Papers in PDF format

Abstract
Browsing 3D Bookmarks in BED
Serge Rezzonico (rezzoni@lig.di.epfl.ch)
Daniel Thalmann
Computer Graphics Lab, Swiss Federal Institute of Technology
LIG-DI-EPFL 1015 Lausanne, Switzerland
In this paper BED, a prototype of a 3D bookmarks generator, is presented. This work tries to show a way of improving navigation in the Web using
a cyberspatial[*] representation based on VRML. First, the general problem of creating a visual representation of abstract data is discussed and
existing systems are reviewed. Then, some 3D space characteristics are explained and finally our generator is introduced and some examples
shown.
Keywords: VRML, abstract data space, bookmarks, automatic generator
1 Introduction
Why do people get lost while moving through the World Wide Web ? Unlike a real spider web, the net millions of people are reported to be using every day
for work and entertainment doesn't have a regular and beautiful structure. Like a real spider web, the net is a trap for the unprepared creatures that wander
into it. Our Web doesn't have apparent limits, is not regular and is too big to be looked at all at once. One reason for this complexity is that there's no one
single spider building and maintaining it. Instead, there's a myriad of single entities building their own sites with countless links to others. Naturally, when a
situation is complex, humans tend to take notes, draw maps or build models. Exploring the web, one can take note of interesting places and build a list of
"hot links". Why not create a 3D scene and navigate through all these links with VR techniques ? Three-dimensional navigation is considered as intuitive
because of the natural human skill of moving in a 3D space. After all, that's where we live (even if we mostly move in 2D, due to gravitational constraints).
2 Creating 3D representations of data
The problem is that a 3D scene has to be generated from data which a priori has no correspondence with real physical space. Any spatial configuration that
we will choose will be arbitrary. Nevertheless, this is not new. A similar problem appears when dealing with a file system and trying to give a user-friendly
view of it. A huge and complex file system can sometimes be as hard to examine and search as a city's sewage system, if done in the archaic command line
mode. Now that the 2D desktop metaphor is adopted by everybody, even PCs, this is an accepted fact. Some projects go one step further and develop a 3D
file system representation. Because files are organized in a hierarchical way, the 3D space correlation is less arbitrary than in the general case.
Cone-Trees
One of the pioneer research groups, Xerox PARC, implemented this information visualization system where directories are situated at the apex of a cone and
files and subdirectories are on the circular base of the cone. Any data element can be selected, the cone-tree then rotates bringing that element to the
foreground for easier inspection. This system allows to display lots of information without becoming unusable. "Perspective walls" can also be used to show
projections of the cone-tree on different planes (like cast shadows).
FSN
Developed at SGI, the "Fusion" File System Navigator [1] [Stra92] visualizes files and directories as 3D bars and platforms connected with paths. A bar's
dimension and color indicates the size and age of that file.
The effort to create advanced visualization systems where the user can "read" the information faster (and possibly understand it better) is not limited to file
systems. According to [Benf95], creating a graphic representation of generic data can be done in four ways:
Data attributes can be mapped onto spatial and visual dimensions, which are the extrinsic and intrinsic dimension described by Benedikt (see section 3).
Data can be clustered with statistical methods that can show some logical similarity.
Data can be organized with a hyperstructure approach, with tree and network drawing schemes. This works well with data that are already hierarchically
structured like file systems (FSN and cone-trees belong to this category).
Data can be represented with real-world metaphors, like the 2D desktop metaphor popularized by Apple with the MacOS or the recent document
visualizer developed by Tenet and Webmaster in VRServer [2]: 3D corridors and doors lead to directories and files.
Q-Pit, VR-Vibe, VR-Mapper
These prototypes, developed within the DIVE system [Carl93], show three different approaches to abstract data visualization systems. All of them are in fact