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Virtual Reality 6

Standard No:ISSN 1359-4338 (print) EISSN 1434-9957 (online)
Links:link.springer.com | Twitter | Table of Contents
  1. VR 2002-03 Volume 6 Issue 1
  2. VR 2002-09 Volume 6 Issue 2
  3. VR 2002-10 Volume 6 Issue 3
  4. VR 2003-08 Volume 6 Issue 4

VR 2002-03 Volume 6 Issue 1

Frustum slicing BIBAKFull-Text 1-10
  K. Bormann
In this paper visibility culling is integrated tightly with an octree data structure. This is done by slicing the frustum in such a way that the minimal distance from the eye to objects in a given frustum slice is twice the minimal eye to object distance of the previous slice. Then, if one has a fixed minimal detail size, i.e. a minimal spatial angle so that objects of lesser angular extensions are not rendered to the screen then, going from one slice to the next, objects must be twice as big in order to be rendered. This corresponds to traversing the octree one level less deeply. Thus the minimal detail size hugely cuts the number of nodes that the rendering algorithm must visit, a fact that becomes even more pronounced when noting that small objects are far more prevalent than are big objects. By splitting the frustum into focal and peripheral frusta and, consequently, splitting frustum slices into focal and peripheral ones, one can further take advantage of detail elision by rendering objects far from the line of sight only to some larger minimal detail size.
Keywords: Octree; Outdoor type VEs; Real-time rendering
Two-handed assembly with immersive task planning in virtual reality BIBAKFull-Text 11-20
  H. Sun; B. Hujun
Assembly modelling is the process of capturing entities and activity information related to assembling and assembly. Currently, most CAD systems have been developed to ease the design of individual components, but are limited in their support for assembly designs and planning capability, which are crucial for reducing the cost and processing time in complex design, constraint analysis and assembly task planning. This paper presents a framework of a two-handed virtual assembly (VA) planner for assembly tasks, which coordinates two hands jointly for feature-based manipulation, assembly analysis and constraint-based task planning. Feature-based manipulation highlights the important assembling features (e.g. dynamic reference frames, moving arrow, mating features) to guide users for the ease of assembly and in an efficient and fluid manner. The users can freely navigate and move the mating pair along the collision-free path. The free motion of two-handed input in assembly is further restricted to the allowable motion guided by the constraints recognised on-line. The allowable motion in assembly is planned by the logic steps derived from the analysis of constraints and their translation in the progress of assembly. No preprocessing or predefined assembly sequence is necessary since the planning is produced in real-time upon the two-handed interactions. Mating features and constraints in databases are automatically updated after each assembly to simplify the planning process. The two-handed task planner has been developed and experimented for several assembly examples including a drill (12-parts) and a robot (17-parts). The system can be generally applied for the interactive task planning of assembly-type applications.
Keywords: Two-handed interface; User interaction; Virtual assembly; Virtual reality
A VE framework to study visual perception and action BIBAKFull-Text 21-32
  F. Panerai; M. Ehrette; P. Leboucher
In the real world, vision operates in harmony with self-motion yielding the observer to unambiguous perception of the three-dimensional (3D) space. In laboratory conditions, because of technical difficulties, researchers studying 3D perception have often preferred to use the substitute of a stationary observer, somehow neglecting aspects of the action-perception cycle. Recent results in visual psychophysics have proved that self-motion and visual processes interact, leading the moving observer to interpret a 3D virtual scene differently from a stationary observer. In this paper we describe a virtual environment (VE) framework which presents very interesting characteristics for designing experiments in visual perception during action. These characteristics arise in a number of ways from the design of a unique motion capture device. First, its accuracy and the minimal latency in position measurement; second, its ease of use and the adaptability to different display interfaces. Such a VE framework enables the experimenter to recreate stimulation conditions characterised by a degree of sensory coherence typical of the real world. Moreover, because of its accuracy and flexibility, the same device can be used as a measurement tool to perform elementary but essential calibration procedures. The VE framework has been used to conduct two studies which compare the perception of 3D variables of the environment in moving and in stationary observers under monocular vision. The first study concerns the perception of absolute distance, i.e. the distance separating an object and the observer. The second study refers to the perception of the orientation of a surface both in the absence and presence of conflicts between static and dynamic visual cues. In the two cases, the VE framework has enabled the design of optimal experimental conditions, permitting light to be shed on the role of action in 3D visual perception.
Keywords: Action; Motion capture; Virtual environments; 3D visual perception; Visuo-motor coherence
WalkMap: Developing an augmented reality map application for wearable computers BIBAKFull-Text 33-44
  J. Lehikoinen; R. Suomela
We have designed, implemented, and evaluated a map application for wearable computer users. Our application, called WalkMap, is targeted at a walking user in an urban environment, offering the user both navigational aids as well as contextual information. WalkMap uses augmented reality techniques to display a map on the surrounding area on the user's head-worn display. WalkMap is constructed by the means of software development, user interface design and evaluations, and existing knowledge on how humans use maps and navigate. The key design driver in our approach is intuitivity of use. In this paper, we present the design and implementation process of our application, considering human-map interfaces, technical implementation, and human-computer interfaces. We identify some of the key issues in these areas, and present the way they have been solved. We also present some usability evaluation results.
Keywords: Augmented reality; Context-awareness; Head-worn display; Human-computer interaction; Human-map interface; Navigational map; Wearable computing
Context calibration BIBAKFull-Text 45-55
  K. Bormann
The basic starting point of this paper is that 'context' constitutes most of the user interface when doing VR-related experiments, but even so one bases performance measures on only a few 'active' tasks. Thus, in order to meaningfully compare results obtained in vastly different experiments one needs to somehow 'subtract' the contribution to observables that are due to the context. For the case where one is investigating whether changes in one observable causes changes in another, a method, context calibration, is proposed that does just that. This method is expected to, to a large extent, factor out the part of one's results that are due to factors that are not explicitly considered when evaluating the experiment, factors that the experimenter might not even suspect influences the experiment. A procedure for systematically investigating the theoretical assumptions underlying context calibration is also discussed as is an initial experiment adhering to the proposed methodology.
Keywords: Context calibration; Experimental methodology; Performance-presence relationship

