Adobe After Effects CS4 - Manual (Page 535)

529 USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
the appearance at 2 revolutions, and so on. To return the Evolution setting to its original state (for example, to create
a seamless loop), use the Cycle Evolution option.
You can specify how much the noise evolves over a period of time by animating Evolution. The more revolutions
within a given amount of time, the more rapidly the noise changes. Large changes in the Evolution value over a short
period of time may result in flashing.
To create a seamless loop, use Cycle Evolution, and set Evolution keyframes at full revolutions with no degrees—
partially completed revolutions may interrupt the loop.
Evolution Options Options for Evolution.
• Cycle Evolution Creates a cycle of Evolution that loops over the set amount of time. This option forces the
Evolution state to return to its starting point, creating a smooth progressive cycle, a nonrepeating cycle, or a loop
segment.
To ensure that a cycle completes full revolutions, choose a Cycle value that either matches or is evenly divisible by the
number of revolutions set for Evolution.
• Cycle (in Revolutions) Specifies the number of revolutions that the noise cycles through before it repeats. The
amount of time between Evolution keyframes determines the speed of these Evolution cycles. This option affects only
the evolution of the noise, not Transform or other controls. For example, if you view two identical states of noise with
different Size or Offset settings, they don’t appear the same.
Note: Cycle is available only if Cycle Evolution is selected.
• Random Seed Sets a random value from which to generate the noise. Animating the Random Seed property results
in flashing from one set of noise to another (within that fractal type), which is usually not the result that you want. For
smooth animation of noise, animate the Evolution property.
You can easily create new fractal noise animations by reusing previously created Evolution cycles and changing only
the Random Seed value. Using a new Random Seed value alters the noise pattern without disturbing the Evolution
animation.
Instead of animating Evolution over the entire composition, save rendering time by prerendering and looping one
short Evolution cycle for the duration you want.
Opacity Opacity of the noise.
Blending Mode The blending operation between the fractal noise and the original image. These blending modes are
identical to the ones in the Modes column in the Timeline panel, with the following exceptions:
• None Renders the fractal noise only and does not composite on the original layer.
• Hue Renders the fractal noise as hue values instead of grayscale. The Saturation and Lightness of the original layer
are maintained. If the original layer is grayscale, nothing happens.
• Saturation Renders the fractal noise as saturation values instead of grayscale. The Hue and Lightness of the original
layer are maintained. If the original layer is grayscale, nothing happens.
Create a seamless loop using Fractal Noise
1 Select a layer in the Timeline panel, and choose Effect > Noise & Grain > Fractal Noise.
2 Set two keyframes for Evolution.
3 Adjust the time between keyframes and the number of Evolution revolutions until you are satisfied with the
animation of the noise.
4 Select Cycle Evolution.