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SYNTHETIC WORLDS SPRING TO LIFE CIENCE

the left and right eyes. This

dis-parity, when processed by the

human brain, results in stereo

vision. Attached to the helmet is

a small sensor that tracks the

viewer's head movements. The

computer accordingly adjusts the

view, so that the user gets the

impression of looking, walking, or

even flying around the virtual

world.

The success of HMDs

stimu-lated excitement about VR and

marked the beginning of an

inno-vative industry. Current I{MDs

range from devices used in

chil-dren's games, costing under a

hundred dollars, to those used for military purposes, priced at

sev-eral hundred thousand dollars.

On the down side, however, most

HMDs are characterized by a

narrow field of view, low-quality

144 THE WORLD & I

displays,

inaccurate motion

tracking, and severe user

dis-comfort.

A less intrusive system is the BOOM (Binocular

0mm-Ori-entation Monitor), marketed by a

company named Fakespace, of

Mountain View, California. The

BOOM, also called a

head-cou-pled display device, has two

dis-play screens housed in a

"float-ing" box that is attached to a

multilink arm. The user looks

into the box through two holes,

sees the virtual world, and guides

the box effortlessly to any

posi-tion within an operaposi-tional space.

The BOOM provides

im-proved display quality, a wider

field of view, and superior

track-ing through special sensors. For the user, the box seems almost

weightless. He may move his

The experience of Immersion In a synthetic environment can be attained using various types of equipment. Left: A head-mounted display with earphones allows synchronous reception of visual and auditory signals, while the wired gloves permit interactions with virtual objects. Opposite: The

BOOMTU, marketed by Fakespace of

Mountain View, California, is less cumbersome and gives higher-quality Images with superior tracking. Here, a student of naval architecture and marine engineering at the University of Michigan uses it to examine the virtual prototype of a

yacht.

head away from the box at any time, either to relax or to show

another person something of

interest in the virtual world.

These practical advantages, com-bined with high-precision

track-ing, have made the BOOM a

favorite device for industrial

applications that require

preci-sion and usefulness in routine

tasks.

Currently, the most

ad-vanced immersive system is

known as the CAVET' (Cave

Automatic Virtual Environment),

based on a radically different

design. Developed by the

Univer-sity of Illinois at Chicago and first

demonstrated in 1992, this sys-tem creates an immersive

envi-ronment by projecting stereo

images on the walls and floor of

a room-sized cube. Coordination

of the projection systems can

result in the illusory

disappear-ance of the corners of the cubical

room.

The CAVE can accommodate

several persons, allowing them to s

walk freely inside the room.

Images for the left and right eyes are projected in a rapid,

alternat-ing sequence. To observe the

images in stereo, viewers wear

lightweight, LCD (liquid crystal

display) shutter glasses, which

alternately block the left and

right eyes, in synchrony with the projection sequence. The immer-sive experience is most convinc-ing, and users sometimes cannot distinguish between real and

vir-tual objects. The one

drawback is that CAVE installations are

expen-sive. They are found

mainly in large research

laboratories and key

industries in the United

States and Europe.

Based on similar

principles but available at much lower cost is a

tablelike device

mar-keted under the names

ImmersaDesk

Pyramid Systems

Southfield, Michigan)

and Immersive

Work-Bench' (by Fakespace).

A stereo image is

pro-jected on a surfa that is

either horizontal or tilted. The

device allows several viewers

equipped with stereo glasses to

interact with a 3-D model that

seems to rise out of the table.

In an immersive

environ-ment, the user is often tempted to touch or grab virtual objects,

leading to the embarrassing

real-ization that "there is nothing

there!" But for many applications,

interactions with virtual objects

are important. One device that

has been developed for this

pur-pose is the data glove, equipped with sensors that monitor hand

and finger movements. The

com-puter generates a 3-D model of

the user's hand, moving it in con-cert with the user's real hand and

displaying it at the appropriate location in the virtual

environ-ment. Alternatively, a simpler

device such as a joystick or hand-held wand may be used.

The illusion of immersion

can be significantly enhanced by

involving nonvisual modalities.

But given the diversity of the

human sensory system, current technology is far from

stimulat-ing nonvisual senses in a realistic

way. Simple, daily experiences such as feeling the weight of an

object, enjoying the warmth of the

sun, or stretching out on a

waterbed are extremely difficult

to reproduce in a virtual setting.

Progress has been made,

however, in the areas of auditory

and haptic (touch-related) tech-nologies. Computer-generated

virtual sounds conveyed through

earphones not only underscore the virtual atmosphere but

pro-vide the user with a stereophonic

impression of the environment. The use of so-called directional sound gives the user the

loca-tions of sound sources within the

virtual world.

The development of haptic devices is also receiving much

attention.