VR 2002-09 Volume 6 Issue 2

A Virtual Reality Tool for Teleoperation Research BIBKFull-Text 57-62
  N. Rodriguez; J.-P. Jessel; P. Torguet
Keywords: Autonomous agents; Distributed environment; Robotics; Teleoperation; Test bed; Virtual reality
Designing Virtual Environments to Support Cooperation in the Real World BIBKFull-Text 63-74
  A. Crabtree; T. Rodden; J. Mariani
Keywords: Cooperative work; Design; Ethnography; Evaluation; Material affordances; Virtual environments
Simulating Self-Motion I: Cues for the Perception of Motion BIBKFull-Text 75-85
  L. R. Harris; M. R. Jenkin; D. Zikovitz; F. Redlick; P. Jaekl
Keywords: Proprioception; Self-motion; Visual and non-visual cues to motion
Simulating Self-Motion II: A Virtual Reality Tricycle BIBKFull-Text 86-95
  R. S. Allison; L. R. Harris; A. R. Hogue; U. T. Jasiobedzka
Keywords: Self-motion simulation; Visual and vestibular egomotion cues
Development of a Learning-Training Simulator with Virtual Functions for Lathe Operations BIBKFull-Text 96-104
  Z. Li; H. Qiu; Y. Yue
Keywords: Lathe; Machining Operations; Simulator; Skill Training; Virtual Reality

