Performance timing for keyframe animation

Keyframing is a standard technique for generating computer animation that typically requires artistic ability and a set of skills for the software package being used. We are interested in addressing the needs of the novice animator who is not necessarily artistically skilled or familiar with keyframing interfaces. From our experience observing novice animators, it is clear that setting keyframe values is straightforward while specifying the keyframe timing is difficult and often time consuming. We present a novel method for novice users to time keyframes using gestures without changing the motion itself. The key to our approach is the separation of specification of keyframe values from the specification of keyframe timing. Our approach allows the user to "act-out" the timing information using a simple 2D input device such as a mouse or pen-tablet. The user's input is analyzed and features of the user's input are mapped to features of the keyframed motion. The keyframes are then distributed in time according to the timing of the user's input path. We have implemented the approach as a plugin to the AliasWavefront Maya modeling and animation package. We demonstrate the approach on several example scenes and discuss its strengths and limitations.