Artificial Intelligence (AI) and indoor sensing increasingly support decision-making in spatial environments. However, traditional visualization methods impose a substantial mental workload when viewers translate this digital information into real-world spaces, leading to inappropriate reliance on AI. Embedded visualizations in Augmented Reality (AR), by integrating information into physical environments, may reduce this workload and foster more appropriate reliance on AI. To assess this, we conducted an empirical study (N = 32) comparing an AR embedded visualization (X-ray) and 2D Minimap in AI-assisted, time-critical spatial target selection tasks. Surprisingly, evidence shows that the embedded visualization led to greater inappropriate reliance on AI, primarily as over-reliance, due to factors like perceptual challenges, visual proximity illusions, and highly realistic visual representations. Nonetheless, the embedded visualization showed benefits in spatial mapping. We conclude by discussing empirical insights, design implications, and directions for future research on human-AI collaborative decision in AR.

Cybersickness remains a major barrier to the widespread adoption of virtual reality (VR) technologies, motivating researchers to investigate its causes and mitigation strategies through comparative human-subjects studies. These experiments may employ either within- or between-subjects designs. Although within-subjects designs require fewer participants and potentially offer higher statistical power, researchers need to wash out carryover effects of cybersickness symptoms before each session to avoid confounding the results. Prior studies have employed washout periods of varying lengths; some required testing conditions on different days, while others allowed only short breaks of less than 15 minutes. Although shorter washout periods are more convenient for experimenters, their impact on study outcomes has not been systematically investigated. In this work, we conducted a meta-analysis to evaluate the effects of study design and washout period length on cybersickness self-reports measured with the Simulator Sickness Questionnaire (SSQ). We found that short washout periods reduce statistical power compared to long washout periods or between-subjects designs. Based on these findings, we provide guidelines to help researchers design more reliable cybersickness studies and improve the generalizability of their results.

We present a visualization design study of creating a collaborative virtual reality (VR) system for radiation treatment planning, with an emphasis on proton therapy. The goal is to support teams of dosimetrists, physicians, and medical physicists as they review and compare multiple possible patient-specific treatment plans, which requires analyzing complex 3D spatial relationships between a radiation dosage volume and anatomical structures. The approach is a novel combination and refinement of interactive visualization techniques including: networked multi-user immersive visualization, interactive volume rendering and slicing with 3D widgets and gestures, superimposed surface rendering with GPU-accelerated curvature-directed lines, smart cursors, teleporting, and avatars. These features are integrated within a workflow that supports three complementary modes of visual data comparison (juxtaposition, interchangeable, and explicit encoding). Results and feedback from multi-year iterative development with users and a summative field deployment in the form of a mock plan-review meeting reveal several advantages relative to current clinical practice and suggest directions for future work.

Subjective measures, such as the Simulator Sickness Questionnaire (SSQ), Fast Motion Sickness Questionnaire (FMS), and discomfort scores, are widely used to assess cybersickness, but they often interrupt the user experience and are prone to bias. To overcome these limitations, researchers have also investigated objective indicators, though some approaches, such as using physiological data, can be cumbersome and impractical. Based on the loss of complexity hypothesis, which suggests that certain conditions, such as disease or aging, can produce a reduction of complexity in physiological system dynamics, we conducted an initial investigation of the relationship between movement complexity and cybersickness. We analyzed motion tracking collected from two previous cybersickness studies using the d95 score, a complexity metric derived using principal component analysis. The results revealed a systematic relationship between movement complexity and cybersickness across both experiments. Higher discomfort scores were associated with a reduction in complexity, thereby supporting the loss of complexity hypothesis. Furthermore, the 9-DOF complexity measure, which includes both physical head movement and virtual camera motion, was a more sensitive indicator than the 6-DOF measure computed from physical movements alone. These initial findings suggest that movement complexity may be a useful objective indicator for future cybersickness research.

This paper quantitatively investigates the feasibility of, and merit in, soliciting continuous subjective cybersickness ratings as participants passively engage in an immersive VR experience. The main research questions addressed are: (1) Feasibility: To what extent will participants successfully engage, unprompted, in continuous cybersickness reporting while engaging with a secondary task? and (2) Merit: To what extent do continuously reported subjective cybersickness ratings offer valuable insights beyond what can be obtained from less frequent querying?

Online(-only) friendships have become increasingly common in daily lives post-COVID despite debates around their mental health benefits and equivalence to ''real'' relationships. Previous research has reflected a need to understand how online friends engage beyond individual platforms, and the lack of platform-agnostic inquiry limits our ability to fully understand the dynamics of online friendship. We employed an activity-grounded analysis of 25 interviews on lived experiences of close online friendship spanning multiple years. Our findings present unique challenges and strategies in online friendships, such as stigma from real-life circles, an ambivalent relationship with online communities, and counter-theoretical reappropriations of communication technology. This study contributes to HCI research in online communities and social interface design by refocusing prior impressions of strong vs. weak-ties in online social spaces and foregrounding time-stable interactions in design for relationship maintenance through technology. Our work also promotes critical reflection on biased perspectives towards technology-mediated practices and consideration of online friends as an invisible marginalized community.

Close relationships are irreplaceable social resources, yet prone to high-risk conflict. Building on findings from the fields of HCI, virtual reality, and behavioral therapy, we evaluate the unexplored potential of retrospective VR-embodied perspective-taking to fundamentally influence conflict resolution in close others. We develop a biographically-accurate Retrospective Embodied Perspective-Taking system (REPT) and conduct a mixed-methods evaluation of its influence on close others’ reflection and communication, compared to video-based reflection methods currently used in therapy (treatment as usual, or TAU). Our key findings provide evidence that REPT was able to significantly improve communication skills and positive sentiment of both partners during conflict, over TAU. The qualitative data also indicated that REPT surpassed basic perspective-taking by exclusively stimulating users to embody and reflect on both their own and their partner’s experiences at the same level. In light of these findings, we provide implications and an agenda for social embodiment in HCI design: conceptualizing the use of ‘embodied social cognition,’ and envisioning socially-embodied experiences as an interactive context.

