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This article addresses some of the challenges involved with creating a stereoscopic video augmented reality “X-ray vision” display for near-field applications, which enables presentation of computer-generated objects as if they lie behind a real object surface, while maintaining the ability to effectively perceive information that might be present on that surface. To achieve this, we propose a method in which patterns consisting of randomly distributed dots are overlaid onto the real surface prior to the rendering of a virtual object behind the real surface using stereoscopic disparity. It was hypothesized that, even though the virtual object is occluding the real object’s surface, the addition of the random dot patterns should increase the strength of the binocular disparity cue, resulting in improved performance in localizing the virtual object behind the surface. In Phase I of the experiment reported here, the feasibility of the display principle was confirmed, and concurrently the effects of relative dot size and dot density on the presence and sensitivity of any perceptual bias in localizing the virtual object within the vicinity of a flat, real surface with a periodic texture were assessed. In Phase II, the effect of relative dot size and dot density on perceiving the impression of transparency of the same real surface while preserving detection of surface information was investigated. Results revealed an advantage of the proposed method in comparison with the “No Pattern” condition for the transparency ratings. Surface information preservation was also shown to decrease with increasing dot density and relative dot size.

BackgroundMany interventions have been implemented to improve hand hygiene compliance, each with varying effects and monetary costs. Although some previous studies have addressed the issue of conspicuousness, we found only 1 study that considered improving hand hygiene by using flashing lights.MethodOur attention theory–based hypothesis tested whether a simple red light flashing at 2-3 Hz affixed to the alcohol gel dispensers, within the main hospital entrance, would increase hand hygiene compliance over the baseline rate. Baseline and intervention observations were completed over five 60-minute periods (Monday-Friday) from 7:30 to 8:30 AM using a covert observation method.ResultsBaseline hand hygiene compliance was 12.4%. Our intervention increased compliance to 23.5% during cold weather and 27.1% during warm weather. Overall, our pooled compliance rate increased to 25.3% (P < .0001).ConclusionsA simple, inexpensive flashing red light affixed to alcohol gel dispensers was sufficiently salient to approximately double overall hand hygiene compliance within the main hospital entrance. We hypothesize that our intervention drew attention to the dispensers, which then reminded employees and visitors alike to wash their hands. Compliance was worse during cold days, presumably related to more individuals wearing gloves.

A two phase project is described for redesigning and evaluating paramedic response bags, one of the key pieces of equipment used by emergency medical services. Adopting a user-centred approach, Phase I involved first educating active service paramedics about ergonomic principles, and then collaborating with them to conceptualise a new type of response bag, based on separate colour coded kits, each containing related equipment items. Phase II describes a formal evaluation study, involving simulated procedures with a patient mannequin and active service paramedics in a real ambulance. Results indicated subjective preferences for the new bags, where 62% of the paramedics believed it was easier to find equipment in the new bag and 65% preferred the new bags overall. No detrimental effects were attributed to the transition to the new bag. Also discussed are the advantages of the participatory design approach, as well as design guidelines and implications for paramedic operations.

A method is proposed for evaluating participants’ performance in a global spatial awareness task involving identification of complex winding routes. Rather than using coarse measures of spatial error, the method of paired comparisons employs impartial judges to compare sets of aggregated experimental data generated by the participants with respect closeness in shape to the target route. The method was applied to a set of data in an experimental investigation of the effect of height on a participant’s ability to identify the route he had just flown over (in a 20 second video). Seven participants performed a total of 48 trials in a 4 (heights) X 2 (trial blocks) within-subjects experiment. Results from the paired comparison analysis suggested that height had a statistically significant effect on correct route identification. Of equal importance in the context of the present paper, the method of paired comparison analysis proved to be effective in quantifying performance data that did not otherwise lend themselves to conventional methods of quantification.

Research using self-paced visual occlusion has traditionally analysed mean occlusion times, thereby neglecting potential insights to be gained from variability across individual visual sampling decisions. This paper proposes a framework for analysing visual occlusion data based on a hierarchy of sampling strategies. The framework describes each sampling decision as being dependent on both system characteristics (mean performance) and information available during sampling (variability). To illustrate the framework, data from an on-road study were analysed. Self-paced occlusion times were shown to fit a descriptive function both for lane deviations observed at the end of previous visual samples and for predicted lane deviations at the end of occlusion intervals. The fact that the latter fit was better suggests that participants, especially the more experienced ones, were indeed able to use predictions in their sampling decisions.

