Towards Understanding Depth Perception in Foveated Rendering

TL;DR

The paper investigates how peripheral blur from foveated rendering affects stereoscopic depth perception in immersive displays. It introduces a broadband stimulus and a psychophysical protocol to map stereo thresholds across eccentricities $\theta$ and blur levels $\sigma$, and then derives a continuous perceptual surface $M(\theta,\sigma)$ described by $M = p_1(\theta)\cdot(\sigma - p_2(\theta))^2 + p_3(\theta)$ with $p_i(\theta)=a_i e^{b_i\theta}+c_i$. The main findings show that stereoacuity is largely unaffected by commonly used peripheral blur, with a measurable tolerance up to about a factor of 2 beyond typical foveation; a validation study confirms the results in natural scenes. These results imply that depth cues can be preserved while applying stronger peripheral blur in foveated rendering, guiding depth-aware rendering and compression strategies in VR/AR systems.

Abstract

The true vision for real-time virtual and augmented reality is reproducing our visual reality in its entirety on immersive displays. To this end, foveated rendering leverages the limitations of spatial acuity in human peripheral vision to allocate computational resources to the fovea while reducing quality in the periphery. Such methods are often derived from studies on the spatial resolution of the human visual system and its ability to perceive blur in the periphery, enabling the potential for high spatial quality in real-time. However, the effects of blur on other visual cues that depend on luminance contrast, such as depth, remain largely unexplored. It is critical to understand this interplay, as accurate depth representation is a fundamental aspect of visual realism. In this paper, we present the first evaluation exploring the effects of foveated rendering on stereoscopic depth perception. We design a psychovisual experiment to quantitatively study the effects of peripheral blur on depth perception. Our analysis demonstrates that stereoscopic acuity remains unaffected (or even improves) by high levels of peripheral blur. Based on our studies, we derive a simple perceptual model that determines the amount of foveation that does not affect stereoacuity. Furthermore, we analyze the model in the context of common foveation practices reported in literature. The findings indicate that foveated rendering does not impact stereoscopic depth perception, and stereoacuity remains unaffected with up to 2x stronger foveation than commonly used. Finally, we conduct a validation experiment and show that our findings hold for complex natural stimuli.

Figures (11)

• Figure 1: Different vergence angles occurring for different points.
• Figure 2: Overview of the controlled stimulus parameters: eccentricity $\theta$, the ring's width, blur intensity $\sigma$, texture scale based on $S_F(\theta)$, depth map $I_D$ based on $w(S_C(\theta))$, and the dithered border.
• Figure 3: Schematic representation of the induced disparity between reference point $p_Z$ and artificially created point $p_I$.
• Figure 4: Our three final stimuli for $\theta \in \{0^\circ, 10^\circ, 20^\circ\}$. The dithered border, as well as a representative depth map $I_D$ are shown in the right halves. The lower left shows the distortion in $I_R$ (blue) based on $I_D$.
• Figure 5: The highlights mark the peaks.