VR 2002-10 Volume 6 Issue 3

Introduction BIBFull-Text 105-106
  D. A. Bowman; M. Billinghurst
Experiments with Face-To-Face Collaborative AR Interfaces BIBAKFull-Text 107-121
  M. Billinghurst; H. Kato; K. Kiyokawa; D. Belcher; I. Poupyrev
We describe a design approach, Tangible Augmented Reality, for developing face-to-face collaborative Augmented Reality (AR) interfaces. Tangible Augmented Reality combines Augmented Reality techniques with Tangible User Interface elements to create interfaces in which users can interact with spatial data as easily as real objects. Tangible AR interfaces remove the separation between the real and virtual worlds, and so enhance natural face-to-face communication. We present several examples of Tangible AR interfaces and results from a user study that compares communication in a collaborative AR interface to more traditional approaches. We find that in a collaborative AR interface people use behaviours that are more similar to unmediated face-to-face collaboration than in a projection screen interface.
Keywords: Augmented reality; Collaboration; Communication; Usability evaluation
Novel Uses of Pinch Gloves™ for Virtual Environment Interaction Techniques BIBAKFull-Text 122-129
  D. A. Bowman; C. A. Wingrave; J. M. Campbell; V. Q. Ly; C. J. Rhoton
The usability of three-dimensional (3D) interaction techniques depends upon both the interface software and the physical devices used. However, little research has addressed the issue of mapping 3D input devices to interaction techniques and applications. This is especially crucial in the field of Virtual Environments (VEs), where there exists a wide range of potential 3D input devices. In this paper, we discuss the use of Pinch Gloves™ -- gloves that report contact between two or more fingers -- as input devices for VE systems. We begin with an analysis of the advantages and disadvantages of the gloves as a 3D input device. Next, we present a broad overview of three novel interaction techniques we have developed using the gloves, including a menu system, a text input technique, and a two-handed navigation technique. All three of these techniques have been evaluated for both usability and task performance. Finally, we speculate on further uses for the gloves.
Keywords: 3D Input Devices; Interaction Techniques; Pinch Gloves; Usability Evaluation; Virtual Environments
Handling of Virtual Contact in Immersive Virtual Environments: Beyond Visuals BIBAKFull-Text 130-139
  R. W. Lindeman; J. N. Templeman; J. L. Sibert; J. R. Cutler
This paper addresses the issue of improving the perception of contact that users make with purely virtual objects in virtual environments. Because these objects have no physical component, the user's perceptual understanding of the material properties of the object, and of the nature of the contact, is hindered, often limited solely to visual feedback. Many techniques for providing haptic feedback to compensate for the lack of touch in virtual environments have been proposed. These systems have increased our understanding of the nature of how humans perceive contact. However, providing effective, general-purpose haptic feedback solutions has proven elusive. We propose a more-holistic approach, incorporating feedback to several modalities in concert. This paper describes a prototype system we have developed for delivering vibrotactile feedback to the user. The system provides a low-cost, distributed, portable solution for incorporating vibrotactile feedback into various types of systems. We discuss different parameters that can be manipulated to provide different sensations, propose ways in which this feedback can be combined with feedback of other modalities to create a better understanding of virtual contact, and describe possible applications.
Keywords: Haptic; Multimodal; Vibrotactile
An Investigation of Visual Cues used to Create and Support Frames of Reference and Visual Search Tasks in Desktop Virtual Environments BIBAKFull-Text 140-150
  S. S. Morar; R. D. Macredie; T. Cribbin
Visual depth cues are combined to produce the essential depth and dimensionality of Desktop Virtual Environments (DVEs). This study discusses DVEs in terms of the visual depth cues that create and support perception of frames of references and accomplishment of visual search tasks. This paper presents the results of an investigation that identifies the effects of the experimental stimuli positions and visual depth cues: luminance, texture, relative height and motion parallax on precise depth judgements made within a DVE. Results indicate that the experimental stimuli positions significantly affect precise depth judgements, texture is only significantly effective for certain conditions, and motion parallax, in line with previous results, is inconclusive to determine depth judgement accuracy for egocentrically viewed DVEs. Results also show that exocentric views, incorporating relative height and motion parallax visual cues, are effective for precise depth judgements made in DVEs. The results help us to understand the effects of certain visual depth cues to support the perception of frames of references and precise depth judgements, suggesting that the visual depth cues employed to create frames of references in DVEs may influence how effectively precise depth judgements are undertaken.
Keywords: Depth Perception; Desktop Virtual Environments; Frames of Reference; Motion Parallax; Visual Depth Cues; Visual Search Tasks
MagicMeeting: A Collaborative Tangible Augmented Reality System BIBAKFull-Text 151-166
  H. T. Regenbrecht; M. Wagner; G. Baratoff
We describe an augmented reality (AR) system that allows multiple participants to interact with 2D and 3D data using tangible user interfaces. The system features face-to-face communication, collaborative viewing and manipulation of 3D models, and seamless access to 2D desktop applications within the shared 3D space. All virtual content, including 3D models and 2D desktop windows, is attached to tracked physical objects in order to leverage the efficiencies of natural two-handed manipulation. The presence of 2D desktop space within 3D facilitates data exchange between the two realms, enables control of 3D information by 2D applications, and generally increases productivity by providing access to familiar tools. We present a general concept for a collaborative tangible AR system, including a comprehensive set of interaction techniques, a distributed hardware setup, and a component-based software architecture that can be flexibly configured using XML. We show the validity of our concept with an implementation of an application scenario from the automotive industry.
Keywords: Augmented reality; Collaboration; CSCW; Tangible user interfaces; 3D user interfaces
Glove Based User Interaction Techniques for Augmented Reality in an Outdoor Environment BIBAKFull-Text 167-180
  B. H. Thomas; W. Piekarski
This paper presents a set of pinch glove-based user interface tools for an outdoor wearable augmented reality computer system. The main form of user interaction is the use of hand and head gestures. We have developed a set of augmented reality information presentation techniques. To support direct manipulation, the following three selection techniques have been implemented: two-handed framing, line of sight and laser beam. A new glove-based text entry mechanism has been developed to support symbolic manipulation. A scenario for a military logistics task is described to illustrate the functionality of this form of interaction.
Keywords: Augmented reality; Glove based interaction; User interactions; Wearable computers

