Adobe After Effects - Manual (Page 562)

Note:
Bottom
Scaling
Repeat Mode
If Layer Size Differs
Blur
Water Surface
Wave Height
Eran Stern provides a video tutorial on the Creative COW website in which he demonstrates how to use the Caustics effect with the Wave World
effect.
The Caustics effect ignores masks and alpha channels on the layer to which it is applied. You can precompose the layer with the effect and
apply the mask to the precomposition layer, or you can precompose the layer with the mask and apply the effect to the precomposition layer,
depending on what result you want to achieve. (See Precomposing, nesting, and pre-rendering.)
This effect works with 8-bpc color.
Original (upper-left), and with Bottom set to the text layer (lower-left) and Water Surface set to the whirl layer with Surface Opacity set to 0%
(lower-right)
To get the most realistic results from Caustics, render the Bottom layer separately, with Render Caustics enabled and Surface Opacity at 0.
Then precompose, and use the resulting layer as the Bottom layer for another Caustics effect with Render Caustics off. With this process you
can offset, scale, or otherwise manipulate the Bottom layer in the precomposed composition, and thus simulate lighting that doesn’t come from
straight overhead.
Bottom controls
The Bottom controls specify the appearance of the bottom of the body of water:
Specifies the layer at the bottom of the body of water. This layer is the image that is distorted by the effect, unless Surface Opacity is
100%.
Makes the bottom layer larger or smaller. If the edges of the bottom layer show, because of the refraction of the light through the waves,
scale up the bottom layer. Scaling down is useful for tiling a layer to make a complex pattern.
Specifies how a scaled-down bottom layer is tiled. Once uses only one tile, basically turning tiling off. Tiles uses the traditional tiling
method of abutting the right edge of one bottom layer tile to the left edge of another bottom layer tile. This option works well if the bottom layer
contains a repeating pattern, like a logo, that needs to read a certain way. Reflected abuts each edge of a bottom layer tile to a mirrored copy of
the tile. This option can eliminate a hard edge where the two tiles meet.
Specifies how to handle the bottom layer when it is smaller than the composition.
Specifies the amount of blur applied to the bottom layer. To make the bottom sharp, set this control to 0. Higher values make the bottom
appear increasingly blurry, especially where the water is deeper.
Water controls
Specifies the layer to use as the surface of the water. Caustics uses the luminance of this layer as a height map for generating a
3D water surface. Light pixels are high, and dark pixels are low. You can use a layer created by using the Wave World or Radio Waves effect;
precompose the layer before using it with Caustics.
Adjusts the relative height of the waves. Higher values make the waves steeper and the surface displacement more dramatic.
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