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VRST Tables of Contents: 979899000102030405060708091012131415

Proceedings of the 2001 ACM Symposium on Virtual Reality Software and Technology

Fullname:VRST'01 ACM Symposium on Virtual Reality Software and Technology
Editors:Chris Shaw; Wenping Wang; Mark Green
Location:Banff, Alberta, Canada
Dates:2001-Nov-15 to 2001-Nov-17
Standard No:ISBN: 1-58113-427-4; ACM DL: Table of Contents hcibib: VRST01
  1. Tracking
  2. Collaboration in Virtual Environments
  3. Software
  4. Algorithms
  5. Display Devices
  6. Panels
  7. Distributed Virtual Environments
  8. Applications
  9. Interaction


Binocular eye tracking in VR for visual inspection training BIBAFull-Text 1-8
  Andrew T. Duchowski; Eric Medlin; Anand Gramopadhye; Brian Melloy; Santosh Nair
This paper presents novel software techniques for binocular eye tracking within Virtual Reality and discusses their application to aircraft inspection training. The aesthetic appearance of the environment is driven by standard graphical techniques augmented by realistic texture maps of the physical environment. The user's gaze direction, as well as head position and orientation, are tracked to allow recording of the user's fixations within the environment. Methods are given for (1) integration of the eye tracker into a Virtual Reality framework, (2) stereo calculation of the user's 3D gaze vector, (3) a new 3D calibration technique developed to estimate the user's inter-pupillary distance post-facto, and (4) a new technique for eye movement analysis in 3-space. The 3D eye movement analysis technique is an improvement over traditional 2D approaches since it takes into account the 6 degrees of freedom of head movements and is resolution independent. Results indicate that although the current signal analysis approach is somewhat noisy and tends to underestimate the identified number of fixations, recorded eye movements provide valuable human factors process measures complementing performance statistics used to gauge training effectiveness.
Inertial and magnetic posture tracking for inserting humans into networked virtual environments BIBAKFull-Text 9-16
  Eric R. Bachmann; Robert B. McGhee; Xiaoping Yun; Michael J. Zyda
Rigid body orientation can be determined without the aid of a generated source using nine-axis MARG (Magnetic field, Angular Rate, and Gravity) sensor unit containing three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers. This paper describes a quaternion-based complementary filter algorithm for processing the output data from such a sensor. The filter forms the basis for a system designed to determine the posture of an articulated body in real-time. In the system the orientation relative to an Earth-fixed reference frame of each limb segment is individually determined through the use of an attached MARG sensor. The orientations are used to set the posture of an articulated body model. Details of the fabrication of a prototype MARG sensor are presented. Calibration algorithms for the sensors and the human body model are also presented. Experimental results demonstrate the effectiveness of the tracking system and verify the correctness of the underlying theory.
Keywords: body tracking, complementary filtering, inertial/magnetic sensors, quaternions, virtual environments
Tracking based structure and motion recovery for augmented video productions BIBAKFull-Text 17-24
  Kurt Cornelis; Marc Pollefeys; Luc Van Gool
Augmented Reality (AR) can hardly be called uncharted territory. Much research in this area revealed solutions to the three most prominent challenges of AR: accurate camera state retrieval, resolving occlusions between real and virtual objects and extraction of environment illumination distribution. Solving these three challenges improves the illusion of virtual entities belonging to our reality. This paper demonstrates an elaborated framework that recovers accurate camera states from a video sequence based on feature tracking. Without prior calibration knowledge, it is able to create AR Video products with negligible/invisible jitter or drift of virtual entities starting from general input video sequences. Together with the referenced papers, this work describes a readily implementable and robust AR-System.
Keywords: accurate registration, augmented reality, jitter reduction

