ICAT-EGVE2018

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https://diglib.eg.org/handle/10.2312/2632674

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Adaptive Filtering of Physical-Virtual Artifacts for Synthetic Animatronics
(The Eurographics Association, 2018) Schubert, Ryan; Bruder, Gerd; Welch, Gregory; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Spatial Augmented Reality (SAR), e.g., based on monoscopic projected imagery on physical three-dimensional (3D) surfaces, can be particularly well-suited for ad hoc group or multi-user augmented reality experiences since it does not encumber users with head-worn or carried devices. However, conveying a notion of realistic 3D shapes and movements on SAR surfaces using monoscopic imagery is a difficult challenge. While previous work focused on physical actuation of such surfaces to achieve geometrically dynamic content, we introduce a different concept, which we call ''Synthetic Animatronics,'' i.e., conveying geometric movement or deformation purely through manipulation of the imagery being shown on a static display surface. We present a model for the distribution of the viewpoint-dependent distortion that occurs when there are discrepancies between the physical display surface and the virtual object being represented, and describe a realtime implementation for a method of adaptively filtering the imagery based on an approximation of expected potential error. Finally, we describe an existing physical SAR setup well-suited for synthetic animatronics and a corresponding Unity-based SAR simulator allowing for flexible exploration and validation of the technique and various parameters.
Analysis of Spatio-temporal Data in Virtual Historic Spaces
(The Eurographics Association, 2018) Artopoulos, Georgios; Charalambous, Panayiotis; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
This paper presents a virtual reality workflow for citizen engagement in the management of neglected historic sites in contested cities, such as Nicosia, Cyprus, the last divided capital of Europe. It is contextualized in an ongoing research for the use of interactive visualization technologies for co-creation and co-management design practices in public space management. We demonstrate initial results from tracking the movement and gaze of users in VR walkthroughs of a historic site with and without user driven interventions and discuss on future directions.
AR based Self-sports Learning System using Decayed Dynamic TimeWarping Algorithm
(The Eurographics Association, 2018) Ikeda, Atsuki; Hwang, Dong Hyun; Koike, Hideki; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
A self-sports learning system that provides users with real-time multimodal feedback about differences between a user's motion and an expert's motion is proposed. We also propose the Decayed Dynamic Time Warping algorithm, which allows the user to change the motion speed dynamically and repeat a target motion without additional operations. The user can thus imitate an expert's motion conveniently and accurately. The proposed system involves training and replay modes. In the training mode, the system provides audio-visual feedback to help the user imitate the expert's motion. The replay mode allows the user to compare their motion to that of the expert. An augmented reality head-mounted display delivers feedback and provides an immersive three-dimensional training experience.
Blowing in the Wind: Increasing Copresence with a Virtual Human via Airflow Influence in Augmented Reality
(The Eurographics Association, 2018) Kim, Kangsoo; Bruder, Gerd; Welch, Gregory; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
In a social context where two or more interlocutors interact with each other in the same space, one's sense of copresence with the others is an important factor for the quality of communication and engagement in the interaction. Although augmented reality (AR) technology enables the superposition of virtual humans (VHs) as interlocutors in the real world, the resulting sense of copresence is usually far lower than with a real human interlocutor. In this paper, we describe a human-subject study in which we explored and investigated the effects that subtle multi-modal interaction between the virtual environment and the real world, where a VH and human participants were co-located, can have on copresence. We compared two levels of gradually increased multi-modal interaction: (i) virtual objects being affected by real airflow as commonly experienced with fans in summer, and (ii) a VH showing awareness of this airflow. We chose airflow as one example of an environmental factor that can noticeably affect both the real and virtual worlds, and also cause subtle responses in interlocutors.We hypothesized that our two levels of treatment would increase the sense of being together with the VH gradually, i.e., participants would report higher copresence with airflow influence than without it, and the copresence would be even higher when the VH shows awareness of the airflow. The statistical analysis with the participant-reported copresence scores showed that there was an improvement of the perceived copresence with the VH when both the physical-virtual interactivity via airflow and the VH's awareness behaviors were present together. As the considered environmental factors are directed at the VH, i.e., they are not part of the direct interaction with the real human, they can provide a reasonably generalizable approach to support copresence in AR beyond the particular use case in the present experiment.
