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.

This paper presents a low-latency Beaming Display system with a 133 μs motion-to-photon (M2P) latency, the delay from head motion to the corresponding image motion. The Beaming Display represents a recent near-eye display paradigm that involves a steerable remote projector and a passive wearable headset. This system aims to overcome typical trade-offs of Optical See-Through Head-Mounted Displays (OST-HMDs), such as weight and computational resources. However, since the Beaming Display projects a small image onto a moving, distant viewpoint, M2P latency significantly affects displacement. To reduce M2P latency, we propose a low-latency Beaming Display system that can be modularized without relying on expensive high-speed devices. In our system, a 2D position sensor, which is placed coaxially on the projector, detects the light from the IR-LED on the headset and generates a differential signal for tracking. An analog closed-loop control of the steering mirror based on this signal continuously projects images onto the headset. We have implemented a proof-of-concept prototype, evaluated the latency and the augmented reality experience through a user-perspective camera, and discussed the limitations and potential improvements of the prototype.

In spatial augmented reality, a widely dynamic projection mapping system has been developed as a novel approach to graphics presentation for widely moving objects in dynamic situations. However, this method necessitates a novel tracking marker design that is resistant to random and complex occlusion and out-of-focus blurring, which conventional markers have not achieved. This article presents a uniform circumferential marker that becomes an ellipse in perspective projection and expresses geometric information. It can track the relative posture of a dynamically moving sphere with high speed, high accuracy, and robustness owing to continuous contour lines, thereby supporting both wide-range movement in the depth direction and human interaction. Moreover, a biased circumferential marker is proposed to embed unique coding, where the absolute posture is decoded with a novel recognition algorithm. Moreover, rough initialization using the geometry of multiple ellipses is proposed for both markers to start the automatic and precise tracking. Real-time rotation visualization onto the surface of a moving sphere is made possible with the high-speed, widely dynamic projection mapping system. The tracking performance is demonstrated to exhibit sufficient basic tracking performance as well as robustness against blurring and occlusion compared to conventional dot-based markers.

Image projection on spheres and their surroundings have been researched for all-around display and motion visualization. However, wide-range projection onto a dynamic sphere can suffer from tracking errors and projection latency. We propose a high-speed projection mapping system for dynamic spheres, and circumferential markers for sphere posture estimation. Marker detection based on ellipse appearance can easily start tracking, and is robust against interactive occlusion; therefore, the system enables projection mapping and rotational visualization for a dynamically moving sphere. We experimentally confirmed sufficient pose estimation accuracy of the circumferential markers compared with initialized dot markers, and sufficient tracking ability against initialization, occlusion, and depth-direction movement. Demonstrations showed accurate, rotation-visualized projection onto a dynamic sphere, which is useful for sports practice applications.

Color-forming display can present digital vision by repeatedly changing its color; this display has been studied in recent research on augmented reality (AR) displays. Previous methods exhibit large-latency and low-speed problems, leading to the lack of interaction in immersive AR experiences. This study proposes a highspeed and low-latency drawing method on dynamically moving objects, using photochromic material colored by ultraviolet light laser, high-speed mirror control, and visual feedback. The experiment evaluated the method's drawing accuracy and we confirmed that this method has an adequate tracking ability against random rotation to produce accurate drawings.