Presence: Teleoperators and Virtual Environments

doi: 10.1162/pres.1993.2.3.iipmid: N/A

doi: 10.1162/pres.1993.2.3.iipmid: N/A

Holmgren, Douglas E.; Robinett, Warren

doi: 10.1162/pres.1993.2.3.171pmid: N/A

Technologies applicable toward a display system in which a laser is raster scanned on the viewer's retina are reviewed. The properties of laser beam propagation and the inherent resolution of a laser scanning system are discussed. Scanning techniques employing rotating mirrors, galvanometer scanners, acoustooptic deflectors, and piezoelectric deflectors are described. Resolution, speed, deflection range, and physical size are strongly coupled properties of these technologies. A radiometric analysis indicates that eye safety would not be a problem in a retina-scanning system. For head-mounted display applications, a monochromatic system employing a laser diode source with acoustooptic and galvanometer scanners is deemed most practical at the present time. A resolution of 1000 × 1000 pixels at 60 frames per second should be possible with such a monochromatic system using currently available off-the-shelf components. A full-color scanned-laser display suitable for head-mounted display use is not judged feasible to build at this time with off-the-shelf components.

Holmgren, Douglas E.; Robinett, Warren

doi: 10.1162/pres.1993.2.3.171pmid: N/A

Technologies applicable toward a display system in which a laser is raster scanned on the viewer's retina are reviewed. The properties of laser beam propagation and the inherent resolution of a laser scanning system are discussed. Scanning techniques employing rotating mirrors, galvanometer scanners, acoustooptic deflectors, and piezoelectric deflectors are described. Resolution, speed, deflection range, and physical size are strongly coupled properties of these technologies. A radiometric analysis indicates that eye safety would not be a problem in a retina-scanning system. For head-mounted display applications, a monochromatic system employing a laser diode source with acoustooptic and galvanometer scanners is deemed most practical at the present time. A resolution of 1000 × 1000 pixels at 60 frames per second should be possible with such a monochromatic system using currently available off-the-shelf components. A full-color scanned-laser display suitable for head-mounted display use is not judged feasible to build at this time with off-the-shelf components.

Ma, Jiantao; Hollerbach, John M.; Hunter, Ian W.

doi: 10.1162/pres.1993.2.3.185pmid: N/A

This paper presents a design concept for a head-mounted display, incorporating color stereo vision using commercial LCDs and our own optical relay design. The focus here is on the optical system design, which must meet specifications for a wide field of view, size and cost constraints, and aberration minimization based on human factors. Two multispherical lens systems are presented and compared, one a straight structure and the other a folded structure, which satisfy the design constraints. Their aberrations (distortion, coma, lateral color, field curvature, and astigmatism) have been well corrected, according to human perceptual constraints explicitly discussed. Each has a 20-mm eye relief and an instantaneous field of view greater than 60°; the former has an exit pupil of 10 mm and the latter of 8 mm.

Ma, Jiantao; Hollerbach, John M.; Hunter, Ian W.

doi: 10.1162/pres.1993.2.3.185pmid: N/A

This paper presents a design concept for a head-mounted display, incorporating color stereo vision using commercial LCDs and our own optical relay design. The focus here is on the optical system design, which must meet specifications for a wide field of view, size and cost constraints, and aberration minimization based on human factors. Two multispherical lens systems are presented and compared, one a straight structure and the other a folded structure, which satisfy the design constraints. Their aberrations (distortion, coma, lateral color, field curvature, and astigmatism) have been well corrected, according to human perceptual constraints explicitly discussed. Each has a 20-mm eye relief and an instantaneous field of view greater than 60°; the former has an exit pupil of 10 mm and the latter of 8 mm.