This paper presents a possible solution to some of the challenges involved with creating a stereoscopic augmented reality ‘X-ray vision‘ display, which enables presentation of computer generated (virtual) objects as if they lie behind a real object surface, while maintaining the ability to effectively perceive any information that might be present on that surface. The method involves overlaying random dot patterns onto a real object surface prior to rendering a virtual object. Results from preliminary experiments have shown that the use of random dot patterns can be effective in contributing to the percept of transparency for the case of flat real surfaces with subtle textures. This suggests that the addition of such patterns may also help in perceiving the correct depth order of virtual objects in such images. Moreover, experimental results indicate that, by controlling the relative dot size and dot density of the patterns, it should be possible also to retain sufficient information about the real surface. Future research should be aimed towards the feasibility and effectiveness of applying this method to more realistic AR conditions.

Little empirical evidence can be found in the visual occlusion literature to justify decisions about how glance durations should be fixed for self-paced visual occlusion investigations. This paper presents a hypothesis about how glance duration may affect performance, based on a theory of how uncertainty develops as an operator's vision is occluded and how it is resolved during visual glances. Data are analysed from two on-road driving experiments involving a range of fixed glance durations. The analysis is repeated with data collected from an analogous study in a low fidelity driving simulator. Both analyses support the hypothesis that increasing glance duration may prolong achievable mean occlusion times, but only up to a certain point, after which essentially no changes are expected. The paper concludes with a practical recommendation for selecting fixed glance durations for (self-paced) visual occlusion studies. Language: en

Objective: This study examined the concept of dynamic viewpoint tethering for enhancing performance in 3-D avatar control tasks. Background: Dynamic viewpoint tethering refers to a viewpoint animation technique that couples a display viewpoint to a controlled avatar through a virtual tether. A dynamic tether, modeled as a mass spring damper system, can potentially generate desirable viewpoint behavior because of its ability to produce frequency-separated viewpoint responses. This study investigated the impact of a tether’s rigidity and damping properties on users’ navigational performance. Methods: Twelve participants took part in a simulated 3-D aerial navigational task. Performance was evaluated with respect to local guidance and global awareness. Results: Root mean square error scores revealed a decrease in local guidance performance when (a) the tether was either severely underdamped or overdamped and (b) the tether’s rigidity approached either zero or infinity. In addition, (c) global performance was better for higher-frequency forcing functions. Conclusion: Critical damping and medium rigidity can be optimized during design for enhancing users’ navigational efficiency. Application: Guidelines generated from this study support future viewpoint design in interactive virtual reality applications.

Ultrasound-guided nerve block (UGNB) allows anesthesiologists to perform regional anesthesia around peripheral nerves using ultrasound images for visual guidance. Compared to conventional peripheral nerve stimulation techniques, UGNB provides a safer and more effective method to perform regional anesthesia. However, identification of peripheral nerves with ultrasound can often be problematic, especially for inexperienced users. This paper provides an in depth analysis of the difficulties associated with targeting and locating peripheral nerves during UGNB and proposes a real-time image processing solution, in the form of a low-pass persistence filter, which should increase target saliency in ultrasound images.

This study investigates the potential benefits of a novel image processing filter, based on introducing persistence to an image to increase visual sensitivity for ultrasound-guided nerve block procedures. The effectiveness of the filter was examined for multiple levels of target velocity and filter persistence, using simulated ultrasound-like images. Subjects were asked to detect a covert target in twelve experimental conditions. The experimental results show that the persistence filter augments the target's saliency and consequently contributes to an effective increase in visual sensitivity. In addition, the results show that the filter is most effective for mid-range target velocities combined with high levels of visual persistence. The study concludes that the filter has the potential to improve present ultrasound-guided nerve block procedures and provides recommendations for implementing the filter in real-world settings.

In this paper, we introduce an innovative conflict detection and resolution display for air traffic control. Our display explicitly incorporates uncertainties in velocity, heading, and position of each airplane in a given air space. Probabilistic, temporal, and spatial information of potential conflicts is provided through integrated graphical patterns.

The difficulties in performing manual control tasks under visual-motor mismatch are well documented. For example, laparoscopic surgeons must operate in an environment where a motor movement and the visual feedback of that same movement are ordinarily misaligned with respect to each other, increasing the risk of control errors. To complement conventional global measures of motor performance, which provide insight into spatial and/or temporal performance averaged over several trials, a bivariate dynamic measure encompassing joint time and space components is proposed. These two components are the instantaneous velocity and movement efficiency, derived from recorded movement trajectories. The dynamic measure consists of a graphical representation of the bivariate data, in conjunction with a non-parametric statistical analysis. An example is given of the dynamic measure applied to movement trajectories from an investigation involving simulated laparoscopic pointing under visual-motor mismatch. Results from both global and dynamic measures are discussed, along with limitations of the multivariate dynamic measure.

