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VRST Tables of Contents: 979899000102030405060708091012131415

Proceedings of the 2008 ACM Symposium on Virtual Reality Software and Technology

Fullname:VRST'08 ACM Symposium on Virtual Reality Software and Technology
Editors:Steven Feiner; Daniel Thalmann; Pascal Guitton; Bernd Frölich; Ernst Kruijff; Martin Hachet; Anatole Lécuyer; Céline Loscos
Location:Bordeaux, France
Dates:2008-Oct-27 to 2008-Oct-29
Publisher:ACM
Standard No:ISBN: 1-59593-951-2, 978-1-59593-951-7; ACM Order Number: 537070; ACM DL: Table of Contents hcibib: VRST08
Papers:75
Pages:288
Links:Conference Home Page
  1. Keynotes
  2. Interaction techniques
  3. Input devices
  4. Physics and simulations
  5. Learning and training
  6. Systems
  7. Human-calibrated interaction
  8. Cognition
  9. Video acquisition
  10. Augmented reality
  11. Posters
  12. Demonstrations

Keynotes

In quest of realism and interactivity for virtual environments BIBAFull-Text 15
  Ming C. Lin
The realism of a computer simulated system for virtual environments often depends heavily on three main components: graphics, behavior, and sound. Thanks to four decades of research in modeling, rendering, and advances in VLSI technologies for graphics hardware, today's game systems are able to render near photorealistic images at interactive rates. To further increase the player's experience and immersion, the recent trend has been on introduction of physics-based simulation and behaviors. However, many computational challenges remain due to the simultaneous quest for sensory realism and performance requirements of these systems. Some of the key research issues include interactive motion synthesis of physically-plausible behavior of soft and articulated bodies, fast simulation of large-scale heterogeneous crowds, and real-time multi-sensory interaction. In this talk, I will present a few highlights of our recent efforts on addressing these problems. I will also demonstrate the results on several interactive applications, including cloth simulation for feature animation, sound rendering for computer games, 3D virtual painting for training and education, catheterization procedure for liver chemoembolization, and crowd simulation for virtual cityscapes. I will conclude by suggesting some research opportunities and applications.
Cognitive strategies for spatial memory of navigation: studies combining virtual reality and brain imaging BIBAFull-Text 16
  Alain Berthoz
This talk will deal with the neural basis of spatial memory during navigation. When navigating or trying to remember a traveled path the brain uses different cognitive strategies. It can use, among others, an egocentric, (topo-kinesthétic), memory of the travel involving kinaesthetic memories of the route and episodic memory, but it can also use allocentric, (topo-graphic), map like, memories. Different brain systems are involved in these strategies and they develop during ontogeny. I will describe studies using virtual reality in normal subjects and patient with hippocampal lesions. In addition I will describe results obtained with fMRI and intracranial recordings in epileptic patients which identify the brain areas involved in these strategies. Virtual reality allows us to selectively identify the brain areas involved in such tasks as perspective change, manipulation of reference frames, decision making and some aspects of social interaction such as empathy etc. The paradigms we have designed for these fundamental studies can also be used for diagnosis of these deficits in Schizophrenia, autism, and other psychiatric or neurological diseases. They could also be used for remediation in these diseases or others like agoraphobia. A new field is now opened in which neuroscientists, neurologists, psychiatrists, otolaryngologists and roboticians can cooperate to try to compensate for this category of deficits in patients, during development or aging.
Semantic modelling for virtual worlds a novel paradigm for realtime interactive systems? BIBAFull-Text 17-20
  Marc Erich Latoschik; Roland Blach
Engineering systems plays a central role in the development of successful Virtual Reality (VR) and Augmented Reality (AR) applications. Increasing computational resources are utilized to build increasingly complex artificial environments and extensive Human-Computer Interaction (HCI) systems. These types of Realtime Interactive Systems (RIS) establish a closed HCI loop. They are characterized as systems continuously analyzing users' input while concurrently synthesizing appropriate output for several of the human senses in real-time.

Interaction techniques

Advantages of velocity-based scaling for distant 3D manipulation BIBAKFull-Text 23-29
  Curtis Wilkes; Doug A. Bowman
Immersive virtual environments (VEs) have the potential to offer rich three-dimensional interaction to users. In many instances, however, 3D interaction tasks are difficult due to both the imprecision of tracking devices and the inability of users to achieve and maintain precise hand positions in 3D space. One way to improve upon existing interaction techniques is to dynamically change the sensitivity of the interaction technique based on user input. Previous research has applied this principle to virtual hand-based manipulation techniques; when the user slows down the movement of her physical hand, the virtual hand slows down even more to allow precise manipulation. In this study we extend the prior research by applying the velocity-based scaling principle to HOMER, an existing at-a-distance manipulation technique based on ray-casting. The scaled HOMER technique offers the user the freedom to accomplish both long- and short-distance manipulation tasks with higher levels of precision without compromising speed. We present results from a user study that shows that the addition of scaling to HOMER significantly improves user performance on 3D manipulation tasks.
Keywords: 3D interaction, usability, user studies
Video agent: interactive autonomous agents generated from real-world creatures BIBAKFull-Text 30-38
  Yoshifumi Kitamura; Rong Rong; Yoshinori Hirano; Kazuhiro Asai; Fumio Kishino
We present a novel approach for interactive multimedia content creation that establishes an interactive environment in cyberspace in which users interact with autonomous agents generated from video images of real-world creatures. Each agent has autonomy, personality traits, and behaviors that reflect the results of various interactions determined by an emotional model with fuzzy logic. After an agent's behavior is determined, a sequence of video images that best match the determined behavior is retrieved from the database in which a variety of video image sequences of the real creature's behaviors are stored. The retrieved images are successively displayed on the cyberspace to make it responsive. Thus the autonomous agent behaves continuously. In addition, an explicit sketch-based method directly initiate the reactive behavior of the agent without involving the emotional process. This paper describes the algorithm that establishes such an interactive system. First, an image processing algorithm to generate a video database is described. Then the process of behavior generation using emotional models and sketch-based instruction are introduced. Finally, two application examples are demonstrated: video agents with humans and goldfish.
Keywords: characters, computer animation, fuzzy logic, image processing, interactive multimedia content, video database
ACTIF: an interactor centric interaction framework BIBAKFull-Text 39-42
  Nicolai Hess; Jan D. S. Wischweh; Kirsten Albrecht; Kristopher J. Blom; Steffi Beckhaus
The design and implementation of interactions in 3D environments remains a challenge. This is especially true for novices. Mechanisms to support the creation of interaction have been developed, but they lack a central metaphor that fits the natural way in which developers conceptualize interaction techniques. In this paper, we introduce a new framework whose design mirrors the essence of interaction throughout the Virtual Reality spectrum, where the user is literally in the center. It also reflects the way in which interactions are actually understood and described, based on the interactor and her actions.
   Based on the central metaphor of the interactor, an implementation that is composed of three phases is developed. Those phases are: input retrieval and shaping, interpretation of user intentions, and execution of changes to the environment. Through these divisions, software requirements like composition and reusability of components are satisfied. The resultant system ACTIF, an ACTor centric Interaction Framework, structures interaction development in a meaningful and understandable way and at the same time eases the design and creation of new and experimental interactions.
Keywords: 3D user interfaces, user centered HCI, virtual reality
Overcoming eye-hand visibility mismatch in 3D pointing selection BIBAKFull-Text 43-46
  Ferran Argelaguet; Carlos Andujar; Ramon Trueba
Most pointing techniques for 3D selection on virtual environments rely on a ray originating at the user's hand whose direction is controlled by the hand orientation. In this paper we study the potential mismatch between visible objects (those which appear unoccluded from the user's eye position) and selectable objects (those which appear unoccluded from the user's hand position). We study the impact of such eye-hand visibility mismatch on selection performance, and propose a new technique for ray control which attempts to overcome this problem. We present an experiment to compare our ray control technique with classic raycasting in selection tasks with complex 3D scenes. Our user studies show promising results of our technique in terms of speed and accuracy.
Keywords: 3D selection, raycasting, virtual pointer
Navidget for immersive virtual environments BIBAKFull-Text 47-50
  Sebastian Knödel; Martin Hachet; Pascal Guitton
We present a novel interaction technique called Immersive Navidget for navigation in immersive virtual environments (VE), see Figure 1. This technique, based on Navidget, allows fast and easy 3D camera positioning from simple controls. In this paper, we focus on the technical issues that are induced by the VR setups and we propose solutions to adapt Navidget to the immersive context. We show that this new approach has many advantages for navigation in immersive VEs.
Keywords: interaction techniques, virtual reality