Collaboration in Virtual Environments

SmartCU3D: a collaborative virtual environment system with behavior based interaction management BIBAKFull-Text 25-32
  Weihua Wang; Qingping Lin; Jim Mee Ng; Chor Ping Low
To support real-time natural interaction in the Collaborative Virtual Environment (CVE) with limited network bandwidth and computer processing power, the development of an efficient interaction management mechanism is a key issue. In this paper, we propose a behavior based interaction management mechanism for managing the collaborative interactions among the distributed users in our developed SmartCU3D, an Internet CVE system. With this mechanism, message routing in the system becomes adaptive to the application and the users' runtime interaction. It is achieved by giving the Object-Oriented style collaborative behavior description along with the 3D environment definition for every individual CVE application. The motivation of this research is to develop a framework to support a flexible and adaptive interaction management mechanism for developing different CVE applications.
Keywords: behavior, collaborative virtual environment, interaction management
An abstraction for awareness management in collaborative virtual environments BIBAFull-Text 33-39
  Miguel Antunes; António Rito Silva; Jorge Martins
This paper describes an object-oriented abstraction for the problem of awareness management in Collaborative Virtual Environments (CVEs). The described abstraction allows for different types of awareness information and awareness management policies to be used. It is also described how the defined abstraction was used to support the awareness management policies of two demo CVEs application.
Audience interaction for virtual reality theater and its implementation BIBAKFull-Text 41-45
  Sang Chul Ahn; Ig-Jae Kim; Hyoung-Gon Kim; Yong-Moo Kwon; Heedong Ko
Recently we have built a VR (Virtual Reality) theater in Kyongju, Korea. It combines the advantages of VR and IMAX theater. The VR theater can be characterized by a single shared screen and by multiple inputs from several hundreds of people. In this case, multi-user interaction is different from that of networked VR systems and must be reconsidered. This paper defines the multi-user interaction in such a VR theater as Audience Interaction, and discusses key issues for the implementation of the Audience Interaction. This paper also presents a real implementation example in the Kyongju VR theater.
Keywords: audience interaction, multi-user interaction, theater, virtual reality


An open software architecture for virtual reality interaction BIBAKFull-Text 47-54
  Gerhard Reitmayr; Dieter Schmalstieg
This article describes OpenTracker, an open software architecture that provides a framework for the different tasks involved in tracking input devices and processing multi-modal input data in virtual environments and augmented reality application. The OpenTracker framework eases the development and maintenance of hardware setups in a more flexible manner than what is typically offered by virtual reality development packages. This goal is achieved by using an object-oriented design based on XML, taking full advantage of this new technology by allowing to use standard XML tools for development, configuration and documentation. The OpenTracker engine is based on a data flow concept for multi-modal events. A multi-threaded execution model takes care of tunable performance. Transparent network access allows easy development of decoupled simulation models. Finally, the application developer's interface features both a time-based and an event based model, that can be used simultaneously, to serve a large range of applications. OpenTracker is a first attempt towards a "'write once, input anywhere"' approach to virtual reality application development. To support these claims, integration into an existing augmented reality system is demonstrated. We also show how a prototype tracking equipment for mobile augmented reality can be assembled from consumer input devices with the aid of OpenTracker. Once development is sufficiently mature, it is planned to make Open-Tracker available to the public under an open source software license.
Keywords: XML, mobile augmented reality, tracking, virtual reality
VRPN: a device-independent, network-transparent VR peripheral system BIBAKFull-Text 55-61
  Russell M., II Taylor; Thomas C. Hudson; Adam Seeger; Hans Weber; Jeffrey Juliano; Aron T. Helser
The Virtual-Reality Peripheral Network (VRPN) system provides a device-independent and network-transparent interface to virtual-reality peripherals. VRPN's application of factoring by function and of layering in the context of devices produces an interface that is novel and powerful. VRPN also integrates a wide range of known advanced techniques into a publicly-available system. These techniques benefit both direct VRPN users and those who implement other applications that make use of VR peripherals.
Keywords: input devices, interactive graphics, library, peripherals, virtual environments, virtual worlds
Exploring the past: a toolset for visualization of historical events in virtual environments BIBAKFull-Text 63-70
  Stanislav L. Stoev; Matthias Feurer; Michael Ruckaberle
In this paper, we present a set of tools and techniques for visualization of and interaction with historical data. First, we briefly describe the data acquisition and preparation. Afterwards, we discuss in detail the interaction approaches for exploration of historical data, containing a time dimension. In particular, we propose (1) a continuous time increment approach for visualizing 3D slices continuously moving in the 4D space; (2) a fly-with mode for viewing the scene from the perspective of the participants in the migration, we are visualizing; (3) a time lens, as an extension of the traditional magic lens for viewing arbitrary event times; (4) a time-space exploration tool for simultaneous viewing more than one event time and location of interest; (5) a guided exploration tool, which allows for viewing events on an interactively defined or pre-defined path in space. Finally, we conclude the paper with a discussion and comparison of the proposed tools.
Keywords: four-dimensional data visualization, human-computer interface, interaction techniques, virtual environment applications


