How to avoid the effect of motion sickness when moving in VR

In the minds of many people, VR glasses are still simply "lenses with monitors in front of the eyes, where instead of a mouse you need to twist your head." Even numerous IT specialists have not yet come to the simple fact that VR is a full-fledged new platform that requires completely new approaches in building human-computer interaction systems, changing management concepts in well-known game genres and UI / UX as a whole. In short, the platform requires research, which has been carried out by many developers for several years now since the introduction of the Oculus Rift DK1.

One of the most vivid examples of the uniqueness of the platform is the problem of free movement in virtual reality and the associated motion sickness effect (motion sickness). Let's still sort it out a little more.

The idea to return to this topic arose after mentioning the problem in several reports and articles, but with very strange explanations of the reason for its occurrence and sometimes controversial examples of its solution. This article is an attempt to approach the issue a little more systematically and describe such solutions that will be useful from the standpoint of commercial development at the moment.

It would seem that there is a game genre that is simply created for virtual reality - first-person shooters. In any case, they most often appear in various books, films and games about VR. But for a large number of users, the classical mechanics of moving from FPS did not make a happy impression at all - they simply cannot walk through the game location - they are sick of it in the most direct sense.
The effect of motion sickness occurs inclusively as a result of sensory dissonance (or sensory conflict) - inconsistency of data coming from the visual channel and information that a person receives from the vestibular apparatus. In other words, when the user moves in virtual reality (runs through the game level), but does not move in objective reality (sits on a chair).
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A more obvious example is the numerous roller coasters and swings in virtual reality, which were very popular some time ago. In fact, what was presented as a result of the immersion possibilities in VR — users screaming, dizziness, difficulty standing on their feet — in fact is the most vivid example of the violation of all possible guidelines for developing virtual reality glasses, which by then were quite formed. We can say that in a sense, all these rides and other crookedly created demos on the knee took part in popularizing VR, but they also formed a stereotype that motion sickness is a fundamental problem of the new platform. And this is not the case.

The problem itself can be divided into three blocks - hardware, software and individual aspects.

Equipment

At the level of iron, modern systems and fixed and mobile VR have gone far ahead of their counterparts from the 90s , which was simply impossible to use. This also applies to the characteristics of the screen and optics, the capabilities of the tracking sensors and ergonomics, as well as the performance of the computers themselves .. Of course, there is still something to strive for and how to improve the user experience. Response time, resolution, field of view, pupil tracking, device weight, general convenience of its use, etc.) - all this can affect the situation with motion sickness, but right now with the right system of interaction, you can achieve excellent results in solving the problem for most users.

At the moment there is a method that allows you to minimize the effect of motion sickness - this is a full body tracking, when all data obtained from the user's body movement in real life is taken into account and reproduced in virtual reality. From the perspective of the consumer version, the Lighthouse tracking system for HTC Vive is closest to this. But this technology (or rather its current form factor) has its own specifics, which impose certain restrictions on use and not all users will be interested only in this experience of interaction in VR, so if we are talking about a project for the massmarket, you need to count on russkale format, and the use of VR in a sitting / standing position.

Also, I now do not take into account the various platforms for the simulation of movement in virtual space, which are often exemplified in similar articles. In spite of the fact that they can solve the designated problem, a certain skepticism about them, as a product for the massmarket, I have already described . Therefore, from the standpoint of commercial development, it is undesirable to focus on such an opportunity when creating a transfer system.

Software part

There has also been significant progress - in recent times, thousands of developers have explored the possibilities of VR, and have not avoided the problem of motion sickness.
Several solutions have been found empirically and a number of recommendations have been made that can significantly reduce unpleasant effects and create a comfortable VR interaction for most users. In previous articles, I pointed out these techniques, but now I want to make out their details.

Using the effect of slow motion and work with the dynamics

In general, the more predictable the actions of the camera and the environment in VR, the less unpleasant effects will occur. Slow motion here at an opportune moment. This may also include the rejection of any sudden camera movements, any accelerations, blurring effects, camera shaking, or the more interception of its control (gaze) of the user.

