Today, we are witnesses to burgeoning consumer-accessible VR, an exciting technology that promises to transform in a fundamental way how we interact with information, our friends, and the world at large.

What is virtual reality? In general, VR is the computer-generated simulation of a 3D environment, which seems very real to the person experiencing it, using special electronic equipment. The objective is to achieve a strong sense of being present (presence) in the virtual environment.

Today's consumer tech VR involves wearing HMD (head-mounted display) goggles to view stereoscopic 3D scenes. You can look around by moving your head, and walk around by using hand controls or motion sensors. You are engaged in a fully immersive experience. It's as if you're really there in some other virtual world. The following photo shows me, the author, experiencing an Oculus Rift Development Kit 2 (DK2) in 2015:

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A sister technology to VR is augmented reality (AR), which combines computer-generated imagery (CGI) with views of the real world. AR on smartphones has recently garnered widespread interest with the introduction of Apple's ARKit for iOS and Google ARCore for Android. Furthermore, the Vuforia AR toolkit is now integrated directly with the Unity game engine, helping to drive even more adoption of the technology. AR on a mobile device overlays the CGI on top of live video from a camera.

The latest innovations in AR are wearable AR headsets, such as Microsoft's HoloLens and Magic Leap. The computer graphics are shown directly in your field of view, not mixed into a video image. If VR headsets are like closed goggles, AR headsets are like translucent sunglasses that combine the real-world light rays with CGI.

A challenge for AR is ensuring that the CGI is consistently aligned with and mapped onto the...

Consumer-level VR started with gaming. Video gamers are already accustomed to being engaged in highly interactive hyper-realistic 3D environments. VR just ups the ante.

Gamers are early adopters of high-end graphics technology. Mass production of gaming consoles and PC-based components in the tens of millions and competition between vendors leads to lower prices and higher performance. Game developers follow suit, often pushing the state of the art, squeezing every ounce of performance out of hardware and software. Gamers are a very demanding bunch, and the market has consistently stepped up to keep them satisfied. It's no surprise that many, if not most, of the current wave of VR hardware and software companies are first targeting the video gaming industry. A majority of the VR apps on the Oculus Store, such as Rift (https://www.oculus.com/experiences/rift/), GearVR (https://www.oculus.com/experiences/gear-vr/), and Google Play for Daydream...

There is not just one kind of VR experience. In fact, there are many. Consider the following types of VR experiences:

• Diorama: In the simplest case, webuilda 3D scene. You're observing from a third-person perspective. Your eye is the camera. Actually, each eye is a separate camera that gives you a stereoscopic view. You can look around.
• First-person experience: This time, you'reimmersedin the scene as a freely moving agent. Using an input controller (a hand controller or some other technique), you can "walk" around and explore the virtual scene.
• Room scale: The first-person experience with physical space. Given positional tracking, you can physically walk around a predefined area. A guardian system will show when you've reached unsafe boundaries.
• Interactive virtual environment: This islikethe first-person experience, but you're more than an observer. While you are in the scene...

Presently, there are two basic categories of HMDs for VR: desktop VR and mobile VR, although the distinctions are increasingly becoming blurred. Eventually, we might just talk about platforms as we do traditional computing, in terms of the operating system—for example, Windows, Android, and console VR. Let's look at each of these HMDs in more detail.

Desktop VR

With desktop VR (and console VR), yourheadsetis peripheral to a more powerful computer that processes the heavy graphics. The computer may be a Windows PC, Mac, Linux, or a game console, although Windows is by far the most prominent PC, and PlayStation is a bestseller intermsof console VR.

The headset is connected to the computer with physical wires (tethered connection) or a near-zero latency wireless connection. The game runs on the remote machine and the HMD is aperipheraldisplay device with a motion-sensing input. The termdesktopis an unfortunate misnomer since it&apos...

So, what is it about VR that's got everyone so excited? With your headset on, you experience synthetic scenes. It appears 3D, it feels 3D, and maybe you will even have a sense of actually being there inside the virtual world. The strikingly obvious thing is that VR looks and feels really cool! But why?

Immersion and presence are the two words that are used to describe the quality of a VR experience. The Holy Grail is to increase both to the point where it seems so real that you forget you're in a virtual world. Immersion is the result of emulating the sensory input that your body receives (visual, auditory, motor, and so on). This can be explained technically. Presence is the visceral feeling that you get of being transported there—a deep emotional or intuitive feeling. You could say that immersion is the science of VR and presence is the art. And that, my friend, is cool.

A number of different technologies and techniques...