Populating the Internet : Supporting Multiple Users and Shared Applications with VRML Wolfgang Broll

Permission to make digital/hard copies of all or part of this material for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage , the copyright notice, the title of the publication an its date appear, and notice is given that Abstract VRML —the Virtual Reality Modeling Language— has established as the standard description language for 3D worlds on the Internet. Although it recently has been extended by features in order to support behaviors and user interactions, enabling authors to realize interactive virtual worlds, there is still a lack of support to share such worlds with other users. In this paper we will present our approach on supporting large-scaled shared virtual worlds based on VRML by an appropriate network infrastructure as well as mechanisms to partition these worlds. We will show how virtual worlds can be populated by worldwide distributed users and applications, and the requirements to share behaviors and interactions between those. 1 INTRODUCTION VRML has established as the standard for the exchange of virtual worlds on the Internet. While the first version of VRML [2] was a static scene description language, its second version [3] [12] [22] as well as other VRML related extensions [1] [7] provide the possibility to create interactive virtual worlds. However the VRML community has already started to go for the next step, allowing several users distributed worldwide to share contents of virtual worlds and VR applications on the In-ternet. While the realization of shared VRML worlds within the current VRML 2.0 standard might only be realized by a skilled programmer (if the browsers supports a scripting language such as Java which provides appropriate network communication mechanisms), a more general approach is required to give a large number of users the ability to author shared VRML worlds. Several prototypes already exist, providing certain multiuser extensions to VRML [6] [8] [13]. Recently a new initiative called Living Worlds [15] was started by a couple of companies in order to provide a framework for networked VRML based on individual (company specific) extensions. In its initial draft it does not define standards for the exchange of data over the network, but allows each provider of multiuser technology (MuTech) to set up appropriate servers and define appropriate network protocols. To provide a uniform node interface to VRML worlds, the required extensions are encapsulated by rather complex …