8
1176 Chapter 15: Lights and Cameras
Shadow Type Advantages Disadvantages
Area Shadows
Supports
transparency and
opacity mapping.
Uses very little
RAM.
Recommended for
complex scenes
with many lights
or faces.
Supports different
formats for area
shadows.
Slower than
shadow maps.
Processes at every
frame.
mental ray
Shadow Maps
Can be quicker
than ray-traced
shadows with
the mental ray
renderer.
Not as accurate
as ray-traced
shadows.
Raytrace
Shadows
Supports
transparency and
opacity mapping.
Processes only
once if there are no
animated objects.
Can be slower than
shadow maps.
Does not support
soft shadows.
Shadow Maps Produces soft
shadows.
Processes only
once if there are no
animated objects.
Fastest shadow
type.
Uses a lot of
RAM. Does not
support objects
with transparency
or opacity maps.
Pr ocedur es
To tur n a light on and off:
• TurntheOntoggleonoroff.
Default=on.
Tip: To make a standard light flash on and off,
set its Multiplier parameter to 0 in repeated
keyframes, and assign a
step tangent (page
2–300)
to this parameter.
To have a li ght cast shad ows:
• In the General Parameters rollout > Shadows
group, make sure On is selected.
The light will now cast shadows when you
render the scene.
Note: With Overshoot turned on, standard
spotlights cast light in a ll direc tions but cast
shadows only within the falloff cone; standard
directional lights cast light throughout the
scene,butcastshadowsonlywithinthefalloff
area.
Left: A spotlight’s projection cone truncates shadows.
Right: An omni light casts complete shadows.
To have a light use the global settings for shadows:
• On the General Parameters rollout, turn on Use
Global Settings.
When Use Global Settings is on, the other
shadowcontrolsaresettothevaluesusedbyall
other shadow-casting lights in the scene that
have Use Global Settings set.
Changing the affected parameters for one light
with Use Global Settings set , changes the m for
all lights w ith Use Global Settings set.
To set a light’s shadow parameters individually:
• On the General Parameters rollout, tur n off Use
Global Settings.
The settings revert to the individual settings
for the light.
By default, Shadow Map is the active shadow
type. In the
Shadow Map Params rollout (page
2–1208)
,thedefaultsettingsare:MapBias=1;
Size=512; Sample Range=4.0; Absolute Map
Bias=Off.