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


  • The 3D display based on binocular disparity is utilized in head-mounted displays and autostereoscopic displays to create 3D images. However, issues such as inducing vergence-accommodation conflicts, caused by the virtual 3D images deviating from real-world stereoscopic viewing conditions, have been identified, leading to decreased quality of stereoscopic perception and discomfort. Therefore, in recent years, gaze-contingent displays have been evolving, attempting to improve stereopsis by providing real-time eye information feedback to the display.

  • One of the eye effects that gaze-contingent displays aim to introduce is ocular parallax, a small parallax generated by the rotational movement of the eyes. As illustrated in Fig. 1 (a), the viewpoint position of the eye is generally located at the corneal nodal point N1, which is different from the center of eye rotation C. Due to eye movements such as saccades, the viewpoint position is constantly moving around the center of eye rotation C, resulting in a small parallax, called ocular parallax. Conventional 3D displays, including head-mounted displays, have ignored ocular parallax. However, with the advancement of today's VR/AR systems, real-time rendering of ocular parallax on commercially available head-mounted displays has become feasible. Nevertheless, significant end-to-end latency cannot be avoided in such commercial devices, which may overestimate or underestimate true effects of ocular parallax rendering.

  • Therefore, this study developed a high-speed, low-latency ocular parallax rendering system, as shown in Fig. 1 (b, c). Stereo cameras are provided for each eye for eye tracking, and a stereoscopic display using anaglyph is installed in front of the subject. The system operates at 360Hz, and the end-to-end system latency was evaluated to be an average of 4.832 ms.

  • Through user experiments using this system, the allowable latency at which movements provided by by ocular parallax rendering are not unaturally perceived was evaluated. Additionally, it was reported that ocular parallax rendering facilitates binocular fusion but has no effect on the determination of front and back textures by monocular vision.
Fig. 1 (a) Comparison between ocular parallax rendering, considering differences in eye viewpoint from the center of eye rotation, and conventional 3D rendering that does not consider this factor. (b,c) The low-latency (4.8 ms) ocular parallax rendering system realized at first in this paper.


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