The more clearly the user will realize where he is in the virtual environment at any given time, the more comfortable he will feel in it.

Any capsule / cabin

This is not necessarily the cockpit of a spacecraft or the passenger compartment - the idea is to surround the user with a static space relative to him (you can even just beat it at the GUI level). This could be, for example, the helmet of a space suit or, as in this example, the elements of a jetpack frame:



The location around the user and in the foreground along the path of his movement of static objects helps to smooth out unpleasant sensations, everything becomes more predictable around him, there is also synchronization between the seated user in real life and also the static avatar inside the virtual "cockpit", which already in turn is in move.

Teleportation and various styles of discrete movement

Everything is quite obvious here - there is no visualization of displacement, and there is no problem of motion sickness during displacement. Teleportation is now one of the most effective ways to reduce the unpleasant effect, since it simply, in principle, removes the cause of its occurrence.

Moving to a point of sight

Basically, lateral displacements left-right or up-down, i.e. movement perpendicular to the direction of view of the user. But if the user moves to where he is looking, the unpleasant effects can be reduced.



Of course, this method, as in principle, and all the rest is far from universal and can be used only in cases where such a system of movement may be appropriate.

Visualization of the trajectory of movement

If there are no abrupt changes in the direction of movement (as on a roller coaster, where the roadbed is the same visualizer), then this is quite a working option - we see where we are going and it is not as annoying as if there is no understanding of the trajectory of movement.
A similar technique is used when moving an avatar with a camera from a third person - the character first moves, setting the direction of movement, then with some inertia in the direction of movement of the avatar, the user's camera starts moving.

Partial or total rejection of body imaging

This moment concerns, not so much a movement, as a similar dissonance - a conflict of perception of oneself in VR, which, as it seems (!), Can also cause not very pleasant sensations or simply worsen the effect of immersion in a virtual environment.

In classical neuroscience there is a concept of a body pattern . Thanks to the scheme of the body, we have an idea of ​​its dynamic characteristics, the current position of its parts, and we can plan movements. Thanks to the scheme, you can touch the tip of the nose with your eyes closed with your finger.
And now, when it comes to user experience from the first person, some developers refuse to render or animate those parts of the body that cannot be tracked in space in real life, in order not to create an dissynchronization between the user's real position during his movement in space and his virtual body.

The creators of Toybox said the same thing on Oculus Connect 2


These are not all the existing ways to solve the issue of moving to VR. Developers continue to experiment and constantly offer new, sometimes rather unusual options:

In fact, the three examples above, to some degree or another, play up to the concept of a kind of “cabin” within which the user looks at the surrounding virtual space, which in this case does not occupy the entire field of view.

Individual aspects

And this is something that is beyond the control of the creators of the VR-devices themselves and software developers. In addition to the fact that the actual location of the user may differ from the virtual (in real life, the person lies, and in the virtual stands on his feet, which worsens the VR experience), there are certain individual physiological features - diseases associated with impaired coordination of movement, just ordinary overwork, lack of sleep The presence of flu is an aspect that cannot be controlled on the developer’s side, but which reinforces the effect of motion sickness. In the end, there is simply a predisposition to ordinary motion sickness - if a person is swayed when he goes inside the car, then it can be assumed that a software solution to reduce the unpleasant effect in VR through the creation of a virtual cabin will hardly help him. But developers can (and should) do their best on their part to create a comfortable interaction. After all, all the tools for this they now have in stock.


The problem with motion sickness, like a number of other specific moments, demonstrates not only the unique differences between VR devices and classical interfaces, but also shows that if earlier game developers and services needed to understand behavioral and social psychology, sociology and perception psychology, then the tasks The creators of projects for VR include the study of neurology and the latest advances in the study of consciousness. After all, now, to build a high-quality system of interaction with the virtual environment, you need to understand not only how a person perceives the world around and other individuals, but also how he perceives himself in this or virtual world. And it will become extremely important when (or for the doubters - if) the virtual reality technology goes into the massmarket area.