The sense of embodiment is important when using a virtual avatar, and by gaining the strong sense of embodiment, the connection with the virtual avatar becomes stronger, and it feels more like the virtual avatar has become your own real body. Therefore, the aim of this study is to propose a method for transitioning to an avatar that uses only a simple virtual environment and is not dependent on a specific task. In this study, we focused on the active nature required for users to transition to an avatar, and we experimented with four general transition methods and examined the effects of these on embodiment sensation. The results of the experiment showed that visual feedback helps to acquire the sense of embodiment and improves the sense of self location and sense of transformation, that passive avatar transitions may cause a shift in the sense of self location, and that active and step-by-step avatar transitions help to acquire the sense of embodiment and improve the sense of embodiment and sense of transformation.

One of the characteristics of VR is the use of virtual avatars, which allow users to control a deformed body that is different from that of humans. However, the use of deformed avatars can easily lead to a decrease in the user’s sense of body ownership, which is the feeling of recognizing the avatar as one s own body. In addition, the relation between the degree of avatar deformity and the task load required to induce the sufficient sense of body ownership is not clear. In this study, four avatars with different degrees of deformity and three tasks with different loads were used to investigate the relation between the degree of avatar deformity and the task load required to induce the sense of body ownership. The experimental results suggest that task load might affect the sense of body ownership of deformed avatars. Therefore, increasing the task load might also increase the sense of body ownership. This might enable avatars to perform tasks with loads appropriate to their deformity.

The use of social VR content to communicate with others in a virtual space has been increasing. It is suggested that the frequency of physical contact is higher in communication on VR than in the real world, which improves the user’s liking for the other party. In this study, we aimed to improve the quality of communication by adding auditory stimuli to physical contact between avatars in a virtual space, and investigated the effects of contact sounds on the impression and presence that the user has of the other avatar. The results showed that the impression and presence of the avatar did not change by the addition of the contact sounds, suggesting that they may be influenced by the first impression of the avatar’s appearance. It was also found that familiar contact sounds that were closer to the reality tended to be preferred.

In recent years, social VR (Virtual Reality) contents for communication have become more and more active. However, social VR contents cannot convey a sense of touch or warmth during the pseudo-body contact. This study investigated whether changing the color of a hand during the pseudo-body contact in virtual reality can produce temperature sensations and a sense of contact from visual stimuli. In addition, changing the color of the hand may affect not only the temperature illusion but also the user’s psychology. Therefore, in order to induce the temperature illusion, the color of the hand during the simulated handshake was changed, and the evaluation of the sense of contact, closeness, and the user’s psychological state was investigated in a subject experiment. The results showed that warm colors of the hands can make users feel warm and enhance the sense of contact. When the color of one’s own hand and the other’s hand were warmer than each other, the feeling of closeness increased. When the other person’s hand is in the cold color, people feel coldness, and increase negative feelings toward the other person, such as a decrease in happiness, and a feeling of anxiety and disgust. By investigating and clarifying the effects of pseudo-body contact in a virtual space, this study contributes to providing an environment for high quality communication in social VR contents.

Our study aims to improve the presence of a remote participant in communications. We examined how display methods affect the presence of a remote participant with some communication tasks. As a result, a method using a hologram pyramid enhanced the presence more than the others regardless of the tasks.

In recent years, the use of virtual reality (VR) attractions has been increasing in amusement facilities with the spread of head-mounted displays (HMDs) and the increase of VR content. VR attractions require less physical space than conventional attractions. However, because it takes a considerable time to adjust an HMD one by one, not many customers can play the attractions. In order to provide VR content with a long subjective time in a short time, this study presents VR content on an HMD that can evoke fear. Fear is one of the factors that influence psychological time. We investigate whether the VR content with fear influences time estimation.

The purpose of this research is to make a change in weight perception by utilizing the potential impression that a person has acquired from visual information. Recently, the illusion caused by changes in visual information, which is represented by the rubber hand illusion and the Proteus effect, has been reported. In this research, we make one’s self-awareness change by the appearance of the own arm through AR technology. We conduct an experiment to verify that the change of the self-awareness influences the weight perception of grasping an actual object.

