ICAT-EGVE2015

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https://diglib.eg.org/handle/10.2312/13833

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Structural Color Display on Retro-reflective Objects
(The Eurographics Association, 2015) Amano, Toshiyuki; Minami, Kensuke; Masataka Imura and Pablo Figueroa and Betty Mohler
Structural color display is an illumination projection display technique that can generate a completely altered appearance. It has potential for the visualization of scientific simulation, material perception display, and other applications. This paper investigates how to alternate the directional illumination distribution to display a desired bidirectional reflectance distribution function (BRDF). For the display technique, we modeled the reflection property of retro-reflective coating and lightfield projection using a projector array. Because the overlap creates an illumination error with respect to the desired appearance when we simply project the desired appearance, we propose a projection image optimization method to ensure that we display the desired structural color. We performed an evaluation on the reflective rainbow of an optical disc, and its effectiveness was confirmed through simulation and hardware experiment.
X-Dimensional Display: Superimposing 2D Cross-Sectional Image inside 3D Wireframe Aerial Image
(The Eurographics Association, 2015) Furuyama, Yoshikazu; Makino, Yasutoshi; Shinoda, Hiroyuki; Masataka Imura and Pablo Figueroa and Betty Mohler
In this paper, we propose a new interactive volumetric display which simultaneously shows a floating 3D image and its 2D cross sectional image inside it. This display enables users to see an arbitrary cross sectional image by inserting a hand-held semi-transparent screen into the 3D image floating in the mid-air. This system has following possibilities: doctors easily see MRI images inside the 3D body image, and designers check the internal structure of a 3D object in CAD. We construct a prototype device to demonstrate our proposed method by combining a 3D display and an aerial imaging technology. The spinning LED array constructs the volumetric image, and which is optically mirrored to appear in the free-space by the transmissive mirror called Aerial Imaging Plate (AIP). We find that a fine meshed silk screen can be inserted into the aerial image without disturbing the shape of it. Cross sectional images can be projected onto it together with the 3D image. We demonstrate how a silk screen diffuses a 3D aerial image and a projected 2D image.
R-V Dynamics Illusion: Psychophysical Phenomenon Caused by the Difference between Dynamics of Real Object and Virtual Object
(The Eurographics Association, 2015) Kataoka, Yuta; Hashiguchi, Satoshi; Shibata, Fumihisa; Kimura, Asako; Masataka Imura and Pablo Figueroa and Betty Mohler
In Mixed-Reality (MR) space, it appeared that the sense of weight can be affected by a MR visual stimulation with a movable portion. We named this psychophysical influence caused by the difference between dynamics of the real object (R) and the virtual object (V) movement, the ''R-V Dynamics Illusion.'' There are many combinations of ex-periments that can be conducted. Previously, we conducted experiments of the case where the real object is rigid and the virtual object is dynamically changeable. In this paper, we conducted experiments of the case where the re-al object is liquid and both the real and the virtual objects are dynamically changeable. The results of the experi-ments showed that the subjects sensed weight differently when virtual object with a movable portion is superim-posed onto a real liquid object.
Fast Robust and Precise Shadow Algorithm for WebGL 1.0 Platform
(The Eurographics Association, 2015) Milet, Tomáš; Tóth, Michal; Pečiva, Jan; Starka, Tomáš; Kobrtek, Jozef; Zemcik, Pavel; Masataka Imura and Pablo Figueroa and Betty Mohler
This paper presents fast and robust per-sample correct shadows for WebGL platform. The algorithm is based on silhouette shadow volumes and it rivals the standard shadow mapping performance. Our performance is usually superior when compared with high resolution shadow maps. Moreover, it does not suffer from a number of artefacts of shadow mapping and always provides per-pixel correct results. WebGL 1.0 provides just vertex and fragment shaders. Thus, we put all our algorithms evaluating silhouette edges to vertex shaders. Specially precomputed data are fed to the vertex shaders that extrude shadow volume sides just for silhouette edges. Some optimizations are deployed for performance and data size reasons that are important especially on low performance configurations, such as cost-effective tablets and mobile phones. The paper evaluates our solution on number of models. Our solution performs on par with high resolution omnidirectional shadow mapping.
CollarBeat: Whole Body Vibrotactile Presentation via the Collarbone to Enrich Music Listening Experience
(The Eurographics Association, 2015) Sakuragi, Rei; Ikeno, Sakiko; Okazaki, Ryuta; Kajimoto, Hiroyuki; Masataka Imura and Pablo Figueroa and Betty Mohler
There are numerous proposals for whole body tactile displays that aim to improve the sense of immersion in audio contents. However, these devices commonly have problems, such as long setup times due to numerous actuators, and user confinement to the system. To address these issues, we proposed to present the vibration to a wide area of the body via bone conduction. In this paper, we first investigated whether presenting vibration to the bone really contributes vibration transmission to wider areas of a user's body. Next, we performed a psychophysical experiment to evaluate subjective vibration feeling with music listening experience using our setup. Results suggest that presenting vibration through the collarbone induces vibration transmission more widely through the user's body and enhances subjective music listening experience.