Nonrigid environments, such as the human colon, present unique challenges in maintaining spatial orientation during navigation. This paper presents a design concept for presenting spatial information in an augmented reality (AR) display, together with results of an experiment conducted to evaluate the relative usefulness of three types of spatial information for supporting navigation and spatial orientation in a nonrigid environment. Sixteen untrained subjects performed a simulated colonoscopy procedure, using rigid and nonrigid colon models and six different AR displays comprising various combinations of direction, location, and shape information related to the scope inside the colon. Results showed that, unlike navigating in rigid environments, subjects took 44% longer to navigate the nonrigid environment and were less efficient, and suggested that it may be useful to train aspiring endoscopists in an equivalent rigid environment initially. A navigational aid presenting shape information was more beneficial than location or direction information for navigating in the nonrigid environment. Even though the AR navigational aid display did not speed up travel time, navigation efficiency and confidence in direction and location judgment for all subjects were improved. Subjectively, subjects preferred having shape information, in addition to position and direction information, in the navigational aid.

This paper reports on an investigation of how manipulation of optical looming cues can influence braking behaviour, for automobile driving in a low-fidelity simulator. Twenty participants were instructed to follow a leading vehicle (LV) and appropriately respond to braking events of the LV, which occurred randomly and at different deceleration rates. During some braking events, the size of the LV was manipulated in different ways, without subjects being aware, in a manner concordant with the optical expansion that would have been observed during braking if the LV had been displaced to be closer or further away. Results showed that subjects braked sooner when confronting an expanding LV and later for a contracting LV, relative to a constant-size LV, to an extent corresponding to the magnitude of the manipulation. The experiment supports the theory that drivers use TTC information derived from optic looming to control braking.

Optical looming has been proposed as a potentially important cue for the perception of time-to-collision (TTC) in the control of locomotion. In this paper, an investigation is reported on how manipulation of the optical looming cue can influence the perception of TTC, and thereby braking behaviour, for automobile driving in a low fidelity simulator. Eleven participants were instructed to follow a leading vehicle (LV) and appropriately respond to the braking events of the LV, which occurred randomly at different deceleration rates. For some braking events, during braking of the LV, size of the LV was expanded without subjects being aware of it. Results showed that subjects braked sooner when confronting an expanding LV compared to a constant-size LV. The experiment supports the theory that drivers use TTC information derived from optic looming to control braking. Potential application of the results to possibly reduce occurrences of rear-end collisions in real automobile driving is also discussed.

Direct manipulation of optical looming provides convincing evidence of the contribution of optical looming in estimating time-to-collision (TTC). Precise manipulation of optical looming cues can be easily accomplished through computational scaling of (real or virtual) objects without impinging upon the naturalness of the task. This paper first discusses three ways to manipulate optical looming by scaling object size in order to influence perception of TTC. Then two principles affecting the implementation of optical looming manipulation are addressed. Next by revisiting the data of previous research, influences of knowledge about the optical looming manipulation and practice on the effect of optical looming manipulation are discussed. This supports our proposed principles and confirms the possibility of introducing the concept of optical looming manipulation into actual automobile design. Finally a potential application of optical looming manipulation, a dynamic brake light system, is proposed for automobile driving, to reduce the frequency of rear-end collisions. Issues in implementation of such a system and future research to validate it are also identified.

Much research has been carried out on providing navigational aids and improving users' wayfinding ability across a variety of navigation related tasks. In this study, we focus on investigating users' navigational performance with respect to the display frame of reference in a large scale virtual environment. Dynamic viewpoint tethering is proposed as a means to improve user control and reduce the need for mental rotations, thus facilitating the acquisition of configurational knowledge about the virtual space. The modelling of dynamic viewpoint tethering is explained and recent research findings are presented. Twelve volunteers participated in an experiment in which they were instructed to control an aircraft-shaped cursor flying through a set of virtual tunnels (local guidance) and to answer questions about the environment (global awareness). Experimental results showed that neither the very loose dynamic tether nor the completely rigid tether supported the best control performance. Rather, an optimal tether configuration lies at the centre of the rigidity continuum. Research results are discussed from the point of view of design of navigational system interfaces.

