Adobe 65008009 - After Effects CS4 Using Manual page 337

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Last updated 12/21/2009 USING AFTER EFFECTS CS4
Drawing, painting, and paths
curved segment; otherwise, it applies the polylines algorithm. Curve applies the algorithm for mask paths that have
curved segments. Polyline applies the algorithm for mask paths that have only straight segments.
Note: The mask path keyframes added by Smart Mask Interpolation are polylines when Polyline Matching Method is
selected, regardless of whether the input mask paths contained curved segments.
Specifies that Smart Mask Interpolation creates a vertex on one mask path that matches the
Use 1:1 Vertex Matches
same-numbered vertex on the other mask path. On each of the input mask paths, Smart Mask Interpolation matches
the first vertices, the second vertices, the third vertices, and so forth. If the two paths have unequal numbers of vertices,
this action may produce undesirable results.
Specifies that Smart Mask Interpolation matches the first vertices in the two mask path keyframes.
First Vertices Match
If not selected, Smart Mask Interpolation searches for the best first-vertex match between the two input mask paths.
Note: To ensure good results, make sure that the first vertices of the input mask paths match, and then select First Vertices
Match.
More Help topics
"Keyframe interpolation" on page 231
Additional resources about animating masks with Smart Mask Interpolation
Chris and Trish Meyer provide some tips on animating masks, including using Smart Mask Interpolation, on the
ProVideo Coalition website.
Move a mask or pan a layer behind a mask
You can adjust the area that is visible through a mask by either moving the mask in the Layer or Composition panel
or panning (moving) the layer behind the mask in the Composition panel. When you move a mask, the Position values
of the masked layer remain constant, and the mask moves in relation to other objects in the Composition panel.
When you use the Pan Behind tool to pan a layer behind a mask, the position of the mask remains constant in the
Composition panel but changes in the Layer panel. The Position values of the masked layer change in relation to the
composition. As you pan past the edges of the layer frame, the Mask Path values on the layer also change. Using the
Pan Behind tool saves steps; without it, you would have to change the Position and Mask Path properties of the masked
layer manually. You can animate a layer panning behind another layer by setting keyframes for the Position and Mask
Path properties of the masked layer.