Motion sickness in virtual reality and how to prevent it.

Through out our demos, people have being concerned about getting dizzy inside VR environment and are reluctant to try for themselves. One reason is that some people get disorienting watching 3D contents and feel like VR will be even worse for them. In fact, Matt, our CTO, also have a degree of motion sickness with 3D games. The other reason is because some of them heard about VR being disorienting through online discussions and posts, and is reluctant to try it out themselves.

This thing also brings back bad memories to a lot of people

First of all, I want to say that a well designed VR experience is not disorienting at all, even to the people with the weakest stomach. So in this post, I'm going to talk about why people get sick and what some of the developers are doing to prevent that.

Let's first start with why people get motion sickness in virtual reality. Motion sickness, or kinetosis, is caused by conflicting signals sent by your inner ear's vestibular system (your balance detection mechanism) and your visual input (your eyes). So when someone gets car sickness, it's because they feel like they are moving but they don't see themselves moving. And that's why a common advice for people who get car sick is to look outside the window, and also why many people no longer feel sick if they are the ones driving.

Similarly, simulation sickness happens for the exact same but opposite reason. People see themselves moving while their body don't feel like they are. That's why some gamers gets sick from playing 3D games for too long. (I think it affects me as well since I've being getting nausea from playing too much Fallout 4 in the past couple of days). And inside virtual reality, it is even more convincing that you are moving because due to increased level of immersion, which means even more likely to get motion sickness. (and also why roller coaster experience inside VR is a huge hit).

Now to get ride of motion sickness in VR, there are two things that must be done. One is to have a high performance and low latency hardware. And the second is to design the software to minimize conflict between real life movement and virtual movement. For the hardware part, Oculus and other VR headset companies are doing their best to bring an ultra-low latency experience with their headsets. Having a high performance computer is also essential for a comfortable experience. A good virtual reality experience requires 90 frame per second (compared to 30 for most movies and games) and a latency of 20 ms or less from the moment you turn your head to you seeing the movement (compared with current gaming control of 50 ms input). And so far, Oculus has being doing tremendously good job on that. Thus the other part of creating a perfect experience is up to the developers.

Traditional movement does not work very well for virtual reality. And unfortunately, most VR demos out there uses the traditional WASD movement or a joystick, and that's very disorienting to its users. Mainwhile, some of the developers out there has being inventing some creative ways to let users move inside VR.

The best way for movement is to let the user physically move. In fact, if the experience is inside a room scale environment, this is the absolutely best way to get around. This video done by Casterol EDGE is a great example of the best immersive experience.

Yes, they actually made this in VR

Now what if you don't have the rooms to move around in VR? Developers have created a lot of creative ways to get around that.

One of the most popular one is teleporting (I know it sounds pretty sci-fi, but it actually feels really natural). Games like The Gallery uses teleportation along with natural walking to let users move around as naturally as possible. In fact, a lot of other applications also use teleportation as the preferred method of movement. Like Janus VR and AltspaceVR all have some form of teleportation system.

Another interesting one is Convrge VR's "ghosting" system. Where you control a "ghost" of yourself and you can let it move around freely, like playing with a robot. Then with a click of a button you would be teleported to where the ghost is. This is a great system as it helps letting you test realistic movement as well as provide a way for locomotion.

A third one I'm going to mention is called "tunneling". I found this one online a couple days ago and it's also very interesting. When you move, you new view appear on a screen in front of you. And once you finish moving, the view in front of you enlarges to become your actual view.

Movement is one area where you need to break the immersion in order to achieve a comfortable experience. Currently, there is no standard or the best way to achieve this yet (and Babylon VR is experimenting with different methods as well). But rest assured, virtual reality can be a really comforting experience with the right design. So there's no need to worry even if you get motion sickness often.

What is virtual reality?

According to Wikipedia, virtual reality (VR) replicates an environment that simulates physical presence in places in the real world or imagined worlds and lets the user interact in that world. Virtual reality artificially creates sensory experiences, which can include sight, hearing, touch, smell, taste, and more.

So essentially, it is The Matrix.

In fact, true VR would be so convincing from the real world that it would really make you wonder which one is the real world. After all, we perceive reality from our five senses. And interestingly, there's already research going on that is trying to find out if we are indeed inside the real world or a computer simulation done by some higher beings. (Are we inside a computer?)

But true virtual reality is difficult to achieve. During Oculus Connect 2, Michael Abrash, the chief scientist at Oculus discussed the type of challenges we face in discovering VR. In summary, we still have a long way to go. and we are barely scratching the surface when it comes to VR. Even in visual VR, we were only able to achieve the 5/6 criteria needed for full visual 3D.

Based on this article from doc-ok.org, in order to achieve visual belie ability, we need to:

1. Make closer objects larger and farther objects smaller

2. Have closer objects block farther objects

3. Have different perspective from both eyes

4. Create parallax; Farther object move slower in relative to closer objects (think of riding a car and looking out the window)

5. Eyes cross when focusing on item

6. Eyes adjust its focus when looking at object at different distances (think of camera focus, when you get these really nice looking artistic shots)

So currently, 3D graphics (on a monitor) is able to achieve 1, 2. And 4 if you count camera movement as head movements. and illusion of 6 using special effects. Clearly not very convincing. And these 3D movie glasses add 3 into the list by creating different images (and unfortunately I have a medical condition called Strabismus which kind of makes 3D movies obsolete for me).

The recent development of VR hardware such as Oculus Rift has being able to achieve 1 to 5, and even 6 with some software programming (if the rift can track eye movement, it'd be able to completely achieve 1 to 6). And this is enough to convince a normal person that they are seeing 3D. So convincing that we experience motion sickness, a symptom that is caused by discrepancy between our vesicular sense and our vision (and even better, it convinced me that I'm seeing 3D even with strabismus, so damn good)! And this also brings in some difficulties in regards to design. We can no longer simulate movement as we did traditionally due to motion sickness. So an entire new design approach needs to be invented.

Hopefully this explains to the basis of how VR works and what we can achieve so far. Stay tuned for more blogs and updates.

Jack


Edit:
After I made this post, I come across this link, and Oculus is working on eye tracking right now as well. We may soon have complete visual VR very soon.

Babylon VR website online now!

Babylon VR's official webpage is now online, we'll be making heavy updates in the next couple of weeks.

--- Jack