Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 508

Copies the force adjustment based on areas of a layer map on both the x and y planes of motion. The
Gradient Force
pixel brightness values in the color channel define the resistance to particle force at each pixel, so the color channel
acts like a layer map of hills and valleys that decrease or increase particle force. In the layer map, areas of equal
brightness result in no adjustment, similar to flat land. Lower pixel values represent less resistance to a particle's force,
similar to a downhill grade. Higher pixel values represent more resistance to a particle's force, similar to an uphill
grade. For best results, use a soft-edged layer map image.
If you are using a layer map for Gradient Force where flat areas equal no adjustment, and you are using the Min and
Max controls (not the Min or Max operators) to set the range of values for Gradient Force, set them to positive and
negative values of the same number (for example, –30 and +30). This ensures that the middle of the range remains
centered at zero.
Copies the coercion along the x axis of motion. Positive values push a particle to the right.
X Force
Copies the coercion along the y axis of motion. Positive values push a particle down.
Y Force
Copies the transparency of a particle, where zero is invisible, and 1 is solid. Adjust this value to fade particles
Opacity
in or out.
Copies the particle mass, which interacts with all properties that adjust force, such as Gravity, Static Friction,
Mass
Kinetic Friction, Torque, and Angular Velocity. It takes greater force to move particles with a larger mass.
Copies the elapsed length of time a particle exists, in seconds. At the end of its lifespan, the particle is
Lifespan
removed from the layer. The default lifespan is effectively immortal.
Copies the value that corresponds to an ASCII text character, making it replace the current particle.
Character
Applies only if you're using text characters as particles. You can specify which text characters appear by painting or
drawing shades of gray on the layer map that correspond to the ASCII characters you want. A value of zero produces
no character. For US English characters, use values between 32 and 127. The range of possible values can accom-
modate Japanese characters. For more information about the ASCII character values for a font you're using, see the
documentation for the font, use a utility such as Character Map (Windows), or contact the font manufacturer.
Note: If you simply want to make certain characters spell a message, it's much easier to type the text directly in the
Options dialog box. The Character property is more useful as a secret message effect in which you scramble text
characters.
Copies the point size of characters. Applies only if you're using text characters as particles. Increase this
Font Size
value to make characters larger.
Copies the Time Offset value used by the Layer Map. Applies only if you used the Layer Map control to
Time Offset
specify a multiframe layer (such as a movie) as a particle source.
Copies the scale of a particle. Positive values expand the particle, and negative values shrink the particle.
Scale Speed
Particles expand or shrink by a percentage per second.
Min and Max controls for Property Mappers
When the overall range of layer map brightness values is too wide or narrow, use Min and Max to stretch, compress,
or shift the range of values produced by the layer map. The following examples describe when you might want to
adjust Min and Max:
• You want to set the smallest font size for your text to 10 points and the largest size to 96 points. Set the Min value
to 10 and the Max value to 96.
• You set the initial color of a particle and then use a layer map to change particle colors. If you find that the color
changes aren't dramatic enough, you can lower the Min value and raise the Max value to increase the contrast of
the color changes.
AFTER EFFECTS CS3 502
User Guide