VR 2003-08 Volume 6 Issue 4

MAS Dynamics on Stage BIBAKFull-Text 181-195
  N. Baerten; P. J. Braspenning
We aim to explore a new kind of user interface solely dedicated to presenting the global inner dynamics of Multi-Agent Systems (MASs) on a higher level. Being complex systems, MASs are often only or barely understood by their designer(s). Could we enable a particular kind of agent to tell the designer's story about the agent- and human-interactive behaviours taking place inside the MAS in a meaningful way? Could a set of virtual actors turn this story into a 'dynamic user-experience'? After taking a closer look at how to gain insight into complex systems and why to pick a drama-based approach, we present the three pillars of perception, interpretation and presentation, on which we base our visualisation efforts. We show how they relate to various research fields such as agent technology, human computer interaction, psychology, computer graphics, animation, drama, body language and cognitive ergonomics. Based upon these insights we introduce a conceptual model for drama-based visualisation, followed by a stepwise description of how this framework could be applied. The article closes with some reflections and conclusions.
Keywords: Conceptual Model; Drama; Intelligent Interfaces; Multi-Agent Systems; Virtual Actors
Polyhedral Objects Metamorphosis Using Convex Decomposition and Morphology BIBAKFull-Text 196-204
  Wen-Yu Liu; Hua Li; Fei Wang; Guang-Xi Zhu
A new technique is presented for computing continuous shape transformations between polyhedral objects. The polyhedron shape transformations can be divided into polyhedron metamorphosis and bi-directional local rigid body rotation transformation. By decomposing two objects into sets of individual convex sub-objects respectively, and establishing the matching between two subsets, the approach can solve the metamorphosis problem of two non-homotopic objects (including concave objects and holey objects). Compared with other methods, this metamorphosis algorithm can be executed automatically for arbitrary polyhedrons and no need user interaction. The user has the ability to choose an automatic matching or to select interactively pairs of corresponding matching convex subsets to obtain special effects. Experiments show that this method can generate natural, high-fidelity, eye-pleasing metamorphosis results with simple computation.
Keywords: Convex Decomposition; Generalised Morphing; Local Rotation; Metamorphosis
Material-Discontinuity Preserving Progressive Mesh Using Vertex-Collapsing Simplification BIBAKFull-Text 205-216
  Shu-Kai Yang; Jung-Hong Chuang
Level Of Detail (LOD) modelling or mesh reduction has been found useful in interactive walkthrough applications. Progressive meshing techniques based on edge or triangle collapsing have been recognised useful in continuous LOD, progressive refinement, and progressive transmission. We present a vertex-collapsing mesh reduction scheme that effectively takes shape and feature preserving as well as material-discontinuity preserving into account, and produces a progressive mesh which generally has more vertices collapsed between adjacent levels of detail than methods based on edge-collapsing and triangle collapsing.
Keywords: Level Of Detail; Material-Discontinuity Preserving; Progressive Mesh; Topology Simplification; Vertex Collapsing; Virtual Reality
A Novel Seven Degree of Freedom Haptic Device for Engineering Design BIBAKFull-Text 217-228
  S. Kim; J. J. Berkley; M. Sato