Input devices

HandNavigator: hands-on interaction for desktop virtual reality BIBAKFull-Text 53-60
  Paul G. Kry; Adeline Pihuit; Adrien Bernhardt; Marie-Paule Cani
This paper presents a novel interaction system, aimed at hands-on manipulation of digital models through natural hand gestures. Our system is composed of a new physical interaction device coupled with a simulated compliant virtual hand model. The physical interface consists of a SpaceNavigator, augmented with pressure sensors to detect directional forces applied by the user's fingertips. This information controls the position, orientation, and posture of the virtual hand in the same way that the SpaceNavigator uses measured forces to animate a virtual frame. In this manner, user control does not involve fatigue due to reaching gestures or holding a desired hand shape. During contact, the user has a realistic visual feedback in the form of plausible interactions between the virtual hand and its environment. Our device is well suited to any situation where hand gesture, contact, or manipulation tasks need to be performed in virtual. We demonstrate the device in several simple virtual worlds and evaluate it through a series of user studies.
Keywords: hands, interaction, virtual reality
Digital foam interaction techniques for 3D modeling BIBAKFull-Text 61-68
  Ross T. Smith; Bruce H. Thomas; Wayne Piekarski
Digital Foam is a new input sensor developed to support clay like sculpting and modeling operations. We present techniques facilitating navigation and manipulation operations performed using Spherical Digital Foam as a sole input device. Our free-form sculpting technique allows manipulation of new and existing 3D models using accumulated sculpting like motions. Digital Foam's multi-point pressure sensitive surface captures the separate locations of a user's fingertips allowing controlled manipulation of multiple model vertices simultaneously. Additionally, we developed a technique that allows the camera view and zoom to be controlled by applying varying pressure to the Digital Foam surface. Furthermore, we have designed a menu system tailored for operation using Spherical Digital Foam as a sole input device using both the internal orientation sensor and the pressure sensitive surface.
   A new higher resolution Spherical Digital Foam input device with 162 unique pressure sensors is presented. This is a significant improvement in comparison to the previous Spherical Digital Foam version with only 21 sensors. We discuss the design issues and how an increased resolution affects the operation and design of the algorithms used. We propose a new dynamic button allocation technique made possible using the new high resolution Spherical Digital Foam. Finally, we performed a trial study using the new 162 sensor Spherical Digital Foam input device to evaluate elements of the menu system.
Keywords: 3D input device, augmented reality, digital foam, interaction techniques, interactive modeling, virtual reality
CubTile: a multi-touch cubic interface BIBAKFull-Text 69-72
  Jean-Baptiste de la Rivière; Cédric Kervégant; Emmanuel Orvain; Nicolas Dittlo
On the one hand, multitouch tactile interfaces offer many advantages and are more and more widespread. Their use as 3D application interfaces are rather limited though, since they offer large horizontal flat projection surfaces that are not suited to many kinds of 3D operations. On the other hand, despite the many propositions that have been made over the past years, no single interface has proven to tackle the numerous specificities related to the 3D interaction constraints. Through the CubTile device proposal, our preliminary work tries to bring the strengths related to multitouch tactile surfaces into a device aimed at 3D interactions. Consisting in a medium-sized cube where 5 out of 6 sides are multitouch, our prototype senses several fingers, offers interaction redundancy and lets a user handle 3D manipulation thanks to single handed and bimanual input.
Keywords: input interface, interaction in 3D virtual environments, multi-touch, tactile
A rigid-body target design methodology for optical pose-tracking systems BIBAKFull-Text 73-76
  Thomas Pintaric; Hannes Kaufmann
The standard method for estimating the rigid-body motion of arbitrary interaction devices with an infrared-optical tracking system involves attaching pre-defined geometric constellations of retro-reflective or light-emitting markers, commonly referred to as "targets", to all tracked objects. Optical markers of the same type are typically indistinguishable from each other, requiring the tracking system to establish their identities through known spatial relationships. Consequently, the specific geometric arrangement of markers across multiple targets has a considerable impact on the system's overall performance and robustness.
   In this paper, we propose a simple new methodology for constructing optically tracked rigid-body targets. Our practically-oriented approach employs an optimization heuristic to compute near-optimal marker arrangements. Using prefabricated mounting fixtures, the assembly step requires only basic hobbyist tools and skills.
Keywords: 6-DOF pose-tracking, marker constellation, model-based object tracking, optical tracking, rigid body, target design

Physics and simulations

GPU techniques for creating visually diverse crowds in real-time BIBAKFull-Text 79-86
  R. Galvao; R. G. Laycock; A. M. Day
Real-time crowds significantly improve the realism of virtual environments, therefore their use has increased considerably over the last few years in a variety of applications, including real-time games and virtual tourism. However, due to current hardware limitations, crowd variety tends to be sacrificed in order for the crowd simulation to execute in real-time, which decreases the quality and realism of the crowd.
   Currently the little variety that is incorporated in real-time crowds tends to be applied by modulating each avatar with random colours, which has a detrimental effect on the texture quality. Furthermore, the existing crowd variety is often hard to define and control. To overcome these problems a set of techniques are presented, which defines and controls crowd variety, to further improve on current variety and quality of crowds. These techniques permit variety to be introduced: by changing the body mass via the application of a displacement map onto the mesh; by scaling the skeleton of the avatar; by applying HSV colour shifts to different parts of the avatar; and by transferring textures between avatar models. The appearance of the avatars under animation is also improved via the use of muscle displacement within the mesh. With the new techniques, the visual quality of the crowd is improved due to the increase in diversity.
Keywords: crowd, real-time, variety
Haptic simulations based on non-smooth dynamics for rigid-bodies BIBAKFull-Text 87-90
  Loïc Tching; Georges Dumont
In the context of virtual reality, haptic interfaces are coupled with simulations, which treat interactions between objects. To simulate contacts or impacts, we focus our attention on simulators based on dynamics for rigid models. In this article, we first propose a brief state of the art on closed-loop haptic interaction. Then, we discuss the use of non-smooth dynamics methods for interactive, haptic-based simulations. We finally present our research software, which proposes a haptic interface coupled with non-smooth dynamics algorithms.
Keywords: haptics, non-smooth dynamics, rigid-body simulations
A VR framework for interacting with molecular simulations BIBAKFull-Text 91-94
  Nicolas Férey; Olivier Delalande; Gilles Grasseau; Marc Baaden
Molecular Dynamics is nowadays routinely used to complement experimental studies and overcome some of their limitations. In particular, current experimental techniques do not allow to directly observe the full dynamics of a macromolecule at atomic detail. Molecular simulation provides time-dependent atomic positions, velocities and system energies according to biophysical models. Many molecular simulation engines can now compute a molecular dynamics trajectory of interesting biological systems in interactive time. This progress has lead to a new approach called interactive molecular dynamics. It allows to control and visualise a molecular simulation in progress. We have developed a generic library, called MDDriver, to facilitate the implementation of such interactive simulations. It allows to easily create a network between a molecular user interface and a physically-based simulation. We use this library in order to study an interesting biomolecular system, simulated by various interaction-enabled molecular engines and models. We use a classical molecular visualisation tool and a haptic device to control the dynamic behavior of the molecule. This approach provides encouraging results for interacting with a biomolecule and understanding its dynamics. Starting from this initial success, we decided to use VR functionalities more intensively, by designing a VR framework dedicated to immersive and interactive molecular simulations. This framework is based on MDDriver, on the visualisation toolkit VTK, and on the vtkVRPN library, which encapsulates the VRPN library into VTK.
Keywords: VRPN, VTK, haptic feedback, interactive molecular dynamics, scientific visualisation

