masahiro ishii - Academia.edu (original) (raw)

Papers by masahiro ishii

1996 IEEE International Conference on Systems, Man and Cybernetics. Information Intelligence and Systems (Cat. No.96CH35929)

The importance of force feedback in a virtual workspace had already been showed in many researche... more The importance of force feedback in a virtual workspace had already been showed in many researches. With force feedback, operators in the virtual workspace can do their “virtual” jobs more speedily and precisely and can feel more real. Nowadays force display is mainly realized by complicated structure. These complicated and heavy structures both make the user feel uncomfortable and limited

The Journal of the Institute of Television Engineers of Japan

The Journal of The Institute of Image Information and Television Engineers

Apparent distance is modulated by accommodation or vergence. There is conflicting evidence about ... more Apparent distance is modulated by accommodation or vergence. There is conflicting evidence about the effect on distance perception when vergence and accommodation are presented simultaneously. In the current study, we investigated whether apparent distance defined by vergence is modulated by changes of accommodation. Subjects observed a dichoptic stimulus that evoked vergence by looking at a fixation target, through concave or convex lenses. This stimulus is called the reference stimulus. Similarly, they observed a target by looking through non-refractive lenses. This stimulus is called the test stimulus. The reference stimulus and the test stimulus appear at different distances if accommodation modulates apparent distance. We examined the point of subjective equality. The subjects changed the apparent distance of the test stimulus by changing the vergence angle of the test stimulus to make them have the same apparent distance. The result showed that apparent distance is modulated by changes of accommodation.

Presence: Teleoperators and Virtual Environments

This paper describes a 3D kinesthetic interface device using tensed strings. The results of the e... more This paper describes a 3D kinesthetic interface device using tensed strings. The results of the experiments on pick-and-place tasks show that not only sensations of collision but also weights of virtual objects are important in virtual environments.

i-Perception, 2011

Depth perception from motion parallax has been investigated with right-and-left head movement. Fr... more Depth perception from motion parallax has been investigated with right-and-left head movement. From ecological point of view, humans move forward more frequently than sideways. The aim of this study was to determine the influence of the head movement direction on depth perception from motion parallax. We investigated depth perception at and above threshold level with lateral head movement and to-and-fro movement. Stimuli were vertical half cylinders, which was concave or convex, depicted with random dots that move synchronously with head. The viewing distance was 78.5 cm on average. The size of each display was 6.6 × 6.6 deg. The dot density in the entire display was always maintained constant for prevention of depth impression from difference in dot density. Four subjects participated the experiments. Mean threshold for lateral and to-and-fro motion were about 0.1 cm and 5 cm respectively. Mean gains of apparent depth for lateral and to-and-fro motion were about 1 and 0.2, respectively.

Journal of Japan Society for Fuzzy Theory and Intelligent Informatics, 2010

Sice 2003 Annual Conference, Sep 6, 2003

ABSTRACT In this paper we propose a hierarchical artificial immune architecture inspired by the l... more ABSTRACT In this paper we propose a hierarchical artificial immune architecture inspired by the living body immune system and apply it to pattern classification. The simulation results illustrate that the proposed immune architecture is capable of developing hierarchical class representation through self-organization and is effective at clustering a wide variety of arbitrary sequences input patterns into stable categories.

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映像情報メディア学会誌映像情報メディア, May 20, 1998

The Journal of The Institute of Image Information and Television Engineers, 2011

The present work aims to overcome human's instability of stereopsis depth perception in virtual e... more The present work aims to overcome human's instability of stereopsis depth perception in virtual environment provided with stereo graphics. We investigated the possibility of integrating both haptic sensation and stereopsis cues to improve the task of localizing and manipulating objects in virtual environment.

IEEJ Transactions on Electronics, Information and Systems, 2008

This paper proposes a novel inter-process communication, between a virtual world manager with slo... more This paper proposes a novel inter-process communication, between a virtual world manager with slow update rate and a haptic controller with fast update rate, which incorporates the integrated force given from the user to the world. High-speed refresh rate, generally 1kHz, is required to present stiff virtual objects that have spring-damper characteristic with haptic display. On the other hand, the managing of an interactive and rich virtual world that takes a lot of computational time makes the refresh rate as low as 10Hz, which is enough for perceptual cycle. The dividing of the process into two has been proposed to interact with such a world and inter-process communication between the processes has been discussed. Although the methods proposed previously work well on condition that the virtual world is static, goes wrong on dynamic world. The importance of the force integration on the object motion acquisition is described and an inter-process communication that cares about the force integration is proposed to remove the influence of the sampling timing. An experimental result shows that the proposed method improve the accuracy of the operation.

Ieice Transactions on Fundamentals of Electronics Communications and Computer Sciences, Jun 1, 2004