While analyzing my library of scenarios, I identified 18 primitive animation operations that cover the most natural ways of expressing the motions and transitions in the animations I collected. To make K-Sketch simultaneously fast, simple, and expressive, I developed a novel interface optimization analysis method. I used this to visualize the tradeoffs of supporting various combinations of animation operations and choose a small but powerful set of capabilities for K-Sketch. This method and the tools I developed can be applied to many other domains.
The final K-Sketch system uses pen input for sketching objects, intuitive demonstration of motion, and a suggestive interface for resolving ambiguous operations. In one laboratory experiment that compared K-Sketch to a more formal novice animation tool (PowerPoint), participants worked three times faster, needed half the learning time, and reported significantly lower cognitive load with K-Sketch. Another laboratory comparison with a less formal novice tool (The TAB Lite) showed that K-Sketch allows novices to express a wide range of animations quickly and intuitively. K-Sketch has been released to the world and is being used by over a thousand people to create rough animations.