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VRST Tables of Contents: 979899000102030405060708091012131415

Proceedings of the 2003 ACM Symposium on Virtual Reality Software and Technology

Fullname:VRST'03 ACM Symposium on Virtual Reality Software and Technology
Location:Osaka, Japan
Dates:2003-Oct-01 to 2003-Oct-03
Publisher:ACM
Standard No:ISBN: 1-58113-569-6; ACM DL: Table of Contents hcibib: VRST03
Papers:30
Pages:235
  1. Keynote
  2. Algorithms
  3. Real-time rendering
  4. Interaction techniques
  5. VR based entertainment & education
  6. Authoring tools & systems
  7. Distributed VR
  8. Devices
  9. Haptics
  10. Human factors in collaborative virtual environment

Keynote

Perceptive agents and systems in virtual reality BIBFull-Text 1-3
  Demetri Terzopoulos
Virtual unreality: storytelling in virtual environments BIBFull-Text 4-6
  Marc Cavazza

Algorithms

Partitioning crowded virtual environments BIBAKFull-Text 7-14
  Anthony Steed; Roula Abou-Haidar
We investigate several techniques that partition a crowded virtual environment into regions that can be managed by separate servers or mapped onto different multicast groups. When constructing a partitioning, we attempt to minimize overhead of the partitioning with respect to network management, whilst maintaining a bound on the number of entities that are mapped to any particular server or group.
   We compare several partitioning schemes: quad tree, k-d tree unconstrained, k-d tree constrained, and region growing. With our simulations of a crowded virtual environment modelled on a part of central London, we find that the region growing technique give the best overall results.
Keywords: distributed virtual environments, multicast groups, spatial partitioning
Significant facet retrieval for real-time 3D sound rendering in complex virtual environments BIBAKFull-Text 15-21
  Chris Joslin; Nadia Magnenat-Thalmann
Sound rendering requires that many different aspects are considered simultaneously, especially when rendering a real-time virtual environment. In 3D sound rendering, much the same as for graphics, one of the major influencing factors is the number of reflective polygons in a scene and due to the increase in the ability of most common graphics cards this number can now be very high, especially when scene designers produce an optimum scene using other optimizing tools such as Polygon Cruncher or Rational Reducer. In addition, the use of programs such as Lightscape™ [20], which is used to produce realistic lighting, by using per vertex shading, increases the number of polygons in a scene by several factors. Therefore a strong, pre-processing method is proposed that dramatically reduces the number of polygons in the scene to a suitable level for real-time sound rendering. The method can also be combined with other methods (e.g. scene partitioning) for even lower CPU usage.
Keywords: bounding-box, scene segmentation, sound rendering, virtual environments
Time-critical collision detection using an average-case approach BIBAKFull-Text 22-31
  Jan Klein; Gabriel Zachmann
We present a novel, generic framework and algorithm for hierarchical collision detection, which allows an application to balance speed and quality of the collision detection.
   We pursue an average-case approach that yields a numerical measure of the quality. This can either be specified by the simulation or interaction, or it can help to assess the result of the collision detection in a time-critical system.
   Conceptually, we consider sets of polygons during traversal and estimate probabilities that there is an intersection among these sets. This can be done efficiently by storing characteristics about the average distribution of the set of polygons with each node in a bounding volume hierarchy (BVH). Consequently, we neither need any polygon intersection tests nor access to any polygons during the collision detection process.
   Our approach can be applied to virtually any BVH. Therefore, we call a BVH that has been augmented in this way an average-distribution tree or ADB-tree.
   We have implemented our new approach with two basic BVHs and present performance measurements and comparisons with a very fast previous algorithm, namely the DOP-tree. The results show a speedup of about a factor 3 to 6 with only approximately 4% error.
Keywords: average-case algorithms, bounding volume trees, hierarchical data structures, hierarchical partitioning, interference detection, probabilistic analysis, virtual prototyping

