Detecting the micromovements of eyes that reflect a person’s inner state can be an essential step in many applications, but most eye trackers need to fix the subject’s head using a chin rest to obtain sufficient data quality. We propose a stand-alone eye tracker that utilizes two 500 fps cameras, a pair of rotating mirrors for gaze control, a liquid lens for focus control and an intensity-controllable light source, and describe how the proposed system works in real-time. The experimental results show that our system covers more than twice as wide a measurement range in the depth direction as the conventional eye tracker while achieving sufficient data quality to analyze microsaccades with an amplitude of down to 0.2 deg. We also examine the practical use of the proposed system for microsaccade detection.

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.

High-speed finger tracking is necessary for augmented reality and operation in human-machine cooperation without latency discomfort, but conventional markerless finger tracking methods are not fast enough and the marker-based methods have low wearability. In this paper, we propose an ellipses ring marker (ERM), a finger-ring marker consisting of multiple ellipses and its high-speed image recognition algorithm. The finger-ring shape has highly wearing continuity, and the surface shape is suitable for various viewing angle observation. The invariance of the ellipse in the perspective projection enables accurate and low-latency posture estimation. We have experimentally investigated the advantage in normal distribution, validated the sufficient accuracy and computational cost in the marker tracking, and showed a demonstration of dynamic projection mapping on a palm.

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.

Projectors, as information display devices, have improved substantially and to achieve both the wide range and high resolution is desired for the dynamic human gaze. However, a fixed projector has a trade-off between the angle of projection and a resolution with limited pixels. Conventional methods with dynamic optical axis control lack the potential speed of the devices. We propose a tracking projection mosaicing with a high-speed projector and a high-speed optical axis controller for a randomly moving position, such as the gaze. We also propose a synchronization strategy by queuing and alternating operations to reduce motion-based artifacts, which realize a high-quality static image projection during the dynamic optical axis control. We have experimentally validated the geometric and temporal consistency of the proposed synchronization method and have attempted a demonstration of the tracking projection mosaicing for the dynamically moving bright spot of a laser pointer.

A precise calibration method for optical high-speed gaze controllers using rotational mirrors is proposed. The mirror-based pan/tilt camera can change gaze direction more quickly than a conventional pan-tilt-zoom camera, which actuates the camera itself. The high-speed gaze controller can track moving objects at high magnification and can utilize new applications of three-dimensional measurement. However, the controller is difficult to calibrate owing to shallow depth of field (DOF) at close focus positions and mechanical differences. We propose to control optics and illumination to detect calibration pattern control points precisely against shallow DOF; we deepen the DOF using a small aperture, coaxial episcopic illumination, and a retroreflective checkerboard pattern. We introduce mirror thickness for an exact gaze control model and bundle adjustment for large center-of-projection translation. We confirm that wide gaze range calibration is achieved more accurately than when mirror thickness is not considered.

Dynamic Projection Mapping, projection-based AR for a moving object without misalignment by a high-speed optical axis controller by rotational mirrors, has a trade-off between stability of highspeed tracking and high visibility for a variety of projection content. In this paper, a system that will provide robust high-speed tracking without any markers on objects against illumination changes, including projected images, is realized by introducing a retroreflective background with the optical axis controller for Dynamic Projection Mapping. Low-intensity episcopic light is projected with Projection Mapping content, and the light reflected from the background is sufficient for high-speed cameras but is nearly invisible to observers. In addition, we introduce adaptive windows and peripheral weighted erosion to maintain accurate high-speed tracking. Under low light conditions, we examined the visual performance of diffuse reflection and retroreflection from both camera and observer viewpoints. We evaluated stability relative to illumination and disturbance caused by non-target objects. Dynamic Projection Mapping with partially well-lit content in a low-intensity light environment is realized by our proposed system.