Rendering and Materials - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 921

Creating a Lighting Scheme
Without a well-thought-out lighting scheme, the scene can look flat and unap-
pealing. In the following sections, you will add a light to represent the sun and
then an additional light to add ambient illumination to the scene.
Creating a Light Source
AutoCAD has four kinds of lighting, each with a distinct method for distributing
light rays into the scene. They are as follows:
Point Light All light rays are emitted from a single location and diverge as they
get farther away. An incandescent light bulb is a real-world example of a point
light, even though the light does not travel in the direction of the light's fixture.
Spotlight With this type of light, rays are emitted from a single point, but they
are restricted to a conical portion of the amount of light that a similar point
light would emit. Flashlights and headlights are examples of spotlights.
Distant Light With this type of light, all light rays are parallel. Although the sun
is technically a point light, at the enormous distance the light rays travel to Earth,
they are nearly parallel.
Weblight Photometric light with real-world distributions. These lights can be
used in conjunction with light distributions derived by manufacturers of real-
world lights. Using manufacturer data to establish lighting distributions helps
ensure more accurate representation of rendered lights than possible using point
or spot lights.
Each light type has a unique set of parameters. The sun is a special distant
light and has its own settings, including determining the light's position based
on the geographic location of the scene and the date and time and the ability to
add ambient light to the drawing.
To add this type of light, you'll use tools in the Visualize tab of the Ribbon:
1. Click the Ribbon's Render tab.
2. In the expanded Lights panel, make sure the Default Lighting option
is turned off.
When it is off, the button will not have a blue background as the
cursor pauses over it and there will be no default illumination in
the scene.