In order to improve the perception of the core part of a virtual soft object when a user squeezes it with his/her bare hand, we apply multisensory integration of visual and auditory stimuli to our proposed AR system. The visual stimuli are real-time stereoscopic images in which the user's bare hand is squeezing the virtual soft object in the actual scene. As the auditory stimuli, we focus on the sound volume change linked to the movements of the user's thumb and index finger. The present paper reports the effects of sound volume change in enhancing the pseudo-softness and the perception of the core part of a virtual soft object. The experimental results of our study statistically show that when a user squeezes a virtual soft object with his/her bare hand, multisensory integration of the visual and auditory stimuli effectively increases the feeling of grasping and facilitates handling of the virtual soft object. In addition, auditory stimuli that have a clearly audible sound volume change at the core part naturally enhance the perception of the core part of the virtual soft object.

In this case study, we explore techniques for the purpose of visualizing isolated flow structures in time-dependent data. Our primary industrial application is the visualization of the vortex rope, a rotating helical structure which builds up in the draft tube of a water turbine. The vortex rope can be characterized by high values of normalized helicity, which is a scalar field derived from the given CFD velocity data. In two related applications, the goal is to visualize the cavitation regions near the runner blades of a Kaplan turbine and a water pump, respectively. Again, the flow structure of interest can be defined by a scalar field, namely by low pressure values. We propose a particle seeding scheme based on quasi-random numbers, which minimizes visual artifacts such as clusters or patterns. By constraining the visualization to a region of interest, occlusion problems are reduced and storage efficiency is gained.

Introduces a refined general definition of a skeleton that is based on a penalized distance function and that cannot create any of the degenerate cases of the earlier CEASAR (Center-line Extraction Algorithm-Smooth, Accurate and Robust) and TEASAR (Tree-structure Extraction Algorithm for Skeletons-Accurate and Robust) algorithms. Additionally, we provide an algorithm that finds the skeleton accurately and rapidly. Our solution is fully automatic, which frees the user from having to engage in manual data pre-processing. We present the accurate skeletons computed on a number of test data sets. The algorithm is very efficient, as demonstrated by the running times, which were all below seven minutes.

An accurate segmentation is critical for clinical application of medical images. The undesirable partial-volume-effect, which lies on a boundary between a high intensity region and a low intensity region, makes unerring boundary determination a difficult task. A new approach to segmentation is required for removing the adverse effect on the boundary, which is unwanted especially from the point of view of volume rendering. Here, the authors propose a gradient magnitude based region growing algorithm for accurate segmentation. The gradient is useful for enhancing the boundary because it emphasizes the difference among voxel values. By analyzing the gradient magnitude, the authors can see the sufficient contrast which must be presented on the boundary region and they use this contrast to increase the accuracy of their segmentation method. The authors pay attention only to the boundary region, not to the whole large volumetric dataset itself, making it more computationally efficient.

We introduce the TEASAR algorithm which is a treestructure extraction algorithm delivering skeletons that are accurate and robust. Volumetric skeletons are needed for accurate measurements of length along branching and winding structures. Skeletons are also required in automatic virtual navigation, such as traveling through human organs (e.g., the colon) to control movement and orientation of the virtual camera. We introduce a concise but general definition of a skeleton, and provide an algorithm that finds the skeleton accurately and rapidly. Our solution is fully automatic, which frees the user from having to engage in data preprocessing. We present the accurate skeletons computed on a number of test datasets. The algorithm is efficient as demonstrated by the running times on a single 194 MHz MIPS R10000 CPU which were all below five minutes.

We present CEASAR, a centerline extraction algorithm that delivers smooth, accurate and robust results. Centerlines are needed for accurate measurements of length along winding tubular structures. Centerlines are also required in automatic virtual navigation through human organs, such as the colon or the aorta, as they are used to control movement and orientation of the virtual camera. We introduce a concise but general definition of a centerline, and provide an algorithm that finds the centerline accurately and rapidly. Our algorithm is provably correct for general geometries. Our solution is fully automatic, which frees the user from having to engage in data preprocessing. For a number of test datasets, we show the smooth and accurate centerlines computed by our CEASAR algorithm on a single 194 MHz MIPS R10000 CPU within five minutes.

We propose a novel approach for segmentation and digital cleansing of endoscopic organs. Our method can be used for a variety of segmentation needs with little or no modification. It aims at fulfilling the dual and often conflicting requirements of a fast and accurate segmentation and also eliminates the undesirable partial volume effect which contemporary approaches cannot. For segmentation and digital cleansing, we use the peculiar characteristics exhibited by the intersection of any two distinct-intensity regions. To detect these intersections we cast rays through the volume, which we call the segmentation rays as they assist in the segmentation. We then associate a certain task of reconstruction and classification with each intersection the ray detects. We further use volumetric contrast enhancement to reconstruct surface lost by segmentation (if any), which aids in improving the quality of the volume rendering.