What is virtual reality?
Virtual reality (Virtual Reality) means experiencing things through our computers that don't really exist. From that simple definition, the idea doesn't sound especially new. When you look at an amazing Canaletto painting, for example, you're experiencing the sites and sounds of Italy as it was about 250 years ago—so that's a kind of virtual reality. In the same way, if you listen to ambient instrumental or classical music with your eyes closed, and start dreaming about things, isn't that an example of virtual reality—an experience of a world that doesn't really exist? What about losing yourself in a book or a movie? Surely that's a kind of virtual reality?If we're going to understand why books, movies, paintings, and pieces of music aren't the same thing as virtual reality, we need to define VR fairly clearly. For the purposes of this simple, introductory article, I'm going to define it as:
A believable, interactive 3D computer-created world that you can explore so you feel you really are there, both mentally and physically.Putting it another way, virtual reality is essentially:
- Believable: You really need to feel like you're in your virtual world (on Mars, or wherever) and to keep believing that, or the illusion of virtual reality will disappear.
- Interactive: As you move around, the VR world needs to move with you. You can watch a 3D movie and be transported up to the Moon or down to the seabed—but it's not interactive in any sense.
- Computer-generated: Why is that important? Because only powerful machines, with realistic 3D computer graphics, are fast enough to make believable, interactive, alternative worlds that change in real-time as we move around them.
- Exploitable: A Virtual Reality world needs to be big and detailed enough for you to explore. However realistic a painting is, it shows only one scene, from one perspective. A book can describe a vast and complex "virtual world," but you can only really explore it in a linear way, exactly as the author describes it.
- Immersive: To be both believable and interactive, Virtual Reality needs to engage both your body and your mind. Paintings by war artists can give us glimpses of conflict, but they can never fully convey the sight, sound, smell, taste, and feel of battle. You can play a flight simulator game on your home PC and be lost in a very realistic, interactive experience for hours (the landscape will constantly change as your plane flies through it), but it's not like using a real flight simulator (where you sit in a hydraulically operated mock up of a real cockpit and feel actual forces as it tips and tilts), and even less like flying a plane.
Types of virtual reality
"Virtual reality" has often been used as a marketing buzzword
for compelling, interactive video games or even 3D movies and
television programs, none of which really count as Virtual Reality because they don't immerse
you either fully or partially in a virtual world. Search for "virtual
reality" in your cellphone app store and you'll find hundreds of
hits, even though a tiny cellphone screen could never get anywhere
near producing the convincing experience of VR. Nevertheless, things
like interactive games and computer simulations would certainly meet
parts of our definition up above, so there's clearly more than
one approach to building virtual worlds—and more than one flavor of
virtual reality. Here are a few of the bigger variations:
Fully immersive
For the complete VR experience, we need three things. First, a plausible, and richly detailed virtual world to explore; a computer model or simulation, in other words. Second, a powerful computer that can detect what we're going and adjust our experience accordingly, in real time (so what we see or hear changes as fast as we move—just like in real reality). Third, hardware linked to the computer that fully immerses us in the virtual world as we roam around. Usually, we'd need to put on what's called a head-mounted display (HMD) with two screens and stereo sound, and wear one or more sensory gloves. Alternatively, we could move around inside a room, fitted out with surround-sound loudspeakers, onto which changing images are projected from outside. We'll explore VR equipment in more detail in a moment.Non-immersive
A highly realistic flight simulator on a home PC might qualify as non immersive virtual reality, especially if it uses a very wide screen, with headphones or surround sound, and a realistic joystick and other controls. Not everyone wants or needs to be fully immersed in an alternative reality. An architect might build a detailed 3D model of a new building to show to clients that can be explored on a desktop computer by moving a mouse. Most people would classify that as a kind of virtual reality, even if it doesn't fully immerse you. In the same way, computer archaeologists often create engaging 3D reconstructions of long-lost settlements that you can move around and explore. They don't take you back hundreds or thousands of years or create the sounds, smells, and tastes of prehistory, but they give a much richer experience than a few pastel drawings or even an animated movie.Collaborative
What about "virtual world" games like Second Life and Mine craft? Do they count as virtual reality? Although they meet the first four of our criteria (believable, interactive, computer-created and exploitable), they don't really meet the fifth: they don't fully immerse you. But one thing they do offer that cutting-edge VR typically doesn't is collaboration: the idea of sharing an experience in a virtual world with other people, often in real time or something very close to it. Collaboration and sharing are likely to become increasingly important features of Virtual Reality in future.Web-based
Virtual reality was one of the hottest, fastest-growing technologies in the late 1980s and early 1990s, but the rapid rise of the World Wide Web largely killed off interest after that. Even though computer scientists developed a way of building virtual worlds on the Web (using a technology analogous to HTML called Virtual Reality Markup Language, VRML), ordinary people were much more interested in the way the Web gave them new ways to access real reality—new ways to find and publish information, shop, and share thoughts, ideas, and experiences with friends through social media. With Facebook's growing interest in the technology, the future of VR seems likely to be both Web-based and collaborative.What equipment do we need for virtual reality?
1) Head-mounted displays (HMDs)
There are two big differences between Virtual Reality and looking at an
ordinary computer screen: in Virtual Reality, you see a 3D image that changes
smoothly, in real-time, as you move your head. That's made possible
by wearing a head-mounted display, which looks like a giant motorbike
helmet or welding visor, but consists of two small screens (one in
front of each eye), a blackout blindfold that blocks out all other
light (eliminating distractions from the real world), and stereo
headphones. The two screens display slightly different, stereoscopic
images, creating a realistic 3D perspective of the virtual world.
HMDs usually also have built-in accelerators or position sensors
so they can detect exactly how your head and body are moving (both
position and orientation—which way they're tilting or pointing) and
adjust the picture accordingly. The trouble with HMDs is that they're
quite heavy, so they can be tiring to wear for long
periods; some of the really heavy ones are even mounted on stands
with counterweights. But HMDs don't have to be so elaborate
and sophisticated: at the opposite end of the spectrum, Google
has developed an affordable, low-cost pair of cardboard goggles
with built-in lenses that convert an ordinary smartphone into a crude HMD.
