Natural Walking in Virtual Reality:A Review

Recent technological developments have finally brought virtual reality (VR) out of the laboratory and into the hands of developers and consumers. However, a number of challenges remain. Virtual travel is one of the most common and universal tasks performed inside virtual environments, yet enabling users to navigate virtual environments is not a trivial challenge—especially if the user is walking. In this article, we initially provide an overview of the numerous virtual travel techniques that have been proposed prior to the commercialization of VR. Then we turn to the mode of travel that is the most difficult to facilitate, that is, walking. The challenge of providing users with natural walking experiences in VR can be divided into two separate, albeit related, challenges: (1) enabling unconstrained walking in virtual worlds that are larger than the tracked physical space and (2) providing users with appropriate multisensory stimuli in response to their interaction with the virtual environment. In regard to the first challenge, we present walking techniques falling into three general categories: repositioning systems, locomotion based on proxy gestures, and redirected walking. With respect to multimodal stimuli, we focus on how to provide three types of information: external sensory information (visual, auditory, and cutaneous), internal sensory information (vestibular and kinesthetic/proprioceptive), and efferent information. Finally, we discuss how the different categories of walking techniques compare and discuss the challenges still facing the research community.</jats:p

Freehand-Steering Locomotion Techniques for Immersive Virtual Environments: A Comparative Evaluation

Virtual reality has achieved significant popularity in recent years, and allowing users to move freely within an immersive virtual world has become an important factor critical to realize. The user’s interactions are generally designed to increase the perceived realism, but the locomotion techniques and how these affect the user’s task performance still represent an open issue, much discussed in the literature. In this article, we evaluate the efficiency and effectiveness of, and user preferences relating to, freehand locomotion techniques designed for an immersive virtual environment performed through hand gestures tracked by a sensor placed in the egocentric position and experienced through a head-mounted display. Three freehand locomotion techniques have been implemented and compared with each other, and with a baseline technique based on a controller, through qualitative and quantitative measures. An extensive user study conducted with 60 subjects shows that the proposed methods have a performance comparable to the use of the controller, further revealing the users’ preference for decoupling the locomotion in sub-tasks, even if this means renouncing precision and adapting the interaction to the possibilities of the tracker sensor

Improving spatial orientation in virtual reality with leaning-based interfaces

Advancement in technology has made Virtual Reality (VR) increasingly portable, affordable and accessible to a broad audience. However, large scale VR locomotion still faces major challenges in the form of spatial disorientation and motion sickness. While spatial updating is automatic and even obligatory in real world walking, using VR controllers to travel can cause disorientation. This dissertation presents two experiments that explore ways of improving spatial updating and spatial orientation in VR locomotion while minimizing cybersickness. In the first study, we compared a hand-held controller with HeadJoystick, a leaning-based interface, in a 3D navigational search task. The results showed that leaning-based interface helped participant spatially update more effectively than when using the controller. In the second study, we designed a "HyperJump" locomotion paradigm which allows to travel faster while limiting its optical flow. Not having any optical flow (as in traditional teleport paradigms) has been shown to help reduce cybersickness, but can also cause disorientation. By interlacing continuous locomotion with teleportation we showed that user can travel faster without compromising spatial updating