Viewpoint tethering, as a way of integrating information from both egocentric and exocentric frames of reference, has been proposed as a means of supporting efficient navigation in virtual environments. In this paper, we report our latest findings on the effects of tether length on navigational performance. Twelve volunteers participated in an experiment in which they were instructed to control an aircraft-shaped cursor flying through a set of virtual tunnels and to answer questions about the environment. Experimental results showed that: (1) subjects' global awareness performance improved with an increase of tether length; and (2) neither the short tether nor the long tether supported the best local guidance performance. Rather, the best performance was observed for an intermediate length tethered display. The existence of an optimal value for this parameter provides useful guidelines for the design of navigational system interfaces.

Numerous automated systems are currently in use to assist controllers during air and naval traffic management. However, inferring the future intentions and courses of numerous aircraft or ships at various points in time remains problematic due to a variety of control disturbances. In this paper, a new graphical display concept was evaluated. This display concept provides predictive information about the time, location, and probability of potential traffic conflicts in the form of topological contour displays that were superimposed onto conventional traffic information. Performances on two formats of the new graphical display were compared to a conventional display that does not present predictive traffic information. Participants in the study engaged in a ship control collision avoidance task by performing a series of ship manoeuvres to minimize the danger levels of potential collisions. Although the results of the study are pending, it is hypothesized that the new graphical displays will assist participants in making improved manoeuvring decisions to avoid potential conflicts compared to the conventional display.

A sensitivity study involving a real-virtual object alignment task was performed in a stereoscopic augmented reality environment, in which the known conflict between binocular fusion and object interposition cues was expected to play a major role. The object was to evaluate subjects' sensitivity to visual texture of a real hemisphere surface and to target position at designated probe points on that surface. Consistent with earlier experiments, the results indicate that: a) both surface texture and target position had significant effects both on real-virtual object alignment and on the estimate of surface normal direction; b) fusion breakdown caused by the conflict between occlusion and binocular disparity could have been used as an extra depth cue to detect virtual and real object interactions. In addition, a practical solution to improving remote 3D measurement accuracy is proposed.

In a rotated visual-motor mapping environment, human spatial performance is seriously affected by misaligned visual and motor reference axes, resulting in elevated spatial errors. In this paper, we propose a history trail display in an augmented reality setting. We investigate the effectiveness of the display in consecutive aiming tasks, under normal visual-motor mapping, as well as mappings with 90°, 135°, and 180° rotations. Spatial movement error and the smoothness of the trajectories were measured and compared between the history trail display and the regular video display. Our results show that, under normal mapping condition, the history trail appears to help reduce the spatial movement error and improve the smoothness of the movement trajectories. With rotated mappings, the benefit of the history trail becomes significant only after a certain degree of adaptation to the rotated mappings has been attained. The history trail appears to enhance the perception of errors, movement direction, and speed information for error-correcting processes during the aiming movements.

Dynamic viewpoint tethering is an innovative display technique which has been proposed to support effective navigation in large-scale virtual environments, by integrating information from different frames of reference. In this paper, we explain the modelling of a dynamic tether and report our latest research findings in investigating the optimal parametric values of tether configuration and their relations to human users' navigational performance. Tethered displays with different parametric configurations were compared. Participants were instructed to control an aircraft-shaped cursor flying in a virtual tunnel and to answer questions about the environment. The results revealed that critically damped tethers supported the best local guidance performance. No significant global awareness performance differences were observed under all display conditions.

Modern medical environments have seen an increase in technological complexity and pressures of handling more patients with fewer resources, resulting in higher demands on medical practitioners. Medical informatics designers will have to focus on the problem of organizing medical information more effectively to enable practitioners to cope with these challenges. This article addresses this research problem for the particular area of medical problem solving in patient care. First, we describe a traditional modeling approach for medical reasoning used as a basis for developing some decision support systems. We argue these models may be faithful to what is known about biomedical knowledge, but they have limitations for human problem solving, especially in unanticipated situations. Second, we present an ontological framework, known as the abstraction hierarchy (Rasmussen, IEEE Trans. Man. Cybernetics 15 (1985) 234-243), for integrating patient representations that are faithful to existing biomedical knowledge and that are consistent with what is known about human problem solving. Through an example of a critical event in the operating room, we reveal how this framework can support medical problem solving in unanticipated situations. Third, we show how to use these representations as a frame of reference for mapping medical roles, responsibilities, sensors, and controls in an operating room context. Finally, we provide some insight for medical informatics designers in using this framework to design novel training programs and human-computer displays.

