Frame Rate: Key to Comfort and Safety in AR for Visual Impairment

(Picture: Sydney Roy, https://www.wowza.com/blog/frame-rate-beginners-guide-live-streaming)

Frame rate, measured in frames per second (FPS), is the frequency at which consecutive images (frames) appear on a display. Imagine a flipbook where each page shows a slightly different picture. When you flip through the pages quickly, the pictures blend together to create a moving image (video). The speed at which you flip the pages determines how smooth the animation looks. Similarly, the frame rate in AR refers to how many frames are displayed per second to create the illusion of motion.

Why Frame Rate Matters

The importance of frame rate is important with any experience of watching a video. If the frame rate is too low, the video appears choppy and can be uncomfortable to watch. Higher frame rates provide smoother and more natural motion. For individuals with visual impairments, maintaining a high frame rate is not just about visual comfort – it’s about functionality and accessibility. For them, high frame rates in AR application are crucial for several reasons:

Reducing Disorientation and Nausea：Low frame rates can cause choppy visuals, leading to disorientation and nausea. This is particularly problematic for visually impaired users who rely heavily on visual cues to navigate and understand their surroundings. Research indicates that the human eye perceives motion smoothly at a minimum of 15 FPS, but for optimal comfort and effectiveness, 30 FPS or higher is ideal. 

Improving Spatial Awareness：High frame rates help in creating fluid motion, which is essential for tracking moving objects and navigating through spaces. For visually impaired users, this can mean the difference between confidently moving through an environment and struggling to interpret delayed or jerky visuals. Several studies highlight this point. For instance, research on the use of Microsoft HoloLens for indoor navigation shows that maintaining a high frame rate is crucial for the accurate and real-time updating of spatial data, which helps users detect and avoid obstacles effectively​. (This study focused on how real-time updates and visual/audio cues could help users detect obstacles and navigate safely.)

Enhancing Hazard Detection: Many AR applications for the visually impaired include features for obstacle detection and navigation aids. These applications often use real-time processing to provide immediate feedback on the user’s surroundings. High frame rates ensure that this feedback is timely and accurate, which is critical for avoiding hazards and safely navigating through various environments​.

Frame Rate Sensitivity: VR vs. AR

Even though frame rate is one of the key factors, the critical dependence on high frame rates seen in VR is somewhat relaxed in AR, making it more forgiving in terms of performance requirements. This is due to their different operational mechanics. VR creates a fully immersive digital environment that isolates the user from the real world.

In contrast, AR superimposes digital information—such as images, videos, or 3D models—onto the real world. This is achieved using devices like AR glasses, smartphones, and tablets. These devices use cameras and sensors to detect the physical environment and then overlay relevant digital content on top of it.

AR technology maintains users’ peripheral vision, allowing them to detect motion and spatial relationships even if the central vision is experiencing lag or stutter. This broader visual field helps maintain spatial awareness and reduces the likelihood of disorientation and nausea.

Sources

• • Dudley, J., Yin, L., Garaj, V. et al. Inclusive Immersion: a review of efforts to improve accessibility in virtual reality, augmented reality and the metaverse. Virtual Reality 27, 2989–3020 (2023). https://doi.org/10.1007/s10055-023-00850-8

• Hommaru, K., Tanaka, J. (2020). Walking Support for Visually Impaired Using AR/MR and Virtual Braille Block. In: Antona, M., Stephanidis, C. (eds) Universal Access in Human-Computer Interaction. Design Approaches and Supporting Technologies. HCII 2020. Lecture Notes in Computer Science(), vol 12188. Springer, Cham. https://doi.org/10.1007/978-3-030-49282-3_24

• Fox, D. R. (2020).Augmented Reality for Visually Impaired People (AR for VIPs). D. R. Fox Design.