Learning and training

SAILOR: a 3-D medical simulator of loco-regional anaesthesia based on desktop virtual reality and pseudo-haptic feedback BIBAKFull-Text 97-100
  Lazar Bibin; Anatole Lécuyer; Jean-Marie Burkhardt; Alain Delbos; Madeleine Bonnet
Anaesthesia is a medical act which eliminates the feeling of pain as well as the motor reactions of a person, before performing a surgical operation. Loco-Regional Anaesthesia (LRA) concerns only a part of the body such as the front arm or leg. This practice is increasingly used today notably because the patient can remain conscious and can recover more rapidly. However, LRA still remains a risky procedure. In this paper, we introduce a novel medical simulator called SAILOR for the training for LRA with neurostimulation. SAILOR is based on desktop virtual reality, realistic 3-D rendering and interactive techniques with a classical mouse and keyboard. It simulates the various biological phenomena which can occur during an anaesthesia procedure. We also introduce a novel pseudo-haptic effect to enhance the palpation of the virtual patient's body and feel the inner organs. The first feedback from users of the commercialized DVD version of SAILOR as well as the results of pilot tests suggest that this simulator is a very promising tool for education and training for LRA.
Keywords: desktop virtual reality, interactive technique, loco-regional anaesthesia, medical simulator, pseudo-haptic
A VR simulator for training and prototyping of telemanipulation of nanotubes BIBAKFull-Text 101-104
  Zhan Gao; Anatole Lécuyer
This paper describes a virtual reality (VR) simulator, for the purpose of education, training and prototyping of telemanipulation of carbon nanotubes. Major challenges in interfacing a human operator with tasks of manipulating nanotubes via a haptic VR interface are outlined. After a review of previous efforts, we present the current state of our VR simulator for nanotube manipulation. The collision detection, interaction force modeling, deformation simulation and haptic rendering of nanotubes are then discussed. Results of virtual manipulation of carbon nanotubes are presented within an immersive VR set-up.
Keywords: VR, nanotube, simulation, telemanipulation
A real-time simulator for interventional radiology BIBAKFull-Text 105-108
  Lindo Duratti; Fei Wang; Evren Samur; Hannes Bleuler
Interventional radiologists manipulate guidewires and catheters and steer stents through the patient's vascular system under X-ray imaging for treatment of vascular diseases. The complexity of these procedures makes training mandatory in order to master hand-eye coordination, instrument manipulation and procedure protocols for each radiologist. In this paper we present a simulator for interventional radiology, which deploys a model of guidewire/catheter based on the Cosserat theory applied to one-dimensional structures. This model starts from the energetic formulation of the flament considering the Hook laws of continuum mechanics. The Lagrange formulations are used to describe the model deformation. This model takes (self-) collisions into account and it is revealed to be very efficient for interactive applications. The simulation environment allows to carry out the most common procedures: guidewire and catheter navigation, contrast dye injection to visualize the vessels, balloon angioplasty and stent placement. Moreover, heartbeat as well as breathing are also simulated visually.
Keywords: Cosserat rod theory, X-ray, interventional radiology, minimally invasive surgery, real-time simulation
Scenario sharing in a collaborative virtual environment for training BIBAKFull-Text 109-112
  Stéphanie Gerbaud; Bruno Arnaldi
In this paper, we describe a system used in the context of virtual training on collaborative maintenance procedures where the focus is on the learning of the industrial procedure rather than technical gestures. In existing collaborative virtual environments for training the distribution of scenario actions among actors is fixed: only one role can be associated with a given scenario action. In this paper, we propose to overcome this limitation and to add a mechanism to deal with this new flexibility. This mechanism is able to dynamically select the best actor for an action, based on various criteria, and to propose a distribution of actions among actors. We also propose to add collaborative profiles to virtual humans to guide them in order to select the next action to perform, possibly following the distribution suggestion. Trainees and virtual humans can then adapt their activities while respecting the reference procedure.
Keywords: collaborative scenario, training, virtual environment

Systems

An image-warping VR-architecture: design, implementation and applications BIBAKFull-Text 115-122
  F. A. Smit; R. van Liere; B. Fröhlich
We describe an architecture that provides a programmable display layer in order to allow the execution of custom programs on consecutive display frames. This replaces the default display behavior of repeating application frames until an update is available. The architecture is implemented using a multi-GPU system. We will show three applications of the architecture typical to VR. First, smooth motion is provided by generating intermediate display frames by per-pixel depth-image warping using 3D motion fields. Smooth motion can be beneficial for walk-throughs of large scenes. Second, we implement fine-grained latency reduction at the display frame level using a synchronized prediction of simulation objects and the viewpoint. This improves the average quality and consistency of latency reduction. Third, a crosstalk reduction algorithm for consecutive display frames is implemented, which improves the quality of stereoscopic images.
Keywords: VR, crosstalk, image-warping, judder, latency, motion, stereoscopic display
A simple method for estimating the latency of interactive, real-time graphics simulations BIBAKFull-Text 123-129
  Anthony Steed
One of the critical determinants of the effectiveness and usability of interactive graphics simulations is the latency with which visual updates can be made based on input from interaction devices. High latency can diminish performance and can lead to simulator sickness. We demonstrate a new method for measuring latency using a standard video camera. The method is simple to configure, sensitive and rapid to use. This is in contrast to previous methods which required specialized equipment, were laborious or could only determine gross changes in latency. We attach a tracker to a pendulum and move a simulated image on the screen using the tracker positions. We video both the pendulum and simulated image together, and fit two sine curves, one to centre of motion of pendulum and one to the centre of motion of the simulated image. From the phase difference between these two sine curves we can determine latency changes significantly less than the frame rate of the camera. We demonstrate the method by comparing the latency of a two different systems for a CAVE™-like display.
Keywords: interactive systems, latency, performance, real-time graphics, system design
Radiometric compensation for a low-cost immersive projection system BIBAKFull-Text 130-133
  Julien Dehos; Eric Zeghers; Christophe Renaud; François Rousselle; Laurent Sarry
Catopsys is a low-cost projection system aiming at making mixed reality (virtual, augmented or diminished reality) affordable. It combines a videoprojector, a camera and a convex mirror and works in a non-specific room. This system displays an immersive environment by projecting an image onto the different parts of the room. However, the presence of an uncalibrated projector, heterogeneous materials and light inter-reflections influence the colors of the environment displayed in the room. Radiometric compensation of the projection process enables the system to reduce this problem.
   In this paper, we present our low-cost immersive projection system and propose a radiometric model and a compensation method which handle the projector response, surface materials and inter-reflections between surfaces. Our method works in two stages. First, the radiometric response of the projection process is evaluated. Then, this radiometric response is used to compensate the projection process in the desired environments.
Keywords: immersive projection, mixed reality, radiometric compensation, virtual reality
Using laser projectors for augmented reality BIBAKFull-Text 134-137
  Björn Schwerdtfeger; Daniel Pustka; Andreas Hofhauser; Gudrun Klinker
The paper explores the use of laser projectors as an alternative to head-mounted displays for Augmented Reality. We describe the development of an Augmented Reality Laser Projector and report on experiences setting up AR systems that use laser projectors, reasoning about several design criteria.
Keywords: augmented reality, industrial augmented reality, laser projector

Human-calibrated interaction

User boresight calibration precision for large-format head-up displays BIBAKFull-Text 141-148
  Magnus Axholt; Stephen Peterson; Stephen R. Ellis
The postural sway in 24 subjects performing a boresight calibration task on a large format head-up display is studied to estimate the impact of human limits on boresight calibration precision and ultimately on static registration errors. The dependent variables, accumulated sway path and omni-directional standard deviation, are analyzed for the calibration exercise and compared against control cases where subjects are quietly standing with eyes open and eyes closed. Findings show that postural stability significantly deteriorates during boresight calibration compared to when the subject is not occupied with a visual task. Analysis over time shows that the calibration error can be reduced by 39% if calibration measurements are recorded in a three second interval at approximately 15 seconds into the calibration session as opposed to an initial reading. Furthermore parameter optimization on experiment data suggests a Weibull distribution as a possible error description and estimation for omni-directional calibration precision. This paper extends previously published preliminary analyses and the conclusions are verified with experiment data that has been corrected for subject inverted pendulum compensatory head rotation by providing a better estimate of the position of the eye. With correction the statistical findings are reinforced.
Keywords: augmented reality, boresight, calibration, line of sight, postural sway
Analyses of human sensitivity to redirected walking BIBAFull-Text 149-156
  Frank Steinicke; Gerd Bruder; Jason Jerald; Harald Frenz; Markus Lappe
Redirected walking allows users to walk through large-scale immersive virtual environments (IVEs) while physically remaining in a reasonably small workspace by intentionally injecting scene motion into the IVE. In a constant stimuli experiment with a two-alternative-forced-choice task we have quantified how much humans can unknowingly be redirected on virtual paths which are different from the paths they actually walk. 18 subjects have been tested in four different experiments: (E1a) discrimination between virtual and physical rotation, (E1b) discrimination between two successive rotations, (E2) discrimination between virtual and physical translation, and discrimination of walking direction (E3a) without and (E3b) with start-up. In experiment E1a subjects performed rotations to which different gains have been applied, and then had to choose whether or not the visually perceived rotation was greater than the physical rotation. In experiment E1b subjects discriminated between two successive rotations where different gains have been applied to the physical rotation. In experiment E2 subjects chose if they thought that the physical walk was longer than the visually perceived scaled travel distance. In experiment E3a subjects walked a straight path in the IVE which was physically bent to the left or to the right, and they estimate the direction of the curvature. In experiment E3a the gain was applied immediately, whereas the gain was applied after a start-up of two meters in experiment E3b. Our results show that users can be turned physically about 68% more or 10% less than the perceived virtual rotation, distances can be up- or down-scaled by 22%, and users can be redirected on an circular arc with a radius greater than 24 meters while they believe they are walking straight.
A psychophysically calibrated controller for navigating through large environments in a limited free-walking space BIBAKFull-Text 157-164
  David Engel; Cristóbal Curio; Lili Tcheang; Betty Mohler; Heinrich H. Bülthoff
Experience indicates that the sense of presence in a virtual environment is enhanced when the participants are able to actively move through it. When exploring a virtual world by walking, the size of the model is usually limited by the size of the available tracking space. A promising way to overcome these limitations are motion compression techniques, which decouple the position in the real and virtual world by introducing imperceptible visual-proprioceptive conflicts. Such techniques usually precalculate the redirection factors, greatly reducing their robustness. We propose a novel way to determine the instantaneous rotational gains using a controller based on an optimization problem. We present a psychophysical study that measures the sensitivity of visual-proprioceptive conflicts during walking and use this to calibrate a real-time controller. We show the validity of our approach by allowing users to walk through virtual environments vastly larger than the tracking space.
Keywords: motion-compression, rotational gains, virtual reality

