The HTC Vive has just been put up for pre-order internationally, shipping at $799/£685. But exactly how does it work?
The HTC Vive’s main selling point is its lifelike accuracy when you’re inside the virtual world: your head and hands move flawlessly, every fraction of a degree of movement loyally mapped in the virtual space.
This degree of accuracy comes courtesy of the 37 sensors that dimple the faceplate of the headset pairing with the sensor boxes that track your movement and position. HTC refers to this method as ‘Lighthouse’ tracking technology – assumedly because the boxes beam out guiding infrared light to the user.
The basestations are set up to form a triangle – the maximum distance between them being 15 feet. This is the ‘play area’ that the stations and the Vive can triangulate your position within.
In order to effectively track the wearer, the stations need to be mounted above head height, and need to face down at a 30-45 degree angle: this is so the station’s 120-degree field-of-view picks up the Vive headset
The Vive ‘play area’ doesn’t have to work in a perfect square – the tracking is sophisticated enough to work in curved rooms, or at slightly more obtuse angles. If you’re a tall player and you have a low ceiling, you might have trouble, however…
The basestations ‘sweep’ the area with structured light lasers to detect anything other than the player in the ‘play area’. This prevents occlusion (over-lapping and object confusion) in the headset and helps things run smoothly.
The Vive features a ‘chaperone’ system – the front-facing cameras in the headset will live-feed any obstacles in the real world into the users view so they can avoid chairs, cats, people or drinks (or anything else) that could potentially be in their way
The Vive controllers also ‘talk’ to the Lighthouse boxes – since the boxes flood the room with invisible light, it’s easy to pick out anything with a sensor in the middle
What Is ‘Lighthouse?’
‘Lighthouse’ tech gets its name because of how it works – rather than using a camera to determine where the objects in the VR space are, it uses non-visible light. Like its namesake, the Lighthouse box simply fires out a flash of light into the 3D space like a radar. An array of LEDs inside the Lighthouse box flash up to 60 times per second, and a laser sweeps a beam of light across the room.
Those sensors dotted all over the Vive pick the light of the LEDs, and the headset begins timing the millisecond it gets hit by this light. Then, it waits until it gets hit by one of the lasers, and uses the data it collects to determine where the photosensor that was hit is, and when the beam was in contact with the headset. That way, the headset can instantly calculate its exact position relative to the basestations.