This paper summarises the results of two laboratory studies conducted to explore the potential benefits of hyperstereoscopic video for aerial search and rescue (SAR). The studies were conducted using a single camera hyperstereoscopic video system (designed for aerial SAR) as the test platform. The first study was designed to evaluate potential benefits of hyperstereopsis provided by large viewpoint separation. It was found that individual differences play an important role in defining a possible “optimal” viewpoint separation for the system. The second study was conducted to test the effect of increased viewpoint separation on tolerance of vertical disparity. The results corroborated expectations that increased viewpoint separation would reduce vertical disparity tolerance. Guidelines are given for future modifications and system implementation.

Misalignments between display and control reference frames complicate execution of many remote control tasks by loading the operator's attentional resources with mental transformations. It is thus important to maintain alignment between an operator's controls and her view of the controlled object or task space. Maximising the operator's situational awareness within this task space by providing an optimal frame of reference also simplifies task execution. Traditional rigid tethering integrates desirable egocentric and exocentric aspects of a display by connecting an exocentric view of the task space to the system being controlled. This paper introduces the concept of dynamic tethering (a superset of rigid tethering) which also preserves the principle of the moving part while maintaining control-display motion compatibility. Two experiments are presented, which show that compliance with these principles decreases the frequency of control reversals, improves reaction times, and decreases the RMS error associated with tracking performance.

Navigating through minimal access surgical environments such as the human colon can be difficult, even for expert gastroenterologists. “Getting lost” is a common experience for endoscopists, especially within the tortuous sigmoid colon where salient landmarks are not generally available. This paper presents the concept of “getting lost” in endoscoppy as a loss of both global and local spatial orientation. For the endoscopist performing a colonoscopy, the consequence of local disorientation is an inability to continue the procedure, or possibly even injury to the patient, while consequences of global disorientation can be mistaking the location of a lesion, and/or incomplete examination, resulting in misdiagnosis. This study provides important insights into the physical and cognitive constraints of the task of navigating in colonoscopy, contributing to disorientation in the colon. The implications of our findings for the design of navigational aids and training tools are also discussed.

The Head Mounted Display (HMD) is discussed as a subset of Mixed Reality (MR) displays. A definition of MR is given, in terms of image mixtures along a Reality-Virtuality (RV) Continuum, including the subclasses of augmented reality (AR) and augmented virtuality (AV). In relation to actual task execution, the relative need for local guidance information versus more global planning and navigational information is discussed. A taxonomic framework for classifying MR systems is presented, in terms of not only the RV continuum, but also the degree of centricity of the observer relative to a nominal viewpoint and the extent of control-display congruence. Several practical examples of MR systems are presented, all from the domain of surgery, and for each a volume within the MR design space is proposed.

The concept of Augmented Reality (AR) displays is defined, in relation to the amount of real (unmodelled) and virtual (modelled) data presented in an image, as those displays in which real images, such as video, are enhanced with computer generated graphics. For the important class of stereoscopic AR displays, several factors may cause potential perceptual ambiguities, however, which manifest themselves in terms of decreased accuracy and precision whenever virtual objects must be aligned with real ones. A review is given of research conducted to assess both the magnitude of these perceptual effects and the effectiveness of a computer assisted Virtual Tape Measure (VTM), which has been developed for performing quantitative 3D measurements on real-world stereo images.

Motivated by the need for human performance evaluations of advanced interface technologies, this paper presents an empirical evaluation of a 3D interface, from the point of view of both display and control, in a pursuit tracking experiment. The paper derives methods for decomposing tracking performance into six dimensions (three in translation and three in rotation). This dimensional decomposition approach has the advantage of revealing overall performance levels in the depth dimension relative to performance in the horizontal and vertical dimensions. With interposition, linear perspective, stereoscopic disparity and partial occlusion cues incorporated into a single 3D display system, subjects' tracking errors in the depth dimension were about 35% (with no practice) to 35% (with practice) larger than those in the horizontal and vertical dimensions. It was also found that subjects initially had larger tracking errors along the vertical axis than along the horizontal axis, likely due to their attention allocation strategy. Analysis of rotation errors generated a similar anisotropic pattern.

We report a two part experiment related to perceiving (virtual) objects in the vicinity of (real) surfaces when using stereoscopic augmented reality displays. In particular, our goal was to explore the effect of various visual surface features on both perception of object location and perception of surface transparency. Surface features were manipulated using random dot patterns on a simulated real object surface, by manipulating dot size, dot density, and whether or not objects placed behind the surface were partially occluded by the surface.