Cognition

The effect of self-embodiment on distance perception in immersive virtual environments BIBAKFull-Text 167-170
  Brian Ries; Victoria Interrante; Michael Kaeding; Lee Anderson
Previous research has shown that egocentric distance estimation suffers from compression in virtual environments when viewed through head mounted displays. Though many possible variables and factors have been investigated, the source of the compression is yet to be fully realized. Recent experiments have hinted in the direction of an unsatisfied feeling of presence being the cause. This paper investigates this presence hypothesis by exploring the benefit of providing self-embodiment to the user through the form of a virtual avatar, presenting an experiment comparing errors in egocentric distance perception through direct-blind walking between subjects with a virtual avatar and without. The result of this experiment finds a significant improvement with egocentric distance estimations for users equipped with a virtual avatar over those without.
Keywords: egocentric distance perception, immersive virtual environments, virtual avatar
Use of auditory cues for wayfinding assistance in virtual environment: music aids route decision BIBAKFull-Text 171-174
  Janki Dodiya; Vassil N. Alexandrov
This paper addresses the crucial problem of wayfinding assistance in the Virtual Environments (VEs). A number of navigation aids such as maps, agents, trails and acoustic landmarks are available to support the user for navigation in VEs, however it is evident that most of the aids are visually dominated. This work-in-progress describes a sound based approach that intends to assist the task of 'route decision' during navigation in a VE using music. Furthermore, with use of musical sounds it aims to reduce the cognitive load associated with other visually as well as physically dominated tasks. To achieve these goals, the approach exploits the benefits provided by music to ease and enhance the task of wayfinding, whilst making the user experience in the VE smooth and enjoyable.
Keywords: auditory navigation, sound and music perception, virtual environments, wayfinding aids
Use of virtual reality for spatial knowledge transfer: effects of passive/active exploration mode in simple and complex routes for three different recall tasks BIBAKFull-Text 175-178
  Grégory Wallet; Hélène Sauzéon; Jérôme Rodrigues; Bernard N'Kaoua
The use of virtual reality in the area of spatial cognition raises the question of the quality of learning transfer from a virtual to a real environment. Among the challenges, one is to determine the best cognitive aids to improve the quality of transfer and the conditions in which this is best achieved. The purpose of this study was to investigate the impact of passive and active exploration mode on quality of transfer in three different spatial recall tasks when the route was simple or complex.
   Ninety subjects (45 men and 45 women) participated in the experiment. Spatial learning was evaluated by 3 tasks: Wayfinding (route reproduction in reality), Sketch-mapping (free hand drawing) and Scene-classification (make a series of pictures in chronological order) in the context of the district of Bordeaux. In the Wayfinding task, active learning in a Virtual Environment (VE) increased performances compared to the passive learning condition, irrespective of the route complexity factor. In the Sketch-mapping task, active learning in a VE induced better performances than the passive condition, but only for complex routes. In the Picture classification task, no benefit was observed from active learning with both simple and complex routes. These results are discussed in terms of the functional demands of the three tasks and the route complexity dimension.
Keywords: exploration mode, knowledge transfer, recall tasks, route complexity, spatial cognition, virtual reality
Virtual reality as a tool for assessing episodic memory BIBAKFull-Text 179-182
  Gaën Plancher; Serge Nicolas; Pascale Piolino
The principal attraction of virtual reality is its potential to create experiments close to daily life with perfect experimental control. We performed an experiment in a virtual town in order to develop a better episodic memory assessment. We tested all components of episodic memory. Young and elderly adults participated in the virtual test: they were either in an active exploration or in a passive exploration of the town. The results showed that older persons recalled the spatiotemporal context and the details of the events in a lower proportion compared to younger ones regardless of the active or passive condition. But no difference was found between active and passive exploration in measures of episodic memory. Finally, correlations mainly appeared between memory complaint and virtual scores, but not with a classical verbal episodic memory test. The virtual test seems to allow a better assessment of episodic memory compared to classical studies, especially because of its components of spatiotemporal memory assessment. In conclusion, virtual reality appears to offer the possibility of developing neuropsychological tools closer to the daily life of patients.
Keywords: action, ageing, episodic memory, virtual reality

Video acquisition

Image-based texture replacement using multiview images BIBAKFull-Text 185-192
  Doron Tal; Ilan Shimshoni; Ayellet Tal
Augmented reality is concerned with combining real-world data, such as images, with artificial data. Texture replacement is one such task. It is the process of painting a new texture over an existing textured image patch, such that depth cues are maintained. This paper proposes a general and automatic approach for performing texture replacement, which is based on multiview stereo techniques that produce depth information at every pixel. The use of several images allows us to address the inherent limitation of previous studies, which are constrained to specific texture classes, such as textureless or near-regular textures. To be able to handle general textures, a modified dense correspondence estimation algorithm is designed and presented.
Keywords: multiview stereo, texture replacement
VirtualizeMe: interactive model reconstruction from stereo video streams BIBAKFull-Text 193-196
  Daniel Knoblauch; Falko Kuester
Tele-Immersion depends on face-to-face, viewpoint corrected, stereoscopic, virtual environments, allowing users to naturally interact with each other and the digital environment surrounding them, via realistic avatars. This paper presents an extraction, modeling and communication methodology for the creation of the needed avatars, based on a scalable focused disparity map (FDM) approach. The FDM enables variable distance reconstruction of dynamic target objects despite restrictions in disparity range. Combined with a pixel-based disparity cost interpolation, a sub-pixel disparity refinement is achieved, providing a high depth-resolution and smooth reconstruction of the target objects. This technique approaches real-time characteristics, extracting avatar models and communicating them to remote render nodes at 15 frames per second.
Keywords: 3D from video, background extraction, disparity maps, point cloud streaming, tele-immersion
Feature points based facial animation retargeting BIBAKFull-Text 197-200
  Ludovic Dutreve; Alexandre Meyer; Saïda Bouakaz
We present a method for transferring facial animation in real-time. The source animation may be an existing 3D animation or 2D data providing by a video tracker or a motion capture system. Based on two sets of feature points manually selected on the source and target faces (the only manual work required), a RBF network is trained and provides a geometric transformation between the two faces. At each frame, the RBF transformation is applied on the new feature points positions of the source face, resulting in new positions for target feature points according with the expression of the source face and the morphology of the target face. According to their displacements along time, we deform the target mesh on the GPU with the linear blend skinning (LBS) method. In order to make our approach attractive to novice user, we propose a procedural technique to automatically rig the target face by generating vertices weights for the skinning deformation. To summarize, our method provides interactive expression transfer with a minimal human intervention during setup and accepts various kind of animation sources.
Keywords: facial animation, performance-driven facial animation, retargeting, skeleton-subspace deformation
A novel method based on color information for scanned data alignment BIBAKFull-Text 201-204
  Shen Yang; Yue Qi; Fei Hou; Xukun Shen; Qinping Zhao
This paper presents a rapid and robust method to align large sets of range scans captured by a 3D scanner automatically. The method incorporates the color information from the range data into the pairwise registration. Firstly, it detects the features using SIFT (Scale-Invariant Feature Transform) on grayscale images generated from two range scans to align. Then a quasi-dense matching algorithm, based on the match propagation principle, is applied to specify the matching pixel pairs between two images. All matches obtained are mapped to 3D space but in different world coordinates, and filtered by the 3D geometry constraint discovered from the range data. The remaining set of point correspondences is used to estimate the rigid transformation. Finally, a modified ICP (Iterative Closest Point) algorithm is applied to refine the result. The paper also describes a framework to use this alignment method for object reconstruction. The reconstruction proceeds by acquiring several range scans with color information from different directions, following which pair-wise of range data are aligned with the above method selectively and iteratively. Then a model graph containing the correct pair-wise matches is created and a span tree specifying a complete model is constructed. Finally a global optimization is performed to refine the result. This reconstruction technique achieves a robust and high performance in the application of rebuilding the 3D models of culture heritages for virtual museum automatically.
Keywords: 3D scanning, automatic registration, coarse registration, multi-view registration
Segmented gesture recognition for controlling character animation BIBAKFull-Text 205-208
  En-Wei Huang; Li-Chen Fu
In this paper, we propose a method which uses vision-based gesture recognition to control character animation. Each animation sequence has a corresponding gesture to be recognized, and we focus on upper-body motions and use one camera to capture images. Human gestures are modeled by a learned graph model whose nodes are key frames of these gestures. The animation sequences are pre-processed to generate a motion graph, and the mapping between the gesture model and the animation motion graph is created. At run time, the recognized node sequence in the gesture model will guide the animation to traverse the animation motion graph. Our method avoids complex process of completely reconstructing the human motion and still holds the advantages such as being intuitive, quickly responsive and versatile. The proposed method can be applied to control avatar actions in a large virtual environment. Our experiments show that the segmented gesture recognition can robustly control the animation with quick response even there are ambiguities in the initial poses of some gestures.
Keywords: character animation, interactive control