Rohling, Robert N.; Hollerbach, John M.; Jacobsen, Stephen C.

doi: 10.1162/pres.1993.2.3.203pmid: N/A

An optimized fingertip mapping (OFM) algorithm has been developed to transform human hand poses into robot hand poses. It has been implemented to teleoperate the Utah/MIT Dextrous Hand by a new hand master: the Utah Dextrous Hand Master. The keystone of the algorithm is the mapping of both the human fingertip positions and orientations to the robot fingers. Robot hand poses are generated by minimizing the errors between desired human fingertip positions and orientations and possible robot fingertip positions and orientations. Differences in the fingertip workspaces that arise from kinematic dissimilarities between the human and robot hands are accounted for by the use of a priority based mapping strategy. The OFM gives first priority to the human fingertip position goals and the second to orientation.

Rohling, Robert N.; Hollerbach, John M.; Jacobsen, Stephen C.

doi: 10.1162/pres.1993.2.3.203pmid: N/A

An optimized fingertip mapping (OFM) algorithm has been developed to transform human hand poses into robot hand poses. It has been implemented to teleoperate the Utah/MIT Dextrous Hand by a new hand master: the Utah Dextrous Hand Master. The keystone of the algorithm is the mapping of both the human fingertip positions and orientations to the robot fingers. Robot hand poses are generated by minimizing the errors between desired human fingertip positions and orientations and possible robot fingertip positions and orientations. Differences in the fingertip workspaces that arise from kinematic dissimilarities between the human and robot hands are accounted for by the use of a priority based mapping strategy. The OFM gives first priority to the human fingertip position goals and the second to orientation.

Slater, Mel; Usoh, Martin

doi: 10.1162/pres.1993.2.3.221pmid: N/A

This paper discusses factors that may contribute to the participant's sense of presence in immersive virtual environments. We distinguish between external factors, that is those wholly determined by the hardware and software technology employed to generate the environment, and subjective factors, that is how sensory inputs to the human participant are processed internally. The therapeutic technique known as neurolinguistic programming (NLP) is used as a basis for measuring such internal factors. NLP uses the idea of representation systems (visual, auditory, and kinesthetic) and perceptual position (egocentric or exocentric) to code subjective experience. The paper also considers one external factor, that is how the virtual environment represents a participant—either as a complete body, or just an arrow cursor that responds to hand movements. A case-control pilot experiment is described, where the controls have self-representation as an arrow cursor, and the experimental group subjects as a simple virtual body. Measurements of subjects' preferred representation systems and perceptual positions are obtained based on counts of types of predicates and references used in essays written after the experiment. These, together with the control variable (possession/absence of a virtual body), are used as explanatory variables in a regression analysis, with reported sense of presence as the dependent variable. Although tentative and exploratory in nature, the data analysis does suggest a relationship between reported sense of presence, preferred representation system, perceptual position, and an interaction effect between these and the virtual body factor.

Slater, Mel; Usoh, Martin

doi: 10.1162/pres.1993.2.3.221pmid: N/A

This paper discusses factors that may contribute to the participant's sense of presence in immersive virtual environments. We distinguish between external factors, that is those wholly determined by the hardware and software technology employed to generate the environment, and subjective factors, that is how sensory inputs to the human participant are processed internally. The therapeutic technique known as neurolinguistic programming (NLP) is used as a basis for measuring such internal factors. NLP uses the idea of representation systems (visual, auditory, and kinesthetic) and perceptual position (egocentric or exocentric) to code subjective experience. The paper also considers one external factor, that is how the virtual environment represents a participant—either as a complete body, or just an arrow cursor that responds to hand movements. A case-control pilot experiment is described, where the controls have self-representation as an arrow cursor, and the experimental group subjects as a simple virtual body. Measurements of subjects' preferred representation systems and perceptual positions are obtained based on counts of types of predicates and references used in essays written after the experiment. These, together with the control variable (possession/absence of a virtual body), are used as explanatory variables in a regression analysis, with reported sense of presence as the dependent variable. Although tentative and exploratory in nature, the data analysis does suggest a relationship between reported sense of presence, preferred representation system, perceptual position, and an interaction effect between these and the virtual body factor.