Adobe After Effects CS4 - Manual (Page 553)

547 USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Displacement Detail Determines how much the original shape of the path is altered while wiggling. Greater values
increase the detail of displacement (or change in shape) in the stroke. Lower values produce less displacement, leaving
the path closer to its original shape.
When Displacement Detail values are set high, the stroke may not resemble its original shape at all. This approach is
useful in creating randomly animated strokes.
Set the Displacement Detail value by using the slider in the Effect Controls panel (preset to values in the range 0–100)
or by clicking the underlined Displacement Detail value and typing a number in the range 0–1000.
Pressure Variation Determines how much the Radius and Opacity values of the stroke vary while wiggling. For strokes
that have Stylus Radius enabled, the Radius wiggles. For strokes that have Stylus Opacity enabled, the Opacity wiggles.
The amount of variation in either the Radius or Opacity value while wiggling depends on the value specified for
Pressure Variation. The Radius and Opacity settings in the Brush Settings act as maximum amounts, not to be
exceeded while wiggling.
Note: Strokes that don’t have either Stylus Radius or Stylus Opacity options selected aren’t affected by the Wiggle Pressure
Settings. However, these options can be enabled even if a tablet isn’t installed.
In the Effect Controls panel, set the Pressure Variation value by clicking the underlined Pressure Variation value and
typing a number between -30,000 and 30,000, or by dragging the Pressure Variation slider.
Pressure Detail Determines how tight the pressure variation appears along the stroke. Higher values create more
dense variations.
Individual Stroke Seeds If selected, this option creates a different random wiggle seed for each stroke on a layer.
Because the wiggle controls apply to all strokes on a layer, the wiggle parameters are always the same. To randomize
the wiggling of the individual strokes, select the Individual Stroke Seeds option.
If Individual Stroke Seeds isn’t selected, all strokes use the same wiggle seed, so they all have the same spatial wiggle
values. For example, two strokes exactly on top of each other wiggle equally. By setting individual seeds for each stroke,
you avoid identical strokes wiggling in the same way.
Composite Paint options
Various options control the way Vector Paint composites strokes on a layer. Select the option you want in the Effect
Controls panel for a layer, from the Composite Paint menu under Vector Paint. These options control two things: what
you see in the Composition panel as you work, and what aspects of the layer the strokes affect, including what happens
when you preview and render the composition.
As you paint and erase, you can either hide or display the footage image. You have similar viewing options when you
paint using matte and alpha channel options.
As you work, painting and erasing can block pixels in an original image, such as a footage file or solid. You can also
paint on a virtual layer above or below that image (although the virtual layer doesn’t appear as a separate layer in the
Timeline panel). You can paint and erase to adjust mattes and alpha channels for the original image. You can restrict
Vector Paint strokes to the areas inside or outside the original alpha channel.
Each Composite Paint option specifies a unique combination of work view, layer type (image, matte, or alpha channel),
and placement of strokes relative to the original image. You can select strokes later and change the Composite Paint
option, but it’s a good idea to understand what results each option produces before you start painting.
The following illustrations use the same basic example of an imported image. A paint stroke has been applied, followed
by an erasure stroke. The original image is the green layer, including an alpha channel that reveals the background
layer.