Real-time rendering

Real-time reflection on moving vehicles in urban environments BIBAKFull-Text 32-40
  Alexandre Meyer; Céline Loscos
In the context of virtual reality, the simulation of complex environments with many animated objects is becoming more and more common. Virtual reality applications have always promoted the development of new efficient algorithms and image-based rendering techniques for real-time interaction. In this paper, we propose a technique which allows the real-time simulation in a city of the reflections of static geometry (eg. building) on specular dynamic objects (vehicles). For this, we introduce the idea of multiple environment maps. We pre-compute a set of reference environment maps at strategic positions in the scene, that are used at run time and for each visible dynamic object, to compute local environment maps by resampling images. To efficiently manage a small number of reference environment maps, compared to the scene dimension, for each vertex of the reconstructed environment we perform a ray tracing in a heightfield representation of the scene. We control the frame rate by adaptative reconstruction of environment maps. We have implemented this approach, and the results show that it is efficient and scalable to many dynamic objects while maintaining interactive frame rates.
Keywords: environment maps, image-based rendering, ray tracing, real-time rendering
Real-time rendering of woven clothes BIBAFull-Text 41-47
  Neeharika Adabala; Nadia Magnenat-Thalmann; Guangzheng Fei
Virtual environments containing humans moving and performing actions in real time are ubiquitous in computer graphics applications. Such characters are often clothed in woven fabrics. This paper presents a technique for visualizing woven clothes in real time, while optimizing the realistic appearance. The proposed approach supports rendering of complex weave patterns by adopting Weaving Information File (WIF), a standard from textile Computer Aided Design (CAD) for representing the grammar of weaving. We develop a realistic rendering scheme by combining the grammar representation obtained from the WIF with a procedural thread texture, a suitable cloth Bi-directional Reflectance Distribution Function (BRDF) and horizon maps. We employ the multi-texturing approach to meet the real time constraint. Thus our approach to visualizing woven clothes begins from weaving grammar specifications and converts them into textures that can be applied on clothes. We demonstrate the versatility of the proposed approach with examples.
Incremental rendering of deformable trimmed NURBS surfaces BIBAKFull-Text 48-55
  Gary K. L. Cheung; Rynson W. H. Lau; Frederick W. B. Li
Trimmed NURBS surfaces are often used to model smooth and complex objects. Unfortunately, most existing hardware graphics accelerators cannot render them directly. Although there are a lot of methods proposed to accelerate the rendering of such surfaces, majority of them are based on tessellation, which is developed primarily for handling non-deforming objects. For an object that may deform in run-time, such as clothing, facial expression, human and animal character, the tessellation process will need to be performed repeatedly while the object is deforming. However, as the tessellation process is very time consuming, interactive display of deforming objects is difficult. This explains why deformable objects are rarely used in virtual reality applications. In this paper, we present a efficient method for incremental rendering of deformable trimmed NURBS surfaces. This method can handle both trimmed surface deformation and trimming curve deformation. Experimental results show that our method performs significantly faster than the method used in OpenGL.
Keywords: NURBS surfaces, deformable objects, real-time rendering, trimmed surfaces
A real-time shadow approach for an augmented reality application using shadow volumes BIBAKFull-Text 56-65
  Michael Haller; Stephan Drab; Werner Hartmann
Shadows add a level of realism to a rendered image. Moreover, they are used as visual clues to determine spacial relationships and real-time shadows will gain importance in current real-time computer graphics applications for this reason. Twenty-five years ago, Crow published the shadow volume approach for determining shadowed regions of a scene. In this paper we present a modified real-time shadow volume algorithm that can be used in an Augmented/Mixed Reality application. Finally, the proposed concepts provide a novel sense of visual output of an AR application.
Keywords: augmented reality, shadow volumes