This paper presents Direction-Based Authentication (DBA), a novel authentication method for virtual reality that combines symbolic input and contextual information to balance efficiency with memorability. In DBA, the password consists of four view directions selected by the user across four virtual environments. The user can either physically turn their head or use buttons to select directions, and remember the directions by either symbol or visual context. We conducted a within-subjects study (N=32) to evaluate the efficiency, memorability, and security compared to methods based on symbols or context only. The results demonstrated that password entry with DBA was more efficient than the contextual-only approach. While recall rate was not significantly higher than the symbolic-only method, participants’ subjective ratings indicated that DBA better supported memorability. All three methods were highly resistant to observational attack, although the user-defined passwords appeared homogeneous in certain cases. Overall, the study shows that combining symbolic and contextual information is promising to balance efficiency with memorability for VR authentication, but potential usability and security issues can arise without careful consideration. Based on these findings, we discussed future directions for optimizing the usability and security of DBA and insights regarding participants’ reliance on symbolic vs. visual information.

This paper investigates the influence of X-ray vision metaphors on distance estimation in optical-see-through augmented reality (AR) in action space. A within-subjects study $(\mathrm{N}=30)$ was conducted to evaluate depth judgments across five conditions, including a novel “invisible mesh” technique. Participants performed a series of blind walking tasks that required estimating the depth of AR objects displayed at multiple distance ranges in front or behind a physical occluding surface. Although quantitative results regarding the impact of different X-ray vision metaphors on distance perception were inconclusive, participant feedback revealed a diversity of strategies and preferences. Overall, the findings suggest that no single metaphor was considered universally superior, and multiple X-ray vision metaphors may be suitable for different users and situations. This research contributes to understanding of X-ray vision techniques and informs the design considerations for AR systems aiming to enhance depth perception and user experience.

The decoupled relationship between the optical and inertial information in virtual reality is commonly acknowledged as a major factor contributing to cybersickness. Based on laws of physics, we noticed that a slope naturally affords acceleration, and the gravito-inertial force we experience when we are accelerating freely on a slope has the same relative direction and approximately the same magnitude as the gravity we experience when standing on the ground. This provides the opportunity to simulate a slope by manipulating the orientation of virtual objects accordingly with the accelerating optical flow. In this paper, we present a novel space deformation technique that deforms the virtual environment to replicate the structure of a slope when the user accelerates virtually. As a result, we can restore the physical relationship between the optical and inertial information available to the user. However, the changes to the geometry of the virtual environment during space deformation remain perceptible to users. Consequently, we created two different transition effects, pinch and tilt, which provide different visual experiences of ground bending. A human subject study (N=87) was conducted to evaluate the effects of space deformation on both slope perception and cyber-sickness. The results confirmed that the proposed technique created a strong feeling of traveling on a slope, but no significant differences were found on measures of discomfort and cybersickness.

Virtual reality interactions that require a specific relationship between the virtual and physical coordinate systems, such as passive haptic interactions, are not possible with locomotion techniques using redirected walking. To address this limitation, recent research has introduced environmental alignment, which is the notion of using redirected walking techniques to align the virtual and physical coordinate systems such that these interactions are possible. However, the previous research has only implemented environmental alignment in a reactive manner, and the authors posited that better results could be achieved if a predictive algorithm was instead used. In this work, we introduce a novel way to model the environmental alignment problem as a version of the inverse kinematics problem which can be incorporated into several existing predictive algorithms, as well as a simple proof-of-concept implementation. An exploratory human subject study (N=17) was conducted to evaluate this implementation’s usability as a tool for authoring planned path redirected walking scenarios that incorporate physical interactivity. To our knowledge, this is the first study to evaluate redirected walking experience design tools and provides a possible framework for future studies. Our qualitative analysis of the results generated both guidance for integrating automatic solvers and broad recommendations for designing redirected path authoring tools.

Redirected walking can effectively utilize a user’s physical space when traversing larger virtual environments by using virtual self-motion gains for a user’s physical motions. In particular, curvature gain presents unique advantages in redirection but can lead to suboptimal orientations. To prevent this and add additional utility in redirected walking, we formally present strafing gain. Strafing gain seeks to add incremental lateral movements to a user’s position causing the user to walk along a diagonal trajectory while maintaining the original orientation of the user. In a study with 27 participants, we tested 11 values to determine the detection thresholds of strafing gain. The study, which was modeled on prior detection threshold studies, found that strafing gain could successfully redirect participants to walk along a 5.57° diagonal to the right and a 4.68° diagonal to the left. Furthermore, a supplementary study with 10 participants was conducted, verifying that orientation was maintained throughout redirection and validating the obtained detection thresholds. We discuss the implications of these findings and potential ways of improving these quantities in real-world applications.

Field-of-view (FOV) restriction is a common technique to reduce cybersickness in commercial virtual reality (VR) applications. However, the majority of existing FOV restriction techniques are implemented as symmetric imagery, which occludes users’ views during virtual rotation. In this paper, we proposed and evaluated a novel variant of FOV restriction, referred to as a side restrictor. Side restriction uses an asymmetric mask to obscure only one side region of the periphery during virtual rotation and laterally shifts the center of restriction towards the direction of the turn. We conducted a study using a between-subjects design that compared the side restrictor, a traditional symmetric restrictor, and a control condition without FOV restriction. Participants were required to navigate through a complex maze-like environment using a controller using one of three restrictors. Compared to the control condition, the side restrictor was effective in mitigating cybersickness, reducing discomfort, improving subjective visibility, and enabling users to remain immersed for a longer period of time. Additionally, we found no empirical evidence of negative drawbacks when compared to the symmetric restrictor, which suggests that side restriction is an effective cybersickness mitigation technique for virtual environments with frequent turns.