가상현실에서 몸의 자세와 공간인지, 공간이동방법, 존재감, 사이버멀미의 상호작용에 대한 연구

학위논문 (박사) -- 서울대학교 대학원 : 인문대학 협동과정 인지과학전공, 2021. 2. 이경민.가상현실은 몸과 마음이 공간에 함께 존재한다는 일상적 경험에 대해 새로운 관점을 제시한다. 컴퓨터로 매개된 커뮤니케이션에서 많은 경우 사용자들은 몸은 배제되며 마음의 존재가 중요하다고 느끼게 된다. 이와 관련하여 가상현실은 사용자들에게 커뮤니케이션에 있어 물리적 몸의 역할과 비체화된 상호작용의 중요성에 대해 연구할 수 있는 기회를 제공한다. 기존 연구에 의하면 실행, 주의집중, 기억, 지각과 같은 인지기능들이 몸의 자세에 따라 다르게 작용한다고 한다. 하지만 이와 같은 인지기능들과 몸 자세의 상호연관성은 여전히 명확히 밝혀지고 있지 않다. 특히 가상현실에서 몸의 자세가 지각반응에 대한 인지과정에 어떤 작용을 하는지에 대한 이해는 매우 부족한 상황이다. 가상현실 연구자들은 존재감을 가상현실의 핵심 개념으로 정의하였으며 효율적인 가상현실 시스템 구성과 밀접한 관계가 있다고 한다. 존재감은 가상공간에 있다고 느끼는 의식상태를 말한다. 구체적으로 가상현실 속 경험을 실재 존재한다고 느끼는 의식상태를 말한다. 이런 존재감이 높을 수록 현실처럼 인지하기에 존재감은 가상현실 경험을 측정하는 중요한 지표이다. 따라서 가상공간에 존재하고 있다는 의식적 경험 ((거기에 있다(being there)), 즉 존재감은 매개된 가상경험들의 인지 연구에 중요한 개념이다. 가상현실은 사이버멀미를 유발하는 것으로 알려져 있다. 이 증상은 가상현실의 사용성을 제약하는 주요 요인으로 효과적인 가상현실 경험을 위해 사이버멀미에 대한 다양한 연구가 필요하다. 사이버멀미는 가상현실 시스템을 사용할때 나타나며 어지러움, 방향상실, 두통, 땀흘림, 눈피로도등의 증상을 포함한다. 이런 사이버멀미에는 개인차, 사용된 기술, 공간디자인, 수행된 업무등 매우 다양 요인들이 관여하고 있어 명확한 원인을 규정할 수 없다. 이런 배경으로 인해 사이버멀미 저감과 관련한 다양한 연구들이 필요하며 이는 가상현실 발전에 중요한 의미를 갖는다. 공간인지는 3차원 공간에서 신체 움직임과 대상과의 상호작용에 중요한 역할을 하는 인지시스템이다. 가상공간에서 신체 움직임은 네비게이션, 사물조작, 다른 에이전트들과 상호작용에 관여한다. 특히 가상공간에서 네비게이션은 자주 사용되는 중요한 상호작용 방식이다. 이에 가상공간을 네비게이션 할때 존재감에 영향을 주지 않고 멀미증상을 유발하지 않는 효과적인 공간이동 방법에 대한 다양한 연구들이 이루어지고 있다. 이전 연구들에 의하면 시점이 존재감과 체화감에 영향을 준다고 한다. 이는 시점에 따라 사용자의 행동과 대상들과의 상호작용 방식에 달라지기 때문이다. 따라서 가상공간에서 경험 또한 시점에 따라 달라진다. 이런 배경으로 몸의 자세, 공간인지, 이동방법, 존재감, 사이버멀미의 상호 연관성에 대한 연구를 시점에 따라 분류해서 연구할 필요가 있다. 이를 통해 가상현실 속 공간 네비게이션에 대한 인지과정을 보다 다각적으로 이해 할 수 있을 것이다. 그동안 존재감과 사이버 멀미에 내재된 매커니즘을 이해하기 위해 다양한 연구들이 진행되어 왔다. 하지만 몸의 자세에 따른 인지작용이 존재감과 사이버멀미에 어떤 영향을 주는지에 대한 연구는 거의 이루어지지 않았다. 이에 본 학위논문에서는 1인칭과 3인칭 시점으로 분류된 별도의 실험과 연구를 진행하여 가상현실에서 몸의 자세와 공간인지, 공간이동방법, 존재감, 사이버멀미의 상호연관성을 보다 심층적으로 이해하고자 한다. 제3장에서는 3인칭시점의 실험과 결과에 대한 내용을 기술했다. 3인칭시점 실험에서는 가상공간에서 몸의 자세와 존재감의 상호연관성 연구를 위해 세가지 몸의 자세 (서있는 자세, 앉은 자세, 다리를 펴고 앉은 자세)와 2가지 타입의 공간이동 자유도 (무한, 유한)를 상호 비교했다. 실험결과에 의하면 공간이동 자유도가 무한한 경우 서있는 자세에서 존재감이 높게 나타났다. 추가적으로 가상공간에서 몸의 자세와 존재감은 공간이동자유도와 관련이 있는 것으로 나타났으며 여러 인지기능 중 주의집중이 몸의 자세, 존재감, 공간인지의 통합적 상호작용을 이끌어 낸 것으로 파악되었다. 3인칭시점의 결과들을 종합해 보면 몸 자세의 인지적 영향은 공간이동자유도와 상관관계가 있는 것으로 추측할 수 있다. 제4장에서는 1인칭시점의 실험과 결과에 대한 내용을 기술했다. 1인칭시점 실험에서는 가상공간에서 몸의 자세, 공간이동방법, 존재감, 사이버멀미의 상호연관성 연구를 위해 두 조건의 몸의 자세 (서있는 자세, 앉아 있는 자세)와 네가지 타입의 이동방법 (스티어링 + 몸을 활용한 회전, 스티어링 + 도구를 활용한 회전, 텔레포테이션 + 몸을 이용한 회전, 텔레포테이션 + 도구를 활용한 회전)의 상호 비교가 이루어 졌다. 실험결과에 의하면 위치이동방식과 회전방식에 따른 공간이동자유도는 성공적인 네비게이션과 관련이 있으며 존재감에 영향을 주는 것으로 나타났다. 추가적으로 연속적으로 시각정보가 입력되는 스티어링 방법은 자가운동을 높여 비연속적 방법인 텔레포테이션보다 사이버멀미를 더 유발하는 것으로 나타났다. 1인칭시점의 결과들을 종합해 보면 가상공간에서 네비게이션을 할때 존재감과 사이버멀미는 공간이동방법과 관련이 있는 것으로 가정할 수 있다. 제3장의 3인칭 시점 실험결과에 의하면 몸의 자세와 존재감은 상관관계가 있는 것으로 제시되었다. 반면 제4장의 실험결과에 의하면 1인칭시점으로 가상공간을 네비게이션 할 때는 공간이동방법이 존재감과 사이버멀미에 영향을 주는 것으로 나타났다. 