A fast implicit integration method for solving dynamic equations of movement BIBAKFull-Text 71-76
  Laurent Hilde; Philippe Meseure; Christophe Chaillou
The use of physics is a way to improve realism in Virtual Reality. In order to calculate virtual objects movement in a real-time physically based simulation, you have to solve ODE (Ordinary Differential Equations) relative to time. This solution has to be fast enough to display the scene at an interactive rate or to control an haptic device and to be as reliable as possible.
   We show that the use of the Euler implicit method is possible in a real-time environment. This one offers control about stability and thus has a good behaviour with stiff ODE, which are hard to solve. For this purpose, we propose to solve the non-linear system from Euler's integration in a way less costly than usual Newton like techniques by applying Broyden's method.
Keywords: Broyden's method, ODE, control of haptic devices, implicit resolution, physically based animation, real-time simulation
Temporal and spatial level of details for dynamic meshes BIBAFull-Text 77-84
  Ariel Shamir; Valerio Pascucci
Multi-resolution techniques enhance the ability of graphics and visual systems to overcome limitations in time, space and transmission costs. Numerous techniques have been presented which concentrate on creating level of detail models for static meshes. Time-dependent deformable meshes impose even greater difficulties on such systems. In this paper we describe a solution for using level of details for time dependent meshes. Our solution allows for both temporal and spatial level of details to be combined in an efficient manner. By separating low and high frequency temporal information, we gain the ability to create very fast coarse updates in the temporal dimension, which can be adaptively refined for greater details.
Real-time shadows for animated crowds in virtual cities BIBAKFull-Text 85-92
  Céline Loscos; Franco Tecchia; Yiorgos Chrysanthou
In this paper, we address the problem of shadow computation for large environments including thousands of dynamic objects. The method we propose is based on the assumption that the environment is 2.5D, which is often the case for virtual cities, thus avoiding complex visibility computation. We apply our method for virtual cities populated by thousands of walking humans, which we render with impostors, allowing real time simulation.
   In this paper, we treat the cases of shadows cast by buildings on humans, and by humans on the ground. To avoid 3D computation, we represent the shadows cast by buildings onto the environment with a 2.5D shadow map. When humans move, we quickly access the shadow information at the current location with a 2D grid. For each new position of a human, we compute its coverage by the shadow, and we render the shadow on top of the impostor with low cost using multi-texturing hardware. We also use the property of an impostor to display the shadow of humans on the ground plane, by projecting the impostor relatively to the light source.
   The method is currently limited to sharp shadows and a single light source. However approximations could be made to allow non-accurate soft-shadows. We show in the results that the computation of the shadows, as well as the display is done in real time, and that the method could be easily extended to real time moving light sources.
Keywords: dynamic shadows, multi-texturing, populated virtual cities, real time rendering, shadow computation

