One of the biggest problems that all virtual reality (VR) developers currently face is movement within virtual reality and the potential of motion sickness. Generally speaking, this problem can be broken down into three components: hardware, software, and each individual’s own perception.
In this post we’ll discuss current solutions to specific problems when it comes to motion sickness and the challenges that developers face. We’ll also explore ways on how motion sickness can be minimized by changing movement mechanics and using such techniques as movement towards the “viewpoint”, visualization of movement trajectories, using slow motion effects, movement through teleportation from point to point and putting a player into a “cabin”.
To illustrate the problem, it might help to look at what seems to be the perfect gaming genre for VR – first-person shooters (FPS). Despite the fact that this genre is being mentioned in combination with VR in many different books, movies and VR games, the classic movement mechanics did not please users that experimented with VR FPS games. VR players cannot even walk normally through the gaming environment – they start vomiting (in a literal sense). This motion sickness happens because of a sensory conflict – a mismatch between the visual data coming in and the information that a human receives through their vestibular system. Simply said, this happens when a user is moving in VR, but does not move in real life.
Another good example of motion sickness is the simulation of rollercoaster rides in VR, which have been popular for awhile now. What was depicted as the possibilities that arise with VR – screaming people, dizziness, and even difficulty of standing on one’s own feet – is really an infringement of all possible guidelines regarding the development of VR projects. One can say that such simulators and demos did not only help to popularize VR, but also formed a stereotype about motion sickness being a fundamental part of the new platform, which is not necessarily true. The first method of tackling this problem is through improvements in the hardware.
Today’s stationary and mobile VR systems are far ahead of their analogues from the 90’s regarding their characteristics. The two best suited solutions to the problem of motion sickness that are available today on the hardware market are the so called full body motion tracking systems and devices that transform movements in VR to the physical world.
When speaking of modern headsets, we can talk about improvements in the characteristics of the screen and the optics, better tracking sensors, as well as an overall increase in the productivity of computers. There is no doubt that many things still need to be improved to increase the quality of the user experience. Response time, resolution, field of view, eye tracking, weight of the device, the comfort of using it – these are all things that contribute to motion sickness in VR, but even nowadays they can be adjusted to receive exceptional results when solving the problem for the majority of the users.
Another method that can lessen the negative effects of motion sickness is complete body tracking, when all the data points received from the body movement in real life are being recreated in virtual reality. Lighthouse room tracking for HTC Vive is such a solution and is available on the market today. However, this solution has its own limitations regarding its use and not all users will be interested in such a method of interacting with VR. Thus, when speaking of a project for the mass market, one has to count in the room scale format, as well as the use of VR in a seating position.
Finally, there are platforms that simulate movements in virtual reality in the physical world – these are often being mentioned in articles talking about the issue. Despite the fact that such a system can solve the issue of motion sickness, one can say that its rather difficult and expensive to implement a platform like this in the home of every VR user. Thus, it is not worth focusing on such a system from a commercial point of view.
There has been a lot of progress on this side also – thousands of developers tackled VR in the last years and they didn’t forget about the problem of motion sickness. Several solutions have been found that decrease the unpleasant effects of motion sickness and create a comfortable interaction with VR for users.
The use of slow motion and working with dynamics
Generally speaking, the more predictable the movement of the camera and the environment in VR is, the less motion sickness effects the users get. Slow motion, fewer sharp camera movements, less accelerations, blur effects, and camera shakes, will all be helpful addressing the issue. The better the user will understand where in a virtual environment he or she is at any given moment, the more comfortable they will fill.
Putting a player into a “cabin”/”capsule”
The idea behind this concept is to surround the user with static environment in relation to them. This can be done on the level of a graphic user Interface, or in the form of a space ship cockpit, a car dashboard, the helmet of a space suit, or some elements of a jetpack.
Static elements surrounding the user during their movements help to reduce uncomfortable feelings as everything becomes more predictable around the user. A synchronization appears between the seated user in the real world and his static avatar in the virtual “cockpit”, which, in turn, is moving forward.
Teleportation and different styles of discrete movement
This solution seems to be obvious and simple – by getting rid of any movement visualization, we can get rid of motion sickness also. Teleportation is currently one of the most effective methods of reducing the unpleasant effect by simply removing the cause of its occurrence.
Movement towards the “viewpoint”
In most cases disorientation is caused by sideward movements and, in particular, a movement perpendicular to the direction of the user’s sight. Thus, if the user is moving in the direction in which he is looking, the related motion sickness effects can be reduced. However, this solution is limited as you cannot apply it in every case.
Visualizing the movement’s trajectory
In a situation where there are not many sharp and unpredictable changes in the direction of the movement, e.g. on a roller coaster, where the rails serve as a visualizer showing the direction of the movement, this is a suitable solution. The visualizer aids the user’s mind in understanding where he is heading, reducing the unwanted effects of motion sickness. A similar method is being used when an avatar moves away from the camera in 3rd person view – at first the avatar moves away, visualizing the direction, followed by the movement of the user camera in that same direction.
Partial or full refusal of body visualization
This section is not concerned with movement in VR, but rather with the conflict of perception of oneself in VR, which can cause unpleasant feelings or simply worsen the effect of immersing into the virtual environment.
In neuroscience there is a concept known as body schema that allows a human to understand the dynamic characteristics of his or her body, its locality, as well as plan movements. It’s due to this concept that you can touch the tip of your nose with your eyes closed. When talking about user experience in VR, some developers refuse to visualize or animate parts of the body that cannot be tracked in the physical world. This helps reduce or get rid of the dissonance that might arise between the user’s position in real life and the position of his avatar during movement in virtual environments. (There is a talk on this topic by the creators of Toybox at Oculus Connect 2)
These are just some of the possible software solutions to motion sickness when moving in VR. Developers are continuing to experiment with different methods and are constantly providing new and, sometimes, very unusual solutions:
The User’s Individual Aspect
Despite all the available hardware and software solutions, there is one aspect that developers cannot directly affect in the process of creating VR experiences.
Fist, the real position of the user can differ from the position of the user in the virtual environment (the user can be lying whereas his virtual avatar can be standing on his feet), worsening the overall experience. Second, there are certain other physiological aspects – illnesses related to the disturbance of movement coordination, casual tiredness, lack of sleep – that are beyond the developers’ control. Some people are just more likely to have kinetosis – if someone is feeling bad when driving in a car or sitting on an airplane, then it is very unlikely that some type of a software solution targeted at reducing the effects of motion sickness is going to help this person. Nevertheless, developers can (and must) do everything possible on their behalf in order to create a comfortable user experience as they now have all the available tools at their disposal.
Issues related to motion sickness, in addition to several other specific challenges, do not only highlight the unique differences between VR devices and classical interfaces, but also show that developers do not only have to be knowledgeable in day-to-day and social psychology, sociology and perception in psychology, but they also have to keep track of scientific developments in neurology and exploring consciousness.
In order to develop a good system of interaction with a virtual environment, one needs to understand not only how the person perceives the surrounding environment and other individuals, but it’s also important to see how this person perceives himself/herself in the real or virtual environment. This knowledge will become even more crucial when VR technology will become available to the mass market.
Denis Tambovtsev, Natasha Floksy and Olga Peshé