Dynamic field-of-view (FOV) restriction is a widely used software technique to mitigate cybersickness in commercial virtual reality (VR) applications. The classical FOV restrictor is implemented using a symmetric mask that occludes the periphery in response to translational and/or angular velocity. In this paper, we introduce adaptive field-of-view restriction, a novel technique that responds dynamically based on real-time assessment of optical flow generated by movement through a virtual environment. The adaptive restrictor utilizes an asymmetric mask to obscure regions of the periphery with higher optical flow during virtual locomotion while leaving regions with lower optical flow visible. To evaluate the proposed technique, we conducted a gender-balanced user study (N = 38) in which participants completed in a navigation task in two different types of virtual scenes using controller-based locomotion. Participants were instructed to navigate through either close-quarter or open virtual environments using adaptive restriction, traditional symmetric restriction, or an unrestricted control condition in three VR sessions separated by at least 24 hours. The results showed that the adaptive restrictor was effective in mitigating cybersickness and reducing subjective discomfort, while simultaneously enabling participants to remain immersed for a longer amount of time compared to the control condition. Additionally, presence ratings were significantly higher when using the adaptive restrictor compared to symmetric restriction. In general, these results suggest that adaptive field-of-view restriction based on real-time measurement of optical flow is a promising approach for virtual reality applications that seek to provide a better cost-benefit tradeoff between comfort and a high-fidelity experience.

Previous research has established redirected walking as a potential answer to exploring large virtual environments via natural locomotion within a limited physical space. However, much of the previous work has either focused on investigating human perception of redirected walking illusions or developing novel redirection techniques. In this paper, we take a broader look at the problem and formalize the concept of a complete redirected walking system. This work establishes the theoretical foundations for combining multiple redirection strategies into a unified framework known as adaptive redirection. This meta-strategy adapts based on the context, switching between a suite of strategies with a priori knowledge of their performance under the various circumstances. This paper also introduces a novel static planning strategy that optimizes gain parameters for a predetermined virtual path, known as the Combinatorially Optimized Pre-Planned Exploration Redirector (COPPER). We conducted a simulation-based experiment that demonstrates how adaptation rules can be determined empirically using machine learning, which involves partitioning the spectrum of contexts into regions according to the redirection strategy that performs best. Adaptive redirection provides a foundation for making redirected walking work in practice and can be extended to improve performance in the future as new techniques are integrated into the framework.

Developing effective strategies for redirected walking requires extensive evaluations across a variety of factors that influence performance. Because these large-scale experiments are often not practical with user studies, researchers have instead utilized simulations to systematically test different algorithm parameters, physical space configurations, and virtual walking paths. Although simulation offers an efficient way to evaluate redirected walking algorithms, it remains an open question whether this evaluation methodology is ecologically valid. In this paper, we investigate the interaction between locomotion behavior and redirection gains at a micro-level (across small path segments) and macro-level (across an entire experience). This examination involves analyzing data from real users and comparing algorithm performance metrics with a simulated user model. The results identify specific properties of user locomotion behavior that influence the application of redirected walking gains and resets. Overall, we found that the simulation provided a conservative estimate of the average performance with real users and observed that performance trends when comparing two redirected walking algorithms were preserved. In general, these results indicate that simulation is an empirically valid evaluation methodology for redirected walking algorithms.

We present a complete end-to-end pipeline for generating dynamically relightable virtual objects captured using a single handheld consumer-grade RGB-D camera. The proposed system plausibly replicates the geometry, texture, illumination, and surface reflectance properties of non-Lambertian objects, making them suitable for integration within virtual reality scenes that contain arbitrary illumination. First, the geometry of the target object is reconstructed from depth images captured using a handheld camera. To get nearly drift-free texture maps of the virtual object, a set of selected images from the original color stream is used for camera pose optimization. Our approach further separates these images into diffuse (view-independent) and specular (view-dependent) components using low-rank decomposition. The lighting conditions during capture and reflectance properties of the virtual object are subsequently estimated from the computed specular maps. By combining these parameters with the diffuse texture, the reconstructed model can then be rendered in real-time virtual reality scenes that plausibly replicate real world illumination at the point of capture. Furthermore, these objects can interact with arbitrary virtual lights that vary in direction, intensity, and color.

Interactions with the physical environment, such as passive haptic feedback, have been previously shown to provide richer and more immersive virtual reality experiences. A strict correspondence between the virtual and real world coordinate systems is a staple requirement for physical interaction. However, many of the commonly employed VR locomotion techniques allow for, or even require, this relationship to change as the experience progresses. The outcome is that experience designers frequently have to choose between flexible locomotion or physical interactivity, as the two are often mutually exclusive. To address this limitation, this paper introduces reactive environmental alignment, a novel framework that leverages redirected walking techniques to achieve a desired configuration of the virtual and real world coordinate systems. This approach can transition the system from a misaligned state to an aligned state, thereby enabling the user to interact with physical proxy objects or passive haptic surfaces. Simulation-based experiments demonstrate the effectiveness of reactive alignment and provide insight into the mechanics and potential applications of the proposed algorithm. In the future, reactive environmental alignment can enhance the interactivity of virtual reality systems and inform new research vectors that combine redirected walking and passive haptics.

This research demo showcases the results of novel approach for estimating the illumination and reflectance properties of virtual objects captured using consumer-grade RGB-D cameras. This method is implemented within a fully automatic content creation pipeline that generates photo realistic objects in real-time virtual reality scenes with dynamic lighting. The geometry of the target object is first reconstructed from depth images captured using a handheld camera. To get nearly drift-free texture maps of the virtual object, a set of selected images from the original color stream is used for camera pose optimization. Our approach further separates these images into diffuse (view-independent) and specular (view-dependent) components using low-rank decomposition. The lighting conditions during capture and reflectance properties of the virtual object are subsequently estimated from the specular maps. By combining these parameters with the diffuse texture, reconstructed objects are then rendered in a real-time virtual reality demo that plausibly replicates the real world illumination and showcases dynamic lighting with varying direction, intensity, and color.