Interaction techniques

Interactive modeling of trees by using growth simulation BIBAKFull-Text 66-72
  Katsuhiko Onishi; Shoichi Hasuike; Yoshifumi Kitamura; Fumio Kishino
We propose a real-time interactive system that enables users to generate, manipulate and edit the shape model of a tree based on growth simulation by directly indicating its global and spatial information. For this purpose, three-dimensional (3D) spatial information is introduced to the well-known L-system as an attribute of the growth simulation. Moreover, we propose an efficient data structure of L-strings in order to speed up the process.
Keywords: L-system, data structure, intuitive interaction, multimodal interface, tree models, virtual reality
A comparative study on user performance in the Virtual Dressmaker application BIBAKFull-Text 73-80
  Markus Wacker; Stanislav L. Stoev; Michael Keckeisen; Wolfgang Straßer
We report on a user study, investigating the efficiency of user interaction in a Virtual Reality application compared to 3D desktop applications.
   The Virtual Dressmaker is a Virtual Reality application for virtual cloth design, assembly, and simulation that supports advanced 6DoF interaction techniques. We conjecture that these interaction techniques are more natural for the users and lead to faster and more precise results than common desktop applications.
   In our user study we investigate interaction tools for positioning garment patterns in VR and compare the results to interaction with common 3D desktop applications. We measure completion time and precision of the positioned patterns and evaluate the subjective impressions of the users.
   The results show that Virtual Environments, and the presented interaction tools in particular, provide a valuable method for cloth design and assembly. Moreover, certain features of current 3D desktop design tools can be exploited for further improvements of VR interaction.
Keywords: cloth modelling and simulation, human performance in VR, interaction techniques, navigation tools, user study
Information-rich virtual environments: theory, tools, and research agenda BIBAKFull-Text 81-90
  Doug A. Bowman; Chris North; Jian Chen; Nicholas F. Polys; Pardha S. Pyla; Umur Yilmaz
Virtual environments (VEs) allow users to experience and interact with a rich sensory environment, but most virtual worlds contain only sensory information similar to that which we experience in the physical world. Information-rich virtual environments (IRVEs) combine the power of VEs and information visualization, augmenting VEs with additional abstract information such as text, numbers, or graphs. IRVEs can be useful in many contexts, such as education, medicine, or construction. In our work, we are developing a theoretical foundation for the study of IRVEs and tools for their development and evaluation. We present a working definition of IRVEs, a discussion of information display and interaction in IRVEs. We also describe a software framework for IRVE development and a testbed enabling evaluation of text display techniques for IRVEs. Finally, we present a research agenda for this area.
Keywords: information visualization, information-rich virtual environments

