The proliferation of interest in collaborative computer applications in the past decade has resulted in a corresponding increase in the interest in multiuser interfaces. This research seeks to contribute to an understanding of the process of developing user models for group interaction and to the design and implementation of multiuser interfaces based on the model. Group ranking was used as an exemplar task. User requirements were identified by observing groups perform the ranking task in a noncomputer environment. A design was proposed based on the identified requirements and a prototype implemented. Feedback from informal user evaluation of the implemented interface is reported. Insights on the methodology are discussed.

In computer cinematography, the process of lighting design involves placing and configuring lights to define the visual appearance of environments and to enhance story elements. This process is labor intensive and time consuming, primarily because lighting artists receive poor feedback from existing tools: interactive previews have very poor quality, while final-quality images often take hours to render.This paper presents an interactive cinematic lighting system used in the production of computer-animated feature films containing environments of very high complexity, in which surface and light appearances are described using procedural RenderMan shaders. Our system provides lighting artists with high-quality previews at interactive framerates with only small approximations compared to the final rendered images. This is accomplished by combining numerical estimation of surface response, image-space caching, deferred shading, and the computational power of modern graphics hardware.Our system has been successfully used in the production of two feature-length animated films, dramatically accelerating lighting tasks. In our experience interactivity fundamentally changes an artist's workflow, improving both productivity and artistic expressiveness.