Currently,

these

devices provide feedback that is

classified as either "tactile" or

"force." Tactile feedback creates

the sensation of touching a

vir-tual objectfor instance, by a

gloved hand that senses tiny

elec-trical currents or the inflation of small bubbles. Force feedback

JANUARY 1998 145

LENCE

L ATTHE EDGE

SYNTHETIC WORLDS SPRING TO LIFE

In a fully immersive system called the CAVE, stereo images are projected onto the walls and floor of a cubical room. Shown here is a model of a second-generation CAVE named C2, designed by a research team at Iowa State University.

devices involve

computer-con-trolled forces that impede the

user's movements. For example,

a force feedback joystick may give

the user the feeling of fighting

inertia when attempting to move

an object.

Applications aplenty

Imrnersive rh-tuaJ reality can be

seen as a new paradigm for

exploring and interacting with

complex, computerized data sets.

Unlike conventional computer capabilities, this technological innovation presents the virtual

world in 3-D, on a scale that

relates properly to human size. It

146 TRE WORLD & I

allows realistic interactions with virtual objects, combines

nonvi-suai modalities with the visual

experience, and has the potential

to allow users at remote sites to

share the immersive experience.

These unique characteristics

make VR highly useful in a broad range of applications.

For instance, VR systems are being used by the U.S. xni]itaiy to

help train fighter pilots in

com-bat scenarios and to prepare

sol-diers for dangerous battlefield encounters at remote locations.

Potential civilian training

appli-cations include the simulated

handling of accidents, the opera-tion of complex equipment, ship maneuvering, and the practice of hot-air balloon landings.

VR offers a superior tool for

the visualization and

under-standing of complex, 3-D

struc-tures, such as in engineering

designs or human anatomy. In addition, virtual environments

allow a person to study reproduc-tions of archaeological structures

and sites; to visit underwater

shipwrecks without knoving how

to dive; or to explore planetary

systems and galaxies,

transcend-ing the limitations of traveltranscend-ing through the real universe.

In architecture and urban

planning, VR systems allow for the presentation and evaluation of envisioned projects. A walk

through a virtual building can

convey the architect's conoept and

its intended impression on a

vis-itor.A virtual model of a new air-port tez-minal allows simulation

of the complex operations in a

busy airport environment.

In the medical arena, VR is

being explored for education and

training in areas like anatomy, diagnosis, surgery, or team

col-laboration. Manufacturers of

medical instruments simulate

equipment operation and set up a virtual surgery room to study

optimal placement of equipment

and personnel. An interesting

development is in the treatment

of phobias. Specifically,

acropho-bia (the fear of heights) can be

readily simulated in a virtual

environment and used to expose a patient gradually to real-world situations.

The author's line of research in VR concentrates on industrial

applications that use the

tech-nology for the analysis of

com-plex, 3-D arrangements as found in aircraft, spacecraft, ships, cars, and similar products. Virtual

pro-totypes of these designs reduce the number of costly,

time-con-suming, physical mock-ups that are built to veri new concepts.

Likewise, virtual simulation of

manufacturing processes,

assem-bly sequences, or maintenance tasks can facilitate early

detec-tion of design flaws.

The immersive experience is ultimately created by processing bits and bytes in a computer. It is therefore just a logical next step

to send these signals through

computer networks and develop distributed VR applications. This

would introduce a truly new

dimension to the immersive

expe-rience. In such a case, users at distant locations could meet in the same virtual environment, see and communicate with one

another, and perform interactive tasks in the shared virtual world. Such environments, however, are

hampered by the need for

extremely high network

trans-mission capabilities.

Today, the term VR is also

used for applications that are not filly immersive. The boundaries

are becoming blurred, but all

variations will be important in

the future. For instance, a viewer

wearing stereo glasses may

observe 3-D environments on a conventional computer monitor with mouse-controlled

naviga-The Immersive WorkBenchTM from

Fakespace provides a semi-immersive experience by projecting 3-D, computer-generated models onto a tabletop. In an application illustrated here, the simulation of a contour-mapped, rough terrain could be used to assist with military engagement planning.

tion. Multiple viewers can be

accommodated by large-screen projection systems that present

full-scale renderings of the

envi-ronment. Amusement parks can

provide virtual rides by hooking

up these systems to seats that

move and shake.

For Internet users, perhaps

the most exciting recent develop-ment is known as VRML (Virtual

Reality Modeling Language), a

new addition to the World Wide Web. While HTML (HyperText Markup Language) is the curvent

standard for authoring home

pages, VRML supports 3-D

worlds on the Web - worlds that can be interactive and fully

func-tional, with hyperlinks to other Web sites. In the future, home

pages may be replaced by home spaces. A Web user can view and manipulate a 3-D VRML model on a computer monitor by using a

standard plug-in to a common

browser (like Netscape Navigator

or Microsoft Internet Explorer). But serious VRML applications

require the user to have powerful computers and high-end network connections.

Another innovation, dubbed augmented reality, combines the virtual and real worlds. Employ-ing a "see-through" HMD device,

the viewer sees virtual objects

superimposed on the real world.

Applications include the use of

virtual cues to guide assembly or

maintenance tasks; the

visual-ization of normally invisible

enti-ties like radiation hazards in a

laboratory; and the virtual recon-struction of an ultrasound image of a fetus at the exact location in the real maternal womb.

