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Virtual Reality 1

Editors:Robert D. Macredie; Rae Earnshaw; John Vince
Standard No:ISSN 1359-4338 (print) EISSN 1434-9957 (online)
Links:link.springer.com | Twitter | Table of Contents
  1. VR 1995-06 Volume 1 Issue 1
  2. VR 1995-12 Volume 1 Issue 2

VR 1995-06 Volume 1 Issue 1

Editorial BIBFull-Text II
  Robert Macredie
The effect of update rate on the sense of presence within virtual environments BIBAKFull-Text 3-15
  Woodrow Barfield; Claudia Hendrix
The current study was done to investigate the effect of varying the update rate of a computer-generated simulation (5, 10, 15, 20, 25 Hz) on the sense of presence within stereoscopic virtual environments. Thirteen subjects navigated a virtual representation of Stonehenge and were asked to search for a rune, inscribed upon the wall of one of Stonehenge's edifices. After performing the search task, subjects completed a questionnaire designed to assess their level of presence within the virtual environment. The results indicated that the subjective report of presence within the virtual environment was significantly less using an update rate of 5 and 10 Hz when compared to update rates of 20 and 25 Hz. Furthermore, the reported level of presence using a 15 Hz update rate was similar to the reported level of presence using update rates of 20 and 25 Hz thus indicating that computational resources could be saved using a slower update rate while maintaining a given level of presence. In addition, a factor analysis procedure indicated that the 13 questions designed to assess the subjects sense of presence within virtual Stonehenge could be grouped into three factors: (1) virtual presence, (2) navigation within the virtual environment, and (3) knowledge of real world surroundings while in the virtual world. Finally, comments on a descriptive model of presence within virtual environments are presented.
Keywords: immersion; presence; update rate; virtual environments
An investigation into nausea and other side-effects of head-coupled immersive virtual reality BIBAKFull-Text 17-31
  Clare Regan
This paper is written from a human factors perspective and discusses research into some of the side-effects of head-coupled immersive virtual reality. The paper provides a broad overview of the history of virtual reality and highlights some of the important current human factors issues. Reasons why side-effects of virtual reality technology may be expected are then discussed with particular reference to the literature on motion sickness and simulator sickness. A study is described which set out to document the frequency of occurrence and severity of side-effects of immersion in virtual reality. One hundred and fifty subjects took part in this study and were immersed in a virtual environment for 20 minutes. Sixty-one percent of the subjects were documented as reporting symptoms at some point during the 20 minute immersion period and a 10 minute post-immersion period. Five percent of the subjects had to withdraw from the study due to the severity of their symptoms. This finding led to further research that attempted to reduce the side-effects observed. Studies investigating the use of adaptation and the anti-motion sickness drug hyoscine hydrobromide are described. Both of these methods of reducing the side-effects of virtual reality proved successful with the hyoscine proving to be a very rapid method of symptom reduction.
Keywords: immersion; virtual reality; simulator sickness; VR sideeffects; adaptation; hyoscine hydrobromide
Learning from virtual reality applications in education BIBAKFull-Text 33-39
  Ralph Schroeder