Display Devices

Life-sized projector-based dioramas BIBAKFull-Text 93-101
  Kok-Lim Low; Greg Welch; Anselmo Lastra; Henry Fuchs
We introduce an idea and some preliminary results for a new projector-based approach to re-creating real and imagined sites. Our goal is to achieve re-creations that are both visually and spatially realistic, providing a small number of relatively unencumbered users with a strong sense of immersion as they jointly walkaround the virtual site.
   Rather than using head-mounted or general-purpose projector-based displays, our idea builds on previous projector-based work on spatially-augmented reality and shader lamps. Using simple white building blocks we construct a static physical model that approximates the size, shape, and spatial arrangement of the site. We then project dynamic imagery onto the blocks, transforming the lifeless physical model into a visually faithful reproduction of the actual site. Some advantages of this approach include wide field-of-view imagery, real walking around the site, reduced sensitivity to tracking errors, reduced sensitivity to system latency, auto-stereoscopic vision, the natural addition of augmented virtuality and the provision of haptics.
   In addition to describing the major challenges to (and limitations of) this vision, in this paper we describe some short-term solutions and practical methods, and we present some proof-of-concept results.
Keywords: augmented virtuality, diorama, immersive visualization, multiprojector display system, shader lamp, spatially-augmented reality, user interface, virtual environment, virtual reality
Balance NAVE: a virtual reality facility for research and rehabilitation of balance disorders BIBAFull-Text 103-109
  Jeffrey Jacobson; Mark S. Redfern; Joseph M. Furman; Susan L. Whitney; Patrick J. Sparto; Jeffrey B. Wilson; Larry F. Hodges
We are currently developing an immersive virtual environment display for research into the rehabilitation of balance disorders, called the Balance NAVE (BNAVE). Using this system, the therapist can create varying degrees of sensory conflict and congruence in persons with balance disorders. With the capability of changing visual scenes based on the needs of the therapist, the BNAVE is a promising tool for rehabilitation. The system uses four PC's, three stereoscopic projectors, and three rear-projected screens, which surround the patient's entire horizontal field of view. The BNAVE can accommodate many types of sensors and actuators for a wide range of experiments.
Stereoscopic video system with embedded high spatial resolution images using two channels for transmission BIBAKFull-Text 111-118
  Takafumi Ienaga; Katsuya Matsunaga; Kazunori Shidoji; Kazuaki Goshi; Yuji Matsuki; Hiroki Nagata
Teleoperation requires both wide vision to recognize a whole workspace and fine vision to recognize the precise structure of objects which an operator wants to see. In order to achieve high operational efficiency in teleoperation, we have developed the Q stereoscopic video system which is constructed of four sets of video cameras and monitors. It requires four video channels to transmit video signals. However, four channels are not always available for a video system because of the limitation of the number of radio channels when multiple systems are used at the same time. Therefore we have tried to reduce the number of channels on this system by sending images from the right and left cameras alternately by field. In experiment 1, we compared the acuity of depth perception under three kinds of stereoscopic video systems, the original Q stereoscopic video system, the Q stereoscopic video system with two channel transmission, and the conventional stereoscopic video system. As the result of the experiment, the original Q stereoscopic video system enabled us to perceive depth most precisely, the Q stereoscopic video system with two channel transmission less so, and the conventional stereoscopic video system even less. In experiment 2, we compared the Q stereoscopic video system with two channel transmission to the original Q stereoscopic video system. The result showed that the operators were able to work more efficiently under the original Q stereoscopic video system than under the Q stereoscopic video system with two channel transmissions. In experiment 3, we compared the Q stereoscopic video system with two channel transmission to the conventional stereoscopic video system. It was found out in this study that the new stereoscopic video system we developed enabled operators to work more efficiently and to perceive depth more precisely than the conventional stereoscopic video system, although the number of channels for image transmission of this system was equal to that of the conventional stereoscopic video system.
Keywords: Q stereoscopic video system, compound image, operational efficiency, teleoperation, temporal resolution


Surround aesthetics: VR as an art form BIBAFull-Text 119
  Diane Gromala; Rebecca Allen
VR has been explored as an artistic medium from its early beginnings in the last century. It has drawn off various other forms, be these theatre or the panorama. What are the current aesthetics of VR? How has content matured, engaged and created a new sense of awe, beauty, social engagement. This is an opportunity to share their work with leading virtual reality artists from around the world.
Virtual reality and public spaces BIBFull-Text 119
  Doug MacLeod; Pierre Boulanger

