A Java web application for allowing multiuser collaboration and exploration of existing VRML worlds
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1 Introduction
Imagine two researchers examining a three dimensional representation of their data together while sitting at desks 3000 miles apart. One of them spots an interesting wrinkle in the data’s otherwise smooth surface. Quickly, she sends off an instant message to the other, “Do you know what’s going on here?” She creates a viewpoint at her current location within the virtual world. The other researcher’s version of the world is updated to include the new viewpoint and he can get to the new location with a click in his browser’s window. “I have a graph that might explain that,” he types, and adds an image of his graph and an audio file containing his explanation at that location in the world. Now their colleagues, who explore the world at a later time, can view their annotations and understand the unusual data.
A Java Web Application for Allowing Multiuser Collaboration and Exploration of Existing VRML Worlds
Clifton G.M. Presser∗ Gettysburg College
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This work describes a new Java web application that enables users to explore and annotate VRML worlds collaboratively. The web application consists of a Java servlet, Java Server Pages (JSP) and supporting classes. There are two significant features of this work. First, users can explore existing standard VRML worlds collaboratively with automatic multiuser augmentation. Second, the user is free from the inconsistencies of interacting web browsers, a VRML browsers and a Java virtual machines. The clients are only required to have a web browser and a working VRML browser that can employ ECMAScript script nodes. Further, Java is not required on the client end. Through this web application, users can collaboratively navigate and annotate a virtual world with images, audio, text, video, viewpoints and tours.
There are a number of collaborative virtual environments that already exist. Most of these employ the Virtual Reality Modeling Language (VRML) along with the External Authoring Interface (EAI) [VRML ] to connect a 3D web browser to a Java applet that
One important contribution of this work is to allow multiple users to explore and collaborate within a virtual world that was built using standard VRML. Most existing systems require some form of extra programming or additions to standard worlds to allow collaboration. This work focuses on taking existing single-user VRML worlds and retrofitting them for a multiuser context. This is particularly important since many virtual world editors and visualization packages will generate standard VRML for users to explore.
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Figure 2: A typical client-server architecture. Communication is always initiated from the client.
Another important contribution of this work is to keep things simple for the user. Adding functionality to VRML worlds by supplying ones own code can be done using Java with the EAI, or by using ECMAScript, an internal scripting language. Java is a wonderful cross platform technology, but the flexibility seems to end when the technology is used with VRML browsers. Not all VRML browsers support EAI. Different web and VRML browsers support different Java virtual machines. Getting a working combination of web browser, VRML browser and Java virtual machine is a difficult task, particularly for someone who just wants to use the computer
∗e-mail: cpresser@gettysburg.edu
Copyright © 2005 by the Association for Computing Machinery, Inc. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Permissions Dept, ACM Inc., fax +1 (212) 869-0481 or e-mail permissions@acm.org. © 2005 ACM 1-59593-012-4/05/0003 $5.00
CR Categories: I.3.2 [Computer Graphics]: Graphics Systems— Distributed/network graphics I.3.6 [Computer Graphics]: Methodology and Techniques—Interaction techniques I.3.7 [ Computer Graphics]: Three-Dimensional Graphics and Realism—Virtual reality C.2.4 [Computer Communication Networks]: Distributed Systems—Distributed applications
can communicate with a server [Lovegrove and Brodlie 1998; Goddard and Sunderam 1999; Kirner et al. 2001; Swing 2000; Wernert and Hanson 1999; Swing 2000; McKinley et al. 1999; Manoharan et al. 2002; DeepMatrix ]. Others operate by adding extensions to the VRML language [Picard et al. 2002; Blaxxun ]. Still others employ different 3D technologies such as Java3D [Wang et al. 2002]. Our work, by contrast avoids the use of EAI and allows the easy use of existing VRML worlds which amount to a simpler environment for the user.
Keywords: VRML, Servlet, Collaboration, Java, ECMAScript, JSP
Figure 1: A screen shot of the client’s browser including a graph added as an annotation.