Graphics Reference
In-Depth Information
Chapter 4
Lighting
When taking a good photograph, lighting is key to the overall success of the image. Studio shots require a
careful balance of light and color created by artificial sources. Outdoor (natural) shots are dependent on get-
ting the right time of day, a good surrounding environment, and even the careful use of reflectors and bounce
cards to get just the right touch. To achieve good results in 3D, similar (but not identical) considerations must
be taken.
This chapter covers the following:
• Using lights in 3D
• Creating a basic light setup
• Setting up environments
• Rendering basics
Using Lights in 3D
As discussed in Chapter 1, “Working in 3D,” there are essentially two broad categories of lights in 3D. One
is a category of lights that attempts to mimic physical lights and is based on mathematical descriptions of a
light's brightness, direction, and size. These “traditional” lights (sometimes referred to as
Direct Lights
) have
been used in 3D computer graphics for many years. The other category of lights is based on a much more
complex math called
radiosity
and results in a much more natural and realistic lighting. Although the typic-
al trade-off between quality and speed exists between these two lighting categories, there is actually a more
complex issue here since the two types of light can be used in conjunction. In many cases, a combination of
traditional Computer Generated lights and radiosity is needed to provide the best results.
Traditional 3D Lights
Even though traditional CG lights lack a fair amount of complexity and realism, it is important to understand
them in order to effectively light a scene. The types of lights found in modo are common to many 3D applica-
tions, and understanding them in modo will allow you to work effectively with lights in most 3D applications.
Before looking at individual types of lights, we should note that all lights have three options for the type of
shadows they cast. The default (Ray Trace) offers realistic and accurate shadows. Deep Shadow Map provides
slightly faster render times. The None option disables the light shadows entirely. In most cases, the default
setting is used because the speed increase of using shadow maps is minimal on modern computer systems.
Next, we will consider each of the types of lights available in modo and how to use them effectively.
