Animation is a powerful communication and visualization medium that is accessible to few, because current tools for creating animation are extremely complex. Simple animation tools exist, but they severely restrict the types of motion that can be expressed. To help novices create a wide range of animations quickly, I have developed a general-purpose, informal, 2D animation sketching system called K-Sketch, a kinetic sketch pad. My investigation began with field studies that explored the many uses of short, rough animations both by expert animators and would-be animators. The most significant results of these studies were evidence of the need for K-Sketch and a library of 72 usage scenarios for such a tool. These scenarios show how rough animation can be useful both to experts creating prototypes of animations and to novices creating animations for entertainment, visualization, or communication of dynamic concepts in a wide variety of educational or business settings.

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.