Graphics Reference
In-Depth Information
1
Introduction to
Photorealistic Rendering
Photorealistic rendering
is the process of image generation by simulating the
physical interaction of light in an environment. Specifically, the simulation in-
volves how light from
light sources
is reflected and scattered throughout the en-
vironment. The environment, or scene, as it is sometimes called, consists of a
collection of mathematically described geometric objects. The shape description
of the objects is known as the
geometric model
of the environment; however,
this is only part of the complete model needed for rendering. Surface properties,
such as color and reflection characteristics, as well as volume elements such as
smoke and fog, affect the light propagation and are therefore a necessary part of
the model. These elements, and a model for the light propagation itself all re-
quire a mathematical representation that can be incorporated into the rendering
simulation.
In this chapter, the basic physical concepts used in rendering are presented.
The model of light propagation most often used in rendering, radiant power car-
ried along light paths in the form of rays, is developed in conjunction with related
physical quantities of light measurement. The basic surface reflectance model
used in rendering is also introduced, and the chapter concludes with a descrip-
tion of the two primary methods of image generation: scanline rendering and ray
tracing.
1.1 Physical Quantities of Light
Modeling light interaction involves the physical quantities associated with light
as electromagnetic radiation. Physically, light consists of electromagnetic waves
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