Degrees of Freedom in AR VR

While the visual fidelity and immersive experiences offered by Augmented Reality (AR) and Virtual Reality (VR) technologies continue to captivate users, a crucial element often remains under the radar: Degrees of Freedom (DOF). This seemingly technical concept plays a pivotal role in shaping the level of realism and interactivity within these groundbreaking domains.

Imagine traversing a virtual world, not just with your gaze(HMD pointer), but with the ability to seamlessly move around objects, lean in for closer inspection, or even physically manipulate elements within the digital landscape. This is where DOF comes into play, acting as the invisible strings that bind the virtual world to our physical movements, transforming passive observation into dynamic engagement.

This technical exploration will dissect the various DOF types, their impact on the user experience, and the ongoing advancements that are pushing the boundaries of what’s possible within the realms of AR and VR. We will delve into the fundamental concepts of 3-DOF and 6-DOF tracking, explore the intricate workings of inside-out and outside-in tracking systems, and analyze the computational challenges associated with high-fidelity DOF implementations.

Please have a look the video before moving forward. It is basic glimpse about the DOF: Exploring Degrees of Freedom in Spatial Computer (youtube.com)

So in short “Degrees of freedom (DoF) refer to the number of ways an object can move through 3D space. Generally it is 6 degrees of freeedom which is divided into 2 parts. The first three correspond to rotational movement around the x, y, and z axes. These are commonly known as pitch, yaw, and roll & the other three correspond to translational movement along those axes. This can be thought of as moving forward or backward, moving left or right, and moving up or down.

Level Of Immersion

The level of immersion within AR/VR experiences is significantly influenced by the number of degrees of freedom (DOF) supported by the system. DOF refers to the number of independent ways an object can move through three-dimensional space.

There are two primary DOF levels commonly encountered in AR/VR:

3 Degrees of Freedom (3DOF):

• Limited Movement Tracking: This level primarily focuses on rotational movement, tracking the user’s head rotations around the X, Y, and Z axes (pitch, yaw, and roll). It does not track physical movement through space, meaning users cannot walk, jump, or move their bodies within the virtual environment.
• Stationary VR Experiences: 3DOF is often found in mobile VR headsets or seated VR experiences where users primarily observe the virtual world from a fixed position.
• Example: Oculus GO

6 Degrees of Freedom (6DOF):

• Full Movement Tracking: This level unlocks both rotational and translational movement tracking. 6DOF systems can track not only head rotations but also the user’s physical movements through space, allowing them to walk, jump, bend down, and interact with the virtual world as if they were truly present.
• Enhanced Immersion: 6DOF creates a significantly more immersive and interactive experience, enabling users to explore the virtual space with greater freedom and realism.
• Applications: Room-scale VR experiences, interactive games, virtual training simulations often utilize 6DOF for heightened immersion.

DOF beyond 6(XDOF):

While not as widely implemented as 3DOF or 6DOF in consumer VR & AR, XDOF systems are being explored for research and development purposes. This level expands upon 6DOF by additionally tracking three rotational degrees of freedom for each hand & Eye, enabling more precise and nuanced hand & eye tracking within the virtual environment. This can be particularly beneficial for applications requiring high-fidelity hand interactions with eye selection, such as manipulating complex objects or performing delicate tasks. However, XDOF systems often require specialized hardware and are currently less commonplace compared to 3DOF and 6DOF setups.

Note: X → Number of direction in full body tracking system

Spectrum of Movements

Imagine being trapped in a fixed position within a virtual world, able to only look around but not truly move. This is the limitation of 3DOF VR. 6DOF, however, breaks these shackles, allowing you to experience the virtual world with the full spectrum of movement, just like you do in the real world.

Think of it like this: 6DOF recognizes six distinct movements:

Rotational:

• Pitch: This refers to tilting your head up and down, allowing you to explore the virtual world from different angles, like looking at the ceiling or peering down at objects.
• Yaw: This refers to turning your head left and right, enabling you to scan the environment around you or follow objects in motion.
• Roll: This refers to tilting your head sideways, creating a sense of leaning or tilting within the virtual space.

Translational:

• Heaving: This refers to moving your body up and down, allowing you to climb, jump, or duck within the virtual environment.
• Surging: This refers to moving your body forward and backward, enabling you to walk, run, or explore the virtual space with realistic strides.
• Swaying: This refers to moving your body left and right, allowing you to sidestep, dodge objects, or navigate through virtual landscapes.