The remote rendering pipeline : managing geometry and bandwidth in distributed virtual environments

Abstract

The contribution of this thesis is at the place where interactive 3-D computer graphics and distributed systems meet. Virtual Environments are concerned with the convincing simulation of a virtual world. One of the most promising aspects of this approach lies in its potential as a way of bringing people together, as a virtual meeting place. To overcome current restrictions in network performance and bandwidth, techniques that have already been used for improving the rendering performance for virtual reality applications can be adopted and enhanced. In this context, we develop the concept of the remote rendering pipeline, that extends the traditional rendering pipeline for interactive graphics to include the network transmission of geometry data. By optimizing the steps of the remote rendering pipeline, and combining these improvements, a system that is better prepared to deal with complex and interesting virtual worlds emerges. After a discussion of the state of the art in the fields of interactive 3-D graphics and distributed virtual environments, the remote rendering pipeline is introduced, a conceptual model of rendering in distributed systems. Its elements are discussed in the following chapters: the demand-driven geometry transmission protocol, a strategy for managing partially replicated geometry databases for virtual environments; an octreebased level of detail generator; smooth levels of detail, a novel data structure for incremental encoding and transmission of polygonal objects; and a modeling and rendering toolkit for directed cyclic graphs allowing a compact representation of a large class of natural phenomena.