With recent advances in hardware technology, autonomous robots are increasingly present in research activities outside of robotics, performing a multitude of tasks such as image capture and sample collection. However, user interfaces for task-oriented robots have not kept pace with hardware breakthroughs. Current planning and control interfaces for robots are not intuitive and often place a large cognitive burden on those who are not highly trained in their use. Augmented reality (AR) has also seen major advances in recent years. This demonstration illustrates an initial system design for an AR user interface for path planning with robotics.

Redirected walking enables users to locomote naturally within a virtual environment that is larger than the available physical space. These systems depend on steering algorithms that continuously redirect users within limited real world boundaries. While a majority of the most recent research has focused on predictive algorithms, it is often necessary to utilize reactive approaches when the user's path is unconstrained. Unfortunately, previously proposed reactive algorithms assume a completely empty space with convex boundaries and perform poorly in complex real world spaces containing obstacles. To overcome this limitation, we present Push/Pull Reactive (P2R), a novel algorithm that uses an artificial potential function to steer users away from potential collisions. We also introduce three new reset strategies and conducted an experiment to evaluate which one performs best when used with P2R. Simulation results demonstrate that the proposed approach outperforms the previous state-of-the-art reactive algorithm in non-convex spaces with and without interior obstacles.

Motion sickness is a major cause of discomfort for users of virtual reality (VR) systems. Over the past several years, several techniques have been proposed to mitigate motion sickness, such as high-quality “room-scale” tracking systems, dynamic field of view modification, and displaying static or dynamic rest frames. At the same time, an absence of real world spatial cues may cause trouble during movement in virtual reality, and users may collide with physical obstacles. To address both of these problems, we propose a novel technique that combines dynamic field of view modification with rest frames generated from 3D scans of the physical environment. As the users moves, either physically and/or virtually, the displayed field of view can be artificially reduced to reveal a wireframe visualization of the real world geometry in the periphery, rendered in the same reference frame as the user. Although empirical studies have not yet been conducted, informal testing suggests that this approach is a promising method for reducing motion sickness and improving user safety at the same time.

Redirected walking (RDW) is a virtual reality (VR) locomotion technique that enables the exploration of a large virtual environment (VE) within a small physical space via real walking. Thus far, the physical environment has generally been assumed to be rectangular, static, and free of obstacles. However, it is unlikely that real-world locations that may be used for VR fulfill these constraints. In addition, accounting for dynamic obstacles such as people helps increase user safety when the view of the physical world is occluded by a head-mounted display. In this work, we present the design and initial implementation of a RDW planning algorithm that can redirect the user in an irregularly shaped physical environment with dynamically moving obstacles. This represents an important step towards the use of RDW in more dynamic, real-world environments.

We present a dynamic omnidirectional texture synthesis (DOTS) approach for generating real-time virtual reality content captured using a consumer-grade RGB-D camera. Compared to a single fixed-viewpoint color map, view-dependent texture mapping (VDTM) techniques can reproduce finer detail and replicate dynamic lighting effects that become especially noticeable with head tracking in virtual reality. However, VDTM is very sensitive to errors such as missing data or inaccurate camera pose estimation, both of which are commonplace for objects captured using consumer-grade RGB-D cameras. To overcome these limitations, our proposed optimization can synthesize a high resolution view-dependent texture map for any virtual camera location. Synthetic textures are generated by uniformly sampling a spherical virtual camera set surrounding the virtual object, thereby enabling efficient real-time rendering for all potential viewing directions.

Motion sickness is a potentially debilitating side effect experienced by certain users of virtual reality systems. Unexpected results from a user study on redirected walking suggest that there is a need to quickly identify participants who have an extremely low tolerance for virtual motion manipulations and remove them from the experience. In this poster, we investigate the use of a previously introduced “fast motion sickness” measure to identify potential outliers with heightened levels of sensitivity. This work demonstrates a promising experimental methodology and suggests possible shared characteristics among users in this group.

It is our great pleasure to welcome you to the 25th IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR), the premiere international conference focused on research in these domains! This year the name of the conference changed since the highly successful 12-year IEEE Symposium on 3D User Interfaces is brought back into the main VR conference. It is a tremendous honor to host the conference in Reutlingen on its first return to Germany since 2005. Reutlingen is situated nicely with respect to our research institutes, the city has the charm of a southern German town, and the recently built (2013) Stadthalle and concert venue has a professional team that is experienced in conferences highlighting innovation in technology. This venue has enabled us to create a large program both in scientific content and in terms of demonstration and exhibit space.

High-fidelity virtual content is essential for the creation of compelling and effective virtual reality (VR) experiences. However, creating photorealistic content is not easy, and handcrafting detailed 3D models can be time and labor intensive. Structured camera arrays, such as light-stages, can scan and reconstruct high-fidelity virtual models, but the expense makes this technology impractical for most users. In this paper, we present a complete end-to-end pipeline for the capture, processing, and rendering of view-dependent 3D models in virtual reality from a single consumer-grade depth camera. The geometry model and the camera trajectories are automatically reconstructed and optimized from a RGB-D image sequence captured offline. Based on the head-mounted display (HMD) position, the three closest images are selected for real-time rendering and fused together to smooth the transition between viewpoints. The specular reflections and light-burst effects can also be preserved and reproduced. We confirmed that our method does not require technical background knowledge by testing our system with data captured by non-expert operators.

