We report an 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.

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.

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, Äî 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.

Coordination definitions and metrics are reviewed from the motor control, biomedical, and human factors literature. This paper presents an alternative measurement called the M-metric, the product of the simultaneity and efficiency of a trajectory, as a means of quantifying allocation of control within a docking task. A 6 degree-of-freedom (DOF) longitudinal virtual docking task experiment was conducted to address how control is allocated across six DOFs, how allocation of control changes with extended practice, and if differences in the allocation of control are input device dependent. The results show that operators, rather than controlling all 6 DOFs equally, allocate their control to the rotational and translational DOFs separately, and switch control between the two groups. With practice, allocation of control within the translational and rotational subsets increases at a faster rate than across all 6 DOFs together.

Study of computer input devices has primarily focused on trial completion time and target acquisition errors.To deepen our understanding of input devices, particularly those with high degrees of freedom @OF), this paper explores device influence on the user's ability to coordinate controlled movements in a 3D interface.After reviewing various existing methods, a new measure of quantifying coordination in multiple degrees of freedom, based on movement efficiency, is proposed and applied to the evaluation of two 6 DOF devices: a free-moving position-control device and a desk-top rate-controlled hand controller.Results showed that while the users of the free moving device had shorter completion time than the users of an elastic rate controller, their movement trajectories were less coordinated.These new findings should better inform system designers on development and selection of input devices.Issues such as mental rotation and isomorphism vs. tools operation as means of computer input are also discussed.

This paper reports on a field study of the behavior of anesthesiologists as expert practitioners in managing a class of complex systems: patients under general anesthesia and surgery. The anesthesiologists studied were found to make extensive use of preparatory strategies, which provided them with many types of resources, including potential problems to be dealt with, materials needed, contingency response plans, desired goals, and the errors that are likely to be committed, The process of preparing these resources usually started with the compilation and review of a set of points for consideration (PFCs). A conceptual model of human planning is proposed which challenges traditional views on problem solving and planning, The model accounts for not only the specific results obtained in this field study, but also for the functional role of planning behavior during interactions with dynamic and complex systems in general, an important aspect of problem solving which has direct implications for the design of human-machine interfaces and cognitive support systems.

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.

The literature has long suggested that the design of computer input devices should make use of the fine, smaller muscle groups and joints in the fingers, since they are richly represented in the human motor and sensory cortex and they have higher information processing bandwidth than other body parts.This hypothesis, however, has not been conclusively verified with empirical research.The present work studied such a hypothesis in the context of designing 6 degree-of-freedom (DOF) input devices.The work attempts to address both a practical need designing efficient 6 DOF input devices -and the theoretical issue of muscle group differences in input control.Two alternative 6 DOF input devices, one including and the other excluding the fingers from the 6 DOF manipulation, were designed and tested in a 3D object docking experiment.Users' task completion times were significantly shorter with the device that utilised the fingers.The results of this study strongly suggest that the shape and size of future input device designs should constitute affordances that invite finger participation in input control. K e y w o r d sInput devices, 3-D interface, 6 DOF input, motor control, muscle group differences, hand, fingers, arm, homunculus model.

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.

This study investigates dynamic 3D target acquisition.The focus is on the relative effect of specific perceptual cues.A novel technique is introduced and we report on an experiment that evaluates its effectiveness.There are two aspects to the new technique.First, in contrast to normal practice, the tracking symbol is a volume rather than a point.Second, the surface of this volume is semi-transparent, thereby affording occlusion cues during target acquisition.The experiment shows that the volumehcclusion cues were effective in both monocular and stereoscopic conditions.For some tasks where stereoscopic presentation is unavailable or infeasible, the new techniaue offers an effective alternative.

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.

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.>

An investigation has been carried out on the effects of skill acquisition of the type of closed circuit video system being used in a teleoperation system. Two experiments were performed, using a mobile explosive ordnance disposal robot equipped with a switchable monoscopic/stereoscopic video system. One experiment comprised a simple, repetitive approach-and-touch task. The other involved a Fitts' law type of speed/accuracy tradeoff task. In both experiments, subjects' learning data were recorded. The results are discussed in terms of relative performance of stereoscopic versus monoscopic viewing, as a function of repetition number and of task difficulty. An important result is that for highly repetitive tasks it is less demanding to perform the task using a stereoscopic display than using a monoscopic display at all levels of experience.>