Distributed Virtual Environments

Scalable data management using user-based caching and prefetching in distributed virtual environments BIBAKFull-Text 121-126
  Sungju Park; Dongman Lee; Mingyu Lim; Chansu Yu
For supporting real-time interaction in distributed virtual environments (DVEs), it is common to replicate virtual world data at clients from the server. For efficient replication, two schemes are used together in general -- prioritized transfer of objects and a caching and prefetching technique. Existing caching and prefetching approaches for DVEs exploit spatial relationship based on distances between a user and objects. However, spatial relationship fails to determine which types of objects are more important to an individual user, not reflecting user's interests. We propose a scalable data management scheme using user-based caching and prefetching exploiting the object's access priority generated from spatial distance and individual user's interest in objects in DVEs. We also further improve the cache hit rate by incorporating user's navigation behavior into the spatial relationship between a user and the objects in the cache. By combining the interest score and popularity score of an object with the spatial relationship, we improve the performance of caching and prefetching since the interaction locality between the user and objects are reflected in addition to spatial locality. The simulation results show that the proposed scheme outperforms the hit rate of existing caching and prefetching by 10% on average when the cache size is set to basic cache size, the size of expected number of objects included in the user's viewing range.
Keywords: DVEs, caching and prefetching, distributed virtual environments, scalable data management, user interest
Prediction-based concurrency control for a large scale networked virtual environment supporting various navigation speeds BIBAKFull-Text 127-134
  Eunhee Lee; Dongman Lee; Seunghyun Han; Soon J. Hyun
Shared sense of a virtual world is often enhanced by replicating the information at each user's site since replication provides acceptable interactive performance, especially when users are geographically distributed over large networks like the Internet. However, multiple concurrent updates may lead to inconsistent views among replicas. Therefore concurrency control is a key factor to maintaining a consistent state among replicas. We proposed a scalable prediction-based scheme in which an ownership request is multicasted to only the users surrounding a target entity. In our previous work, we assumed that all the users navigate a virtual world with a single speed. It, however, is quite common in a networked virtual environment like a network game that users are allowed to change their navigation speed as they interact with a virtual world for adding more realism. This paper proposes an enhancement to support users with various speeds. The enhanced scheme allows as many Entity Radii as the number of different speed and allocates a separate queue for users of each speed. Each queue is examined in parallel to predict the next owner candidate and among the selected candidates is chosen the final candidate, which has a minimum predicted collision time. It contributes to the timely advanced transfer of ownership by using appropriate Entity Radius based on a user's speed, fair granting of ownership by reducing the interference between users with different speed and latency, and high prediction accuracy by reducing the redundant ownership transfer.
Keywords: advance ownership request and transfer, concurrency control, prediction, entity radius, generality, scalability, various navigation speed
A hybrid motion prediction method for caching and prefetching in distributed virtual environments BIBAKFull-Text 135-142
  Addison Chan; Rynson W. H. Lau; Beatrice Ng
Although there are a few methods proposed for predicting 3D motion, most of these methods are primarily designed for predicting the motion of specific objects, by assuming certain object motion behaviors. We notice that in desktop distributed 3D applications, such as virtual walkthrough and computer games, the 2D mouse is still the most popular device being used as navigation input. Through studying the motion behavior of a mouse during 3D navigation, we propose a hybrid motion model for predicting the mouse motion during a 3D walkthrough. At low motion velocity, we use a linear model for prediction and at high motion velocity, we use an elliptic model for prediction. We describe how this prediction method can be integrated into our distributed virtual environment for object model caching and prefetching. We also demonstrate the effectiveness of the prediction method and the resulting caching and prefetching mechanisms through extensive experiments.
Keywords: 3D navigation, caching, distributed virtual environments, motion prediction, prefetching, virtual walkthrough