This paper presents an overview of the uses of virtual reality in education. It draws particularly on three projects, the West Denton High School in Newcastle, the Human-Computer Interface Technology Laboratory's summer school in Seattle and the Shepard School for children with special needs in Nottingham. In each of these projects, there is distinctive relationship between the learning experience and the experience of virtual worlds. Here, the concern will not be with the pedagogical value of these projects, which have been documented elsewhere, but with the wider contribution that they can make to our understanding of virtual environments. To do this, it examines in each case how the virtual reality systems are integrated into the curriculum, how these systems relate to the learning process, the usability of the systems, and the possibilities and constraints of the virtual worlds. By comparing these with other emerging virtual reality applications, such as entertainment games, it can be seen that different systems present a variety of possibilities for constructing presence in, and interaction with, virtual environments.
Keywords: virtual reality; education; special needs education; applications of virtual reality; human-computer interaction
Collision detection methodologies for rigid body assembly in a virtual environment BIBAKFull-Text 41-48
  J. J. Fang; D. E. R. Clark; J. E. L. Simmons
In this paper, a simulated three-dimensional virtual environment is created with a virtual 3D track ball for virtual object control. We propose a new technique called HV Partition to detect accurate collision in the assembly of two polyhedral solids in virtual simulation. This is a solid interference detection methodology achieved by automatically partitioning the object into smaller solid boxes. An important advantage of this methodology compared with other approaches is that it can deal with non-convex objects. This means that mechanical components, represented by non-convex polyhedra, traversing any degree of freedom, can be used in this virtual environment. Using this HV Partition method, the precise interference between two polyhedral solid objects can be found. The HV Partition methodology is applied following initial approximate collision detection using traditional bounding box and bounding sphere methods. The smaller the number of smaller boxes, the quicker is the performance of the collision algorithm. An optimal partition method is also given to reduce the number of smaller boxes in an object.
Keywords: virtual environment; collision detection; assembly; virtual space ball; bounding box; bounding sphere; HV Partition
Musings on volumetric level of detail for virtual environments BIBAKFull-Text 49-55
  Martin Reddy
This paper considers the extension of a real-time graphics renderer to support fovea enhancement -- the technique of localising visual detail to the particular region of the display which the user is looking towards. This is performed by extending the standard notion of distance Level of Detail (LOD) into three dimensions to give volumetric LOD; whereby the LOD of an object is related to its presence within a three-dimensional volume which is aligned with the user's gaze. Before introducing this technique, some background details are discussed regarding the relevant characteristics of the human visual system and current solutions for effective gaze tracking. Subsequently, a brief cross-section of relevant research is presented and a conceptual model of volumetric LOD is formulated. Finally, implementation factors for such a system are considered and a theoretical evaluation is proffered.
Keywords: eye-tracking; fovea enhancement; level of detail; polygonal complexity; visual acuity
Use of a modified Kalman filter for a visually coupled system application BIBAKFull-Text 57-67
  P. Dunnett; R. M. Harwood; G. R. Brookes; D. P. Wills
Spatial tracking devices are frequently used in virtual environments, such as in the case of helmet mounted displays, to dynamically determine the user's viewpoint and line of sight. Temporal distortion effects are perceived by the user as a result of the lag between head movement and visual feedback. Measurements of phase lag have been made and to help alleviate these problems, predictive filtering techniques are frequently used. We report on studies that have been made in the use of a modified Kalman filter algorithm. The implementation provides favourable results in terms of reduction on the effect of phase lag.
Keywords: Kalman filter; phase lag; prediction algorithms; spatial tracking