이 두 실험에 대한 연구 결과를 통해 가상현실에서 몸의 자세와 공간인지 (네비게이션)의 상호연관성에 대한 이해를 확대하고 존재감 및 사이버멀미와 공간이동방법의 관련성을 밝힐 수 있을 것으로 기대한다.Immersive virtual environments (VEs) can disrupt the everyday connection between where our senses tell us we are and where we are actually located. In computer-mediated communication, the user often comes to feel that their body has become irrelevant and that it is only the presence of their mind that matters. However, virtual worlds offer users an opportunity to become aware of and explore both the role of the physical body in communication, and the implications of disembodied interactions. Previous research has suggested that cognitive functions such as execution, attention, memory, and perception differ when body position changes. However, the influence of body position on these cognitive functions is still not fully understood. In particular, little is known about how physical self-positioning may affect the cognitive process of perceptual responses in a VE. Some researchers have identified presence as a guide to what constitutes an effective virtual reality (VR) system and as the defining feature of VR. Presence is a state of consciousness related to the sense of being within a VE; in particular, it is a ‘psychological state in which the virtuality of the experience is unnoticed’. Higher levels of presence are considered to be an indicator of a more successful media experience, thus the psychological experience of ‘being there’ is an important construct to consider when investigating the association between mediated experiences on cognition. VR is known to induce cybersickness, which limits its application and highlights the need for scientific strategies to optimize virtual experiences. Cybersickness refers to the sickness associated with the use of VR systems, which has a range of symptoms including nausea, disorientation, headaches, sweating and eye strain. This is a complicated problem because the experience of cybersickness varies greatly between individuals, the technology being used, the design of the environment, and the task being performed. Thus, avoiding cybersickness represents a major challenge for VR development. Spatial cognition is an invariable precursor to action because it allows the formation of the necessary mental representations that code the positions of and relationships among objects. Thus, a number of bodily actions are represented mentally within a depicted VR space, including those functionally related to navigation, the manipulation of objects, and/or interaction with other agents. Of these actions, navigation is one of the most important and frequently used interaction tasks in VR environments. Therefore, identifying an efficient locomotion technique that does not alter presence nor cause motion sickness has become the focus of numerous studies. Though the details of the results have varied, past research has revealed that viewpoint can affect the sense of presence and the sense of embodiment. VR experience differs depending on the viewpoint of a user because this vantage point affects the actions of the user and their engagement with objects. Therefore, it is necessary to investigate the association between body position, spatial cognition, locomotion method, presence, and cybersickness based on viewpoint, which may clarify the understanding of cognitive processes in VE navigation. To date, numerous detailed studies have been conducted to explore the mechanisms underlying presence and cybersickness in VR. However, few have investigated the cognitive effects of body position on presence and cybersickness. With this in mind, two separate experiments were