Situational visualization BIBAKFull-Text 143-150
  David M. Krum; William Ribarsky; Christopher D. Shaw; Larry F. Hodges; Nickolas Faust
In this paper, we introduce a new style of visualization called Situational Visualization, in which the user of a robust, mobile visualization system uses mobile computing resources to enhance the experience and understanding of the surrounding world. Additionally, a Situational Visualization system allows the user to add to the visualization and any underlying simulation by inputting the user's observations of the phenomena of interest, thus improving the quality of visualization for the user and for any other users that may be connected to the same database. Situational Visualization allows many users to collaborate on a common set of data with real-time acquisition and insertion of data. In this paper, we present a Situational Visualization system we are developing called Mobile VGIS, and present two sample applications of Situational Visualization.
Keywords: dynamic databases, location and time-specific user input, location-specific services, mobile users and collaborators, real-time acquisition and insertion of data, synchronized databases
Visualization of particle traces in virtual environments BIBAKFull-Text 151-157
  Falko Kuester; Ralph Bruckschen; Bernd Hamann; Kenneth I. Joy
Real-time visualization of particle traces in virtual environments can aid in the exploration and analysis of complex three dimensional vector fields. This paper introduces a scalable method suitable for the interactive visualization of large time-varying vector fields on commodity hardware. A real-time data streaming and visualization approach and its out-of-core scheme for the pre-processing and rendering of data are described. The presented approach yields low-latency application start-up times and small memory footprints. A proof of concept systems was implemented on a low-cost Linux workstation equipped with spatial tracking hardware, data gloves and shutter glasses. The system was used to implement a virtual wind tunnel in which a volumetric particle injector can introduce up to 60000 particles into the flow field while an interactive rendering performance of 60 frames per second is maintained.
Keywords: computational fluid dynamics, out-of-core visualization, particle tracing, scientific visualization, simulation, stereoscopic rendering, virtual reality, virtual wind tunnel
Is semitransparency useful for navigating virtual environments? BIBAKFull-Text 159-166
  Luca Chittaro; Ivan Scagnetto
A relevant issue for any Virtual Environment (VE) is the navigational support provided to users who are exploring it. Semitransparency is sometimes exploited as a means to see through occluding surfaces with the aim of improving user navigation abilities and awareness of the VE structure. Designers who make this choice assume that it is useful, especially in the case of VEs with many levels of occluding surfaces, e.g. virtual buildings or cities. This paper is devoted to investigate this assumption with a proper experimental evaluation on users. First, we discuss possible ways for improving navigation, and focus on implementation choices for semitransparency as a navigation aid. Then, we present and discuss the experimental evaluation we carried out. We compared subjects' performance in three conditions: local exploitation of semitransparency inside the VE, a more global exploitation provided by a bird's-eye-view, and a control condition where neither of the two features was available.
Keywords: evaluation, navigation aids, wayfinding


FreeDrawer: a free-form sketching system on the responsive workbench BIBAKFull-Text 167-174
  Gerold Wesche; Hans-Peter Seidel
A sketching system for spline-based free-form surfaces on the Responsive Workbench is presented. We propose 3D tools for curve drawing and deformation techniques for curves and surfaces, adapted to the needs of designers. The user directly draws curves in the virtual environment, using a tracked stylus as an input device. A curve network can be formed, describing the skeleton of a virtual model. The non-dominant hand positions and orients the model while the dominant hand uses the editing tools. The curves and the resulting skinning surfaces can interactively be deformed.
Keywords: 3D drawing, 3D sketching, 3D user interfaces, computer aided conceptual design, curve and surface deformations, immersive shape modeling, responsive workbench, variational modeling, virtual environments
VRID: a design model and methodology for developing virtual reality interfaces BIBAKFull-Text 175-182
  Vildan Tanriverdi; Robert J. K. Jacob
Compared to conventional interfaces, Virtual reality (VR) interfaces contain a richer variety and more complex types of objects, behaviors, interactions and communications. Therefore, designers of VR interfaces face significant conceptual and methodological challenges in: a) thinking comprehensively about the overall design of the VR interface; b) decomposing the design task into smaller, conceptually distinct, and easier tasks; and c) communicating the structure of the design to software developers. To help designers to deal with these challenges, we propose a Virtual Reality Interface Design (VRID) Model, and an associated VRID methodology.
Keywords: design methodology, design model, user interface software, virtual reality
Interactive content for presentations in virtual reality BIBAKFull-Text 183-189
  A. L. Fuhrmann; Jan Prikryl; Robert F. Tobler; Werner Purgathofer
In this paper, we develop concepts for presenting interactive content in form of a slideshow in a virtual environment, similar to conventional desktop presentation software. We demonstrate how traditional content like text and images can be integrated into 3D models and embedded applications to form a seamless presentation combining the advantages of traditional presentation methods with 3D interaction techniques and different 3D output devices. We demonstrate how different combinations of output devices can be used for presenter and audience, and discuss their various advantages.
Keywords: augmented reality, content representation, embedded applications, presentation, virtual reality