. Instead of
specifying lighting intensity with arbitrary
values, light intensity is specified using
photometric units (lumens, candelas, and
so on). In addition, the characteristics of
real-world lighting fixtures can be defined
using industry-standard Luminous Intensit y
Distr ibution files (such as
IES (page 2–1172) ,
CIBSE (page 3–1015) ,and LTLI (page
3–1058)
), which are obtainable from most
lighting manufacturers. By b eing able to work
w ith a real-world lighting interface, you can
intuitively set up the lighting in your scenes.
You can focus more on your design exploration
than on the computer graphic techniques
required to visualize them accurately.
Top: A scene rendered without radiosity.
Bottom: The same scene rendered with radiosity.
Computer Gr aphi cs R ender i ng
The3Dmodelscreatedin3dsMaxcontain
geometric data defined in relationship to a 3D
Cartesian coordinate system, referred to as
world
space (page 3–1130)
.Themodelalsocontains
other information about the material of each of
the objects and the lighting in the scene. The
image on a computer monitor is made up of many
illuminated dots, called
pixels (page 3–1089) .The
task in creating a computer graphics image of a
geometric model is to determine the color for