VR based entertainment & education

The ANIMUS project: a framework for the creation of interactive creatures in immersed environments BIBAKFull-Text 91-99
  Daniel Torres; Pierre Boulanger
This paper describes the architecture of the ANIMUS framework. This framework facilitates the creation of synthetic characters that convey the illusion of being alive. The components of ANIMUS are inspired by observations made in biological organisms, and provide means for creating autonomous agents that mimic awareness of their environment, of other agents, and of human audience. They also show particular roles, personality, and emotions, active and reactive behavior, automatic reflexes, and selective attention; use temporal memory and learning capabilities to evolve in their dynamic virtual worlds, and express their thought and emotions with a flexible animation system while they interact with the user in immersive 3D environments. ANIMUS creatures follow artistic conceptual designs and constraints that determine the way they behave, react and interact with other creatures and the user, allowing the designer to create meaningful and interesting characters. The framework can be applied to complex immersive environments like CAVE systems or other interactive applications like video games and advanced man-machine interfaces, providing high level tools for creating a new generation of responsive believable agents.
Keywords: VR entertainment, agent architectures, artificial intelligence, artificial perception, believable agents, broad agents, human-machine interaction, immersive environments, intelligent agents, interactive art, synthetic creatures
Alternative reality: a new platform for virtual reality art BIBAKFull-Text 100-107
  Marc Cavazza; Simon Hartley; Jean-Luc Lugrin; Mikael Le Bras
Virtual Reality Art involves the design of artificial worlds that offer new experiences to spectators. An important aspect for the development of VR Art installations is the principled definition of behaviour for the environment as a whole, which would facilitate experiments with alternative laws of physics, time, and causality. We describe the first results of an ongoing project dedicated to the development of software tools for the use of Intelligent Virtual Environments in VR Art. Using the architecture of a state-of-the-art game engine, we have developed Artificial Intelligence techniques that support the definition of alternative laws of physics. After discussing the principles behind alternative reality we describe two complementary modes of description for alternative behaviour: qualitative physics and causal simulation. This is illustrated by examples integrated into the virtual environment.
Keywords: intelligent virtual environments, modelling and simulation, qualitative physics, virtual reality for art and entertainment
Tele-sports and tele-dance: full-body network interaction BIBAKFull-Text 108-116
  Benjamin Schaeffer; Mark Flider; Hank Kaczmarski; Luc Vanier; Lance Chong; Yu Hasegawa-Johnson
Researchers have had great success using motion capture tools for controlling avatars in virtual worlds. Another current of virtual reality research has focused on building collaborative environments connected by networks. The present paper combines these tendencies to describe an open source software system that uses motion capture tools as input devices for realtime collaborative virtual environments. Important applications of our system lie in the realm of simulating interactive, multiparticipant physical activities like sport and dance. Several challenges and their respective solutions are outlined. First, we describe the infrastructure necessary to handle full-body articulated avatars as driven by motion capture equipment, including calibration and avatar creation. Next, we outline the PC cluster solution chosen to render our worlds, exploring methods of data sharing and synchronization, both within the PC cluster nodes and between different sites in the distributed system. Finally, virtual sports require physics, and we describe the simulation algorithms used.
Keywords: PC Cluster, immersive virtual environment, motion capture, networking

Authoring tools & systems

Towards virtual environment authoring tools for content developers BIBAKFull-Text 117-123
  Mark Green
The development of digital media requires the skills of both technical and creative individuals. Technical experts produce the underlying technology that makes the medium possible, but without high quality content the medium won't be successful. In order for a digital medium to be successful it must be possible for content designers to have as much access as possible to the technology without requiring the hands-on assistance of technology experts. This paper examines the problem of creating authoring tools for virtual environments that allow content designers to produce interesting artistic environments without the direct assistance of programmers. Over the past two years we have been developing authoring tools for artistic virtual environments, and these tools form the basis of our virtual reality courses. Most of the students in these courses have limited programming abilities, so they cannot use programming based tools for producing their virtual environments. This paper presents some of the important things that we have learned and a brief discussion of the tools that we have produced.
Keywords: authoring tools
A novel method for supporting collaborative interaction management in Web-based CVE BIBAKFull-Text 124-131
  Qingping Lin; Weihua Wang; Liang Zhang; Tian Fook Choo
The capabilities of Virtual Reality Modeling Language (VRML)/Extensible 3D (X3D) permit building collaborative virtual environments (CVE) using the Internet and the World Wide Web. However, they do not provide a multi-user collaborative interaction management mechanism for CVE applications except the External Authoring Interface that allows communication between external program and VRML browser. The authors of such applications must manage the interactions among the interactive entities by themselves through capturing user interaction with particular virtual entities and propagating them to the affected users. This application-specific method leads to inflexibility in reusing collaborative role definitions and adapting various collaborative interaction management methods. In this paper, we propose a Collaborative Behavior Description Language (CDBL) to address the identified issues. The syntax and sample applications of CBDL will be presented in details. Our work shows that CBDL enables the reuse of collaborative role definitions and scene descriptions to construct flexible CVE with adaptive underlying collaborative interaction management methods.
Keywords: collaborative behavior description language, collaborative role, collaborative virtual environment, interaction management
Mimicking video: real-time morphable 3D model fitting BIBAKFull-Text 132-139
  Kazuhiro Hiwada; Atsuto Maki; Akiko Nakashima
This paper presents a new automatic scheme for tracking a 3D non-rigid object surface such as a human face in a real-time video sequence. We introduce a coordinate-oriented error minimization method for estimating the tracking parameters, whereas we base our algorithm on a morphable 3D model consisting of a combination of 3D linear bases, and show that it is extremely well suited to the task of fitting the 3D model to the target object in real time. The algorithm is straightforward, allowing the parameters of an object's pose and non-rigid motion to be computed in an integrated manner. Also, it is found that the illumination variability on the object surface, for instance due to the target motion, can be handled easily. Through the experiments we not only show that on-line tracking is indeed possible, but also demonstrate the effect of our technique of video mimicking.
Keywords: 3D model based tracking, human interface, real time

