Movement

Movement is a tricky mechanic to implement in VR. With current widespread technology [23][24], it’s safe to assume almost all people in VR will be sitting, or walking around a small area. Also there likely won’t be any match between their physical environment and the virtual environment.

User Movement

Given that users will likely need to move themselves in the virtual world in ways that don’t match with their movement/position in the real world, it’s important to consider how to best make those virtual movements feel natural.

If they don’t feel natural and there’s a disconnect between what we see and feel, then we run into motion sickness [25]. And in VR, we’re mainly limited to affecting the user’s sight and hearing. So here are some ways to effectively manage what the user sees and hears, to prevent motion sickness:

Move the user slowly [3][9]

Minimize accelerations and decelerations [27][30]

Give the user a preview of their new orientation after moving [30]

Avoid unexpected involuntarily movements [3]

If you must move the user, move them in the direction they’re looking [3]

Avoid vertical diagonal movements [3][9]

Move the user slowly [3][9]

Image

The video below shows a player rapidly moving while holding a rope. The speed shown is likely to cause motion sickness.

Game: Superfly

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Environment Movement

Not only does the user move in a VR experience, but often so does the virtual environment.

Depth becomes difficult to discern at far distances [9]. Telling the distance between your hand and your computer monitor is much easier than trying to tell the difference between two mountain peaks in the distance.

This is an issue that’s compounded by the low quality of the view in VR headsets. This means that if a user is trying to discern the depth of a small object in a scene or an object far away, they will feel extra eye strain. So here are ways to prevent needless eye strain:

Move approaching/retreating objects slowly [8]

Image

Below is an example of an object moving too quickly away from the user. While here the object’s speed was determined by the user, in general it’s best to avoid having objects able to move quickly away/near like this. The quickly changing focal point causes eye strain in VR.

Game: Rec Room

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Below is an example [22] of moving objects done well- the cubes do quickly move towards the user, but they only travel a short distance so the user’s focal point doesn’t change much. The cubes actually start from very far back, but they are very small until they get close to the user.

Game: Beat Saber

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