P1: IXL/GEG P2: IXL
WL040A-22 WL040/Bidgolio-Vol I WL040-Sample.cls June 20, 2003 17:34 Char Count= 0
598 VIRTUALREALITY ON THEINTERNET:COLLABORATIVEVIRTUALREALITYtraditional interface tools and applications. Collaborators
may also augment their virtual reality displays with hand-
held computers: Laptops, hand helds, and tablets provide
additional simultaneous display of additional informa-
tion.THE FUTURE
In the 1990s, large, specialized graphics computers were
required to drive virtual reality displays. Today, commod-
ity personal computers with high-end graphics cards do
very well. The future will see faster PCs with more power-
ful graphics cards, allowing more people to join in collab-
orative virtual environments. Currently, for under than
$10,000, a person can build a passive stereo projection-
based virtual reality system driven by a PC that allows
the user to collaborate with others (www.geowall.org). If
Moore’s law continues to hold true, every 18–24 months
these PCs will double in capability while their cost re-
mains constant.
The capacity of high-speed networks is growing even
faster than is stated in Moore’s law. Currently, network ca-
pacity is doubling every 8 months. Such technologies such
as dense wave division multiplexing allow multiple light
waves to share a single fiber-optic cable. Each of these
light waves can provide between 1 and 10 Gbits/s of band-
width, and each fiber is able to hold hundreds of light
waves. Two challenges are emerging from this. The first is
to find ways to bring this extreme amount of bandwidth
to end users’ desktops—what is commonly known as the
“last-mile problem.” That is, there is an explosive growth
of network capacity at the core of the network but no way
to extend that capacity to end users. The second challenge
comes from a realization that there is more network ca-
pacity available than a single user’s desktop computer can
possibly generate or absorb. This means that future appli-
cations of high-capacity networks will consist of clusters
of computers communicating with other clusters of com-
puters. The extremely-high-capacity networks that con-
nect these clusters of computers will become the new sys-
tem bus. The computer will no longer be thought of as the
box on your desktop. The desktop computer will simply be
the display peripheral for the larger computer that is dis-
persed around the world, interconnected by high-capacity
networks.
For collaborative virtual reality, this will translate
into ever more realistic visual experiences, where virtual
worlds are populated by synthetic participants who are
indistinguishable from human participants. If the virtual
experience is compelling enough, some users may prefer
to forego physical travel altogether and travel only within
cyberspace. For example, they may prefer to take virtual
vacations. For people with disabilities that make difficult
the rigors of physical travel, this can be a very liberat-
ing experience. But even for able-bodied travelers, virtual
travel could mean the end of waiting in security lines at
airports and sitting in airplanes for hours.
The challenge then will be in developing more com-
pelling experiences or ways for participants to create their
own experiences. This is likely to be the future of the video
game and movie industry.CONCLUSION
Our goal isn’t simply to make working in collaborative
virtual reality environments possible. It’s to make it conve-
nient: convenient access to virtual reality hardware, con-
venient access to virtual worlds, convenient synchronous
or asynchronous access to collaborators, and convenient
methods for sharing data. As the technology becomes
cheaper and more available, more and more people in
different domains will work in collaborative virtual real-
ity environments, and more applications will be created
and evaluated. Their success will be based not on how they
recreate reality but on how they leverage virtual reality to
make the collaboration better than being there in person.GLOSSARY
Asynchronous Collaboration Two or more people co-
operating in a task at different moments in time; com-
munication not in real time but through passed mes-
sages and shared artifacts.
Avatar A computer-generated representation of a parti-
cipant in a shared virtual reality environment.
CAVE CAVE automatic virtual environment; a projec-
tion-based virtual reality display environment created
at the Electronic Visualization Laboratory consisting
of three walls and a floor, a tracking system, an audio
system, and an interface controller.
Jitter Variability in latency.
Latency The time it takes for a piece of data to get from
one site to another.
QoS Quality of service; the ability to provide guarantees
on bandwidth and latency for the transfer of informa-
tion over networks; important when multiple hetero-
geneous real-time data streams (audio, video, avatar
data, control data, etc.) are moving between clients in
a collaborative virtual reality environment.
Synchronous Collaboration Two or more people coop-
erating in a task at the same time and having real-time
feedback on their partners’ actions.
TCP Transmission control protocol; a reliable Internet
protocol that requires more overhead than does UDP,
which makes it suitable for transmitting control infor-
mation in collaborative virtual reality environments.
UDP User datagram protocol; an unreliable Internet
protocol that requires less overhead than does TCP,
making it suitable for transmitting avatar position
information in collaborative virtual reality environ-
ments.CROSS REFERENCES
See Distance Learning (Virtual Learning); GroupWare;
Interactive Multimedia on the Web; Multimedia; Virtual
Enterprises; Virtual Teams.REFERENCES
Churchill, E., Snowdon, D., & Munro, A., Eds. (2001).
Collaborative virtual environments: Digital places and
spaces for interaction. New York: Springer Verlag.
Imai, T., Qui, Z., Behara, S., Tachi, S., Aoyama, T.,
Johnson, A., & Leigh, J. (2000). Overcoming time-zone