5.1.1

Chapter 21 3D compositing 942
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Intensity: A slider that acts as a dimmer switch for lighting. If you use a Directional light at
100% intensity pointed straight at a red object, the object looks red. If you lower the intensity,
the object and scene get darker. However, if you increase the intensity above 100% you can
begin to overexpose your scene, eventually causing the object to appear white. The Intensity
value slider ranges from 0 and 400, but there is no upper limit for Intensity (use the adjacent
value slider to set a value above 400).
Note: Multiple lights interacting with an object combine to increase the object’s apparent
brightness as they would in the real world. If you have two spot lights overlapping in space
and pointing in the same direction with Intensity set to 100%, you see the same result as
having a single spot light with its Intensity set to 200%.
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Fallo Start: A slider that enables you to adjust where the fallo point of a light begins. In
the real world, light falls o—or has less of an eect—as the distance from the light source
increases. Usually fallo starts at the center of the light object. Setting Fallo Start adds
additional control to your lighting. This parameter applies to light types that use a Position
parameter (Point and Spot).
In the example below, a light is positioned slightly above the origin of the scene. There are
three rings of cards at a distance of 200, 500, and 1000 units from the light. (In this example, a
visible light source—the bulb at the center of the rings of cards—is simulated for illustrative
purposes.) The light’s Intensity is set to 100% and Fallo is set to 10%. When Fallo Start is set
to 0 (left, below), the light begins to fall o by the time it hits the innermost ring. When Fallo
Start is set to 200 (right, below), the inner ring is lit at 100% intensity and the outer rings are
slightly brighter than before.
Falloff Start set to 0 Falloff Start set to 200
When Fallo Start is increased to 500 (left, below), the inner and middle rings are lit at 100%
intensity, and the outer ring is brighter than before. Finally, when Fallo Start is set to 1000
(right, below), all rings are lit at 100% intensity.
Falloff Start set to 500 Falloff Start set to 1000
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