VRML: From the Web to Interactive Multi-User Virtual Reality

1 Abstract VRML (Virtual Reality Modeling Language) has already established itself as a standard for the exchange of 3D descriptions on the Internet. However, it is a completely static description, with no support for virtual worlds with several users and applications, or with a high number of dynamic objects. In this paper we want to examine how VRML can be extended to fit the requirements of an interactive, distributed, multiuser virtual environment. This paper considers three major fields where VRML needs to be extended: (1) the network components to support multiple users and to achieve consistent worlds, (2) an event model, including a naming scheme and support for arbitrary input and output devices , and (3) an object-oriented interaction model, which allows the modeling of interactions and behaviors , that can be extended to support complex applications. Already a few month after the first Internet browsers were released, VRML was established as the standard 3D format for the distribution of virtual worlds on the Internet. In its initial version it is still closely related to existing products. On the one hand the WWW (World Wide Web), which uses the same protocol (HTTP) to transmit data. Additionally VRML browsers are usually called from HTML pages at the Web. On the other hand Open Inventor [Wer94], since the initial draft specification was almost a subset of it. Nevertheless the development of VRML started very fast to become a dynamic process, as VRML becomes more and more independent of its parents. Currently, VRML still is a static scene description language, which does not include interaction or object behavior. The aim of this paper is to show possible extensions to add multiuser support as well as interactions and rich behavior. MultiUser Support In the first part of this paper we want to examine how VRML could be extended to support cooperative, multiuser worlds on the Internet. We wish to examine how cooperation can be supported without radically altering VRML. As an emerging standard radical changes are unacceptable. Currently each VRML client communicates isolated to a HTTPD server. Ideally we should be able to provide a smooth transition from the existing, isolated-client model to a communicating clients model. The problem of the distribution of artifacts in virtual worlds can be tackled at two levels. Firstly there are problems of multiuser access to virtual worlds and how changes to shared environments might be managed. Secondly there …