Validation is critically important when human performance models are used to predict the effect of future system designs on human performance. A model of air traffic control (ATC) operations was validated using a rigorous iterative model validation process that illustrated the success of representing ATC operations in NextGen en route operations. A gold-standard model was compared to three model iterations that represented different task management and human time estimation processes when dealing with handoff operations.

This study investigates human performance when using semitransparent tools in interactive 3D computer graphics environments. The article briefly reviews techniques for presenting depth information and examples of applying semitransparency in computer interface design. We hypothesize that when the user moves a semitransparent surface in a 3D environment, the “partial-occlusion” effect introduced through semitransparency acts as an effective cue in target localization—an essential component in many 3D interaction tasks. This hypothesis was tested in an experiment in which subjects were asked to capture dynamic targets (virtual fish) with two versions of a 3D box cursor, one with and one without semitransparent surfaces. Results showed that the partial-occlusion effect through semitransparency significantly improved users' performance in terms of trial completion time, error rate, and error magnitude in both monoscopic and stereoscopic displays. Subjective evaluations supported the conclusions drawn from performance measures. The experimental results and their implications are discussed, with emphasis on the relative, discrete nature of the partial-occlusion effect and on interactions between different depth cues. The article concludes with proposals of a few future research issues and applications of semitransparency in human-computer interaction.

Case rounds are a prominent and important means of training in medical domains. As part of a field study of anesthesiologists’ problem solving activities, we audiotaped the discussion of 10 cases spreading over 4 case rounds. This paper describes the method used in data collection and analysis, followed by the major findings of the study. The study identified three types of skills transferred in case rounds: procedural knowledge, sensitivity to precursors of potential problems, and the ability to prepare for contingencies. The study also showed the potential of case rounds in studying cognitive activities in naturalistic settings.

This paper reports on asymmetrical spatial accuracy of human subjects in tracking of an object which moves randomly with 6 degrees-of-freedom (DOF) in a 3D environment. It was found that, for translational errors, RMS deviations in the depth (Z) direction were 40% higher than those in the horizontal (X) direction, for an experimental display which provided binocular disparity (stereopsis), perspective and partial occlusion cues. In general, translational tracking errors in the vertical (Y) direction were greater than those in the X direction and smaller than those in the Z direction. In early stages of practice, vertical errors were similar to those in the Z direction, but as learning progressed, errors in the X and Y dimensions converged. These finding were consistent across two types of controllers and different tracking paths in the 3D environment. It would appear that horizontal movement requires higher attentional resource priority over vertical movement in such a tracking task.

Four experiments were conducted to examine the effects of periodic visual occlusion on one-handed ball catching. Tennis balls were projected one at a time over distances of 8-12 m, and liquid-crystal visual occlusion spectacles provided intermittent vision by opening and closing the lens shutters at different frequencies. As well as frequency, we manipulated duty cycle, or the proportion of time that the lenses were open. Generally, catching performance deteriorated as frequency was reduced. Although longer visual samples (i.e., increased duty cycle) mediated this effect to some extent, the most potent variable was the time between visual samples; performance deteriorated rapidly when this interval was greater than 80 ms (i.e., 10 Hz with 20-ms lens open times). Presumably this occurred because subjects had difficulty integrating visual information separated by longer temporal intervals.

Interactions between a human operator and objects in his/her world afford a wide range of possible viewing and control options, which can vary with respect to time, space, proximity, and frame of reference. Whereas it is conventionally recognised that essentially any kind of interaction metaphor can in principle be simulated in a virtual environment, modern image processing technology now permits greatly increased flexibility also for real world interactions with indirect viewing, Ai as the common video camera has gone beyond being a simple eye on the (remote) real world to being an instrument that is able to integrate and interpolate real world images spatially and temporally, in real time.In the talk, I shall propose a framework for classifying viewing and manipulation interactions for any task where visual feed back is provided.The framework involves identifying key components of the environment that are central to the interaction, in terms of the multidimensional couplings among the components, where the configuration and characteristics of the couplings determine the nature of the visual and manual control interactions experienced by the operator. The framework is domain independent, and is intended to be used both to classify current display-control interactions and to identify future areas of research.

