When Ubisoft built Eagle Flight, its VR game about flying as an eagle, the team gave the player a beak. It wasn't there for the look. Game director Olivier Palmieri told a developer conference that our brains are used to seeing our own noses, so the beak was added to give the brain an extra reference point, UploadVR reported in 2016.
It's a small detail with a long history behind it. Every VR game that lets you go anywhere has to solve the same problem first: your eyes report that you're moving, and the rest of you reports that you're standing in the lounge. Most of what VR players now see in a settings menu, from teleporting and smooth movement to snap turning, tunnel vision and store comfort ratings, is the medium's answer to that one argument between the eyes and the inner ear. Nobody puts it on the box. It may be the most useful thing VR design has built.
Blinking across the room
Cloudhead Games spent years on the problem while making The Gallery, and its developers wrote the story up for Road to VR in 2018. In spring 2015, with an early HTC Vive, the studio tried the obvious thing: ordinary gamepad-style movement, plus variations where your body or your arm became the joystick. The results were unglamorous. All of them, the developers wrote, made you feel like you were going to fall over. Accelerate instantly and you got a lurch in your stomach; accelerate gradually and you got a different lurch.
The way out came from Valve. An early scan of Valve's office, released for SteamVR, let visitors zip between information nodes instead of sliding around. Cloudhead's team "instantly liked it", they wrote, because it felt cool and didn't make you sick. By mid-2015 they had removed the nodes and let players teleport anywhere within set limits of height and distance, an approach they describe as nausea-free.
Then they did something that tells you a lot about the craft. An instant jump hurt the pace of The Gallery, a slow exploration game, so Cloudhead made the teleport a fade to black, called Blink, whose length matched the distance travelled. The sound designer added footsteps, so you could hear yourself walking while the screen was dark. It's a comfort feature dressed up as a sense of time passing, and nobody needs to notice for it to work.
The same article mentions a less famous trick. When players moved with a stick, visible play-area boundaries in the corner of the eye gave a stable point that helped with vection, the illusion of self-motion, and with nausea.
Narrowing the world
Eagle Flight's team came at it from the other end. Palmieri's group, formed in September 2014, spent close to two years on research before shipping, according to UploadVR's write-up of his talk. Their starting point was the link between the inner ear and vision. As Palmieri explained it, when what you see and what your inner ear senses disagree, the brain treats it as a sign that a toxin has got into the body, hence the nausea. It can go either way: feeling motion you can't see, as when reading in a car, or seeing motion you can't feel, which is the VR player's lot.
A flying game can't teleport, so Ubisoft narrowed the view instead. Its "dynamic blinders" cut into the edges of the screen during flight. Palmieri admitted people were sceptical when they heard about them, but said that when playtesters were asked whether they'd noticed anything in particular, they hadn't. The team also avoided instant speed changes and, drawing on NASA research into space sickness, used fade-to-black screens when the player hit an obstacle.
His advice to other developers was plain: reduce the conflicts between the inner ear and vision, and never move the camera without the player's input. Those two rules sit underneath most of what came after.
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