Distributed VR

The role of structural reflection in distributed Virtual Reality BIBAKFull-Text 140-149
  Paul Okanda; Gordon Blair
The emergence of collaborative virtual world applications that run over the Internet has presented Virtual Reality (VR) application designers with new challenges. In an environment where the public internet streams multimedia data and is constantly under pressure to deliver over widely heterogeneous user-platforms, there has been a growing need that distributed virtual world applications be aware of and adapt to frequent variations in their context of execution. In this paper, we argue that in contrast to research efforts targeted at improvement of scalability, persistence and responsiveness capabilities, much less attempts have been aimed at addressing the flexibility, maintainability and extensibility requirements in contemporary Distributed VR applications. We propose the use of structural reflection as an approach that not only addresses these requirements but also offers added value in the form of providing a framework for scalability, persistence and responsiveness that is itself flexible, maintainable and extensible.
Keywords: Distributed Virtual Environment (DVE), Virtual Reality (VR), adaptation, object behaviour, reflection
Deployment issues of a VoIP conferencing system in a Virtual Conferencing Environment BIBAKFull-Text 150-159
  R. Venkatesha Prasad; Richard Hurni; H. S. Jamadagni; H. N. Shankar
Real-time services have been supported by and large on circuit-switched networks. Recent trends favour services ported on packet-switched networks. For audio conferencing, we need to consider many issues -- scalability, quality of the conference application, floor control and load on the clients/servers -- to name a few. In this paper, we describe an audio service framework designed to provide a Virtual Conferencing Environment (VCE). The system is designed to accommodate a large number of end users speaking at the same time and spread across the Internet. The framework is based on Conference Servers [14], which facilitate the audio handling, while we exploit the SIP capabilities for signaling purposes. Client selection is based on a recent quantifier called "Loudness Number" that helps mimic a physical face-to-face conference. We deal with deployment issues of the proposed solution both in terms of scalability and interactivity, while explaining the techniques we use to reduce the traffic. We have implemented a Conference Server (CS) application on a campus-wide network at our Institute.
Keywords: Conference Server, Real-Time Audio, SIP, VCE, VoIP, simultaneous speakers
A scalable dynamic load distribution scheme for multi-server distributed virtual environment systems with highly-skewed user distribution BIBAKFull-Text 160-168
  Kyungmin Lee; Dongman Lee
This paper proposes and evaluates a scalable dynamic load distribution scheme for multi-server distributed virtual environment systems, where users are highly skewed rather than uniformly distributed over a virtual environment. In the proposed scheme, an overloaded server initiating load distribution selects a set of servers to be involved in load distribution by dynamically adapting to the workload status of other servers, unlike the existing approaches. Upon completion of server selection, the initiating server repartitions the regions dedicated to the involved servers using a graph partitioning algorithm so that all the involved servers have the roughly equal workload. The involved servers then migrate their workloads with each other in a peer-to-peer manner according to the result of repartitioning. We present and analyze the simulation results that compare the performance of the proposed scheme with that of the existing schemes.
Keywords: distributed virtual environment, dynamic load distribution, multiple server architecture