VR 1995-12 Volume 1 Issue 2

Editorial BIBFull-Text I
  Rae Earnshaw; Robert Macredie; John Vince
Virtual tools that carry attributes for interactively specifying intermediate manufacturing processes BIBAKFull-Text 71-90
  T. Kesavadas; D. J. Cannon
This paper describes an interactive system for specifying robotic tasks using virtual tools that allow an operator to reach into a live video scene and direct robots to use corresponding real tools in complex scenarios that involve integrating a variety of otherwise autonomous technologies. The attribute rich virtual tools concept provides a human-machine interface that is robust to unanticipated developments and tunable to the specific requirements of a particular task. This Interactive Specification concept is applied to intermediate manufacturing tasks.
Keywords: virtual reality; augmented reality; human computer interaction; manufacturing automation; telerobotics
Virtual reality: A distributed perspective BIBAKFull-Text 91-94
  Simon J. E. Taylor; Shirley Moody
This paper considers the implications of Distributed Virtual Reality in terms of user interaction and networking. It is argued that the allocation strategy of data in such a system is one of the fundamental problems faced by designers of Distributed Virtual Reality applications. The need to use experience and techniques drawn from distributed databases is highlighted.
Keywords: distributed virtual reality; user interaction; networking; distributed databases
A survey of level of detail support in current virtual reality solutions BIBAKFull-Text 95-98
  Martin Reddy
The technique of Level of Detail (LOD) offers a powerful method of reducing the computational burden of a virtual reality (VR) system. As a result, it represents a valuable and important facility which one would expect to find in all serious VR graphics systems. This survey aims to present many of the rendering engines commonly employed in state-of-the-art VR solutions and details the degree of support which these systems provide for LOD. The investigation reveals a significant lack of support for this facility over the range of packages reviewed. Consequently, a call is made for improved LOD support in future VR products.
Keywords: level of detail; interactivity; performance; virtual reality
Update rates and fidelity in virtual environments BIBAKFull-Text 99-108
  Rycharde Hawkes; Simon Rushton; Martin Smyth
Interaction is the primary characteristic of a Virtual Environment and update rate is normally taken as an index or measure of the interactivity of the system. The speed of many systems is dictated by the slowest component which is often the Computer Image Generator (CIG). It is common for the workload of the CIG to vary and hence the performance of the system. This paper shows how a variable update rate can produce undesirable results. Two solutions to this problem are presented: service degradation and worst-case. In the case of the CIG, service degradation would require the quality of the image to be reduced such that the time taken never exceeds a given deadline. The worst-case technique works by finding the longest time taken to render any view and then uses that as the deadline for completion. The support of predictive methods is one of several benefits of this approach. An implementation of the worst-case technique is described which takes finer control over the CIG than usual and may be applied to many existing systems with little modification.
Keywords: Virtual Reality; computer image generators; real-time graphics; update rate; Tau theory
A behavioural test-bed using a dataglove input device BIBAKFull-Text 109-116
  Hanqiu Sun
In many cases, traditional hand-drawn animation has been replaced by computer technology. Computer-supported approaches can essentially be characterised as two interface types: keyframing and coding. However, these two interface types offer limited editing ability for scene animation applications, which usually consist of a large testing space of similar behaviours. The testing cycle, using either predefined keyframe sequences or general coding interface, tends to be costly and time consuming. This paper reports work which uses the DataGlove device to support and test variable schooling behaviours of fish in a virtual marine world. This is put forward as a representative example of scene animation. The glove-based interface places the user as a participant in the behavioural simulation process. In the work, hand shapes and motions are recognised and used for either event triggering or role switching. The specific shapes and motions of the user's hand trigger control signals or commands through a menu-based interface. The hand can itself be used to simulate an object in the scene. The object, which can be either static or dynamic, participates in the control process. Using hand movements in this way allows the user to interactively specify the paths of moving objects in the scene, and also creates a diversity of dynamic situations which can be useful for testing variable scene behaviours. The application presented in this paper looks at examples of controlling fish behaviour in a limited pond environment controlled by glove-based interaction.
Keywords: computer animation; behaviour simulation; DataGlove; virtual reality
An investigation into the modelling of virtual objects with sound vibration properties BIBAKFull-Text 117-121
  David Rossiter; George Baciu; Andrew Horner
In order to increase the power of virtual environments, several different attempts have been made to incorporate sound interactivity in some form. For example, several implementations of virtual environments permit the playing of a previously recorded soundfile upon the triggering of an associated event. The user may then, for instance, perceive the sound of a creaky door when one is opened. However, a relatively more effective system for entertaining joint audio and visual response may be derived by using physical modelling techniques. We have undertaken a pilot investigation in which virtual objects are implemented in a manner such that they implicitly possess vibration properties analogous to that of the real world. Consequently these objects are able to vibrate in response to stimulus. The vibrations may be visually perceived as, for example, wave patterns on the surface of an object, and acoustically perceived by mapping values representative of surface displacement to a loudspeaker. This paper discusses the current state of the project.
Keywords: virtual environments; virtual objects; digital waveguides; acoustics; sound
Correct spatial visualisation using optical tracking BIBAKFull-Text 122-126
  Franz Madritsch
Graphical representations of 3-dimensional scenes on computer screens are not satisfying in all cases of application. One reason is that traditional visualisation-tools reduced the spatial scene to a two-dimensional projection to deal with the flat computer screen. Today, devices become available which can present different images to both eyes of a viewer and in this manner generate stereoscopic impressions. However, in order to maintain the 3-dimensional illusion even if the user moves his head, it is necessary to track the position of the head relatively to the screen and to update the images sufficiently fast. We introduce a method to obtain the information about the users attitude, based on a single CCD-camera mounted on top of the monitor. This paper describes the hardware configuration, the algorithms to extract the head-position and the required information about the attitude of the user's head from the live video input, to make this kind of visualisation work. We also give an outlook of the potential of such optical tracking methods for further applications.
Keywords: interactive visualisation; optical tracking; stereoscopic display; head-tracking