Adobe After Effects CS4 - Manual (Page 588)

582 USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Transparency Controls the clarity of the water by adjusting how opaque the alpha channel is in shallower areas. For
example, you can easily see to the bottom of a pool filled with fresh water, but you can see only an inch or two into a
pool filled with coffee. This control is most useful when compositing a Wave World effect into another scene. For
example, you can use a Wave World composition as a source layer for Caustics, and also as a track matte for the effect
layer.
Simulation controls
The Simulation controls specify the resolution of the water surface and ground grids.
Grid Resolution Specifies the number of horizontal and vertical divisions that make up the wave surface and ground
grids. Higher values greatly increase the precision of the simulation but require more memory and increase rendering
time.
Grid Res Downsamples Reduces the internal simulation resolution when the output resolution decreases, increasing
the rendering speed. However, the result may cause the output to look very different.
Wave Speed Specifies how fast waves travel away from their starting point.
Damping Specifies how quickly the energy of a wave is absorbed by the liquid it travels through. The higher the value,
the quicker the wave energy is absorbed, and the shorter the distance the wave travels.
Wave Speed, Damping Specify the apparent viscosity of the liquid, and the apparent size of the body of liquid. For
example, waves in water move faster and farther than waves in honey; waves in a sink move much faster and fade out
much more quickly than waves in a lake.
Note: Wave World is optimized for small- to medium-sized bodies of water—anything from a teacup to a small lake.
Large bodies of water, like an ocean, include swells or wide, stable waves with no apparent slowdown. Even at the lowest
settings, Wave World cannot generate swells because the waves fade out relatively quickly.
Reflect Edges Specifies how waves bounce off the edges of the layer and back into the scene.
Pre-roll (seconds) Specifies when the waves start moving. By default, the effect starts with a still surface without waves
or ripples. Use this control to start the waves moving before the layer begins. The settings at the first frame of the effect
are applied to the layer during the pre-roll.
Ground controls
The Ground controls specify the appearance of the ground layer.
Ground Specifies the layer that appears at the bottom of the water. If you use an animated layer for the ground, Wave
World samples only the first frame. Wave World determines the intersection of the water surface with the edge of the
ground, computes the waves bouncing off the shore, and properly adjusts the speed of the waves depending on the
depth. The brightness of the layer determines the ground surface: White represents higher elevation, and black
represents lower elevation.
Steepness Adjusts the steepness of the ground by expanding and contracting the height of the displaced wireframe.
The mesh is locked at the black level, so it always grows up from the bottom. In other words, you cannot adjust the
bottom of a canyon to be deeper; instead, you can adjust the rim to be higher. To make the canyon deeper, combine a
higher Steepness setting with a lower Height setting.
Height Controls the distance between the water surface and the deepest possible point of the ground. Use this control
to make the body of water deeper or shallower. When you change the depth of the water, the waves behave accordingly:
They move faster in deep water and slower in shallow water. (Adjusting the Height control when using the wireframe
preview may appear to lower the ground level, but the wireframe camera always moves with the water level.)
Wave Strength Controls how big the resulting waves are when the ground height or steepness is animated. A value of
0 results in no waves.