BuzzwireVR: An Immersive Game to Supplement Fine-Motor Movement Therapy
(The Eurographics Association, 2018) Christou, Chris G.; Michael-Grigoriou, Despina; Sokratous, D.; Tsiakoulia, M.; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Recovery of upper-body fine-motor skills after brain trauma, e.g. after a stroke, involves a long process of movement rehabilitation. When the arms and hands are affected patients often spend many hours exercising in order to regain control of their movements, often using children's toys. This paper describes the process of development of a Virtual Reality (VR) system designed to supplement rehabilitation by encouraging hand movements while playing a fun game. The system is based on the well-known Buzzwire children's toy that requires steady hand-eye coordination to pass a ring along a wire without touching the wire. The toy has in the past been used in a variety of research studies, but we considered it ideal for motor rehabilitation because it requires steady hand and finger movements. In our virtualised version of the toy the wire consists of a parametric spline curve with cylindrical cross-section positioned in front of the player. Cylinders at the ends of the 'wire' change colour to indicate which hand to use. The parametric nature of the wire allows us to record performance variables which are not readily available in the physical version. We report on two initial experiments which tested and evaluated various aspects of performance on able-bodied participants and stroke patients, followed by a description of how we developed the toy into a multi-level game that encourages increasingly intricate hand movements. In the first evaluation we tested if performance variables (such as average speed, and distance from the wire) could distinguish between dominant and non-dominant hands of able-bodied participants. We also compared performance with and without binocular viewing. Results showed that our metrics could distinguish between the players dominant versus non-dominant hand. We also noted a dramatic disruption of performance when binocular stereopsis was not available. The second experiment was a usability study involving a sample of stroke-affected participants with post-stroke hemiparesis. Results showed positive acceptance of the technology with no fatigue or nausea. Our gamified version of the task utilizes learnings from the previous studies to create an enjoyable multi-level game involving auditory guidance as feedback. Results are discussed in terms of potential benefits of using such technology in addition to conventional therapy.
Compression Of 16K Video For Mobile VR Playback Over 4K Streams
(The Eurographics Association, 2018) Vazquez, Iker; Cutchin, Steve; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Mobile virtual reality headset devices are currently constrained to playing back 4K video streams for hardware, network, and performance reasons. This strongly limits the quality of 360 degrees videos over 4K streams; which in turn translates to insufficient resolution for virtual reality video playback. Spherical stereo virtual reality videos can be currently captured at 8K and 16K resolutions, with 8K being the minimal resolution for an acceptable quality video playback experience. In this paper, we present a novel technique that uses object tracking to compress 16K spherical stereo videos captured by a still camera into a format that can be streamed over 4K channels while maintaining the 16K video resolution for typical video captures.
Effects of Embodiment on Generic and Content-Specific Intelligent Virtual Agents as Exhibition Guides
(The Eurographics Association, 2018) Schmidt, Susanne; Bruder, Gerd; Steinicke, Frank; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Intelligent Virtual Agents (IVAs) received enormous attention in recent years due to significant improvements in voice communication technologies and the convergence of different research fields such as Machine Learning, Internet of Things, and Virtual Reality (VR). Interactive conversational IVAs can appear in different forms such as voice-only or with embodied audio-visual representations showing, for example, human-like contextually related or generic three-dimensional bodies. In this paper, we analyzed the benefits of different forms of virtual agents in the context of a VR exhibition space. Our results suggest positive evidence showing large benefits of both embodied and thematically related audio-visual representations of IVAs. We discuss implications and suggestions for content developers to design believable virtual agents in the context of such installations.