Physical Space Requirements for Redirected Walking: How Size and Shape Affect Performance
(The Eurographics Association, 2015) Azmandian, Mahdi; Grechkin, Timofey; Bolas, Mark; Suma, Evan; Masataka Imura and Pablo Figueroa and Betty Mohler
Redirected walking provides a compelling solution to explore large virtual environments in a natural way. However, research literature provides few guidelines regarding trade-offs involved in selecting size and layout for physical tracked space. We designed a rigorously controlled benchmarking framework and conducted two simulated user experiments to systematically investigate how the total area and dimensions of the tracked space affect performance of steer-to-center and steer-to-orbit algorithms. The results indicate that minimum viable size of physical tracked space for these redirected walking algorithms is approximately 6m 6m with performance continuously improving in larger tracked spaces. At the same time, no ''optimal'' tracked space size can guarantee the absence of contacts with the boundary. We also found that square tracked spaces enabled best overall performance with steer-to-center algorithm also performing well in moderately elongated rectangular spaces. Finally, we demonstrate that introducing translation gains can provide a useful boost in performance, particularly when physical space is constrained. We conclude with the discussion of potential applications of our benchmarking toolkit to other problems related to performance of redirected walking platforms.
Roles in Collaborative Virtual Environments for Training
(The Eurographics Association, 2015) Claude, Guillaume; Gouranton, Valérie; Arnaldi, Bruno; Masataka Imura and Pablo Figueroa and Betty Mohler
In this paper we present a novel approach to role modelling for Collaborative Virtual Environments with an Action Oriented Scenario Engine. Our role model is able to take into account different data about the actions such as the abilities, rights or resources required by an actor to determine whether he or she can execute an action. Furthermore, it considers that any data about an actor can have an influence on his or her role in the simulation. We provide also a team organisation model to define the impacts of the rules of the team on the role of the actors as suggested by the role theory. To illustrate our work, we used our model in a Collaborative Virtual Environment for the Training of a neurosurgery procedure.
Development of Encountered-type Haptic Interface that can Independently Control Volume and Rigidity of 3D Virtual Object
(The Eurographics Association, 2015) Takizawa, Naoki; Yano, Hiroaki; Iwata, Hiroo; Oshiro, Yukio; Ohkohchi, Nobuhiro; Masataka Imura and Pablo Figueroa and Betty Mohler
This paper describes the development of an encountered-type haptic interface that can independently present the physical characteristics of 3D virtual objects, such as shape and rigidity, in the real world. This interface consists of nonexpandable balloons, syringe pumps, pressure sensors, linear actuators, and a PC. To change the rigidity of the balloon, the volume of air in the balloon is controlled by using a linear actuator and a pressure sensor based on Hooke's law. Furthermore, to change the volume of the balloon, the exposed surface area of the balloon is controlled by using another linear actuator with a trumpet-shaped tube. Performance tests of the system were conducted, and the effectiveness of the proposed interface was verified.
An Evaluation of the Effects of Hyper-Natural Components of Interaction Fidelity on Locomotion Performance in Virtual Reality
(The Eurographics Association, 2015) Nabiyouni, Mahdi; Bowman, Doug A.; Masataka Imura and Pablo Figueroa and Betty Mohler
Virtual reality (VR) locomotion techniques that approximate real-world walking often have lower performance than fully natural real walking due to moderate interaction fidelity. Other techniques with moderate fidelity, however, are intentionally designed to enhance users' abilities beyond what is possible in the real world. We compared such hyper-natural techniques to their natural counterparts on a wide range of locomotion tasks for a variety of measures. The evaluation also considered two independent components of interaction fidelity: bio-mechanics and transfer function. The results show that hyper-natural transfer functions can improve locomotion speed and some aspects of user satis-faction, although this can come at the expense of accuracy for complicated path-following tasks. On the other hand, hyper-natural techniques designed to provide biomechanical assistance had lower performance and user acceptance than those based on natural walking movements. These results contribute to a deeper understanding of the effects of interaction fidelity and designer intent for VR interaction techniques.
