中文导读
可以想象戴着虚拟现实眼镜坐过山车时那种淋漓尽致的刺激吗？最近，佛罗里达州的奥兰多主题公园让游客们真实体验“穿梭海底世界”，在这背后是VR技术和过山车快速变换景象的无缝结合，能缓解眩晕恶心感。我们将期待VR和跳楼机等更多刺激的游乐园项目的完美结合……
VR gives old rides new purpose
KRAKEN, a 17-year-old rollercoaster at SeaWorld Orlando, an amusement park in Florida, reopened in June after several months of refurbishment. That, in itself, is unusual. The normal fate of old rides is demolition and replacement by new ones offering fresh thrills. More unusual still is that Kraken, though it had not undergone any physical upgrade during its refurbishment, had customers queuing eagerly to get on it as though it were a brand new offering. Which, in a sense, it was.
SeaWorld Orlando is the latest in a string of parks to turn to virtual reality (VR) to recycle rollercoasters of days past. In the case of Kraken, the rider wears a headset that takes him on an underwater journey which matches the coaster’s movements, dodging prehistoric sea creatures such as pliosaurs, careering down into an underwater canyon, and straining to escape the clutches of the terrible, tentacled monster after which the ride is named.
Building a new ride is pricey, even for a big attraction like SeaWorld. For small parks, with low budgets, it can be an existential bet. VR, though, has given parks an opportunity to breathe new life into old rides, saving money as they do so. Adding VR to a rollercoaster does, however, present challenges beyond those involved when the headset wearer is either stationary or using his own muscles to move around. Matching what is seen with the sensation of movement is crucial. Get it wrong and the result is nausea. Yet, when executed properly, the pairing of rollercoasters and VR, two things that can both, by themselves, be nauseating experiences, actually helps reduce the risk of sickness.
One cause of VR-induced nausea is high latency—too long a delay between users moving their heads (and thus their expected view of the virtual world) and the headset’s response to that movement. High latency sends confusing signals to the brain and prompts “cue conflict”, the body’s response to receiving mixed signals from the eyes, which provide vision, and the ears, which contain the organs that register movement and balance. In the 1990s, when VR was still in its infancy, high latency was common. As the technology has improved, though, latency has decreased, minimising the risk of nausea.
But not, however, eliminating it. For there is a second cause of cue conflict in VR: the eyes seeing movement that the body is not experiencing. And this is something rollercoasters can help solve, by providing the missing experience of movement. Match the signal from the headset to the coaster’s motion and the brain’s inputs from eyes and ears will also match.
That match, though, must be precise. Even a small discrepancy between the headset’s image and the coaster’s motion can have a drastically nauseating effect. To ensure perfect correspondence, VR firms such as Figment Productions, a British company that worked on the new Kraken ride, map the entire track using devices called inertial measurement units (IMUs) before the visuals are created.
These IMUs are sophisticated versions of the widgets that smartphones and tablet computers use to work out which way up the screen display should be. Simon Reveley, Figment’s boss, says the firm chose these sensors because their ability to detect changes in movement is similar to that of a blindfolded human being—which is exactly what someone wearing an immersive headset is. IMUs are, in other words, adept at sensing alterations in motion and path, while being poor at registering speed or distance travelled.
Once the IMU map has been made, video can be created to match it. To make sure everything stays in synchrony, each of Kraken’s cars is fitted with IMUs that compare its behaviour during an actual run with the map employed to make the video. Any discrepancy is used to adjust the speed of the video, in order to preserve verisimilitude.
The VR augmentation of rides is unlikely to remain limited to rollercoasters. Six Flags, one of the world’s biggest amusement-park companies, is experimenting with adding VR to drop towers—devices in which the rider experiences several seconds of free-fall before being decelerated for a safe landing. Park visitors, then, should expect to don more headsets when they strap in for their favourite rides.
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July 13th 2017 | Science and technology | 737 words