conducted in the present study on viewpoint within VR (i.e., third-person and first-person perspectives) to further the understanding of the effects of body position in relation to spatial cognition, locomotion method, presence, and cybersickness in VEs. In Chapter 3 (Experiment 1: third-person perspective), three body positions (standing, sitting, and half-sitting) were compared in two types of VR game with a different degree of freedom in navigation (DFN; finite and infinite) to explore the association between body position and the sense of presence in VEs. The results of the analysis revealed that standing has the most significant effect on presence for the three body positions that were investigated. In addition, the outcomes of this study indicated that the cognitive effect of body position on presence is associated with the DFN in a VE. Specifically, cognitive activity related to attention orchestrates the cognitive processes associated with body position, presence, and spatial cognition, consequently leading to an integrated sense of presence in VR. It can thus be speculated that the cognitive effects of body position on presence are correlated with the DFN in a VE. In Chapter 4 (Experiment 2: first-person perspective), two body positions (standing and sitting) and four types of locomotion method (steering + embodied control [EC], steering + instrumental control [IC], teleportation + EC, and teleportation + IC) were compared to examine the relationship between body position, locomotion method, presence, and cybersickness when navigating a VE. The results of Experiment 2 suggested that the DFN for translation and rotation is related to successful navigation and affects the sense of presence when navigating a VE. In addition, steering locomotion (continuous motion) increases self-motion when navigating a VE, which results in stronger cybersickness than teleportation (non-continuous motion). Overall, it can be postulated that presence and cybersickness are associated with the method of locomotion when navigating a VE. In this dissertation, the overall results of Experiment 1 suggest that the cognitive influence of presence is body-dependent in the sense that mental and brain processes rely on or are affected by the physical body. On the other hand, the outcomes of Experiment 2 illustrate the significant effects of locomotion method on the sense of presence and cybersickness during VE navigation. Taken together, the results of this study provide new insights into the cognitive effects of body position on spatial cognition (i.e., navigation) in VR and highlight the important implications of locomotion method on presence and cybersickness in VE navigation.Chapter 1. Introduction 1 1.1. An Introductory Overview of the Conducted Research 1 1.1.1. Presence and Body Position 1 1.1.2. Navigation, Cybersickness, and Locomotion Method 3 1.2. Research Objectives 6 1.3. Research Experimental Approach 7 Chapter 2. Theoretical Background 9 2.1. Presence 9 2.1.1. Presence and Virtual Reality 9 2.1.2. Presence and Spatiality 10 2.1.3. Presence and Action 12 2.1.4. Presence and Attention 14 2.2. Body Position 16 2.2.1. Body Position and Cognitive Effects 16 2.2.2. Body