Graphics Reference
In-Depth Information
I
Geometry-Based Approaches
In computer graphics,
rendering
is the process of creating an image of an ob-
ject or a general scene from a mathematical representation. Just as styles of paint-
ing and drawing in art range from the representational to the abstract, there are
different styles of rendering. Early rendering methods, much like early artwork,
concentrated on producing recognizable representations of objects—early render-
ings did not look at all real.
Photorealistic rendering
is the process of reproducing
what an object or scene would look like if it were constructed and photographed,
and this involves simulating how reflected and scattered light illuminate a real en-
vironment.
The interaction of light and matter in nature is very complicated, and has
been studied in the natural sciences for many years. By the mid-twentieth centu-
ryit had become commonplace in manufacturing to represent objects using spa-
tial coordinates and mathematical expressions. New approaches for representing
curved surfaces emerged by the 1960s. By then, the theoretical foundations of
light transport were mostly complete, but the application of physically based light
simulation was not feasible until sufficient computer processing power became
available in the early 1980s. Since then photorealism has been a major goal of
research in computer graphics.
Just like studies in any field of science, researchers in photorealistic render-
ing took the approach of starting simple. Specifically, basic surface reflection was
modeled first, and illumination effects were studied in very simple scenes. More
complex environments and volume effects such as smoke and fog were considered
later. Research then shifted to scattering and re-emission of light from beneath a
surface, an effect observed in hair and skin. Since 2000, much research has fo-
cused on generating photorealistic renderings at interactive rates, driven in part
by the emergence of high-speed graphics hardware technology. In Part I, methods
of photorealistic rendering that work on geometric models are introduced along
with methods for implementing them on graphics hardware.
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