A distributed virtual walkthrough environment allows users connected to the geometry server to walk through a specific place of interest, without having to travel physically. This place of interest may be a virtual museum, virtual library or virtual university. There are two basic approaches to distribute the virtual environment from the geometry server to the clients, complete replication and on-demand transmission. Although the on-demand transmission approach saves waiting time and optimizes network usage, many technical issues need to be addressed in order for the system to be interactive. CyberWalk is a web-based distributed virtual walkthrough system developed based on the on-demand transmission approach. It achieves the necessary performance with a multiresolution caching mechanism. First, it reduces the model transmission and rendering times by employing a progressive multiresolution modeling technique. Second, it reduces the Internet response time by providing a caching and prefetching mechanism. Third, it allows a client to continue to operate, at least partially, when the Internet is disconnected. The caching mechanism of CyberWalk tries to maintain at least a minimum resolution of the object models in order to provide at least a coarse view of the objects to the viewer. All these features allow CyberWalk to provide sufficient interactivity to the user for virtual walkthrough over the Internet environment. In this paper, we demonstrate the design and implementation of CyberWalk. We investigate the effectiveness of the multiresolution caching mechanism of CyberWalk in supporting virtual walkthrough applications in the Internet environment through numerous experiments, both on the simulation system and on the prototype system.

Article Free Access Share on On caching and prefetching of virtual objects in distributed virtual environments Authors: Jimmy H. P. Chim Department of Computing, The Hong Kong Polytechnic University, Hong Kong Department of Computing, The Hong Kong Polytechnic University, Hong KongView Profile , Mark Green Department of Computer Science, University of Alberta, Edmonton, Alberta, T6G 2H1, Canada Department of Computer Science, University of Alberta, Edmonton, Alberta, T6G 2H1, CanadaView Profile , Rynson W. H. Lau Department of Computer Science, City University of Hong Kong, Hong Kong Department of Computer Science, City University of Hong Kong, Hong KongView Profile , Hong Va Leong Department of Computer Science, City University of Hong Kong, Hong Kong Department of Computer Science, City University of Hong Kong, Hong KongView Profile , Antonio Si Sun Microsystems, 901 San Antonio Road, Palo Alto, CA Sun Microsystems, 901 San Antonio Road, Palo Alto, CAView Profile Authors Info & Claims MULTIMEDIA '98: Proceedings of the sixth ACM international conference on MultimediaSeptember 1998 Pages 171–180https://doi.org/10.1145/290747.290769Published:01 September 1998Publication History 51citation594DownloadsMetricsTotal Citations51Total Downloads594Last 12 Months27Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Distributed virtual environments allow users at different geographical locations to share and interact within a common virtual environment via a local network or through the Internet. To deliver a good performance for such applications, we need to address several issues in different research disciplines. First, we must be able to model virtual objects effectively. The recently developed multi-resolution techniques for object modeling are of great value here, since they are capable of simplifying the object models and therefore reducing the time to render them. This may greatly reduce the demand for rendering performance on the client machines. Second, with the constraint of the limited bandwidth of the Internet, we need to reduce the response time by reducing the amount of data requested over the network. Caching of suitable object models of high affinity will reduce the amount of data requested over the network for a faster response time. Prefetching object models by predicting those ...