Expo/Theater/Virtual Environments

| Back | Map | Information |

Virtual Reality Systems

Each environment provides a slightly different perspective on the virtual world. Each attempts to make it easier for you to interact with computers. Each transforms data analysis into a sensory as well as cognitive experience.

Described below are the most common virtual environments. Explore all three.

Head-mounted display

Carnegie Mellon University

Looking like oversized motorcycle helmets, head-mounted displays are actually portable viewing screens that add depth to otherwise flat images. If you look inside the helmet you will see two lenses through which you look at a viewing screens. As a simulation begins, the computer projects two slightly different images on the screen: one presenting the object as it would be seen through your right eye, the other, through your left. These two stereo images are then fused by your brain into one 3D image.

To track your movements, a device on top of the helmet signals your head movements relative to a stationary tracking device. As you move your head forwards, backwards, or sideways, or look in a different direction, a computer continually updates the simulation to reflect your new perspective.

Because head-mounted displays block out the surrounding environment, they are favored by VR operators who want the wearers to feel absorbed in the virtual environment, such as in flight simulators. And as you might expect, these displays also are popular with the entertainment industry. The cost of a little escapism, however, can be an aching neck. Most head-mounted displays weigh several pounds.

Datagloves and wands are the most common interface devices used with head-mounted displays.


Picture of Boom
National Center for Supercomputing Applications

The Binocular Omni Orientation Monitor, or BOOM, is similar to a head-mount except that there's no fussing with a helmet. The BOOM's viewing box is suspended from a two-part, rotating arm. Simply place your forehead against the BOOM's two eyeglasses and you're in the virtual world. To change your perspective on an image, grab the handles on the side of the viewing box and move around the image in the same way you would if it were real: Bend down to look at it from below; walk around it to see it from behind. Control buttons on the BOOM handles usually serve as the interface although you can hook up datagloves or other interface devices.


Cave Animation
Electronic Visualization Laboratory
Animation in the Cave
QuickTime Movie (3.9 MB); MPEG Movie (1.2 MB); Sound File (1.7 MB);

Computer Image
of The CAVE

Electronic Visualization Laboratory

"In the CAVE, you are no longer on the outside looking in but on the inside looking out."
Thomas DeFanti, co-developer of the CAVE and director, University of Illinois at Chicago's Electronic Visualization Laboratory
JPEG Image (38K)

Data immersion 
in the Cave

One of the newest, most "immersive" virtual environments is the CAVE (CAVE Automatic Virtual Environment). Stepping into this 10 x 10 x 9-foot darkened cubicle is like jumping into the viewing box of the BOOM or climbing into your computer screen. No longer are you observing data through portals or just a flat screen; rather, the display enables you to experience the sensation of being "inside" the data.
JPEG Image (42K)

Larry Smarr, NCSA/University of Illinois, on-camera
Movie/Sound Byte
QuickTime Movie (4.7 MB); Sound File (2.0 MB); Text

This greater sense of being inside, or immersed in, the data results from two advantages the CAVE has over other virtual environments. The first advantage is unencumbered movement. No clunky helmuts or viewing boxes are needed here. The only required gear are a funky pair of glasses and a wand.

The second advantage of the CAVE is its large field of view. In the CAVE, data are projected in stereoscopic images onto the walls and floor of the CAVE so that they fill the cubicle. In a simulated aquarium, fish not only swim in front of you or on your left and right but below and behind you as well.

Larry Smarr, on-camera
Movie/Sound Byte
QuickTime Movie (3.7 MB); Sound File (1.5 MB); Text

To get a 3D effect, the computer projects stereoscopic images in rapid, alternating succession while it controls the lenses in the viewing glasses in synchronization with the images being flashed on the screen. The undetectably fast shuttering produces the stereo vision.

A tracking device attached to the glasses relays the viewer's position to the computer that then recomputes the image to reflect the viewer's new perspective at a rate of 10 frames per second. Wands are the most commonly-used interface devices.

Because the 3D images can be seen by anyone wearing the CrystalEyes shuttering glasses, the CAVE is ideal for collaborative work. One or several people can simultaneously observe and analyze a simulation, though only from the perspective of whomever is wearing the tracking device. For now, everyone must be in the same CAVE but it won't be long before CAVE-to-CAV E sessions are as commonplace as teleconferences.

Some images are accompanied by sounds mapped to the same data driving the imagery. A virtual trip to the beach is so much more compelling when you can hear the sound of waves crashing on the shore and the cry of seagulls. But beyond providing ambiance, sounds can reveal fine features in data not easily captured in images, such as speed and frequency. How easy it is to hear the subtle swirls and eddies of air as it flows across the surface of jet! A bang can tell you when two molecules connect. A beep emitted as a beacon can guide you home to Earth from your explorations in a vi rtual galaxy.

Larry Smarr, on-camera
Movie/Sound Byte
QuickTime Movie (2.1 MB); Sound File (1.0 MB); Text

Larry Smarr, on-camera
Movie/Sound Byte
QuickTime Movie (2.9 MB); Sound File (1.3 MB); Text

But what about feeling the virtual world you're exploring, such as the resistance of a gear or the incline of a slope? New input devices now coming online, such as stairsteppers and other tactile devices, will allow you to do just that. In short, you're all set to see, hear, and feel the digital world you choose to venture into, and all in real time.

Small is golden

Whatever the answers, VR technology clearly is evolving toward smaller, cheaper, more flexible systems with greater resolution. ImmersaDesks, for instance, will serve as streamlined versions of the CAVE bringing 3D, immersible technology into the office at a fraction of the cost. About the size of a drafting table, Immersadesks are portable yet large enough to fill the field of view of the person sitting in front of it (thus giving the illusion of immersion). Images are viewed with the same lightweight stereoscopic glasses used in the CAVE. Scientists will be able to design applications for the CAVE on Immersadesks in their offices. Architects will design buildings in 3D, then switch modes, and escort their clients on a virtual walk-through of the model.


Electronic Visualization Laboratory
Immersion ImmersaDesk
Part 2
JPEG Image (65K) JPEG Image (44K)

Interface devices

Return to VR: Technology

Exhibit Map
Information Center

Copyright © 1995, The Board of Trustees of the University of Illinois

NCSA & EVL. Last modified 10/24/95