How to Time Travel in Highly Immersive Virtual Reality
(The Eurographics Association, 2015) Pizarro, Rodrigo; Berkers, Keren-Or; Slater, Mel; Friedman, Doron; Masataka Imura and Pablo Figueroa and Betty Mohler
What would it be like to be able to time travel to the past, meet your previous self, and override your previous actions in order to achieve a better outcome? While we cannot (yet?) achieve physical time travel, digital technologies now allow us to experience virtual time travel. We have developed a method for implementing time travel in highly immersive virtual reality (VR) and here we describe the underlying technology in the context of a scenario that involves a shooting event in a virtual gallery. Our method includes two layers of abstraction: i) a narrative layer that represents scenarios as a set of events and state transitions, and uses preconditions to enforce consistency, and ii) a VR layer that includes low level controllers for low level synchronization and animation. The narrative layer is designed to ensure that following time travel the events would unfold exactly as they did in the previous time around, except for the specific changes resulting from the actions of the time traveling participant. The VR layer controls the fine details, including recording and replaying motion capture data and audio, which allows the participants to experience their own previous selves as animated avatars. The system was used for a psychological experiment, and in this paper we focus on the technical method and on the lessons learned from implementing VR time travel.
Ring-shaped Haptic Device with Vibrotactile Feedback Patterns to Support Natural Spatial Interaction
(The Eurographics Association, 2015) Ariza Núñez, Oscar Javier; Lubos, Paul; Steinicke, Frank; Bruder, Gerd; Masataka Imura and Pablo Figueroa and Betty Mohler
Haptic feedback devices can be used to improve usability, performance and cognition in immersive virtual environments (IVEs) and have the potential to significantly improve the user's virtual reality (VR) experience during natural interaction. However, there are only few affordable and reliable haptic devices that have a light-weight, unencumbering, simple and versatile form factor which does not prevent natural interaction with other objects or devices at the same time. In this paper we present such a ring-shaped wireless haptic feedback device, and we describe different vibrotactile signal patterns which can be used to provide proximity-based cues during 3D interaction with virtual objects. We present a usability study in which we evaluated the device and feedback patterns.
Anthropomorphism and Illusion of Virtual Body Ownership
(The Eurographics Association, 2015) Lugrin, Jean-Luc; Latt, Johanna; Latoschik, Marc Erich; Masataka Imura and Pablo Figueroa and Betty Mohler
In this paper we present a novel experiment to explore the impact of avatar realism on the illusion of virtual body ownership (IVBO) in immersive virtual environments, with full-body avatar embodiment and freedom of movement.We evaluated four distinct avatars presenting an increasing level of anthropomorphism in their detailed compositions. Our results revealed that each avatar elicited a relatively high level of illusion. However both machine-like and cartoon-like avatars elicited an equivalent IVBO, slightly superior to the human-ones. A realistic human appearance is therefore not a critical top-down factor of IVBO, and could lead to an Uncanny Valley effect.
Comparison and Evaluation of Viewpoint Quality Estimation Algorithms for Immersive Virtual Environments
(The Eurographics Association, 2015) Freitag, Sebastian; Weyers, Benjamin; Bönsch, Andrea; Kuhlen, Torsten W.; Masataka Imura and Pablo Figueroa and Betty Mohler
The knowledge of which places in a virtual environment are interesting or informative can be used to improve user interfaces and to create virtual tours. Viewpoint Quality Estimation algorithms approximate this information by calculating quality scores for viewpoints. However, even though several such algorithms exist and have also been used, e.g., in virtual tour generation, they have never been comparatively evaluated on virtual scenes. In this work, we introduce three new Viewpoint Quality Estimation algorithms, and compare them against each other and six existing metrics, by applying them to two different virtual scenes. Furthermore, we conducted a user study to obtain a quantitative evaluation of viewpoint quality. The results reveal strengths and limitations of the metrics on actual scenes, and provide recommendations on which algorithms to use for real applications.
Yther: A Proposal and Initial Prototype of a Virtual Reality Content Sharing System
(The Eurographics Association, 2015) Steed, Anthony; Masataka Imura and Pablo Figueroa and Betty Mohler
There are many virtual reality development tools, but we argue that none has solved the disparate problems of ease of content creation, openness of access for developers and broad support for a variety of immersive and nonimmersive virtual reality systems. Yther is a proposal and initial prototype of a platform for sharing immersive and non-immersive virtual environments. Yther doesn't propose a new content standard, but builds upon the Unity system. The first contribution of Yther is a clear separation of concerns between development of content (zones) and support for specific hardware. The second contribution is a set of abstractions that allow developer to author interaction techniques and behaviours without specific reference to the interaction devices that any particular runtime instance has. The third contribution is a mechanism within the Unity development environment for publishing content so that it can be made available for testing and sharing very easily. The current implementation of Yther is a prototype but it already demonstrates capabilities that distinguish it from similar systems.
