Adobe After Effects CS4 - Manual (Page 261)

255 USING AFTER EFFECTS CS4
Animation and keyframes
Last updated 12/21/2009
When you place the first pin, the area within an outline is automatically divided into a mesh of triangles. An outline is
only visible when the Puppet effect has been applied and a Puppet tool pointer is over the area that the outline defines.
(See “
How the Puppet effect creates outlines ” on page 258.) Each part of the mesh is also associated with the pixels of
the image, so the pixels move with the mesh.
Note: To show the mesh, select Show in the Tools panel.
When you move one or more Deform pins, the mesh changes shape to accommodate this movement, while keeping
the overall mesh as rigid as possible. The result is that a movement in one part of the image causes natural, life-like
movement in other parts of the image.
For example, if you place Deform pins in a person’s feet and hands and then move one of the hands to make it wave,
the motion in the attached arm is large, but the motion in the waist is small, just as in the real world.
If a single animated Deform pin is selected, its Position keyframes are visible in the Composition panel and Layer panel
as a motion path. You can work with these motion paths as you work with other motion paths, including setting
keyframes to rove across time. (See “
Smooth motion with roving keyframes ” on page 243.)
You can have multiple meshes on one layer. Having multiple meshes on one layer is useful for deforming several parts
of an image individually—such as text characters—as well as for deforming multiple instances of the same part of an
image, each with a different deformation.
The original, undistorted mesh is calculated at the current frame at the time at which you apply the effect. The mesh
does not change to accommodate motion in a layer based on motion footage, nor does the mesh update if you replace
a layer’s source footage item.
Note: Don’t animate the position or scale of a continuously rasterized layer with layer transformations if you are also
animating the layer with the Puppet tools. The render order for continuously rasterized layers—such as shape layers and
text layers—is different from the render order for raster layers. You can precompose the shape layer and use the Puppet
tools on the precomposition layer, or you can use the Puppet tools to transform the shapes within the layer. (See “
Render
order and collapsing transformations ” on page 64 and “ Continuously rasterize a layer containing vector graphics ” on
page 158.)
The motion created by the Puppet tools is sampled by motion blur if motion blur is enabled for the layer and the
composition, though the number of samples used is half of the value specified by the Samples Per Frame value. (See
“
Motion blur ” on page 227.)
You can use expressions to link the positions of Deform pins to motion tracking data, audio amplitude keyframes, or
any other properties.
More Help topics
“ Motion paths ” on page 223
“ Expression basics ” on page 646
Online resources for the Puppet tools
For a video tutorial on using the Puppet tools, go to the Adobe website at www.adobe.com/go/vid0274 .
Aharon Rabinowitz provides a tutorial on the Creative COW website that shows a creative way to use the Puppet tools
with a particle generator to simulate airflow over a car.
John Dickinson provides a video tutorial on the Motionworks website that shows how to use the Puppet tools to
animate to music.
For a step-by-step tutorial demonstrating the use of the Puppet tools, see the “Distorting Objects with the Puppet Tools
in After Effects” chapter of the
After Effects Classroom in a Book on the Peachpit Press website.