Equivalent Physical Constant Hypothesis for Skill Transmission in Scale Conversion Telexistence
(The Eurographics Association, 2018) Miyamoto, Hiroki; Furukawa, Masahiro; Wada, Kosuke; Kurokawa, Masataka; Matsumoto, Kohei; Maeda, Taro; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Scale conversion telexistence can have an inconsistency in the motions of a human and robot of different scales. We assumed that the inconsistency is caused by the different apparent physical constants for the human and robot. We propose an equivalent physical constant hypothesis for motion skill transmission, which we verified experimentally by transmitting the standing-up movement of a human to a small robot. The robot successfully managed to stand up by compensating for the gravity. This proves the validity of the hypothesis.
Error Correction in Redirection: Rotational Manipulation for Natural Walking and Control of Walking Paths
(The Eurographics Association, 2018) Mizutani, Junya; Matsumoto, Keigo; Nagao, Ryohei; Narumi, Takuji; Tanikawa, Tomohiro; Hirose, Michitaka; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
This study proposes a novel rotational manipulation method for redirection when users attempt to turn around a corner within a virtual environment. The basic manipulation of conventional redirection can be classified into translational, rotational, and curvature manipulations. In conventional rotational manipulation, users must stop and rotate. However, this behavior is not natural in everyday walking. In addition, because the manipulated rotation varies depending on the amount of the user's rotation, this manipulated rotation could differ from the assumed rotation if the user does not rotate by the assumed angle during this manipulation. Correspondingly, the actual walking path may deviate from the planned path. Misalignment of the walking path may cause a deviation in the interaction with an object in real space, thus resulting in collision with real-space objects and other users. We devised a basic manipulation of redirection and formulated a novel method for manipulating the amount of rotation when users rotate while moving. Using this method, we changed the axis of rotational manipulation for preventing mismatches between real and virtual environments, and set an area to correct the error in rotational manipulation. The results of our experiments demonstrated that it is possible to control the walking paths and manipulate the amount of rotation during movement without changing the amount of rotation perceived by users, and without increasing discomfort. The results demonstrated that our method is useful for manipulating the viewpoint when a user walks naturally.
Feasibility Study of an Augmented Reality System for People with Dementia
(The Eurographics Association, 2018) Andrade Ferreira, Luis Duarte; Cavaco, Sofia; Bermúdez i Badia, Sergi; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
While augmented reality (AR) can be valuable in therapy with people with dementia (PwD), when designing an AR system for PwD, it is important to understand how PwD interact with to such systems. Here we discuss an experiment that aims to study how PwD can complete a set of activities using a variety of human - computer interaction techniques in an AR environment. During our analysis, we will answer 4 research questions: (RQ1) How autonomous are PwD while using the proposed system? (RQ2) How engaging is the system? (RQ3) How proficient are PwD in doing the proposed activities using errorful and errorless approaches? (RQ4) How useful is the proposed system as perceived by therapists? There were 7 people diagnosed with dementia participating in the study. We also invited 3 health professionals to provide feedback regarding the overall usefulness of the AR system for stimulation purposes in PwD who are at initial to intermediate stages of dementia.The experiment showed that, in general, participants did enjoy doing the activities and were able to complete them independently. As far for the therapists, they showed interest in using the system for stimulation purposes in the future interventions. However, the experiment also revealed that it is important to adapt the activities to the patient's profile.
Frontmatter: ICAT-EGVE 2018 - International Conference on Artificial Reality and Telexistence and Eurographics Symposium on Virtual Environments
(The Eurographics Association, 2018) Bruder, Gerd; Yoshimoto, Shunsuke; Cobb, Sue; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Geometrical Algorithms for Real Time Sound Rendering Using Intelligent Prioritization
(The Eurographics Association, 2018) Charalampous, Panagiotis; Michael-Grigoriou, Despina; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Geometrical algorithms have been the main subject of research in the field of real time sound rendering. These algorithms are variants of the image source and ray tracing algorithms, enhanced with improvements that speed up substantially their performance. The fundamental concepts behind the improvements achieved up to now was the reduction of the processed information and the acceleration of the actual processing. In this paper, we show how altering the traversal method affects significantly the algorithm's performance. These optimizations alter its behavior, providing better results for real time purposes. We separate the techniques into three major categories and we propose a stochastic Monte Carlo algorithm which involves optimizations based on prioritization.
