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COLLABORATIVEVIRTUALREALITY 593steering. The ultimate goal is not to reproduce a face-
to-face meeting in every detail, but to provide the next-
generation interface for collaborators, worldwide, to work
together in a virtual environment that is seamlessly en-
hanced by computation and access to large databases. Al-
though the goal of audio and video teleconferencing is to
allow distributed participants to interact as though they
are in the same physical location, collaborative virtual
reality allows them to interact as though they are the same
immersive virtual environment. This way they can inter-
act with each other as well as the objects in their shared
environment.
This shared environment may be for designing a new
car, visualizating climatological data, or visiting other 3D
space that either does not exist physically or cannot be
physically accessed. The participants are not talking about
a thunderstorm, they are standing inside one; they are
not looking at a scale model of a new car design, they
are standing inside the full-size engine block. We believe
that by transmitting gestures as well as audio and video
between collaborators, these shared virtual environments
give their users a greater sense of presence in the shared
space than do other collaborative mediums. By encourag-
ing collaboration and conversation within the data, these
environments may become the preferred place to work
and interact even when traditional face-to-face meetings
are possible. However, collaborative virtual reality is not
going to replace e-mail, phone calls, or existing telecon-
ferencing systems. They each have their strengths and
uses. Just as word processing documents, spreadsheets,
and white boards shared across the Internet put discus-
sions in their appropriate contexts, so does sharing a vir-
tual space as well as the 3D design being considered or the
simulation being visualized. A more thorough discussion
can be found elsewhere (Leigh, Johnson, Brown, Sandin,
& DeFanti, 1999)
For example, General Motors uses collaborative virtual
reality to allow design and manufacturing teams based in
several sites around the world to import 3D computer-
aided design (CAD) models into the CAVE for quick vi-
sual inspection and design reviews at 1:1 scale. The goal
is to allow designers to both synchronously and asyn-
chronously access a design that persists and evolves over
time from locations scattered around the world rather
than forcing collaborators to meet physically at the 1:1
scale clay model. A typical working scenario involves a
designer making modifications on a workstation in a 3D
modeling package and having those changes propagate
automatically to the networked virtual environment, al-
lowing all collaborating participants to see the changes
simultaneously. They are then able to critique the design
and suggest changes to the designer who can do so imme-
diately at the CAD work station.
The Virtual Reality in Medicine Laboratory at the Uni-
versity of Illinois at Chicago uses collaborative virtual
reality to allow a remotely located physician to teach med-
ical students about the 3D structure and function of the
inner ear. In this environment, the students and instruc-
tor may point at and rotate the ear to view it from various
perspectives. They may also strip away the surrounding
outer ear and temporal bone to more clearly view the in-
ner anatomy. Audio from the voice conference is used tomodify the flapping of the eardrum to illustrate its func-
tion. This application is effective because it leverages the
stereoscopic capabilities of virtual reality to disambiguate
the spatial layout of the various structures in the inner
ear—something difficult to do on standard flat images in
medical textbooks.
College undergraduates at Central Missouri State Uni-
versity and other universities use Virtual Harlem, a vir-
tual reality reconstruction of Harlem, New York, during
the 1920s, in their English classes. Virtual Harlem was
designed to immerse students of the Harlem Renaissance
directly in the historical context of the literature of that
period to reinforce active learning. The goal is to develop
rich, interactive, and narrative learning experiences to
augment classroom activities for students in the human-
ities. Collaborative virtual reality allows classes at differ-
ent universities to meet and share their views within its
space, as well as allowing remote expert tour guides to
take classes through Virtual Harlem and discuss impor-
tant issues that the space brings up. This is discussed fur-
ther elsewhere (Sosnoski & Carter, 2001).
Some virtual environments will only exist while people
are inside it; others will be maintained by a computer sim-
ulation that is constantly left running. This space exists
and evolves over time. Users enter the space to check on
the state of the simulated world, discuss the current situ-
ation with other collaborators in the space, make adjust-
ments to the simulation, or leave messages for collabora-
tors who are currently asleep on the far side of the planet.
For example, in a computational steering application, a
supercomputer may be running a large simulation that
takes several days to complete. At regular intervals, the su-
percomputer produces a 3D snapshot of the current data,
perhaps a visualization of cosmic strings. A scientist can
then step into a CAVE and look at the 3D data that has been
produced to see whether the simulation is progressing cor-
rectly or whether it needs be tuned, to focus on particular
details rather than wait for the simulation to complete.Avatars
Presence in the virtual world is typically maintained us-
ing anavatar,or a computer-generated representation of
a person. These avatars may be as simple as a pointer
that depicts the position and orientation of the wand in
the virtual world. However, having representations of the
physical bodies of the collaborators can be helpful in aid-
ing conversation and understanding in the virtual space,
as you can see where your collaborators are and what
they are looking at or pointing at. Tracking the user’s head
and hand position and orientation allows the computer
to draw computer-generated characters representing each
of the remote collaborators. These articulated characters
move along with the remote user and are able to transmit a
reasonable amount of body language, such as pointing at
objects and nodding or tilting the head. This style of avatar
is useful in task-oriented situations, but do not work as
well in negotiations.
Seeing high-quality live video of a person’s face can im-
prove negotiations. Video avatars, full-motion full-body
videos of users, are realistic looking, which improves
recognition of collaborators but require much higher