The present research investigated the effectiveness of rotational and stereoscopic display techniques as applied to practical applications in computer graphics. In the described experiments, depth perception was evaluated by examining accuracy in a 3D path-tracing task, with stimulus displays resembling the structure of cerebral angiograms. In the first experiment, task performance was determined without 3D enhancements, with either technique used alone and with both techniques combined. The results indicated that performance improved using either technique, however, performance with rotational displays was superior to stereoscopic displays, and performance was best when both techniques were combined. The results of a second experiment revealed that rotational displays were no better than stereoscopic displays enhanced with multiple static viewing angles. The experimental findings are discussed in terms of the visual information available using either 3D display technique as well as with respect to the hardware requirements of both display systems. The results are also related to the weighted additive model of depth perception.

This paper describes a number of aspects of a display technology under development, which involves the integration of stereoscopic computer graphics and stereoscopic video displays. The background and justification for this development are discussed, based on the need of operators of remotely controlled vehicles and/or manipulators to estimate absolute sizes and locations of objects at a remotely viewed site. The basic technology involves superimposing an interactively controllable computer-generated stereographic cursor onto a stereoscopically viewed video image. Absolute measurements can be made with this system, based on relative comparison of cursor position with target object location. Experimental results are presented in which the ability of subjects to perform such tasks was investigated. In general, results were promising; subjects were able to align virtual pointers with real targets essentially as well as they were able to manipulate real objects. A number of implications of this technology for the enhancement of three dimensional video displays are discussed.

The mathematical modeling of manually controlled teleoperator systems using the well-known optimal control model (OCM) is considered. An experienced human operator can be modeled as an optimal controller executing continuous control in an environment in which the system is subject to random external disturbances. The basic OCM theory is extended to allow the human operator to have an imperfect internal model of the system being controlled, and the effects of discrepancies between the system and human models are investigated. A mechanism for closed-form modeling of performance for systems equipped with predictor displays is also added to the original theory. To validate the model, model predictions are compared to the results of experiments with a simulated tetherless submersible. The experimental results show that the modified optimal control model (MOCM) holds promise as a tool for the design and analysis of teleoperated control systems. >

Time estimation is a fundamental behavioral characteristic used by all humans when completing task sequences in the real world. Properly characterizing the manner that humans engage in time-critical tasks, as well as the interaction among these tasks, is necessary when developing reliable computational models of human performance to be used to simulate real-world humansystem performance. The current paper introduces the notion of estimating time available, time required, and time onset to complete behaviors within real environmental contexts. It also summarizes relevant research on over- and under-estimating of time, and outlines critical factors ‐ workload and windows of opportunity ‐ that impact estimates of time. The paper culminates in the development of a new domain- and platform-independent conceptual model, dubbed TEMPORA, the Time Estimation Model for Predicting Onset, Required and Available time. The relationship between this conceptual model and the general requirements specifications for computational model development are highlighted.

A basic three-dimensional line enhancement (tether) is investigated in real and stereoscopic graphic (SG) (virtual) forms and with monoscopic and stereoscopic displays, within the context of a peg-in-hole task. Results from two experiments indicated that a tether provided useful spatial information to the operator viewing a stereoscopic video (SV) display but not a standard (monoscopic) display: subjects made fewer errors and were more consistent. Performance with the virtual tether enhancement was superior to performance with a real tether. The results suggest that, given a properly calibrated system, people should be able to make practical use of SG overlays on SV in carrying out in-the-loop teleoperations. >

The director/agent (D/A) metaphor of telerobotic interaction is discussed as a potential means for achieving human-robot synergy. In order for the human operator to communicate spatial information to the robot during D/A operations, the medium of augmented reality through overlaid virtual stereographics is proposed, leading to what is referred to as virtual control. An overview is given of the ARGOS (Augmented Reality through Graphic Overlays on Stereovideo) system. In particular, the uses of overlaid virtual pointers for enhancing absolute depth judgement tasks, virtual tape measures for real-world quantification, virtual tethers for perceptual enhancement in manual teleoperation, virtual landmarks for enhancing depth scaling, and virtual object overlays for on-object edge enhancement and display superposition are all presented and discussed.

A unique measuring tool for use with a surgical operating microscope was developed in prototype form. Stereo-video images of the surgical field obtained through the operating microscope were combined with stereo-computer graphics to create a virtual tape measure. This augmented reality display allows accurate absolute distance measurements to be made between any two points of interest in the 3D surgical space. The overall performance of the system has a 95% confidence interval for the absolute measurement error of 0.2 to 0.7 mm. This paper describes the motivation for the development of the system, the configuration of the hardware and software components, and details of accuracy testing.

