Low-Latency Ocular Parallax Rendering and Investigation of Its Effect on Depth Perception in Virtual Reality

With a demand for an immersive experience in virtual/augmented reality (VR/AR) displays, recent efforts have incorporated eye states, such as focus and fixation, into display graphics. Among these, ocular parallax, a small parallax generated by eye rotation, has received considerable attention for its impact on depth perception. However, the substantial latency of head-mounted displays (HMDs) has made it challenging to accurately assess its true effect during free eye movements. To address this issue, we propose a high-speed (360 Hz) and low-latency (4.8 ms) ocular parallax rendering system with a custom-built eye tracker. Using this proposed system, we conducted an investigation to determine the latency requirements necessary for achieving perceptually stable ocular parallax rendering. Our findings indicate that, in binocular viewing, ocular parallax rendering is perceived as significantly less stable than conventional rendering when the latency exceeds 43.72 ms at 1.3 D and 21.50 ms at 2.0 D. We also evaluated the effects of ocular parallax rendering on binocular fusion and monocular depth perception under free viewing conditions. The results demonstrated that ocular parallax rendering can enhance binocular fusion but has a limited impact on depth perception under monocular viewing conditions when latency is minimized.