Virtual Reality

How Virtual Reality Works

If Facebook, Sony and HTC have their way, next year’s most coveted consumer technology product will not be a smartphone or a giant, paper-thin flatscreen TV. It will be a virtual-reality (VR) headset: computerised goggles that transport users to an immersive, three-dimensional universe. Here they can watch panoramic films, take virtual tours, or experience whatever other alluring distractions a growing group of VR programmers might dream up. How does the technology behind the vision work?

Brendan Iribe, the CEO of Oculus, a VR startup that was bought for $2 billion by Facebook in 2014, describes VR as a “hack on the human sensory system”. It makes sense, then, for VR companies to focus their hacking efforts on the sense that humans rely on most: vision. Humans have stereoscopic vision, which means that they perceive depth by noting the subtle differences between the images received by each of their eyes. VR headsets have two tiny screens, one for each eye, which exploit that. By carefully altering the images fed to each eye, the user’s brain is persuaded that it is looking at an entire three-dimensional world instead of a pair of flat images.

The next trick is to make it seem as if that world surrounds the user. Modern VR headsets are fitted with tiny sensors similar to those used in smartphones—accelerometers, gyroscopes and the like—which let them keep track of the movements of the wearer’s head. When the user looks around, the computer can update the view on the screens. But those sensors must update themselves dozens of times a second, and errors accumulate quickly. So headsets are also equipped with LEDs. That allows a camera, mounted elsewhere in the room, to keep track of the headset and to correct errors in the embedded sensors as they accumulate. It also allows the computer to keep track of the user’s body. That allows hand-held controls to give users a pair of virtual arms and hands, and means that walking forward in the real world results in movement in the virtual one.

That all sounds fairly simple in theory. But building a usable headset stretches modern computing technology to its limits (some readers may remember the last wave of VR hype, in the 1990s, before it became clear that technology was not up to the task). For VR to work, the illusion must be extraordinarily slick. Humans are extremely sensitive to visual inconsistencies; even small snags can cause “VR sickness”, an affliction like motion-sickness. So images must update very quickly. That requires beefy computing hardware capable of generating 90 or more frames of animation a second (standard TV, and most video games, target only 30 updates per second). And the sensors that track the user’s head must be able to talk to the computer at least that fast: any delay can cause an unpleasant dragging sensation. Despite the difficulties, engineers are convinced that such problems have, at last, been banished. They will learn whether they are right when the headsets go on sale in the next few months.

( Source: The Economist )

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