Loading and Rendering Optimization for Networked Virtual Worlds

Internet-based collaborative virtual environments allow users to explore and interact with many virtual worlds containing a very large number of objects that are downloaded in real time rather than been pre-distributed. Client's bandwidth fluctuation during the enjoyment of particularly complex environments, can produce a bottleneck that generates very long downloading and rendering time. This bottleneck can compromise the correct enjoyment of collaborative virtual environments, arising synchronization and shard state consistency problems that are keys factors in these applications. To avoid too much long waiting times during objects' download, we have developed a method to reduce bandwidth congestion. This is possible thanks to the download of only the exact portion of geometries that is necessary for rendering, according to its own field of view and to the semantic rules defined by the designer during the phase of contents population. Such approach consists in the use of a data structure that is based on different levels of priority and allows in this way a selective download. We have applied this solution to WT04 framework which is a research project whose aim is to achieve a framework for generating and enjoining 3D collaborative virtual experiences. WT04 framework supports collaborative rules definitions suitable to perfectly govern virtual experiences.