HTC Vive Pro Time Performance Benchmark for Scientific Research
(The Eurographics Association, 2018) Chénéchal, Morgan Le; Goldman, Jonas Chatel; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Widespread availability of consumer-level virtual reality (VR) devices creates a venue for their massive use in psychology and neuroscience research. The application of VR to scientific research however poses significant constraints on system performance and stability. In particular, studies with multimodal measurement of human behavior and physiology require precise hardwaresoftware synchronization with precise event labeling (within 10 milliseconds). Previous works investigating suitability of VR systems for research have mainly focused on benchmarking performance in spatial tracking. Therefore, it remains unclear if timing parameters such as latency or jitter in VR motion capture and VR audiovisual stimulation allow for carrying out science under strong time constraints. Here we present the first quantitative test of time performance in VR input and VR feedback of the current state-of-the-art HTC Vive Pro system. Using both low-level Python-based API and a high-level game engine (Unity), our multilevel testing procedure allows us to isolate software influence on observed results. We report that, in both test conditions, latencies are non-negligible considering fine synchronization with multimodal measurements; however, jitters are stable and low, which allows to counter-balance the effect of latency by using constant offsets to re-synchronize multimodal data. Finally, we plan to share our testing hardware setup as an open-source and low-cost benchmark toolkit, allowing objective testing to be easily reproduced by the community in an open collaborative framework.
Individualized Calibration of Rotation Gain Thresholds for Redirected Walking
(The Eurographics Association, 2018) Hutton, Courtney; Ziccardi, Shelby; Medina, Julio; Rosenberg, Evan Suma; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Redirected walking allows the exploration of large virtual environments within a limited physical space. To achieve this, redirected walking algorithms must maximize the rotation gains applied while remaining imperceptible to the user. Previous research has established population averages for redirection thresholds, including rotation gains. However, these averages do not account for individual variation in tolerance of and susceptibility to redirection. This paper investigates methodologies designed to quickly and accurately calculate rotation gain thresholds for an individual user. This new method is straightforward to implement, requires a minimal amount of space, and takes only a few minutes to estimate a user's personal threshold for rotation gains. Results from a user study support the wide variability in detection thresholds and indicate that the method of parameter estimation through sequential testing (PEST) is viable for efficiently calibrating individual thresholds.
Invisible Long Arm Illusion: Illusory Body Ownership by Synchronous Movement of Hands and Feet
(The Eurographics Association, 2018) Kondo, Ryota; Ueda, Sachiyo; Sugimoto, Maki; Minamizawa, Kouta; Inami, Masahiko; Kitazaki, Michiteru; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
We feel as if a fake body is our own body by synchronicity between the fake body and the actual body (illusory body ownership) even if the body has a different shape. In our previous study, we showed that illusory body ownership can be induced to an invisible body through the synchronous movement of just the hands and feet. In this study, we investigated whether illusory body ownership can be induced to the invisible body even when the arm length of the invisible body was different from the usual body. We modified the length of arm of a full body avatar or changed the position of the hand of the invisible body stimulus, and found that the illusory body ownership was induced to the transformed body by synchronous movement. Participants' reaching behavior gradually changed to use the longer arm more during the learning of the transformed body.
Materiality Manipulation by Light-Field Projection from Reflectance Analysis
(The Eurographics Association, 2018) Murakami, Kouki; Amano, Toshiyuki; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
In this paper, we report a method for changing the appearance of an object to different colors as a function of viewing perspective with multiple projectors and cameras. If such appearance manipulation becomes possible, morpho butterfly colors, metallic reflection, and other structural colors can be expressed. For such appearance editing, we proposed a reflection model which describes the optical response of projectors and cameras. We also propose methods for calculating the reflectance matrix and the optimized projection images using non-negative minimization. Through experimental results, we confirmed our method allowed perspective-dependent appearance to be designed by choosing the appropriate reflectance from the non-Lambert reflection area.
