Virtual reality

Last updated: June 26, 2007.

Imagine swimming with dolphins before breakfast and climbing Everest an hour later. What about crawling over the dusty surface of Mars after lunch and then shrinking yourself down to the size of an atom to explore the world of nanotechnology before you go to bed? In a few years time, all these things may be possible thanks to a type of computer technology known as virtual reality (VR). The basic idea of VR is to create an entirely artificial sensory world that fools our brains into thinking we're somewhere else. Virtual reality is incredibly useful and raises all kinds of exciting possibilities. But will the attractions of the virtual world mean people stop meeting and socializing with one another in real reality?

Photo: Using a virtual reality system. Note the head-mounted display (HMD) helmet and the data glove. The large screen shows us what the user sees on his display. Picture by courtesy of Defense Visual Information Service.

What is virtual reality?

You know where you are and what you're doing at any given moment because your five senses (vision, hearing, smell, touch, and taste) are sending a constant stream of information to your brain. This information is called the brain's sensory or perceptual input. When you're sitting on a beach, you know you're there because you can smell the salt water, hear the waves crashing down, and feel the sand between your toes... and (if you're unluckly) also taste it in your sandwiches!

Have you ever done one of those relaxation exercises when someone tells you to close your eyes and imagine you're on a beach? It's not quite the same thing and it never really works because your brain is not receiving the same sensory information. In short, you might feel relaxed, but you're never convinced you're actually on a beach. But what if you sat in a laboratory with a mad scientist who was determined to fool you into thinking you really were on a beach? She could sit you in a huge sand tray, up close to a TV monitor playing a surfing video, with an audio track of crashing waves playing in your ears, while she tips grains of sand from a bucket over your fingers and toes. Would you be fooled?

Virtual reality is a bit like this: it tries to persuade your brain into thinking you're somewhere else in the world, only using advanced computer technology instead of real-world props.

What equipment do you need for virtual reality?

To enter a virtual world, you need to wear a special headset called a head-mounted display (HMD), which contains two small LCD screens. With one of these screens positioned just in front of each eye, presenting a slightly different perspective from the other, you get the sensation of being in a truly 3D (three-dimensional) computer world. Some HMDs also have small built-in earphones or loudspeakers that play an audio track synchronised with the visual images you see on the HMD.

Photo: This is what virtual reality goggles look like on the inside. The two small screens present a slightly different computerized picture to each eye, fooling the brain into seeing a single 3D image. Picture by courtesy of US Airforce.

That takes care of your main sensory inputs, but how do you negotiate your way through a virtual world? The computer you're hooked up to somehow needs to figure out how your body is moving and where it wants to go. Typically you wear a data glove: something that slips over your hand with fiber-optic or mechanical sensors on the outside that can detect your movements. As you move your fingers or swivel your wrist, thesensors detect these movements and send details to the computer. The computer figures out how you want to move and adjusts the display accordingly.

Suppose you're playing virtual reality tennis. The display shows you a computerized picture of what you think is your wrist holding a tennis racquet. The virtual ball comes zooming toward you. You move your hand back and then forward again—as though you're going to hit a real ball. The glove detects that movement, the computer figures out what you've done, and then shows you a new image of the computerized hand moving the racquet forward, hitting the ball back over the net.

Photo: An advanced virtual reality glove developed by NASA. The mechanism surrounding this scientist's hand is clumsy, but it can detect the precise movements of her fingers. Picture by courtesy of NASA Marshall Space Flight Center (NASA-MSFC).

Who's kidding whom?

One way of looking at virtual reality is as a means for a computer to take the place of "real reality" by substituting computerized pictures, sounds, and so on for the real-world sensory inputs we're accustomed to. In other words, VR involves computers fooling humans.

But there's another way of seeing it too. The computer that controls the VR display and glove is using your movements as its input and presenting a new version of reality to you (on the screen and through your headphones) as its output. So in a sense, you're fooling the computer as well, in precisely the opposite way. You and the computer are locked together in a mutual exercise that distorts each other's idea of what is really real: you provide the computer's input and it provides yours. That's why it's fair to say that VR involves a merging of mind and machine.

What good is virtual reality?

Isn't virtual reality a bit sad? Why would anyone want to play tennis on a computer screen when they can go out and hit a ball with a friend in the real world? Many of us already play computer games in which we pretend we're inside artificial worlds, slaying dragons, jumping off skyscrapers, and generally saving the world. Although some of these offer a kind of virtual reality, and Internet games like Second Life create an entirely artificial world, ordinary computer games do not "immerse" you in a non-existent sensory world in the same way as true VR because they do not fully take over your senses in the same way: you don't wear a headset, special gloves, and other equipment when you're playing ordinary computer games. Some computer games manufacturers have already experimented with developing their own HMDs and data gloves. In the future, computer games are likely to take us much deeper into virtual worlds.

The real applications of virtual reality are in training people to do things that are difficult or expensive for them to do in real life. For example, pilots have long trained on flight simulators because that's much cheaper and safer than having beginners go out and crash lots of airplanes. The US Air Force still trains its pilots this way, and its paratroopers practice their landings wearing HMDs and real parachute harnesses in realistic virtual simulations. NASA too has long used virtual reality to train astronauts and other space scientists. It's not easy to practice being on Mars without going there, but artificial VR simulations can help us imagine what it might be like—and get ourselves ready for meeting the real thing!

A brief history of virtual reality

• 1920s: Edwin Link (1904–1981) develops early mechanical flight simulators in the United States.
• 1960s: Computer pioneer Ivan Sutherland (1938–) invents intuitive computer input devices, including the first head-mounted display (HMDs) in 1965.
• 1970s: US Airforce is using HMDs to train fighter pilots.
• 1980s: Computer scientist and musician Jaron Lanier (1960–) coins the term "virtual reality" in 1984 and his company VPL Research develops the first commercial VR glove (the DataGlove) in 1987.
• 1980s-1990s: Popular books and films like Tron, The Lawnmower Man (where the characters become immersed in a virtual world), and The Matrix bring virtual reality to mass public attention. Virtual reality moves onto the World Wide Web (WWW) with the development of Virtual Reality Markup Language (VRML).