INTRODUCTION Current neuroendoscopic instruments lack the required size, accuracy, dexterity, and reachability to perform complex intraventricular procedures (i.e. endoscopic third ventriculostomy) [1-2]. Surgical robots offer a potential solution, however the unique and critically constrained workspace within the ventricle system poses major challenges. Concentric tube robots consist of telescoping, precurved, superelast ic n i t inol tubes that when rotated/translated relative to each other, allows precise control of robot shape and position [3]. We have developed a miniaturized, teleoperated concentric tube robot and implemented it on a validated silicone hydrocephalic brain phantom [4].

This study examines potential advantages of using stereoscopic video for underwater inspection under turbid conditions, a task which is affected also by low illumination and camouflaging. An overview is given of earlier research on the theoretical effects of these factors on visual perception. An experiment was carried out to investigate performance using stereoscopic video in a simulated underwater inspection task involving detection of a camouflaged object, at four turbidity levels and three camera separation levels. In general, it was found that detection rate and sensitivity were consistently and significantly better using stereoscopic compared to monoscopic video. Of equal importance was the discovery of an interaction between camera and turbidity treatments, suggesting that use of stereoscopic video should decelerate performance degradation for increasing turbidity. It was also found that diminished display brightness due to the use of shuttering glasses detracted very little from performance with monoscopic video, implying that addition of stereo glasses should not offset the expected advantages of stereoscopic viewing. Finally, the magnitude of stereoscopic disparity was found to have only a slight effect on detection performance, implying that a minimal level of disparity is sufficient for overcoming turbidity significantly.

A quantitative description of the human information processor is required for predicting operator workload and performance from the simulated task time line data generated by task network models and related methods. Although many models of workload exist, few appear to be well founded in theory or to provide a satisfactory basis for a quantitative representation of operator load. Adherents of both time-and intensity-based models of operator load individually claim success for their methods. which might suggest that both factors are operating in determining operator workload and performance. This paper describes a study that explicitly investigates the relationship between a time-based factor and an intensity-based factor (amount of information to be processed) within a simulated air traffic control environment. A model is developed that posits that the load on the human information-processing system results directly from the ratio of the time necessary to process the required information to the time allowable for making a decision. This ratio, which can be identified with time pressure, determines subjective estimates of workload as well as operator performance. The model is tested against the data from the air traffic control simulation.

Teleoperation in unstructured environments is conventionally restricted to direct manual control of the robot. Under such circumstances operator performance can be affected by inadequate visual feedback from the remote site, caused by, for example, limitations in the bandwidth of the communication channel. This paper introduces ARTEMIS (Augmented Reality TEleManipulation Interface System), a new display interface for enabling local teleoperation task simulation. An important feature of the interface is that the display can be generated in the absence of a model of the remote operating site. The display consists of a stereographical model of the robot overlaid on real stereovideo images from the remote site. This stereographical robot is used to simulate manipulation with respect to objects visible in the stereovideo image, following which sequences of robot control instructions can be transmitted to the remote site. In the present system, the update rate of video images can be very low, since continuous feedback is no longer needed for direct manual control of the robot. Several features of the system are presented and its advantages discussed, together with an illustrative example of a pick-and-place task.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes our studies on perception of virtual object locations. We explore the behavior of various factors related to depth perception, especially the interplay of fuzziness and binocular disparity. Experiments measure this interplay with the use of a three- dimensional display. Image fuzziness is ordinarily seen as an effect of the aerial perspective in two-dimensional displays for distant objects. We found that it can also be a source of depth representation also in three-dimensional display space. This effect occurs with large individual variations, and for subjects who have good stereopsis it does not significantly affect their depth perception. However, it can be a very strong depth cue for subjects who have weak stereopsis. A subsequent experiment measured the effects when both size and brightness of sharp stimuli are adjusted to a standard fuzzy stimulus. The results suggest that the fuzziness cue at short range is explained by other cues (i.e. the size cue and the brightness cue). This paper presents results of a series of such experiments.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper we discuss augmented reality (AR) displays in a general sense, within the context of a reality-virtuality (RV) continuum, encompassing a large class of `mixed reality' (MR) displays, which also includes augmented virtuality (AV). MR displays are defined by means of seven examples of existing display concepts in which real objects and virtual objects are juxtaposed. Essential factors which distinguish different MR display systems from each other are presented, first by means of a table in which the nature of the underlying scene, how it is viewed, and the observer's reference to it are compared, and then by means of a three dimensional taxonomic framework comprising: extent of world knowledge, reproduction fidelity, and extent of presence metaphor. A principal objective of the taxonomy is to clarify terminology issues and to provide a framework for classifying research across different disciplines.