As the focus of virtual reality technology is shifting from singleperson experiences to multi-user interactions, it becomes increasingly important to accommodate multiple co-located users within a shared real-world space. For locomotion and navigation, the introduction of multiple users moving both virtually and physically creates additional challenges related to potential user-on-user collisions. In this work, we focus on defining the extent of these challenges, in order to apply redirected walking to two users immersed in virtual reality experiences within a shared physical tracked space. Using a computer simulation framework, we explore the costs and benefits of splitting available physical space between users versus attempting to algorithmically prevent user-to-user collisions. We also explore fundamental components of collision prevention such as steering the users away from each other, forced stopping, and user re-orientation. Each component was analyzed for the number of potential disruptions to the flow of the virtual experience. We also develop a novel collision prevention algorithm that reduces overall interruptions by 17.6% and collision prevention events by 58.3%. Our results show that sharing space using our collision prevention method is superior to subdividing the tracked space.

Virtual objects are essential for building environments in virtual reality (VR) applications. However, creating photorealistic 3D models is not easy, and handcrafting the detailed 3D model from a real object can be time and labor intensive. An alternative way is to build a structured camera array such as a light-stage to reconstruct the model from a real object. However, these technologies are very expensive and not practical for most users. In this work, we demonstrate a complete end-to-end pipeline for the capture, processing, and rendering of view-dependent 3D models in virtual reality from a single consumer-grade RGB-D camera. The geometry model and the camera trajectories are automatically reconstructed from a RGB-D image sequence captured offline. Based on the HMD position, selected images are used for real-time model rendering. The result of this pipeline is a 3D mesh with view-dependent textures suitable for real-time rendering in virtual reality. Specular reflections and light-burst effects are especially noticeable when users view the objects from different perspectives in a head-tracked environment.

Abstract We demonstrate a system that can generate a photorealistic, interactive 3‐D character from a human subject that is capable of movement, emotion, speech, and gesture in less than 20 min without the need for 3‐D artist intervention or specialized technical knowledge through a near automatic process. Our method uses mostly commodity or off‐the‐shelf hardware. We demonstrate the just‐in‐time use of generating such 3‐D models for virtual and augmented reality, games, simulation, and communication. We anticipate that the inexpensive generation of such photorealistic models will be useful in many venues where a just‐in‐time 3‐D reconstructions of digital avatars that resemble particular human subjects is necessary.

Redirected walking enables the exploration of large virtual environments while requiring only a finite amount of physical space. Unfortunately, in living room sized tracked areas the effectiveness of common redirection algorithms such as Steer-to-Center is very limited. A potential solution is to increase redirection effectiveness by applying two types of perceptual manipulations (curvature and translation gains) simultaneously. This paper investigates how such combination may affect detection thresholds for curvature gain. To this end we analyze the estimation methodology and discuss selection process for a suitable estimation method. We then compare curvature detection thresholds obtained under different levels of translation gain using two different estimation methods: method of constant stimuli and Green's maximum likelihood procedure. The data from both experiments shows no evidence that curvature gain detection thresholds were affected by the presence of translation gain (with test levels spanning previously estimated interval of undetectable translation gain levels). This suggests that in practice currently used levels of translation and curvature gains can be safely applied simultaneously. Furthermore, we present some evidence that curvature detection thresholds may be lower that previously reported. Our estimates indicate that users can be redirected on a circular arc with radius of either 11.6m or 6.4m depending on the estimation method vs. the previously reported value of 22m. These results highlight that the detection threshold estimates vary significantly with the estimation method and suggest the need for further studies to define efficient and reliable estimation methodology.

Creating and animating realistic 3D human faces is an important element of virtual reality, video games, and other areas that involve interactive 3D graphics. In this paper, we propose a system to generate photorealistic 3D blendshape-based face models automatically using only a single consumer RGB-D sensor. The capture and processing requires no artistic expertise to operate, takes 15 seconds to capture and generate a single facial expression, and approximately 1 minute of processing time per expression to transform it into a blendshape model. Our main contributions include a complete end-to-end pipeline for capturing and generating photorealistic blendshape models automatically and a registration method that solves dense correspondences between two face scans by utilizing facial landmarks detection and optical flows. We demonstrate the effectiveness of the proposed method by capturing different human subjects with a variety of sensors and puppeteering their 3D faces with real-time facial performance retargeting. The rapid nature of our method allows for just-in-time construction of a digital face. To that end, we also integrated our pipeline with a virtual reality facial performance capture system that allows dynamic embodiment of the generated faces despite partial occlusion of the user's real face by the head-mounted display.

We are pleased to present the technical papers for the 2016 IEEE Virtual Reality Conference (IEEE VR 2016), held March 19–23, 2016, in Greenville, South Carolina, USA.

Redirected walking algorithms require the prediction of human motion in order to effectively steer users away from the boundaries of the physical space. While a virtual walking trajectory may be represented using straight lines connecting waypoints of interest, this simple model does not accurately represent typical user behavior. In this poster we present a more realistic walking model for use in real-time virtual environments that employ redirection techniques. We implemented the model within a framework that can be used for simulation of redirected walking within different virtual and physical environments. Such simulations are useful for the evaluation of redirected walking algorithms and the tuning of parameters under varying conditions. Additionally, the model can also be used to animate an artificial humanoid “ghost walker” to provide a visual demonstration of redirected walking in virtual reality.

Redirection techniques allow users to explore large virtual environments on foot while remaining within a limited physical space. However, research has primarily focused on redirection through manipulation of the visuals used to represent the virtual environment. We describe a within-subjects study (n=31) exploring if participants' ability to detect differences between real and virtual rotations is influenced by the addition of sound that is spatially aligned with its virtual source. The results revealed similar detection thresholds for conditions involving moving audio, static audio, and no audio. This may be viewed as an indication of visual dominance during scenarios such as the one used for the current study.

