Field of View: A Look Through the Lens of AR and VR

Imagine yourself peering through a window. The wider the window, the more you can see of the world outside, right? Field of View (FoV) in Augmented Reality (AR) and Virtual Reality (VR) works similarly. It defines the extent of the visible world — real or virtual — that you can perceive at any given moment through the lens of your AR/VR headset. A wider FoV translates to a more encompassing view, and a narrower FoV restricts what you can see. But how does FoV differ between AR and VR, and how does it impact the way we experience these immersive technologies?

Please have a look the video before moving forward. It is basic glimpse about the FOV: Field of view (FOV) The Science Behind in AR & VR (youtube.com)

Understanding Field of View

FoV is typically measured in degrees. Here’s a visual representation to help you grasp the concept:

Imagine this line segment as your entire field of view. In the real world, the average human eye boasts a horizontal FoV of around 100–120 degrees. This means you can comfortably see about 100–120 degrees to either side of your direct gaze without needing to move your head.

Now, let’s explore how FoV plays out in AR and VR:

There are two main ways to measure FOV:

1. Angular Field of View (AFOV): This is like measuring the angle of the window you’re looking through. It’s typically specified in degrees and represents the total area the camera “sees” horizontally, vertically, or diagonally.
2. Sized Field of View (Object Size): This is more like measuring the actual size of what the camera captures within a certain distance. Imagine holding a ruler up to the window — the sized FOV would be the length of that ruler that fits within the window frame at a specific distance from the camera. This measurement is usually given in millimeters or meters.

The lens and sensor size of your camera work together to determine the FOV. Here’s the key:

• Lens focal length: Think of the lens as the adjustable part of the window. A shorter focal length creates a wider FOV, like a large window revealing more of the scene. Conversely, a longer focal length acts like a narrower window, focusing on a smaller area with more detail.
• Sensor size: Imagine the sensor as the “film” inside the camera that captures the image. A larger sensor, like a bigger window, can capture a wider FOV at the same focal length compared to a smaller sensor.

In most cameras, FOV is measured horizontally because most sensors are rectangular. This measurement is typically expressed in millimetre and indicates the actual width captured on the sensor at a specific distance.

How Field of View Shapes Your VR and AR Experience

Imagine stepping into a virtual world or having digital information layered onto your real-world view. Field of View (FOV) plays a critical role in how immersive and comfortable these experiences feel. Here’s how FOV impacts your journey in VR and AR:

• Immersion: Wider FOV in VR creates a more realistic experience, like a larger window showcasing a vast virtual world.
• Comfort: Finding the sweet spot between a wide FOV (potentially causing strain) and a narrow FOV (straining eyes) is key.
• Navigation: Wider FOV in VR improves spatial awareness, while a narrow FOV in AR might limit your view of digital content.
• User Interface: Limited FOV requires central placement of information, while a wider FOV allows for more flexibility.
• Realism in AR: A wider FOV creates a seamless integration of digital content into the real world.

The User Focus: Designing for Comfort and Joy

Great VR/AR goes beyond technical specs. Designers prioritize user experience by:

• Testing with Users: Gathering feedback on comfort, immersion, and ease of use.
• Adapting to Devices: Ensuring content works across various FOV capabilities.
• Minimizing Head Strain: Designing experiences that don’t require constant head movement.
• Clear Information Flow: Placing important elements within easy view.
• Inclusivity for All: Making VR/AR accessible to diverse users.

FOV: The Balancing Act in VR and AR Hardware

The magic of VR and AR lies in how they trick your brain into believing a virtual world or digital information exists within your real-world. FOV dictates how much of the virtual or augmented world fits within your natural vision. Here’s how VR and AR hardware approaches differ when it comes to FOV:

VR: Prioritizing a Wide Window

VR headsets aim for immersion, like stepping into another world. They prioritize a wider FOV using:

• Displays: Inexpensive, flat panels (like phone screens) render a wider FOV but with lower detail.
• Optics: Simple optics allow for wider FOV but sacrifice angular resolution (detail).

Trade-off: Wider FOV in VR creates a more immersive experience, but image quality can be lower.

AR: Balancing View with Resolution

AR focuses on seamlessly integrating digital elements with the real world, requiring a balance between FOV and resolution:

• Displays: AR utilizes microdisplays, tiny high-resolution screens, for crisp visuals.
• Optics: Combiner optics (expensive) superimpose digital information onto the real world, but limit FOV width.

Trade-off: Microdisplays offer superior resolution, but achieving a very wide FOV is challenging due to cost and size limitations. As a result, AR headsets typically have a narrower FOV (around 50 degrees) compared to VR.

FOV: The Balancing Act in VR and AR Hardware

The magic of VR and AR lies in how they trick your brain into believing a virtual world or digital information exists within your real-world. FOV dictates how much of the virtual or augmented world fits within your natural vision. Here’s how VR and AR hardware approaches differ when it comes to FOV:

VR: Prioritizing a Wide Window

VR headsets aim for immersion, like stepping into another world. They prioritize a wider FOV using:

• Displays: Inexpensive, flat panels (like phone screens) render a wider FOV but with lower detail.
• Optics: Simple optics allow for wider FOV but sacrifice angular resolution (detail).

Trade-off: Wider FOV in VR creates a more immersive experience, but image quality can be lower.

AR: Balancing View with Resolution

AR focuses on seamlessly integrating digital elements with the real world, requiring a balance between FOV and resolution:

• Displays: AR utilizes microdisplays, tiny high-resolution screens, for crisp visuals.
• Optics: Combiner optics (expensive) superimpose digital information onto the real world, but limit FOV width.

Trade-off: Microdisplays offer superior resolution, but achieving a very wide FOV is challenging due to cost and size limitations. As a result, AR headsets typically have a narrower FOV (around 50 degrees) compared to VR.

Less is More: Rethinking FOV in VR and AR

Experts argue we overestimate the Field of View (FOV) needed in VR and AR displays. Here’s why a wider FOV might not be the holy grail:

• Misconceptions: People often think they need a wider FOV than they actually do, even in movie theaters.
• Focus on Application: Many AR applications, designed for information display, might not require a wide FOV.
• Human Vision: Our sharpest vision area (fovea) is tiny, covering just a few degrees.

Studies show comfortable reading only requires a narrow FOV. Experts suggest a similar range for AR content placement to avoid discomfort and real-world obstruction.

The Future of FOV in AR: Striking the Right Balance

AR’s potential flourishes with diverse use cases, each requiring a unique approach. While some clamor for a VR-like FOV, tasks like reading text prioritize high angular resolution — a factor often neglected. AR developers face a complex equation: balancing a wide FOV, high resolution, a sleek design, and long battery life. Current bulky, “jack-of-all-trades” headsets exemplify this challenge.

The future of AR hinges on achieving the right balance. By carefully considering FOV, resolution, form factor, and usability for each specific application, AR developers can unlock its true potential and deliver groundbreaking experiences.