DIRECT MANIPULATION ANIMATION (1994)

This research introduced a new set of interface techniques for visualizing and editing animation directly in a single three-dimensional scene. Motion is edited using direct-manipulation tools that satisfy high-level goals such as “reach this point at this time” or “go faster at this moment”. These tools can be applied over an arbitrary temporal range and maintain arbitrary degrees of spatial and temporal continuity.

The interface separates spatial and temporal control of position by using two curves for each animated object: the motion path which describes the 3D spatial path along which an object travels, and the motion graph, a function describing the distance traveled along this curve over time. Our direct-manipulation tools are implemented using displacement functions, a straightforward and scalable technique for satisfying motion constraints by composition of the displacement function with the motion graph or motion path. The research focuses on applying displacement functions to positional change. However, the techniques presented are applicable to the animation of orientation, color, or any other attribute that varies over time.

A refined version of these techniques were incorporated into Adobe After Effects between 1994 and 1996 and are still in use.

Publications

Snibbe, S. A Direct Manipulation Interface for 3D Computer Animation. Computer Graphics Forum, Proceedings of EUROGRAPHICS 95, pp. 271-283.

Snibbe, S. Gestural Controls for Computer Animation. Master’s Thesis. Brown University 1994

ACKNOWLEDGMENTS

This research was supported by Professor Andy van Dam, and my Masters’ Thesis Advisor Professor John Hughes, who provided many stimulating discussions and helped me develop the underlying mathematical techniques. Cindy Grimm, Brook Conner and many other members of the Brown Graphics Group provided excellent feedback on several drafts of this paper. This research was sponsored in part by NASA, the NSF/ARPA Science and Technology Center for Computer Graphics and Scientific Visualization, Sun, Autodesk, Taco Inc., NCR, HP, IBM, DEC, Apple, Microsoft and Adobe Systems.