Creating and animating a realistic 3D human face has been an important task in computer graphics. The capability of capturing the 3D face of a human subject and reanimate it quickly will find many applications in games, training simulations, and interactive 3D graphics. In this paper, we propose a system to capture photorealistic 3D faces and generate the blendshape models automatically using only a single commodity RGB-D sensor. Our method can rapidly generate a set of expressive facial poses from a single Microsoft Kinect and requires no artistic expertise on the part of the capture subject. The system takes only a matter of seconds to capture and produce a 3D facial pose and only requires 4 minutes of processing time to transform it into a blendshape model. Our main contributions include an end-to-end pipeline for capturing and generating face blendshape models automatically, and a registration method that solves dense correspondences between two face scans by utilizing facial landmark detection and optical flow. We demonstrate the effectiveness of the proposed method by capturing 3D facial models of different human subjects and puppeteering their models in an animation system with real-time facial performance retargeting.

Redirected walking techniques have been introduced to overcome physical limitations for natural locomotion in virtual reality. Although subtle perceptual manipulations are helpful to keep users within relatively small tracked spaces, it is inevitable that users will approach critical boundary limits. Current solutions to this problem involve breaks in presence by introducing distractors, or freezing the virtual world relative to the user's perspective. We propose an approach that integrates into the virtual world narrative to draw users' attention and to cause them to temporarily alter their course to avoid going off bounds. This method ties together unnoticeable translation, rotation, and curvature gains, efficiently reorienting the user while maintaining the user's sense of immersion. We also discuss how this new method can be effectively used in conjunction with other reorientation techniques.

Redirected Walking is technique that leverages human perception characteristics to allow locomotion in virtual environments larger than the tracking area. Among the many redirection techniques, some strictly depend on the user's current position and orientation, while more recent algorithms also depend on the user's predicted behavior. This prediction serves as an input to a computationally expensive search to determine an optimal path. The search output is formulated as a series of gains to be applied at different stages along the path. An example prediction could be if a user is walking down a corridor, a natural prediction would be that the user will walk along a straight line down the corridor, and she will choose one of the possible directions with equal probability. In practice, deviations from the expected virtual path are inevitable, and as a result, the real world path traversed will differ from the original prediction. These deviations can not only force the search to select a less optimal path in the next iteration, but also in cases cause the users to go off bounds, requiring resets, causing a jarring experience for the user. We propose a method to account for these deviations by modifying the redirection gains per update frame, aiming to keep the user on the intended predicted physical path.

Recent advances in scanning technology have enabled the widespread capture of 3D character models based on human subjects. However, in order to generate a recognizable 3D avatar, the movement and behavior of the human subject should be captured and replicated as well. We present a method of generating a 3D model from a scan, as well as a method to incorporate a subjects style of gesturing into a 3D character. We present a study which shows that 3D characters that used the gestural style as their original human subjects were more recognizable as the original subject than those that don't.

Redirected walking techniques enable natural locomotion through immersive virtual environments that are considerably larger than the available real world walking space. However, the most effective strategy for steering the user remains an open question, as most previously presented algorithms simply redirect toward the center of the physical space. In this work, we present a theoretical framework that plans a walking path through a virtual environment and calculates the parameters for combining translation, rotation, and curvature gains such that the user can traverse a series of defined waypoints efficiently based on a utility function. This function minimizes the number of overt reorientations to avoid introducing potential breaks in presence. A notable advantage of this approach is that it leverages knowledge of the layout of both the physical and virtual environments to enhance the steering strategy.

The USC Institute for Creative Technologies will demonstrate a pipline for automatic reconstruction and animation of lifelike 3D avatars acquired by rotating the user's body in front of a single Microsoft Kinect sensor. Based on a fusion of state-of-the-art techniques in computer vision, graphics, and animation, this approach can produce a fully rigged character model suitable for real-time virtual environments in less than four minutes.

Consumer adoption of virtual reality technology has historically been held back by poor accessibility, the lack of intuitive multi-user capabilities, dependence on external infrastructure for rendering and tracking, and the amount of time and effort required to enter virtual reality systems. This poster presents the current status of our work creating MuVR, a Multi-User Virtual Reality platform that seeks to overcome these hindrances. The MuVR project comprises four main goals: scalable and easy to use multi-user capabilities, portable and self-contained hardware, a rapidly deployable system, and ready accessibility to others. We provide a description of the platform we developed to address these goals and discuss potential directions for future work.

ABSTRACT We demonstrate a method of acquiring a 3D model of a human using commodity scanning hardware and then controlling that 3D figure in a simulated environment in only a few minutes. The model acquisition requires four static poses taken at 90° angles relative to each other. The 3D model is then given a skeleton and smooth binding information necessary for control and simulation. The 3D models that are captured are suitable for use in applications where recognition and distinction among characters by shape, form, or clothing is important, such as small group or crowd simulations or other socially oriented applications. Because of the speed at which a human figure can be captured and the low hardware requirements, this method can be used to capture, track, and model human figures as their appearances change over time. Copyright © 2014 John Wiley & Sons, Ltd.

Summary form only given. The ICT Mixed Reality Lab will demonstrate a pipeline for rapidly generating personalized avatars from multiple depth and RGB scans of a user with a consumer level sensor such as a Microsoft Kinect. Based on a fusion of state-of-the-art techniques in graphics, surface reconstruction, and animation, our semi-automatic method can produce a fully rigged, skinned, and textured character model suitable for real-time virtual environments in less than 15 minutes. First, a 3D point cloud is collected from the sensor using a simultaneous localization and mapping (SLAM) approach to track the device's movements over time (see Figure 1.a). Next, surface reconstruction techniques are employed to generate a watertight 3D mesh from the raw 3D points (see Figure 1.b). The resulting model is then analyzed to determine the human joint locations, and if a skeleton can be successfully generated for the model, the mesh is then rigged and skinned using weights that are calculated automatically [2]. Finally, photos captured periodically during the scanning process using the sensor's RGB camera are used to texture the final model. The resulting avatar is suitable for real-time animation using a virtual environment or video game engine (see Figure 1.c). We will demonstrate our avatar generation pipeline at IEEE Virtual Reality 2013. Conference attendees may opt to be scanned, and their generated avatar will be provided to them either on a USB stick or through email. A video of this demo can be found at the MxR Lab website [1].