Augmented reality

Opportunistic controls: leveraging natural affordances as tangible user interfaces for augmented reality BIBAKFull-Text 211-218
  Steven J. Henderson; Steven Feiner
We present Opportunistic Controls, a class of user interaction techniques for augmented reality (AR) applications that support gesturing on, and receiving feedback from, otherwise unused affordances already present in the domain environment. Opportunistic Controls leverage characteristics of these affordances to provide passive haptics that ease gesture input, simplify gesture recognition, and provide tangible feedback to the user. 3D widgets are tightly coupled with affordances to provide visual feedback and hints about the functionality of the control. For example, a set of buttons is mapped to existing tactile features on domain objects. We describe examples of Opportunistic Controls that we have designed and implemented using optical marker tracking, combined with appearance-based gesture recognition. We present the results of a user study in which participants performed a simulated maintenance inspection of an aircraft engine using a set of virtual buttons implemented both as Opportunistic Controls and using simpler passive haptics. Opportunistic Controls allowed participants to complete their tasks significantly faster and were preferred over the baseline technique.
Keywords: 3D interaction, augmented reality, selection metaphor, tangible user interfaces
Detection of moving objects and cast shadows using a spherical vision camera for outdoor mixed reality BIBAKFull-Text 219-222
  Tetsuya Kakuta; Lu Boun Vinh; Rei Kawakami; Takeshi Oishi; Katsushi Ikeuchi
This paper presents a method to detect moving objects and remove their shadows for superimposing them on Mixed Reality (MR) systems. We cut out the foreground from a real image using a probability-based segmentation method. Using color, spatial, and temporal priors, we can improve the accuracy of the segmentation. Energy minimization is executed by graph cuts. Then we remove the shadow region from the foreground with F-value calculated from the pixel value and the spectral sensitivity characteristic of the camera. Finally we superimpose virtual objects using the stencil buffer, which is used to limit the area of rendering for each pixel. Synthesized images of an outdoor scene show the efficiency of the proposed method.
Keywords: augmented reality, foreground extraction, mixed reality, shadow removal
Napkin sketch: handheld mixed reality 3D sketching BIBAKFull-Text 223-226
  Min Xin; Ehud Sharlin; Mario Costa Sousa
This paper describes, Napkin Sketch, a 3D sketching interface which attempts to support sketch-based artistic expression in 3D, mimicking some of the qualities of conventional sketching media and tools both in terms of physical properties and interaction experience. A portable tablet PC is used as the sketching platform, and handheld mixed reality techniques are employed to allow 3D sketches to be created on top of a physical napkin. Intuitive manipulation and navigation within the 3D design space is achieved by visually tracking the tablet PC with a camera and mixed reality markers. For artistic expression using sketch input, we improve upon the projective 3D sketching approach with a one stroke sketch plane definition technique. This coupled with the hardware setup produces a natural and fluid sketching experience.
Keywords: 3D design, mixed reality, sketch-based design
Mutual occlusions on table-top displays in mixed reality applications BIBAKFull-Text 227-230
  Daniel Kurz; Kiyoshi Kiyokawa; Haruo Takemura
This paper describes an approach to dealing with mutual occlusions between virtual and real objects on a table-top display. Display tables use stereoscopy to make virtual content appear to exist in 3 dimensions on or above a table top. The actual image, however, lies on the physical plane of the display table. Any real physical object introduced above this plane therefore obstructs our view of the display surface and disrupts the illusion of the virtual scene. The occlusions result between real objects and the display surface, not between real objects and virtual objects. For the same reason virtual objects cannot occlude real ones. Our approach uses an additional projector located near the user's head to project those parts of virtual objects that should occlude real ones directly onto the real objects. We describe possible applications and limitations of the approach and its current implementation. Despite its limitations, we believe that the proposed approach can significantly improve interaction quality and performance for mixed reality scenarios.
Keywords: mixed reality, mutual occlusions, table-top displays
Watercolor inspired non-photorealistic rendering for augmented reality BIBAKFull-Text 231-234
  Jiajian Chen; Greg Turk; Blair MacIntyre
Non-photorealistic rendering (NPR) is an attractive approach for seamlessly blending virtual and physical content in Augmented Reality (AR) applications. Simple NRP techniques, that use information from a single rendered image, have been demonstrated in real-time AR systems. More complex NRP techniques require visual coherence across multiple frames of video, and typical offline algorithms are expensive and/or require global knowledge of the video sequence. To use such techniques in real-time AR, fast algorithms must be developed that do not require information past the currently rendered frame. This paper presents a watercolor-like NPR style for AR applications with some degree of visual coherence.
Keywords: Voronoi diagrams, augmented reality (AR), non-photorealistic rendering (NPR)