Global Landmarks Do Not Necessarily Improve Spatial Performance in Addition to Bodily Self-Movement Cues when Learning a Large-Scale Virtual Environment
(The Eurographics Association, 2015) Meilinger, Tobias; Schulte-Pelkum, Jörg; Frankenstein, Julia; Berger, Daniel; Bülthoff, Heinrich H.; Masataka Imura and Pablo Figueroa and Betty Mohler
Comparing spatial performance in different virtual reality setups can indicate which cues are relevant for a realistic virtual experience. Bodily self-movement cues and global orientation information were shown to increase spatial performance compared with local visual cues only. We tested the combined impact of bodily and global orientation cues by having participants learn a virtual multi corridor environment either by only walking through it, with additional distant landmarks providing heading information, or with a surrounding hall relative to which participants could determine their orientation and location. Subsequent measures on spatial memory only revealed small and non-reliable differences between the learning conditions. We conclude that additional global landmark information does not necessarily improve user's orientation within a virtual environment when bodily-self-movement cues are available.
Frontmatter: Virtual Environments 2015
(The Eurographics Association, 2015) Imura, Masataka; Figueroa, Pablo; Mohler, Betty; Masataka Imura and Pablo Figueroa and Betty Mohler
Effectiveness of Spatial Coherent Remote Drive Experience with a Telexistence Backhoe for Construction Sites
(The Eurographics Association, 2015) Fernando, Charith Lasantha; Saraiji, MHD Yamen; Seishu, Yoshio; Kuriu, Nobuo; Minamizawa, Kouta; Tachi, Susumu; Masataka Imura and Pablo Figueroa and Betty Mohler
In this paper, a spatial coherent remote driving system was designed and implemented to operate a telexistence backhoe over a wireless network. Accordingly, we developed a 6 degrees of Freedom (DOF) slave robot that can mimic the human upper body movement; a cockpit with motion tracking system and a Head Mounted Display (HMD) where the operator was provided with a HD720p ultra low latency video and audio feedback from the remote backhoe, and a controller to manipulate the remote backhoe. Spatial coherent driving could help manipu- lating heavy machinery without any prior training and perform operations as if they were operating the machinery locally. Moreover, construction work could be performed uninterrupted (24/7) by operators remotely log-in from all over the world. This paper describes the design requirements of developing the telexistence backhoe followed by several field experiments carried out to verify the effectiveness of spatial coherent remote driving experience in construction sites.
An HMD-based Mixed Reality System for Avatar-Mediated Remote Collaboration with Bare-hand Interaction
(The Eurographics Association, 2015) Noh, Seung-Tak; Yeo, Hui-Shyong; Woo, Woontack; Masataka Imura and Pablo Figueroa and Betty Mohler
We present a novel system for mixed reality based remote collaboration system, which enables a local user to interact and collaborate with another user from remote space using natural hand motion. Unlike conventional system where the remote user appears only inside the screen, our system is able to summon the remote user into the local space, which appears as a virtual avatar in the real world view seen by the local user. To support our avatar-mediated remote collaboration concept, we derive a systematic framework design that consists of the hardware and software configuration with various devices. We explore novel techniques for calibrating and managing the coordinate system in asymmetric setup, sensor fusion between devices and generating human-like motion for the avatar. For validating our proposal, we implemented a proof-of-concept prototype using off-the-shelf hardware and report the experimental results. We believe that our system overcomes not only several limitations of previous systems but also creates new possibilities in remote collaboration domain.
Mutual Proximity Awareness in Immersive Multi-User Virtual Environments with Real Walking
(The Eurographics Association, 2015) Podkosova, Iana; Kaufmann, Hannes; Masataka Imura and Pablo Figueroa and Betty Mohler
Are users aware of each other in an immersive multi-user virtual environment if they cannot see or hear each other? We present a study on users' awareness of other users who share the same physical space. The goal of our research is to investigate proximity awareness when walking in multi-user virtual environments. The high degree of immersion in our virtual environment is achieved through the use of a head-mounted display and real walking in a large tracked space. In our experiment, pairs of participants are required to walk on pre-defined paths towards or side by side to each other and point at their test partners if they feel their presence. Our results show that 1/3 of the participants who had a-priori knowledge about the possible proximity of their test partners could notice their test partners during the experiment at a distance shorter than 1m. The test subjects who did not have any a-priori knowledge proved to be not aware of other users.
Influence of Path Complexity on Spatial Overlap Perception in Virtual Environments
(The Eurographics Association, 2015) Vasylevska, Khrystyna; Kaufmann, Hannes; Masataka Imura and Pablo Figueroa and Betty Mohler
Real walking in large virtual indoor environments within a limited real world workspace requires effective spatial compression methods. These methods should be unnoticed by the user. Scene manipulation that creates overlapping spaces has been suggested in recent work. However, there is little research focusing on users' perception of over-lapping spaces depending on the layout of the environment. In this paper we investigate how the complexity of the path influences the perception of the overlapping spaces it connects. We compare three spatial virtual layouts with paths that differ in complexity (length and number of turns). Our results suggest that an increase of the path's length is less efficient in decreasing overlap detection than a combination of length and additional turns. Furthermore, combination of paths that differ in complexity influences the distance perception within overlapping spaces.

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