Advancements and challenges in positional tracking for VR
Virtual reality (VR) technology allows users to immerse themselves in a 360-degree simulated environment of the world without any boundary restrictions. For VR to work efficiently, positional tracking is essential since it allows accurate monitoring of head and body movements. Positional tracking in VR has made significant advancements over the years but has also encountered its share of difficulties.
Note: To learn about the basics of VR, check out the following Educative Answer: What is Virtual Reality?
Let’s look at a couple of advancements and challenges in positional tracking for VR.
Advancements
The advancements in VR tracking are leading toward an improved user experience, increased precision, and seamless immersion.
Six degrees of freedom (6DoF)
The three degrees of freedom (3DoF) VR models initially offered rotational tracking, restricting head movement over three axes. The 6DoF tracking advancement, on the other hand, allows for six axes of head movement in a virtual world, including up, down, forward, backward, left, right, pitch, roll, and yaw.
Lighthouse tracking
VR positional tracking measures use lighthouses to emit precise laser beams, which are picked up by sensors in the controller and headset. This modular architecture ensures accurate and low-latency location tracking with a minimal setup, offering excellent accuracy with little external influence.
Inside-out tracking
VR technology initially used outside-in tracking, utilizing external cameras and sensors for positional tracking. As technology developed, it shifted to inside-out tracking, integrating cameras, sensors, and computer vision algorithms within the hardware. This simplified the setup, as well as facilitating VR headsets and controllers.
Hybrid tracking
Both inside-out and outside-in measures are used in hybrid tracking. Utilizing both of them reduces the downsides of each and improves positional tracking efficiency. While outside-in tracking can aid with more precision and less blockage, inside-out tracking can help with mobility and ease. Together, they offer positional tracking in VR that is incredibly seamless and accurate.
Low latency
Latency refers to the time between a user’s motion and the virtual environment change. Minimal latency provides an engaging and relaxing virtual world, reducing motion sickness caused by high latency.
Low latency enhances realism, presence, and spatial awareness by matching real-world positions with VR, improving user experience.
Challenges
Despite these advancements, several problems surface, requiring innovative approaches to ensure the continuous advancement of virtual reality.
Occlusion
Occlusion is a scenario where the VR loses sight of the tracked object (headset or controller) because something is blocking the line of sight of the object being tracked by the tracking sensors. This takes place in both inside-out and outside-in tracking of positions.
If some physical object obscures a VR controller held by a user, the system will capture inaccurate and delayed results of hand movements.
Motion sickness
Motion sickness can be brought on by significant latency and a mismatch in the user’s perception. Due to the gap between the visual information from the headset and the motion through the inner ear, tracking location in virtual reality is often difficult. This causes issues such as nausea and pain.
Physical constraints
Virtual environments have physical limitations, such as users’ positions and movements where they may choose to lie down, crouch, or move rapidly, which can disrupt the accuracy of VR systems designed with positional tracking. Space limitations also significantly impact the user experience.
Accuracy and precision
Due to the dynamic settings, achieving great accuracy and precision in positional tracking for VR is difficult. To address this issue, robust algorithms, such as advanced sensor fusion and filtering techniques, alongside calibration methods like aligning virtual and physical positions precisely, are required. Accuracy and precision are impacted by harsh lighting as well.
Multi-user scenarios
Single-user VR being incompatible with multi-users could create inconvenience. Furthermore, due to high traffic volume, VR positional tracking faces challenges in synchronizing multiple users’ actions in the following:
- Physical and virtual environments
- Tracking user positions
- Achieving reliable results without interference
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