| Editorial | | BIB | Full-Text | II | |
| Robert Macredie | |||
| The effect of update rate on the sense of presence within virtual environments | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | |||
| Editorial | | BIB | Full-Text | I | |
| Rae Earnshaw; Robert Macredie; John Vince | |||
| Virtual tools that carry attributes for interactively specifying intermediate manufacturing processes | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | | BIBAK | Full-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 | |||