Devices

Super wide viewer using catadioptrical optics BIBAKFull-Text 169-175
  Hajime Nagahara; Yasushi Yagi; Masahiko Yachida
Many applications have used a Head-Mounted Display (HMD), such as in virtual and mixed realities, and tele-presence. The advantage of HMD systems is the ease of feeling a 3D world in the display of animation or movies. However, the field of view (FOV) of commercial HMD systems is too narrow for feeling immersion. The horizontal FOV of many commercial HMDs is around 60 degrees, significantly narrower than that of humans. In this paper, we propose a super wide field of view head-mounted display consisting of an ellipsoidal and a hyperboloidal curved mirror. The horizontal FOV of the proposed HMD is 180 degrees and includes the peripheral view of humans. It increases reality and immersion of users. As well, the central region (60 degrees) of the FOV can measure 3D distances using stereoscopics.
Keywords: Head Mount Display, catadioptrical optics, tele-presence, wide field of view
Performance evaluation of programmable graphics hardware for image filtering and stereo matching BIBAKFull-Text 176-183
  Kaoru Sugita; Takeshi Naemura; Hiroshi Harashima
It is obvious that faster processors are essential for virtual reality applications. Recently, we have a new generation of graphics hardware which can enhance the reality of interactive graphics. Although it is designed for rendering purpose, its programmability is expected to be effective for other general applications. This paper evaluates its performance as an image processing unit especially for image filtering and stereo matching. First, we focus on image filtering, and compare GPU (ATI RADEON 9700 Pro) implementations to optimized CPU (Intel Pentium 4 3.06GHz) ones. Experimental results show that, for linear filtering, GPUs are from three to six times faster than CPUs. Then, we implement a block-based stereo matching algorithm using filters and depth-test-based optimization on the GPU. This implementation is shown to be twice faster than a CPU implementation. Finally, a system based on this algorithm is constructed to estimate depth from two video sequences in real time.
Keywords: image filtering, programmable graphics hardware, real-time image processing, stereo matching
The optical tweezers: multiple-point interaction technique BIBAKFull-Text 184-187
  Sergey V. Matveyev; Martin Göbel
The proposed multiple-point interaction technique realizes direct interaction and control in a virtual environment and presentation. The device for interaction is constructed on the basis of the infrared (IR) laser which is invisible for a human eye and does not interfere with the visual channel of a presentation, since there can be no coincidence of the color of the infrared laser and the visible object on the screen.
   The special designed optical scheme splits a laser beam into three with a small angle of divergence. As a result we receive the three IR spots on the screen.
   The coordinates of the laser spots received from the infrared camera are interpreted as a position of the (pointer) cursor after the mathematical processing which is displayed with the help of the projection system and can be interpreted as commands of the application control.
Keywords: direct interaction, laser pointer, tremor

Haptics

A haptic feedback device based on an active mesh BIBAKFull-Text 188-195
  Andrea Mazzone; Christian Spagno; Andreas Kunz
This paper introduces a preliminary study about the Smart-Mesh, a novel type of active structure capable of deforming actively its shape and thus being able to form objects. It is a new approach to find a solution to the difficulties that are encountered in the field of haptic interaction in virtual environments. The paper describes the basic working principles of the structure, which allow the generation of overhanging surfaces. A first prototype based on 16 nodes and 48 linkages with prismatic joints is presented. The SmartMesh can be embedded into a table, into walls, ceilings and floors. The resolution of the SmartMesh depends on the amount of nodes and the length of the linkages. The linkages can be replaced by linear actuators.
Keywords: active mesh, active structures, actuators, free hand haptic feedback devices, haptic displays, linear actuators, smart materials
Novel actuators for haptic displays based on electroactive polymers BIBAKFull-Text 196-204
  Andrea Mazzone; Rui Zhang; Andreas Kunz
After a wrap-up in the human physiology and an overview on physical principles, this paper introduces four novel types of actuators for haptic feedback devices based on electroactive polymers, which were developed and evaluated for their suitability for haptic feedback devices. The electroactive polymers show many promising properties, such as big expansion, high frequency range and big force exertion for instance. Unfortunately they are still in the fledgling state and are not available on the market yet. The actuators presented in this paper are a contribution to the haptic and to the electro active polymer researchers community.
Keywords: actuators, electroactive polymers, force feedback, haptic displays, human factors, smart materials
The CAT for efficient 2D and 3D interaction as an alternative to mouse adaptations BIBAKFull-Text 205-212
  Martin Hachet; Pascal Guitton; Patrick Reuter
We present the first usable prototype of the CAT (Control Action Table). The CAT is a 6 degree of freedom freestanding device, mixing isotonic and isometric sensing modes. It allows a group of users to interact with virtual environments by means of 3D and 2D interaction techniques. The innovating design of the CAT unifies the principle advantages of existing input devices while rejecting their main limitations. We present the resulting characteristics and compare the CAT to existing input devices. A 3D docking task experiment and a demo application have shown that the CAT can be used more efficiently than an 3D isometric desktop device and that the users preferred the CAT. The CAT is contributing to the development of real VR applications.
Keywords: evaluation, input device, user interface