A Novel Approach for Cooperative Motion Capture (COMOCAP)
(The Eurographics Association, 2018) Welch, Gregory; Wang, Tianren; Bishop, Gary; Bruder, Gerd; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Conventional motion capture (MOCAP) systems, e.g., optical systems, typically perform well for one person, but less so for multiple people in close proximity. Measurement quality can decline with distance, and even drop out as source/sensor components are occluded by nearby people. Furthermore, conventional optical MOCAP systems estimate body posture using a global estimation approach employing cameras that are fixed in the environment, typically at a distance such that one person or object can easily occlude another, and the relative error between tracked objects in the scene can increase as they move farther from the cameras and/or closer to each other. Body-relative tracking approaches use body-worn sensors and/or sources to track limbs with respect to the head or torso, for example, taking advantage of the proximity of limbs to the body. We present a novel approach to MOCAP that combines and extends conventional global and body-relative approaches by distributing both sensing and active signaling over each person's body to facilitate body-relative (intra-user) MOCAP for one person and body-body (inter-user) MOCAP for multiple people, in an approach we call cooperative motion capture (COMOCAP). We support the validity of the approach with simulation results from a system comprised of acoustic transceivers (receiver-transmitter units) that provide inter-transceiver range measurements. Optical, magnetic, and other types of transceivers could also be used. Our simulations demonstrate the advantages of this approach to effectively improve accuracy and robustness to occlusions in situations of close proximity between multiple persons.
Positioning of Subtitles in Cinematic Virtual Reality
(The Eurographics Association, 2018) Rothe, Sylvia; Tran, Kim; Hussmann, Heinrich; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Cinematic Virtual Reality has been increasing in popularity in recent years.Watching 360 degree movies with a head mounted display, the viewer can freely choose the direction of view and thus the visible section of the movie. Therefore, a new approach for the placements of subtitles is needed. In a preliminary study we compared several static methods, where the position of the subtitles is not influenced by the movie content. The preferred method was used in the main study to compare it with dynamic, worldreferenced subtitling, where the subtitles are placed in the movie world. The position of the subtitles depends on the scene and is close to the speaking person. Even if the participants did not prefer one of these methods in general, for some cases in our experiments world-referenced subtitles led to a higher score of presence, less sickness and lower workload.
Safe Walking Zones: Visual Guidance for Redirected Walking in Confined Real-World Spaces
(The Eurographics Association, 2018) Lubos, Paul; Bruder, Gerd; Steinicke, Frank; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Walking is usually considered the most natural form of self-motion in a virtual environment (VE). However, the confined physical workspace of typical virtual reality (VR) labs often prevents natural exploration of larger VEs. Redirected walking (RDW) has been introduced as a potential solution to this restriction, but corresponding techniques often induce enormous manipulations if the workspace is considerably small and lack natural experiences therefore. In this paper we propose a user interface approach that supports natural walking in a potentially infinite virtual scene while confined to a considerably restricted physical workspace. This virtual locomotion technique relies on a safety volume, which is displayed as a semi-transparent half-capsule, inside which the user can walk without manipulations caused by RDW. We designed a circular redirection approach when the user leaves this safety volume that is complemented by a deterrent approach for user guidance outside the safety volume. We discuss in detail the process of transferring user movements inside these regions to the virtual camera in order to enable walking between points of interest in VEs, and we present the results of a usability study in which we evaluate the approach.
Scalable Autostereoscopic Display with Temporal Division Method
(The Eurographics Association, 2018) Kurogi, Tadatoshi; Nii, Hideaki; Peiris, Roshan Lalintha; Minamizawa, Kouta; Bruder, Gerd and Yoshimoto, Shunsuke and Cobb, Sue
Science-fiction has frequently depicted people directly interacting with life-size autostereoscopic images projected from the walls of buildings in public places. In this paper, we present a large modularized autostereoscopic display. The shape and size can be easily changed by rearranging the number of the multiple display modules. We propose a reconfigurable temporal division multiplexed autostereoscopic display module that can display aerial images. More-over, we show that the temporal division multiplexing method allows the autostereoscopic display to be viewed from a broad range of positions. In this paper, we discuss the design and implementation of this modularized 3D display technology. Furthermore, user evaluations confirmed that the depth perception of the image was improved by con-necting the multiple display modules.

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