Some systems, known as

telepresence, immerse the viewer

in a distant world that is

AT THE EDGE

ATURAL

SYNTHETIC WORLDS SPRING TO LIFE

hENCE

tarieously recorded by video cam-eras. As the person looks around, the cameras move in synchrony,

providing the corresponding view.

The 1997 Mars Pathfinder

mis-sion employed a similar concept to view the Martian surface from

a robotic vehicle. Space explo-ration also benefits from

telero-botics, which allows remote

manipulation of real objects via

robotic manipulators. In

telemed-icine and telesurgery, VR

tech-nologies can be applied to control delicate medical procedures from a distant location.

Limitations

It should be pointed out that most of the above applications are still

being tested, and only selected ones have found their way into routine use. The technology is

expensive, unfamiliar to most

potential users, and plagued by a

number of shortcomings.

The problems include low

image quality and poor

resolu-tion, unnatural restrictions on the

field of view, insufficient real-time

response, image instability, and

user discomfort caused by

intru-sive gear. These shortcomings

reduce the usefulness of the tech-nology in certain applications. At present, solutions to these prob-lems require expensive, high-end equipment.

Once the equipment is in

place, the difficult part begins:

creation of a 3-D computer model for an envisioned application,

fol-lowed by implementation of

inter-actions and functionality of the virtual world. The task requires highly trained technical experts

with a thorough knowledge of the

application field, a basic under-standing of human factors, and sufficient imagination and

cre-ativity

148 THE WORLD &

Besides the technical

limita-tions, we do not know the

psy-chological and physiological

effects on users who spend

extended periods in immersive VR, especially in environments

with emotional content. Various ethical issues have therefore been

raised. For instan, can the new

technologies induce druglike

addiction? Can they be used for brainwashing? Once the

bound-aries between virtual and real

worlds are blurred, how will that

affect self-awareness and inter-personal relations? To address

these questions, disciplines such as cognitive and perceptual

psy-chology and physiology need to

become involved in the design of both immersive devices and vir-tuai environments.

Looking ahead

Given our tendency to make new technologies better, faster, cheaper, and easier to use, we will surely overcome a

The author uses the virtual environment of a CAVE to inspect the interior of a conceptual car. Manufacturers can take advantage of this approach to design and review virtual prototypes of cars and other complex products, reducing the number of costly physical mock-ups that would otherwise have to be built. (Note that while the stereo projection appears blurred to the photographer, it is a sharp, 3-D image for the viewer with stereo

A safe means to treat patients with acrophobia is to give them impressions of looking down from great heights in virtual worlds. For this purpose, a program simulating views from an elevator was developed by Prof. Larry Hodges and his team at the Georgia Institute of

Technology.

number of limitations and

make VR more useful and

affordable. The work

cur-rently under way suggests

directions for the foreseeable future. Improvements in

non-visual technologies are in

process, and new modalities like

virtual smell are being investi-gated. The scheduled launching of space-based telecommunica-tion systems and the new Inter-net2 initiative will provide the

network capabilities required for

shared environments in coming

years. Browsing through 3-D

VRML models on the World Wide

Web by wearing a fully immer-sive HMD device is just the next

logical step. And, in the more

dis-tant future, holography may

merge with VR.

Virtual reality will move out of the laboratory and most likely

find a permanent niche in the

workplace. Designers will be able

to quickly transform an idea into

a virtual representation and

dis-cuss the design with a remote

customer, meeting at a virtual

site. It will become common to use VR to train employees for new job assignments. From the

workplace, VR will probably

move into education and,

eventu-ally, daily life.

While immersive virtual

games will become more common

at home and may even allow

browsing through a 3-D Web, it is

hard to predict if a wider

audi-ence will ultimately use the antic-ipated capabilities of VR, moving

frequently between

computer-generated and real environments. Applications for home education,

relaxation, and entertainment

are appealing. And through the

virtual modeling and communi-cation of ideas, VR can become a new tool for self-expression.

The amazing developments

on the present World Wide Web illustrate both the potential value

and the possible problems. The

new technology can be easily

mis-used to falsify reality or to com-municate offensive content. On the other hand, VR may lose its appeal to a wider audience after the initial thrill has evaporated,

or it may be overshadowed by

new technologies yet to come. While VR still rides the wave

of enthusiasm and offers many useful applications, its future is wide open. Is the claim that VR

will "revolutionize society" just an

overstatement to grab attention?

Or will VR make a sweeping

impact like the telephone or TV set? The combination of

excite-ment and unease about this new frontier in cyberspace is currently

expressed in only some circles. This new technology certainly deserves greater attention as it

continues to develop and expand

well into the next millennium1

Kkzus-Peter Beier holds severa! positions

at the University of Michigan: He is

director of the Virtual Reality

Labora-tory, associate director of the Labo ratozy for &ientific Computation, research

sci-entist with the College of Engineering,

and a faculty member of the Department ofNava! Architecture and Marine Engi-neering.