In this paper we introduce the concept of flexible spaces - a novel redirection technique that generalizes the use of overlapping (impossible) spaces and change blindness in an algorithm for dynamic layout generation. Flexible spaces is an impossible environment that violates the real world constancy in favor of providing the experience of seamless, unrestricted natural walking over a large-scale virtual environment (VE).

As wider field-of-view displays become more common, the question arises as to whether or not data collected on these displays are comparable to those collected with smaller field-of-view displays. This document describes a pilot study that aimed to address these concerns by comparing medium-field distance judgments in a 60° FOV display, a 150° FOV display, and a simulated 60° FOV within the 150° FOV display. The results indicate that participants performed similarly in both the actual and simulated 60° FOV displays. On average, participants in the 150° FOV display improved distance judgments by 13% over the 60° FOV displays.

We describe two approaches for unobtrusively sensing subtle nonverbal behaviors using a consumer-level depth sensing camera. The first signal, respiratory rate, is estimated by measuring the visual expansion and contraction of the user's chest cavity during inhalation and exhalation. Additionally, we detect a specific type of fidgeting behavior, known as “leg jiggling,” by measuring high-frequency vertical oscillations of the user's knees. Both of these techniques rely on the combination of skeletal tracking information with raw depth readings from the sensor to identify the cyclical patterns in jittery, low-resolution data. Such subtle nonverbal signals may be useful for informing models of users' psychological states during communication with virtual human agents, thereby improving interactions that address important societal challenges in domains including education, training, and medicine.

Thin computing clients, such as smartphones and tablets, have exhibited recent growth in display resolutions, processing power, and graphical rendering speeds. In this poster, we show how we leveraged these trends to create virtual reality (VR) training games which run entirely on a commodity mobile computing platform. This platform consists of a commercial off-the-shelf game engine, commodity smartphones, and mass produced optics. The games utilize the strengths of this platform to provide immersive features like 360 degree photo panoramas and interactive 3D virtual scenes. By sharing information about building such applications, we hope to enable others to develop new types of mobile VR applications. In particular, we feel this system is ideally suited for casual “pick up and use” VR applications for collaborative classroom learning, design reviews, and other multi-user immersive experiences.

Our demonstration will exhibit a number of low cost virtual reality systems built using smartphones, inexpensive optics, and game engine software. These systems will demonstrate how VR researchers and developers can leverage current trends in commodity hardware and software to bring virtual reality to a wider audience. This demonstration dovetails with the Workshop on Off-the-Shelf Virtual Reality (OTSVR), which we will also be organizing at the VR conference. The Mixed Reality Lab at the USC Institute for Creative Technologies works to advance the design and practice of mixed reality and virtual reality. The lab is particularly focused on the research and development of new technologies and techniques to enhance immersion and interaction for learning and training.

Using video games in rehabilitation settings has the potential to provide patients with fun and motivating exercise tools. Within the Medical VR and MxR groups at the USC Institute for Creative Technologies, we have been leveraging the technology of the Microsoft Kinect 3D depth-sensing camera. Our Kinect-based rehabilitation game “JewelMine” consists of a set of static balance training exercises which encourage the players to reach out of their base of support. We plan to demonstrate a sophisticated post-session analysis tool and several content themes which can be changed dynamically during a therapy session.

Natural walking can provide a compelling experience in immersive virtual environments, but it remains an implementation challenge due to the physical space constraints imposed on the size of the virtual world. The use of redirection techniques is a promising approach that relaxes the space requirements of natural walking by manipulating the user's route in the virtual environment, causing the real world path to remain within the boundaries of the physical workspace. In this paper, we present and apply a novel taxonomy that separates redirection techniques according to their geometric flexibility versus the likelihood that they will be noticed by users. Additionally, we conducted a user study of three reorientation techniques, which confirmed that participants were less likely to experience a break in presence when reoriented using the techniques classified as subtle in our taxonomy. Our results also suggest that reorientation with change blindness illusions may give the impression of exploring a more expansive environment than continuous rotation techniques, but at the cost of negatively impacting spatial knowledge acquisition.

Walking is only possible within immersive virtual environments that fit inside the boundaries of the user's physical workspace. To reduce the severity of the restrictions imposed by limited physical area, we introduce "impossible spaces," a new design mechanic for virtual environments that wish to maximize the size of the virtual environment that can be explored with natural locomotion. Such environments make use of self-overlapping architectural layouts, effectively compressing comparatively large interior environments into smaller physical areas. We conducted two formal user studies to explore the perception and experience of impossible spaces. In the first experiment, we showed that reasonably small virtual rooms may overlap by as much as 56% before users begin to detect that they are in an impossible space, and that the larger virtual rooms that expanded to maximally fill our available 9.14 m x 9.14 m workspace may overlap by up to 31%. Our results also demonstrate that users perceive distances to objects in adjacent overlapping rooms as if the overall space was uncompressed, even at overlap levels that were overtly noticeable. In our second experiment, we combined several well-known redirection techniques to string together a chain of impossible spaces in an expansive outdoor scene. We then conducted an exploratory analysis of users' verbal feedback during exploration, which indicated that impossible spaces provide an even more powerful illusion when users are naive to the manipulation.