Posters

A framework for scalable virtual worlds using spatially organized P2P networks BIBAKFull-Text 237-238
  Romain Cavagna; Maha Abdallah; Christian Bouville
The general craze for virtual environments, the potential of augmented reality applications and the announced revolution of the Internet world (Web 2.0, Web 3D.0) are key points for the emergence of an 'ambient' Web which will make it possible for users to communicate, collaborate, entertain, work and exchange content. In this context, content storage, delivery, and reproduction are among the essential points for the deployment of a highly scalable platform of wide reality. In this paper, we propose a self-scalable peer-to-peer architecture for the navigation in network-based virtual worlds. To reach this goal, we propose a fully distributed and adaptive streaming method that quickly adapts the reproduced content according to user interaction. Our content delivery strategy has been implemented and tested on a dedicated simulator with a large 3D city model.
Keywords: peer-to-peer, self-adaptation, self-distribution, self-repartition, self-scalabity, virtual environments
Gesture recognition in flow based on PCA and using multiagent system BIBAKFull-Text 239-240
  Ronan Billon; Alexis Nédélec; Jacques Tisseau
In our context of Virtual Theater, a virtual actor performs with a real actor. They communicate through movements and choreography. The system has to interpret the real actor's gesture into a symbolic representation. Therefore, we present a method for real-time recognition. We use properties from Principal Component Analysis (PCA) to create signature for each gesture and a multiagent system to perform the recognition.
Keywords: gesture recognition, motion-capture, synthetic actor, virtual theatre
Clutter-aware adaptive projection inside a dynamic environment BIBAKFull-Text 241-242
  Thitirat Siriborvornratanakul; Masanori Sugimoto
This paper presents a framework for a computationally adaptive projection metaphor using a handheld projector inside a dynamic cluttered environment. In addition to conventional self-correcting projection features, the framework uses multiple clutter tracking and adaptive target generation to define the clutter-aware target area for projection in a reliable manner. Using a paired projector-camera system, the framework first builds high spatial frequency feature maps using a Laplacian pyramid approach. The feature maps are then passed to a rejection step to eliminate spurious features caused by contents of the projected image. After the resulting features representing clutters are processed by the appropriated design tracker, the target area for projection is generated. Finally, the desired information for projection is rendered and sent back to the projector. The framework can be used effectively for a clutter-aware handheld projector-based system without the need for a complex hardware setup or with any prior need to clean up the environment.
Keywords: adaptive projection, clutter-aware, handheld projector, laplacian pyramids, multiple target tracking, particle filters
A hybrid approach towards fully automatic 3D marker tracking BIBAKFull-Text 243-244
  Matthias Weber
Motion Capture is a powerful approach to track 3D position, usually utilizing markers. Especially passive markers do not hinder natural motion. Unfortunately, such systems do not provide any information about which anatomical landmark their markers belong to. Multiple manual actions are often required to guide the tracking process. This work presents a hybrid approach for nearly fully automatic identification and tracking of such markers. It encompasses three methods for identification, using PCA-based alignment or tree-based optimization, and tracking, using a neural network with self-organizing characteristics.
Keywords: hybrid tracking, motion capture, neural networks
Development and evaluation of a virtual reality simulator for training of thyroid gland nodules needle biopsy BIBAKFull-Text 245-246
  Ilana de Almeida Souza; Claudiney, Jr. Sanches; Marcia N. S. Kondo; Marcelo Knorich Zuffo
The fine needle biopsy is an important procedure for investigations in tumors, low-cost considered, minimally invasive and ideal for supplying an accurate diagnosis in cases of thyroid gland nodules. This work investigated the possibility of the development of a virtual reality simulator for the training of the ultrasound guided needle biopsy of thyroid gland nodules, using 3D models and haptic devices. The developed system is also an educative tool, because besides practicing the procedure, the user can visualize a thyroid 3D model and touch it to feel its texture, as well as rotate a complete model of the neck with transparancy in order to study all its internal organs.
Keywords: medical simulation, needle biopsy, thyroid gland, virtual reality
Software platform for real-time room acoustic visualization BIBAKFull-Text 247-248
  Rami Ajaj; Lauri Savioja; Christian Jacquemin
This paper presents a novel platform for interactive virtual room acoustics simulation and visualization. The platform is based on two autonomous modules: EVERTims for acoustic simulation and Audio2graphical for graphical rendering and interaction management. The system is a tool for acousticians and architects to understand better the acoustic properties of a closed space. Beside visualizing sound reflections, it allows navigation as well as geometrical properties modification of a given sound source and a listener.
Keywords: 3D visualization, real-time audio beam-tracing, room acoustic
On the hybrid aid-localization for outdoor augmented reality applications BIBAKFull-Text 249-250
  I. M. Zendjebil; F. Ababsa; J-Y. Didier; M. Mallem
In mobile outdoor augmented reality applications, accurate localization is critical to register virtual augmentations over a real scene. Vision-based approaches provide accurate localization estimates but are still too sensitive to outdoor conditions (brightness changes, occlusions, etc.). This drawback can be overcome by adding other types of sensors. In this work, we combine a GPS and an inertial sensor with a camera to provide accurate localization. We will present the calibration process and we will discuss how to quantify the 3D localization accuracy. Experimental results on real data are presented.
Keywords: 3D localization, calibration, error prediction, hybrid sensor, outdoor augmented reality
FlowVR-VRPN: first experiments of a VRPN/FlowVR coupling BIBAKFull-Text 251-252
  Sébastien Limet; Sophie Robert
This paper describes a generic coupling between the middleware FlowVR designed to develop modular VR applications for distributed architectures like PC clusters and VRPN which is a library that manages a large number of physical devices. This generic coupling takes the advantages of the FlowVR programming model to provide all the services offered by VRPN in FlowVR applications.
Keywords: VR system, interaction, middleware
MRPipeline: a module based architecture for self adaptive mixed reality applications BIBAKFull-Text 253-254
  Christian Reimann; Florian Klompmaker; Holger Santelmann
This paper introduces MRPipeline -- a module based, configurable and self adaptive approach for developing Mixed Reality applications. This work describes how our system can be configured and used for application creation by defining replaceable modules via XML. Each module has parameters that may be manipulated during run time. Self adaptation is applied by permanently measuring, evaluating and optimising the output of the whole system. We therefore created measurement methods, evaluation functions and optimisation algorithms that especially focus on the requirements for mobile Mixed Reality applications.
Keywords: augmented reality, mixed reality, self adaptation
Hand's 3D movement detection with one handheld camera BIBAKFull-Text 255-256
  Mingming Fan; Liang Zhang; Yuanchun Shi
This paper presents a scheme to create a real-time and reliable method for recognizing vision-based hand's 3D movement and to use the movement parameters for controlling 3D objects. The algorithm for 3D movement detection is totally based on analyzing feature points from the only camera in user's hand. As the algorithm is based on frames captured from one camera in untrained environment, it's difficult to distinguish similar movements on optical flow images, especially between shifting and rotating. A novel differentiation algorithm by voting from some weak classifiers is used. The algorithm provides a method of direct mapping user's hand movement to object control. We design an application of controlling a virtual 3D cube's movement and estimate the accuracy of the algorithm. And the experiments' result presents that the 3D movement detection algorithm is efficient and robust enough for real-time interaction.
Keywords: 3D movement, classifiers, features points, handheld camera, virtual interaction
Wind turbines' landscape: using virtual reality for the assessment of multisensory perception in motion BIBAKFull-Text 257-258
  Jihen Jallouli; Guillaume Moreau; Ronan Querrec
Wind turbines (WT) are socially controversial because of their visual and acoustic impacts on landscape. Virtual reality (VR) is here proposed -- thanks to immersion and interaction potentialities -- as an immersive and multisensory approach in order to assess WT impacts. For that, a comparison between a real park and the same virtual one is needed to evaluate VR for landscape impacts restitution. The parks are evaluated using an urban path-based method (perception in motion): the real walking is simulated by a Wiimote in vitro. The results, while very similar to the in situ study show the limits of the lack of free motion.
Keywords: impacts, landscape, motion, perception, wind turbines
Multimodal prop-based interaction with virtual mock-up: CAD model integration and human performance evaluation BIBAKFull-Text 259-260
  Damien Chamaret; Paul Richard
This paper presents a methodology for the efficient integration of CAD models in a physical-based virtual reality simulation that provides the user with multi-modal feedback. User interacts with virtual mock-up using a string-based haptic interface. Hand tracking is realized using a motion capture system. Stereoscopic images are displayed on a 2m x 2.5m retro-projected screen and viewed using polarized glasses. The proposed methodology implemented in a low-cost system, has been validated through an experimental study. Six participants were instructed to remove a car lamp from the virtual mockup and replace it in correct position. A prop was used to provide local haptic sensation related to the car lamp. Three experimental conditions were tested concerning sensory feedback from collisions: (1) no feedback (graphics only), (2) visual feedback and (3) haptic feedback. Results show that visual and haptic feedback allowed to increase performance, as compared with the open-loop case (no feedback), by respectively 17.8% and 35.2%.
Keywords: CAD model, human-scale haptics, multimodality, virtual mock-up, virtual reality
VRPN and Qwerk: fast MR device prototyping and testing BIBAKFull-Text 261-262
  Camilo A. Perez; Pablo Figueroa
We present a platform that offers designers flexibility on device design, fast prototyping, and integration of new devices to a mixed reality infrastructure. Our solution is based on the integration of a commercial embedded system, the Qwerk, and the Virtual Reality Peripheral Network (VRPN), a network-transparent interface between applications and typical virtual reality (VR) devices. This solution creates a hardware and software layer between new devices and VR applications that facilitate development. We show here a design process for new MR devices. With our hardware and software layer we allow designers concentrate more in the interaction rather than the way sensors are connected. To test our design process and our platform we implement three simple examples.
Keywords: augmented reality, embedded system, prototyping, virtual reality
Multi-touch gestural interaction in X3D using hidden Markov models BIBAKFull-Text 263-264
  Sabine Webel; Jens Keil; Michael Zoellner
Multi-touch interaction on tabletop displays is a very active field of todays HCI research. However, most publications still focus on tracking techniques or develop gesture configurations for a specific application setup using a small set of simple gestures. In this work we present a new approach to easily set up the recognition of even complex gestures for multi-touch applications. Our gesture recognition module is based on Hidden Markov Models, which offer a robust recognition of multiple gestures in real-time. An X3D interface of the recognition module is provided to qualify designers and other non-programmers to apply gesture recognition functionalities to multi-touch applications in an easy and straightforward manner.
Keywords: X3D, gesture recognition, multi-touch, multi-user, tabletop interaction
Identification judgment of self-viewpoint movie BIBAKFull-Text 265-266
  T. Kayahara
Does self-viewpoint "life-log" movie taken by a CCD camera at a person's forehead contain any cue information by which one can identify his/her own movie from others? In particular, do dynamic and non-episodic aspects of the self-viewpoint movie (scene shake by walking) make it possible to distinguish "my" movie from others? To examine this question, subjects were asked to distinguish a movie taken by a CCD camera placed at their forehead and body from a movie taken at the head and body of others. Before experiment, all subjects walked through a gymnasium whose visual condition was kept constant between subjects to take a movie of subjects' viewpoint as experimental stimuli. Any episodic visual event was eliminated from the content of the movie. The rate of correct judgment of distinguishing the movie from "my" viewpoint from others was examined with 2IFC procedure and was significantly higher than that of control condition in which subjects' judgment were executed with still image, suggesting that self-viewpoint movie might contain some non-episodic ID information.
