Kenya Uomori

Binocular fixation-point shifts induced by a limb occlusion

We analyzed binocular eye movements to investigate how human see a limb when limb-occlusion occurs. The results suggest that human tend to shift each eyes fixation-point outward when they perceive limb-occlusion. Limb-occlusion has a greater effect for the fixation-point shifts than the depth discontinuity due to differences of visual distance.

Measurement and analysis of human brain function through head and eye movement

This paper describes the measurement system of head and eye movement for analyzing brain function. This system is able to measure the movement of the gaze in space in real time by converting the degree of head movement to that of eye movement. It superimposes this calculation result onto the image seen by the subject. For analysis of brain function, such us a comparative study of the gaze movements of Alzheimers disease patients and healthy people, this system provides two methods. One is for movement data of the head and eyes while the subject is tracking changes in targets, and the other is for minute eye movement data while the subject stares at a fixed point.

A model of saccade mechanism based on occlusion detection and depth estimation processes

We measured binocular eye movements to analyze how the human visual system worked in the situation of gazing at an object when occlusion was occured. We obtained the following results. First, a mechanism which detects occlusion situations is implemented in an early stage of visual processing. Second, the distribution of gazing positions in 3D space changes depending on visual cues, and reflects the depth perception. Based on these results, we propose a model of saccade mechanism based on the occlusion detection by matching binocular retinal images in an early stage of visual processing and depth estimation processes.

Saccade Mechanism Based on Processes for Depth Estimation and Incongruity Detection between Binocular Retinal Images. Analysis of Gazing Positions and Inter-saccade Intervals.

We analyzed binocular gazing positions in the existence of a rim occlusion. When a human gazes at the rim of a textured cylinder, the gazing position shifts from the fixation target. When a human gazes at the rim of a cylinder whose upper-surface is visible, the gazing points are located at the estimated surfaces depth. In this paper, to investigate the mechanism changing the gazing point, we analyzed inter-saccade intervals. The result shows that an occlusion detection mechanism exists at an early stage of human visual processing, and the mechanism causes a shorter-interval saccade when incongruity regions between left and right retinal images are detected. We propose a saccade mechanism which includes processes for depth estimation and incongruity detection between binocular retinal images based on relationships between the gazing positions and the results of inter-saccade intervals.

Three-Dimensional Image. Measurement of Binocular Fusional Limit under Fixating and Free-observing Condition as Applied to a Design of Stereoscopic Image Parameters.

Binocular fusional limits are measured under two conditions for observing a small stereoscopic display with a short viewing distance. One is a free-observing condition in which a subject changes his gaze point between a far and a near target alternately and estimates fusional limit at each fixating point the other is a fixating condition in which a subject fixates on a center point and estimates the fusional limit for the whole screen. In the free-observing condition, fusional limit is in proportion to the viewing angle and has weak dependence on viewing distance. In some cases the fusional limit of the far point is smaller than the disparity when the lines of sight are parallel. In the fixating condition, the fusional limit is ± 40 [arc min] as a maximum, larger than Panums fusional limit, and has weak dependence on viewing angle and viewing distance. A method to design stereoscopic image parameters to display all objects within a subjects fusional limit is examined using the measured fusional limits.

Binocular Eye Movements While Showing a Moving Stimulus to One Eye Only

To investigate the role of binocular eye movements to stereoscopic images, we constructed a new 3D image processing system and a binocular eye-movement analyzer. The system can control 3D image output, measuring binocular eye movements simultaneously. We focused on the interaction between both eyes and measured binocular eye movements while showing a moving stimulus to one eye and a stationary stimulus to the other. Asymmetric conjugate or convergent eye movement occurred, and there was a tendency for convergence eye movement with stereopsis. The tendency for binocular eye movement differs individually. There was a tendency for convergent eye movement when the stimulus was in front of the screen. Also, the dominant eye had a tendency to reach peak velocity earlier than the other eye even if the dominant eye did not see the moving stimulus.