Thin computing clients, such as smartphones and tablets, have experienced recent growth in display resolutions and graphics processing power. In this poster, we show how to leverage these trends to create an experimental wide field of view, 3D stereoscopic head mounted display (HMD), based on two high resolution smart-phones. This HMD prototype is unique in that the graphics system is entirely onboard, allowing it to be lightweight, wireless, and convenient to use.

We present change blindness redirection, a novel technique for allowing the user to walk through an immersive virtual environment that is considerably larger than the available physical workspace. In contrast to previous redirection techniques, this approach, based on a dynamic environment model, does not introduce any visual-vestibular conflicts from manipulating the mapping between physical and virtual motions, nor does it require breaking presence to stop and explicitly reorient the user. We conducted two user studies to evaluate the effectiveness of the change blindness illusion when exploring a virtual environment that was an order of magnitude larger than the physical walking space. Despite the dynamically changing environment, participants were able to draw coherent sketch maps of the environment structure, and pointing task results indicated that they were able to maintain their spatial orientation within the virtual world. Only one out of 77 participants across both both studies definitively noticed that a scene change had occurred, suggesting that change blindness redirection provides a remarkably compelling illusion. Secondary findings revealed that a wide field-of-view increases pointing accuracy and that experienced gamers reported greater sense of presence than those with little or no experience with 3D video games.

The Flexible Action and Articulated Skeleton Toolkit (FAAST) is middleware to facilitate integration of full-body control with virtual reality applications and video games using OpenNI-compliant depth sensors (currently the PrimeSensor and the Microsoft Kinect). FAAST incorporates a VRPN server for streaming the user's skeleton joints over a network, which provides a convenient interface for custom virtual reality applications and games. This body pose information can be used for goals such as realistically puppeting a virtual avatar or controlling an on-screen mouse cursor. Additionally, the toolkit also provides a configurable input emulator that detects human actions and binds them to virtual mouse and keyboard commands, which are sent to the actively selected window. Thus, FAAST can enable natural interaction for existing off-the-shelf video games that were not explicitly developed to support input from motion sensors. The actions and input bindings are configurable at run-time, allowing the user to customize the controls and sensitivity to adjust for individual body types and preferences. In the future, we plan to substantially expand FAAST's action lexicon, provide support for recording and training custom gestures, and incorporate real-time head tracking using computer vision techniques.

Children with autism show substantial benefits from rigorous physical activity, however it is often difficult to motivate these individuals to exercise due to their usually sedentary lifestyles. To address the problem of motivation, we have developed Astrojumper, a stereoscopic virtual reality exergame which was designed to fit the needs of children with autism. During the game, virtual space-themed objects fly forward toward the user who must use their own physical movements to avoid collisions. Preliminary playtesting of Astrojumper on neuro-typical participants has been positive, and we plan to run an extensive evaluation assessing the psychological and physiological effects of this system on children with and without autism.

We present a technique for exploiting change blindness to allow the user to walk through an immersive virtual environment that is much larger than the available physical workspace. This approach relies on subtle manipulations to the geometry of a dynamic environment model to redirect the user's walking path without becoming noticeable. We describe a virtual environment which was implemented both as a proof-of-concept and a test case for future evaluation. Anecdotal evidence from our informal tests suggest a compelling illusion, though a formal study against existing methods is required to evaluate the usefulness of this technique.

We report a series of experiments conducted to investigate the effects of travel technique on information gathering and cognition in complex virtual environments. In the first experiment, participants completed a non-branching multilevel 3D maze at their own pace using either real walking or one of two virtual travel techniques. In the second experiment, we constructed a real-world maze with branching pathways and modeled an identical virtual environment. Participants explored either the real or virtual maze for a predetermined amount of time using real walking or a virtual travel technique. Our results across experiments suggest that for complex environments requiring a large number of turns, virtual travel is an acceptable substitute for real walking if the goal of the application involves learning or reasoning based on information presented in the virtual world. However, for applications that require fast, efficient navigation or travel that closely resembles real-world behavior, real walking has advantages over common joystick-based virtual travel techniques.

This paper presents the design of the final stage of a new game currently in development, entitled cMotion, which will use virtual humans to teach emotion recognition and programming concepts to children. Having multiple facets, cMotion is designed to teach the intended users how to recognize facial expressions and manipulate an interactive virtual character using a visual drag-and-drop programming interface. By creating a game which contextualizes emotions, we hope to foster learning of both emotions in a cultural context and computer programming concepts in children. The game will be completed in three stages which will each be tested separately: a playable introduction which focuses on social skills and emotion recognition, an interactive interface which focuses on computer programming, and a full game which combines the first two stages into one activity.

We report on a study in which we investigate the effects of travel technique on simulator sickness in a real and virtual environment. Participants explored either a real maze or a virtual maze using either natural walking or simulated walking. Reported scores for measures of overall simulator sickness, disorientation, nausea, and occulomotor discomfort were all higher in the natural walking condition than either the simulated walking or real world conditions. This indicates that simulated walking is a better choice for reducing simulator sickness during tasks requiring a navigationally complex environment and a long amount of time.

We investigated the effects of using immersive virtual humans to teach users social conversational verbal and non-verbal protocols in south Indian culture. The study was conducted using a between-subjects experimental design, and compared instruction and interactive feedback from immersive virtual humans against instruction based on a written study guide with illustrations of the social protocols. Participants were then tested on how well they learned the social conversational protocols by exercising the social conventions in front of videos of real people. The results of our study suggest that participants who trained with the virtual humans performed significantly better than the participants who studied from literature.

In this paper, we describe our current work in developing a computer-based educational tool for Occupational Therapy students learning client evaluation techniques. The software is dialog-based and allows the student to interact with a virtual client. Students carry out an evaluation, following the appropriate procedures and assessing both the client's physical and emotional state as they proceed. Students' actions are saved to a file for instructor and self evaluation of their performance. The software is being developed using the Source® game engine SDK developed by Valve™.