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