ADOBE AFTER EFFECTS 7.0
User Guide
509
In both the Persistent and Ephemeral Property Mappers, you can control up to three particle properties indepen-
dently by using a single RGB image as a layer map. Particle Playground achieves this by extracting brightness values
separately from the red, green, and blue channels in the image. You don’t have to use all three channels if you want
to modify just one property. To change just one property or change up to three properties using the same values, use
a grayscale image as the layer map because the RGB channels are identical. (See “Creating an RGB layer map for
Particle Playground (Pro only)” on page 513.)
To use Particle Playground Property Mapper controls (Pro only)
In combination with keyframes, the Property Mappers provide complete control over individual particle properties
in space and time. Using layer maps, you can change particle properties at any location within a frame. By applying
keyframes to Property Mapper options and animating a layer map, you can control how particle properties change.
1 For Use Layer As Map, choose a layer map to use as the source for values that modify particle values. The layer
map must be part of the composition. (See “Replacing default particles with layers using Layer Map (Pro only)” on
page 504.)
2 To apply the effect to a subset of particles, specify the Affects controls as necessary. (See “Affects controls for
Particle Playground (Pro only)” on page 508.)
3 Choose a property for each of the Map Red To, Map Green To, and Map Blue To controls. You don’t have to map
properties to all of the color channels. For example, if you want to change scale over an image map, you can map the
color red to scale without setting other properties.
4 Specify the minimum and maximum values you want the layer map to produce for each Map To group. Min is the
value to which a black pixel is mapped, and Max is the value to which a white pixel is mapped. The complete tonal
distribution between Min and Max is then scaled proportionally. (See “Using Min and Max controls for Property
Mappers (Pro only)” on page 511.)
5 If using the Ephemeral Property Mapper, you can apply an operator the value of a particle property and the value
of the corresponding layer map pixel. (See “Operator controls for the Ephemeral Property Mapper (Pro only)” on
page 511.)
Note: Because particle properties use many kinds of units, such as pixels, degrees, and seconds, you may want to
compress or expand the range of values from the layer map so that all the resulting values are usable in the measurement
system of a specific particle property. First, use the Min and Max controls, which define the range of values to use from
the layer map. If further adjustment is necessary and you’re using the Ephemeral Property Mapper, use the Operator
control and choose a mathematical operator to amplify, attenuate, or limit the effect of a layer map.
Particle Playground Property Mapper controls (Pro only)
InboththePersistentandEphemeralPropertyMappers,youcanusealayermap’salphachanneltomakemoresubtle
changes to the value of a particle property. For example, particles over a layer-map pixel in which the alpha channel
value is 255 are fully affected, while lower values affect particles less. Layer-map pixels that are completely trans-
parent have no effect on particle properties. (See “Replacing default particles with layers using Layer Map (Pro only)”
on page 504.)
Whenyouchooseanyofthefollowingproperties,ParticlePlaygroundcopiesthevaluefromthelayermap(thatis,
the layer selected in the Use Layer as a Map menu) and applies it to the particle.
None Modifies no particle property.
Red, Green, Blue Copy the value of the particle’s red, green, or blue channel within a range of 0.0–1.0.
Kinetic Friction Copies the amount of resisting force against a moving object, typically within a range of 0.0–1.0.
Increase this value to slow down or stop moving particles as if braking.
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