Keywords: identification judgment, self-viewpoint movie, wearable computing
Size estimation in product visualization using augmented reality BIBAKFull-Text 267-268
  Alberto Gómez; Pablo Figueroa
This paper describes an experiment on how AR-based product visualization has an impact on product size selection, compared to traditional techniques in sales. Our study suggests that the use of our AR system is preferred in comparison to using a tape measure and a printed catalog with size information. We also found that users had difficulty in the selection of adequately sized models when the space to be filled is large, both with our catalog and our AR based solution.
Keywords: ARToolKit, augmented reality, user interfaces, user studies on size estimation
SqueezeOrb: a low-cost pressure-sensitive user input device BIBAKFull-Text 269-270
  Thomas Pintaric; Thomas Kment; Wolfgang Spreicer
This paper introduces a new low-cost pressure-sensitive user input device called "SqueezeOrb". The device is built from an assembly force-sensing resistors embedded in an elastic hand exerciser. A USB-enabled microcontroller continuously samples the sensors, applies a double-exponential noise-reduction filter and streams the resulting "handgrip strength" measurement to an attached host computer at a frequency of up to 1000 Hz. When combined with optical motion-tracking, the SqueezeOrb becomes a pressure-sensing input device for three-dimensional interaction.
Keywords: force sensor, handgrip measurement, haptic monitoring, pressure-sensitive input device
Compared distortion effects between real and virtual ophthalmic lenses with a simulator BIBAKFull-Text 271-272
  Gildas Marin; Edith Terrenoire; Martha Hernandez
In this study we have compared the subjective effect of distortions simulated ophthalmic lenses in a virtual lens simulator to the equivalent real ophthalmic test lenses, in static monocular and dynamic, monocular and binocular conditions, taking care of matching as best as possible virtual and real conditions. Though visual perception was found to be similar in static condition, distortions were judged to be exaggerated by the virtual lenses in dynamic conditions.
Keywords: distortion, ophthalmic simulator, subjective comparison, subjective perception, virtual reality
Real-time rendering of solvent-accessible surfaces for molecular models BIBAKFull-Text 273-274
  Jun Lee; Sungjun Park; Youngjin Choi; Hyung Seok Kim; Jee-In Kim
In molecular modeling, it is quite useful to exercise real-time rendering of solvent-accessible surfaces for three dimensional models. The real-time rendering helps researchers in analyzing three dimensional structures and behaviors of molecular simulations. The researchers can determine whether critical parts of molecular models are correctly visualized and properly combined at right locations. However, it is quite difficult to render solvent-accessible surfaces in real-time using conventional molecular modeling tools. It is because the surfaces are visualized as isosurfaces which express chemical information and three dimensional positions. In this paper, we propose a method which facilitates real-time rendering of solvent-accessible surfaces for three dimensional molecular models. We evaluated real-time interactivity of our method with molecular models. Therefore, researchers can observe and manipulate solvent-accessible surfaces of three dimensional molecular models in real-time.
Keywords: animation, metaballs, solvent-accessible surface
A movable-screen immersive projection display BIBAKFull-Text 275-276
  Yuichi Tamura; Hiroaki Nakamura; Atsushi Ito
We propose a new room-sized immersive projection display. The display consists of a cylindrical screen that can be moved horizontally and vertically, allowing the user to easily change his/her field of view by moving the screen to any angle. The angle of the screen is measured by a motion sensor, and the projected stereo images are changed in response to the measured angle.
   With this cylindrical screen system, it is necessary to project a distorted image onto the screen to produce a correct image. We make the distorted image using a multi-pass rendering method. In addition, a magnetic sensor measures the position and angle of the user and the screen images are changed if the user moves.
Keywords: 3D display, immersive projection display, virtual reality, visualization
An attempt of real-time CG control with multi-touch devices BIBAKFull-Text 277-278
  Asako Soga; Masahito Shiba; Tetsuya Kawamoto
We have been developing real-time CG control systems with Lemurs, which are multi-touch devices. We have developed two prototype systems that control CG objects and animation and a practical system that supports creating of TV contents. Our system, which provides an easy and intuitive way to control two or more parameters simultaneously, allows users to control such complicated data as real-time CG contents. We verified that the system can be used in actual broadcasting.
Keywords: CG control, multi-touch, user interface
AVACHAT: a new comic-based chat system for virtual avatars BIBAKFull-Text 279-280
  Soo-Hyun Park; Seung-Hyun Ji; Dong-Sung Ryu; Hwan-Gue Cho
We propose AVACHAT, a new comic-stylized communication interface for avatar agents. We show that the 3-D word balloon could be successfully exploited to depict chat dialogues and the atmosphere of groups talking, such as cheerful laughing or loud quarrelling without adding any multimedia functions. Finally, we propose a new data structure to manage the chat dialogues among virtual avatars. It can be used to reconstruct the social-graph for chat agents in a virtual world.
Keywords: chat communication, stylized comics, virtual avatar
Cross-modal information display to improve driving performance BIBAKFull-Text 281-282
  Shin'ichi Onimaru; Taro Uraoka; Naoyuki Matsuzaki; Michiteru Kitazaki
We developed a driving simulator with visual and/or auditory information display to enhance the perception of lateral position of the driving car in real-time. The purpose of this study was to test effects of the cross-modal assistance information on the driving performance. We found the discrete visual assistance improved the driving accuracy, but increased the driving load. For auditory and audio-visual assistances, the continuous information improved the accuracy without increasing the load. Thus, the cross-modal information is useful for assisting and improving driver's performance with fewer loads.
Keywords: auditory perception, cross-modal information, driving simulator, steering control, vision
Force model for CAD selection BIBAKFull-Text 283-284
  F. Picon; M. Ammi; P. Bourdot
In this paper we investigate attraction techniques, using the haptic modality, for CAD applications. An important issue in CAD systems is the modification of the Boundary Representation (B-Rep) of 3D objects. However, this fundamental task is possible only if a geometric element (vertex, edge, face) has already been selected. This paper focuses on a generic force feedback model of haptic attraction for CAD applications. Our model is flexible and allows the experimentation of several behaviours. Several evaluation studies are carried out to compare the impact of the model parameters on the user performance and comfort of use.
Keywords: CAD-VR integration, haptic attraction
Comparing disparity based label segregation in augmented and virtual reality BIBAKFull-Text 285-286
  Stephen D. Peterson; Magnus Axholt; Stephen R. Ellis
Recent work has shown that overlapping labels in far-field AR environments can be successfully segregated by remapping them to predefined stereoscopic depth layers. User performance was found to be optimal when setting the interlayer disparity to 5-10 arcmin. The current paper investigates to what extent this label segregation technique, label layering, is affected by important perceptual defects in AR such as registration errors and mismatches in accommodation, visual resolution and contrast. A virtual environment matched to a corresponding AR condition but lacking these problems showed a reduction in average response time by 10%. However, the performance pattern for different label layering parameters was not significantly different in the AR and VR environments, showing robustness of this label segregation technique against such perceptual issues.
Keywords: label placement, mixed reality, stereoscopic displays, user interfaces, visual clutter
A surround interface using the Wii controller with multiple sensor bars BIBAKFull-Text 287-288
  Torben Schou; Henry J. Gardner
A previous paper [Schou and Gardner 2007] has described a project to port a games engine into a two-walled Immersive Projection Theatre (IPT) and to interact with that environment using the Nintendo "Wii" Remote[Nintendo 2008]. In the present work, we update this project to describe how Wii controllers have now been demonstrated to work with a custom-built, multiple "Sensor Bar" array to achieve a greater coverage of the IPT.
Keywords: Wii remote, game engine, immersive projection theatre, sensor bar, virtual reality
Using the Wii Balance Board as a low-cost VR interaction device BIBAKFull-Text 289-290
  Gerwin de Haan; Eric J. Griffith; Frits H. Post
We demonstrate the use of the Wii Balance Board™ as a low-cost virtual reality input device. We provide an overview of obtaining and working with the sensor input. By processing the sensor values from the balance board, we are able to use it for both discrete and continuous input, which can be used to drive a variety of VR interaction metaphors. Using continuous input, the balance board is well suited for interactions requiring two simultaneous degrees of freedom and up to three total degrees of freedom, such as navigation or rotation. The discrete input is suitable for control input, such as mode switching or object selection.
Keywords: balance board, input devices, virtual reality
Alternative online extrinsic calibration techniques for minimally invasive surgery BIBAKFull-Text 291-292
  Arun Kumar Raj Voruganti; Dirk Bartz
One of the main challenges in external optical tracking device based augmented reality (AR) is the extrinsic calibration. Such an example is calibration of the endoscope camera with the tracking device to estimate the transformation between the endoscope-mounted marker and endoscope sensor. In this paper, we describe two alternative techniques to the Hand-Eye method for online calibration. First, we describe a direct technique based on estimating rigid transformation from corresponding point sets and our idea of improving the calibration efficiency by collecting corresponding points covering broader area of the endoscope and tracker field-of-view (FOV). Then, we describe a technique based on estimation of position and orientation of a planar object from camera image. The main advantage of these techniques is that they are easily repeatable in applications where a change in the relation between camera sensor and camera-mounted marker is possible during the run-time of the AR application.
Keywords: extrinsic calibration, hand-eye, pose estimation
VR spray painting for training and design BIBAKFull-Text 293-294
  Jonathan Konieczny; Gary Meyer; Clement Shimizu; John Heckman; Mark Manyen; Marty Rabens
A system is introduced for the simulation of spray painting. Head mounted display goggles are combined with a tracking system to allow users to paint a virtual surface with a spray gun. Ray tracing is used to simulate droplets landing on the surface of the object, allowing arbitrary shapes and spray gun patterns to be used. This system is combined with previous research on spray gun characteristics to provide a realistic simulation of the spray paint including the effects of viscosity, air pressure, and paint pressure. The simulation provides two different output modes: a non-photorealistic display that gives a visual representation of how much paint has landed on the surface, and a photorealistic simulation of how the paint would actually look on the object once it dried. Useful feedback values such as overspray are given. Experiments were performed to validate the system.
Keywords: VR applications, paint, user training, visualization
Localization system for large indoor environments using invisible markers BIBAKFull-Text 295-296
  Yusuke Nakazato; Masayuki Kanbara; Naokazu Yokoya
We propose a user localization system that uses invisible markers for wearable augmented reality (AR) in large indoor environments. Wearable AR systems have received a great deal of attention as a new method for displaying location-based information in the real world. For using wearable AR systems, it is necessary to measure the position and orientation of a user using a positioning infrastructure without the undesirable visual effects that arise from merging real and virtual worlds. In addition, the infrastructure of the localization environment must be constructed easily and cheaply. The proposed system can estimate the position and orientation of a user precisely by affixing wallpapers containing printed invisible markers on ceilings or walls. The user's position and orientation are estimated by recognizing the markers using an infrared camera with infrared LEDs. To construct environments for the localization system, we developed an initialization tool that calibrates the alignment of the markers from photographs taken by flash illumination using a digital still camera.
Keywords: augmented reality, invisible marker, localization

