Adobe After Effects CS3 - Manual (Page 167)

AFTER EFFECTS CS3
User Guide
162
You can use Brainstorm on any property that has numeric values or options in a pop-up menu in the Timeline panel.
Examples of properties on which you can’t use Brainstorm are Source Text, Mask Path, and the Histogram property
for the Levels effect; however, you can use Brainstorm on the properties of the Levels (Individual Controls) effect.
Brainstorm operates on all selected keyframes. For a property with no keyframes, Brainstorm operates on the global,
constant value.
If you use Brainstorm on a single one-dimensional property (such as Opacity, but not Position), the Randomness
value that controls the amount of variation (mutation) is replaced by a Spread value. The variants that are presented
in the Brainstorm dialog box are then not random, but represent a range of values around the central value. The
original composition appears in the center tile of the dialog box, and you can only select one variant on which to base
the next Brainstorm operation.
Though you can’t directly use Brainstorm on expressions, you can use Brainstorm on the properties of Expression
Control effects, to which expressions can refer.
1 Set a work area and region of interest for the duration and spatial area of the composition that you want to preview
during the Brainstorm session. (See “Set the work area” on page 112 and “Work with the region of interest” on
page 111.)
2 Select one more properties or property groups in the Timeline panel, and click the Brainstorm button at the
top of the Timeline panel.
The variant compositions all play in the Brainstorm dialog box simultaneously. Controls for each variant are only
visible when the pointer is over it. Use the playback controls at the bottom of the Brainstorm dialog box to play,
pause, or rewind the previews.
3 In the Brainstorm dialog box, do any of the following:
• To get a better look at a variant, click its Maximize Tile button. Click the Restore Tile Size button to return
to the grid view of all variants.
• To show or hide the transparency grid, click the Toggle Transparency Grid button at the bottom of the Brain-
storm dialog box.
• To mark a variant for inclusion in the next Brainstorm operation, click that variant’s Include In Next Brainstorm
button.
• To save a variant as a new composition in the current project, click that variant’s Save As New Composition
button.
• To increase the randomness or spread for the next generation, adjust the Randomness or Spread value at the
bottom of the Brainstorm dialog box. Make this number small for precision work; make it larger for experimen-
tation and exploration.
4 (Optional) To create another generation of variants from those marked for inclusion in the next Brainstorm
operation, click Brainstorm at the bottom of the Brainstorm dialog box and return to step 2. If you click Brainstorm
without marking any variants for inclusion, the Brainstorm operation is repeated using the same input as the current
generation.
If the Brainstorm operation uses Randomness, the variants marked for input into the next generation are included
unchanged into the next generation, and remain in their positions in the dialog box. If the Brainstorm operation uses
Spread, only one variant is carried into the next generation, and it appears in the center tile.
Repeat this cycle until you have found the variant that you want to save as the current composition.