Why does the Oculus Rift make you feel sick?

The Rift is probably the first step that we are taking into the world of VR. It is an amazing experience to try it. Although the current state of VR worlds leave a lot to be desired, it is something that I would definitely recommend everyone to try once. The whole feel is unique. Having said that, I should tell you that it has one side effect that cannot be avoided. Prolonged use makes a person dizzy, motion sick and very disoriented. Let us try and see why this happens

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This is how the headset looks. And inside the headset there is a pair of lenses that act as the additional display to your computer. The smart trick here is the fact that while the computer thinks that it is just another screen, the headset splits the incoming visual into two slightly different images that trick the mind into rendering them as a three dimensional image that “feels” real. This sounds simple when I say it like that, but it is extremely complicated.

This involved tricking your mind into showing you something that really isn’t there in front of you, so it obviously has side effects! There are many reasons, primarily about the way we perceive and react to reality, that your brain rejects the reality of a screen mounted a few inches in front of your eyeballs.

Gizmodo recently did a piece on this. In the early years of VR when it was nascent and developing, which it is even today, it was impossible to spend more than a few minutes with a VR simulator without feeling sick. This has now come down drastically and you can spend more time with VR.

There are many reasons why the Oculus Rift makes you sick. Here are a few of them.

The main reason is latency, or the tiny but noticeable delay between when you move your head in VR and when the image you see changes-creating a disparity between the motion we feel (with our inner ears) and the image we see (with our eyes). Continued exposure compounds this and makes the sickness very pronounced. I was almost puking after the first 20 mins in the VR world. It also makes your stomach queasy! Like riding up a windy hill road in a bumpy jeep.

Gizmodo says that you can look at the far-off horizon of a virtual beach but still feel like you’re in a room. This could be partly the result of subtle feedback from the muscles surrounding your eyes. At its worst, it can cause painful eyestrain and headaches.

Here’s what happens. Put a finger in front of your face and gradually move it to your nose; your eyes will naturally move closer together to track your finger. This is vergence, where our eyes converge and diverge to look at close and distant objects, respectively. At the same time, the lenses in your eyes focus so the image of your finger remains clear while the background is fuzzy. This is called accommodation.

In VR, however, vergence and accommodation no longer integrate seamlessly. The screen of a typical head-mounted display sits three inches or so in front of your eyes. A set of lenses bends the light, so the image on the screen looks about one to three meters away. However, any objects further or closer than that can look blurry. And the entire screen is always in focus, no matter where your eyes are looking. This can make spending an extended period of time in VR pretty uncomfortable.

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There are high-flying ideas about how to get around the problem, and the name on everyone’s lips is Magic Leap. The company hasn’t publicly revealed much, though its patents show an interest in light field technology, where a screen of pixels is replaced by an array of tiny mirrors that reflect light directly into the eyes. The objects rendered through light are supposed to achieve true depth, coming in and out of focus as a real object might.

Even in a world with perfect motion tracking and zero latency, we still have motion sickness. And that means that there’s an additional hurdle to creating a realistic experience in virtual spaces.

This goes back to the mismatch between the images we see and the movements we feel. If you’re controlling a character with a joystick in an immersive virtual environment, there’s always going to be a mismatch. The only way around it is perfect 1:1 motion in the real and virtual world, which means physically walking a mile if your character is walking a mile. This becomes pretty darn impractical if you want to play games in your living room.

One solution is simply game design, which is the exact topic of a 53-page Oculus Best Practices Guide. For example, when people are put in a virtual cockpit, they can sit still and drive or fly around with less motion sickness-kind of like driving a car in the real world. But this pretty obviously negates the fun of a truly interactive VR experience.

My take on this is that it is going to take atleast another 5 years to make VR Tech completely and instanttaneously sync with your head movements and eliminate this ugly side effect. Till then, keep a lemon handy when you use the Oculus Rift!

 

  • Raj Khanna

    Interesting article.