In After Effects, each mask vertex (the yellow squares) interpolates in a straight line from old to new positions. The red lines illustrate some of these paths. The First Vertex is the largest box – in this case, the one in the upper left corner of the M and I.
Masking is one of the core features of After Effects. Most know how to create and edit Mask Shapes; fewer how to control the way these shapes animate – which is important, especially with the popularity of creating cel or Flash type animations these days.
After Effects can seem to have a twisted mind of its own when interpolating between two different Mask Shapes. In reality, it has a very narrow, simple mind. However, there are some tricks you can employ to coax it down a path closer to the one you want. When you need even more precise control, you can employ the Smart Mask Interpolation keyframe assistant, included in the Professional edition of After Effects (including CS3 Professional).
Chris & Trish Meyer are the founders of CyberMotion, an award-winning Los Angeles motion graphic design studio. Their design and animation work has appeared on shows and promos for CBS, NBC, ABC, Fox, The Learning Channel, HBO, and PBS. CyberMotion was one of the first studios to create major release film opening titles using desktop tools (including major films such as The Taleneted Mr. Ripley), and they have also created promotional and trade show videos for corporate clients from Apple Computer to Xerox. They specialize in unusual format videos, having animated for IMAX, CircleVision, the NBC AstroVision sign in Times Square, and the four-block-long Fremont Street Experience in Las Vegas.