Human factors in collaborative virtual environment

Visual attention based information culling for Distributed Virtual Environments BIBAFull-Text 213-222
  Ashweeni Kumar Beeharee; Adrian J. West; Roger Hubbold
The central goal in Distributed Virtual Environments (DVEs) is to provide an experience of the shared world that is perceptually plausible for the immersed user. This has to be achieved in the face of network issues such as bandwidth limitations and latencies which make total synchronism impossible. Techniques have been devised to help; some optimise network use by limiting what is transmitted, others try to disguise the effects of network 'glitches' at the user's client machine -- for example smoothing policies. To date such techniques tend to be system-based rather than user-oriented. Yet there is an active body of psychological research, for example in visual attention, which has successfully been employed by the graphics community to yield better perceived results for a given resource. Immersive DVEs are even more critically dependent upon the users' perceived experience. We may expect therefore that such 'psychologically' oriented approaches have even more to offer here. In this paper a visual attention model which exploits the peculiarities of the human visual system is presented. It is based on previous work, and on a series of carefully designed experiments which are used to guide the implementation of the model and to design architectures for DVEs. The proposed architectures are then tested using different DVE experimental applications, which include a highly populated virtual city. The results demonstrate that the characteristics of the human visual system can be exploited to improve network usage and generate a more perceptually plausible environment in the face of incomplete synchronisation.
A model of dynamic interest management: interaction analysis in collaborative virtual environment BIBAKFull-Text 223-230
  Dawei Ding; Miaoling Zhu
Most previous collaborative virtual environments mainly use spatial aspect to implement interest management. However, it turns to be difficult to manage awareness using semantic or organization considerations, specially in densely populated open space environments. Aiming at this kind of applications, we propose a novel interest management model with dynamic interaction analysis in CVE. Our work is concerned with dynamic interaction in crowds, from which we derive the semantics of user behaviors, more specifically, the alteration of interest focus of users. Above all, we would define the construction of Interest Network. Then an interaction analysis approach is introduced to find out the interest focus of virtual humans. Psychology effects in crowd or a group of participants are also analyzed and incorporated in our approach. Lastly, a prototype virtual conference application is implemented to demonstrate the effects of our model on optimizing collaborative awareness.
Keywords: CVE (Collaborative Virtual Environment), VRML, interaction analysis, interest management, interest network
Design and evaluation of team work in distributed collaborative virtual environments BIBAKFull-Text 231-238
  Gernot Goebbels; Vali Lalioti; Martin Göbel
We present a framework for the design and evaluation of distributed, collaborative 3D interaction focussing on projection based systems. We discuss the issues of collaborative 3D interaction using audio/video for face-to-face communication and the differences in using rear projection based Virtual Environments. Further, we explore how the use of video/audio, input device representations and other disturbance factors typical of projection-based virtual environments affect co-presence, co-working and co-knowledge in distributed CVEs. We present results from co-presence and co-working evaluation sessions of about 60 users of various profiles. An extensive statistical, group and variation group analysis of the results is carried out. The findings and the resulting design guidelines are presented in this paper in respect to the above factors.
Keywords: CVE Design Model, awareness, collaborative virtual environments, evaluation, guidelines, tele-presence