Demonstrations

Grimage: 3D modeling for remote collaboration and telepresence BIBAKFull-Text 299-300
  Benjamin Petit; Jean-Denis Lesage; Jean-Sébastien Franco; Edmond Boyer; Bruno Raffin
Real-time multi-camera 3D modeling provides full-body geometric and photometric data on the objects present in the acquisition space. It can be used as an input device for rendering textured 3D models, and for computing interactions with virtual objects through a physical simulation engine. In this paper we present a work in progress to build a collaborative environment where two distant users, each one 3D modeled in real-time, interact in a shared virtual world.
Keywords: PC cluster, collaborative 3D interactions, marker-less 3D modeling, multi-cameras, telepresence
Parallel LOD for static and dynamic generic geo-referenced data BIBAKFull-Text 301-302
  Simon Arvaux; Joeffrey Legaux; Sébastien Limet; Emmanuel Melin; Sophie Robert
We propose to illustrate a generic Levels Of Details (LOD) technique which is a key point to construct distributed VR application involving large static or dynamic datasets, issued from measurements or big simulations. This demo focus on a parallel LOD algorithm for GIS and presents a 3D textured section of the Loire river near Orléans. Since all visualized data are handle in RAM memory without complex pre-processing, this method is transposable into more dynamic context where texture data are generated from simulations.
Keywords: GIS, VR applications, collaborative and distributed VR, scientific visualization
Collaborative exploration of 3D scientific data BIBAKFull-Text 303-304
  Thierry Duval; Cédric Fleury; Bernard Nouailhas; Laurent Aguerreche
This demonstration introduces new ways for exploring Collaborative Virtual Environments (CVE) that contain 3D scientific data sets obtained by simulation. In order to make decisions accordingly to their collective knowledge and understanding of the simulation, the users must collaborate and share experiences and comments. We provide tools to enable a good coordination between the users, and to make each user aware of the activity of others. Each user can navigate within the CVE: change her own position, orientation and scale. Each user can also add annotations within the virtual universe. We propose several 3D layouts for the presentation of the data, associated with different 3D navigation tools. Consequently, the user can explore the data according to various parameters such as time or temperature. Last we propose a new 3D interaction tool, called 2D Cursor / 3D Pointer, dedicated to selection and manipulation of 3D objects, and application control. This 2D cursor is associated with a 3D geometry in order to make people aware of the activity of the users who are using this tool.
Keywords: 3D interaction, 3D scientific visualization, collaborative virtual environments
Wired gloves for every one BIBAKFull-Text 305-306
  Hernando Ortega-Carrillo; Erika Martínez-Mirón
Wired gloves are one of the most useful tools in the field of Virtual Reality. By using them, the users can interact more realistically with Virtual Environments than when using a joystick, mouse, trackball or so. Despite some attempts to develop low-budget wired gloves have been made, these useful devices remain as very expensive tools for the common user.
   Motivated by this situation, we propose the design and implementation of wired gloves based on a low budget novel technology. This technology uses indirect video-analysis to detect joint movements, which are transferred via a set of wires attached to the joints. As a result, these gloves can be acquired at a very low price or even enthusiast people could try to reproduce them.
Keywords: flexible sensors, opto-mechanical, wired gloves
ArcheoTUI -- tangible interaction with foot pedal declutching for the virtual reassembly of fractured archaeological objects BIBAKFull-Text 307-308
  Patrick Reuter; Guillaume Rivière; Nadine Couture; Stéphanie Mahut; Nicolas Sorraing; Loïc Espinasse
In this demonstration, we present ArcheoTUI, a new tangible user interface for the efficient assembly of the 3D scanned fragments of fractured archaeological objects. The key idea is to use tangible props for the manipulation of the virtual fragments. In each hand, the user manipulates an electromagnetically tracked prop, and the translations and rotations are directly mapped to the corresponding virtual fragments on the display. For each hand, a corresponding foot pedal is used to clutch the movements of the hands. Hence, the hands of the user can be repositioned, or the user can be switched. The software of ArcheoTUI is designed to easily change assembly hypotheses, beyond classical undo/redo, by using a scene graph.
Keywords: 3D interaction, tangible user interfaces