In this paper, the authors intend to demonstrate a new intuitive force-feedback device that is ideally suited for engineering design. Force feedback for the device is tension-based and is characterised by 7 degrees of freedom (3 DOF for translation, 3 DOF for rotation, and 1 DOF for grasp). The SPIDAR-G (SPace Interface Device for Artificial Reality with Grip) allows users to interact with virtual objects naturally by manipulating two hemispherical grips located in the centre of a device frame. Force feedback is achieved by controlling tension in cables that are connected between a grip and motors located at the corners of a frame. Methodologies will be discussed for displaying force and calculating translation, orientation and grasp using the length of 8 connecting cables. The SPIDAR-G is characterised by smooth force feedback, minimised inertia, no backlash, scalability and safety. Such features are attributed to strategic cable arrangement and control that results in stable haptic rendering. Experimental results validate the feasibility of the proposed device and example applications are described.
Keywords: CAD; Force Feedback; Haptics; Virtual Design
Methods and Algorithms for Constraint-based Virtual Assembly BIBAKFull-Text 229-243
  Y. Wang; U. Jayaram; S. Jayaram; S. Imtiyaz
Constraint-based simulation is a fundamental concept used for assembly in a virtual environment. The constraints (axial, planer, etc.) are extracted from the assembly models in the CAD system and are simulated during the virtual assembly operation to represent the real world operations. In this paper, we present the analysis of 'combinations' and 'order of application' of axial and planar constraints used in assembly. Methods and algorithms for checking and applying the constraints in the assembly operation are provided. An object-oriented model for managing these constraints in the assembly operation is discussed.
Keywords: Virtual Assembly; Assembly Constraints; Constrained Motion Simulation
A Virtual Environment for the Design and Simulated Construction of Prefabricated Buildings BIBAKFull-Text 244-256
  Norman Murray; Terrence Fernando; Ghassan Aouad
The construction industry has acknowledged that its current working practices are in need of substantial improvements in quality and efficiency and has identified that computer modelling techniques and the use of prefabricated components can help reduce times, costs, and minimise defects and problems of on-site construction. This paper describes a virtual environment to support the design and construction processes of buildings from prefabricated components and the simulation of their construction sequence according to a project schedule. The design environment can import a library of 3-D models of prefabricated modules that can be used to interactively design a building. Using Microsoft Project, the construction schedule of the designed building can be altered, with this information feeding back to the construction simulation environment. Within this environment the order of construction can be visualised using virtual machines. Novel aspects of the system are that it provides a single 3-D environment where the user can construct their design with minimal user interaction through automatic constraint recognition and view the real-time simulation of the construction process within the environment. This takes this area of research a step forward from other systems that only allow the planner to view the construction at certain stages, and do not provide an animated view of the construction process.
Keywords: Modular Construction; Prefabricated Components; Virtual Construction Environment
Aspects of Haptic Feedback in a Multi-modal Interface for Object Modelling BIBAKFull-Text 257-270
  J. De Boeck; C. Raymaekers; K. Coninx
In our everyday life, interaction with the world consists of a complex mixture of audio (speech and sounds), vision and touch. Hence, we may conclude that the most natural means of human communication is multi-modal. Our overall research goal is to develop a natural 3D human-computer interaction framework for modelling purposes without mouse or keyboard and where many different sensing modalities will be used simultaneously and cooperatively. This article will focus on the various interface issues on the way to an intuitive environment in which one or more users can model their prototypes in a natural manner. Some technical framework decisions, such as messaging and network systems, will also be investigated.
Keywords: Multi-modal Interface; Force Feedback; Haptic Feedback; Virtual Modelling