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Locomotion virtual environments

Designing for physical locomotion often restricts spatial creativity. However, by incorporating artificial locomotion, dynamic elements like ladders, gaps, and ledges can enrich app maps.

This page includes guides for creating effective environments, introducing various forms of design challenges such as managing technical aspects like camera collisions and user height adjustments.

Test environment

Create a test environment that encompasses all potential locomotion scenarios a user might encounter in an immersive experience. Typically, this includes a variety of slopes, materials, doorway dimensions, step heights, path obstructions, tunnels, and ceilings of various heights, as well as features like ledges and ladders. This will effectively test and refine the locomotion implementation within an application.

Minimize movement on slopes

Navigating slopes in fully immersive experiences can cause vertical accelerations and vection due to the avatar’s movement following the terrain. It’s advisable to limit movement to flat surfaces and avoid slopes and stairs when possible.

Design for forward movement

Forward movement is generally more comfortable due to slower expansion of visual points across the retina. Avoid movements like strafing, back-stepping, spinning, and continuous turning, which can induce discomfort. Design environments that minimize the need for such movements and avoid features like spiral staircases.

Keep walls at a distance

Textured surfaces such as walls create more optic flow, which can be increasing risk of motion sickness. Design environments with open spaces or large rooms that keep users away from walls to reduce optic flow.

Elevator and stair design

Elevators and stairs can overwhelm the field of view with strong visual motion cues, triggering discomfort. If necessary, simplify the visual elements in these areas, use gentle slopes instead of stairs, minimize steps, and reduce texture details to limit optic flow.

Climbing

Climbing presents unique design challenges in fully immersive experiences. For instance, consider what happens if a user physically moves away from a climbing surface like a rock wall. Key scenarios to address include: Transitioning to and from a climbing surface, Turning while climbing, climbing down.

To avoid issues, consider teleporting the player to a safe spot near the top or bottom of the climbing surface. If hand-over-hand climbing is implemented, using grab, plan how the avatar will respond if the user moves physically while climbing.

Leaping

If the environment has a gap that the user must get over, use a teleport with a warping mechanic to avoid the vection and potential physical injury of leaping using physical locomotion.

Camera collisions

Deciding whether the camera will collide with the environment is crucial in fully immersive experience design. Both approaches have different effects on usability, design, and comfort.

Cameras without collision

Implementing cameras without collision can lead to several challenges:

Exposure of hidden areas: Users might move their headset into restricted areas, revealing narrative elements meant to be hidden.
Unintended interactions: Users could interact with elements in neighboring rooms unintentionally.
Unrestricted movement: Since virtual movement mimics physical movement, creating inaccessible areas becomes challenging.

Solutions:

Enable environmental collisions: Prevent the camera from passing through solid objects.
Disable rendering in invalid spaces: If the camera moves into an invalid area, such as inside a wall, the display could show a blank screen or visual effects to guide the user back.

Camera collisions

Camera collisions can be necessary for certain design goals but may cause discomfort of movement when not moving. Challenges:

Physical and virtual discrepancy: If a user walks into a virtual wall, the camera stops, but the user’s physical world movement continues, creating a disorienting experience.

Best Practices:

Manage moving objects: Be aware of doors, projectiles, or other moving objects that might collide with the camera.
Selective collisions: Only enable collisions for stationary objects or essential moving objects like elevators.
Handling collisions with moving objects: If the camera collides with a moving object, either move the object away or ignore the collision without causing graphical glitches.

By carefully planning camera behavior and collision handling, user experience is enhanced while maintaining control over the narrative and environment interaction in a fully immersive application.

Peeking over ledges

When users lean over a ledge or cliff, there’s a risk that their avatar might accidentally fall if the virtual movement strictly follows the headset’s position. Here are two potential solutions to address this issue:

Widen the avatar’s collision capsule: This reduces the risk of accidental falls when peeking over ledges but restricts the ability to lean over objects. A larger capsule may also hinder movement in other parts of the environment.

Constrain the avatar’s capsule with a short leash: This method allows the headset to move a short distance without moving the character’s capsule. It enables users to lean over edges without the risk of dragging the avatar off. Additionally, equipping the headset with its own collision sphere can help detect and respond to environmental collisions effectively.

Leaning over objects

When users lean over objects like desks or walls, their avatar’s collision capsule, typically tied to the headset’s position, can prevent further movement if it collides with these objects. To address this, apply the positional constraint solution similar to the one used for peeking over ledges. This allows users to lean over objects within the limits of the constraint, while keeping the character capsule appropriately positioned next to the object.

Adjusting for height

In environments with varying ceiling heights, it’s crucial to consider how the avatar’s collision capsule interacts with overhead obstacles. Standard fixed-height capsules can cause issues, such as taller users hitting the ceiling or shorter users being blocked by obstacles they can physically pass under. There are two possible solutions:

Dynamic capsule adjustment: Modify the avatar’s collision capsule height based on the headset’s distance from the ground. This adjustment allows users to crouch under low obstacles and prevents them from hitting low ceilings. However, dynamically changing the capsule height can be complex. For example, if a user stands up under a low ceiling, the system must still function comfortably without causing the avatar to collide with the ceiling.

Collision-free camera movement: Allow the camera to move without collision, similar to the approach discussed in the “Cameras without Collision” section. While this can enhance movement freedom, it may reduce immersion, as users might move the camera through solid objects unrealistically.

Both methods aim to enhance user comfort and mobility in fully immersive environments with varying vertical spaces.

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