Position and Postural Control 18 2.2.3. Body Position and Postural Stability 19 2.3. Spatial Cognition: Degree of Freedom in Navigation 20 2.3.1. Degree of Freedom in Navigation and Decision-Making 20 2.4. Cybersickness 22 2.4.1. Cybersickness and Virtual Reality 22 2.4.2. Sensory Conflict Theory 22 2.4.3. Postural Instability Theory 23 2.5. Self-Motion 25 2.5.1. Vection and Virtual Reality 25 2.5.2. Self-Motion and Navigation in a VE 27 2.6. Navigation in Virtual Environments 29 2.6.1. Translation and Rotation in Navigation 29 2.6.2. Spatial Orientation and Embodiment 32 2.6.3. Locomotion Methods 37 2.6.4. Steering and Teleportation 38 Chapter 3. Experiment 1: Third-Person Perspective 40 3.1. Quantification of the Degree of Freedom in Navigation 40 3.2. Experiment 3.2.1. Experimental Design and Participants 41 3.2.2. Stimulus Materials 42 3.2.2.1. First- and Third-person Perspectives in Gameplay 43 3.2.3. Experimental Setup and Process 44 3.2.4. Measurements 45 3.3. Results 45 3.3.1. Presence: two-way ANOVA 45 3.3.2. Presence: one-way ANOVA 46 3.3.2.1. Finite Navigation Freedom 46 3.3.2.2. Infinite Navigation Freedom 47 3.3.3. Summary of the Results 48 3.4. Discussion 49 3.4.1. Presence and Body Position 49 3.4.2. Degree of Freedom in Navigation and Decision-Making 50 3.4.3. Gender Difference and Gameplay 51 3.5. Limitations 52 Chapter 4. Experiment 2: First-Person Perspective 53 4.1. Experiment 53 4.1.1. Experimental Design and Participants 53 4.1.2. Stimulus Materials 54 4.1.3. Experimental Setup and Process 55 4.1.4. Measurements 56 4.2. Results 57 4.2.1. Presence: two-way ANOVA 58 4.2.2. Cybersickness: two-way ANOVA 58 4.2.3. Presence: one-way ANOVA 60 4.2.3.1. Standing Position 60 4.2.3.2. Sitting Position 60 4.2.4. Cybersickness: one-way ANOVA 62 4.2.4.1. Standing Position 62 4.2.4.2. Sitting Position 62 4.2.5. Summary of the Results 63 4.3. Discussion 65 4.3.1. Presence 4.3.1.1. Presence and Locomotion Method 66 4.3.1.2. Presence and Body Position 68 4.3.2. Cybersickness 4.3.2.1. Cybersickness and Locomotion Method 69 4.3.2.2. Cybersickness and Body Position 70 4.4. Limitations 71 Chapter 5. Conclusion 72 5.1. Summary of Findings 72 5.2. Future Research Direction 73 References 75 Appendix A 107 Appendix B 110 국문초록 111Docto

Towards Naturalistic Interfaces of Virtual Reality Systems

Interaction plays a key role in achieving realistic experience in virtual reality (VR). Its realization depends on interpreting the intents of human motions to give inputs to VR systems. Thus, understanding human motion from the computational perspective is essential to the design of naturalistic interfaces for VR. This dissertation studied three types of human motions, including locomotion (walking), head motion and hand motion in the context of VR. For locomotion, the dissertation presented a machine learning approach for developing a mechanical repositioning technique based on a 1-D treadmill for interacting with a unique new large-scale projective display, called the Wide-Field Immersive Stereoscopic Environment (WISE). The usability of the proposed approach was assessed through a novel user study that asked participants to pursue a rolling ball at variable speed in a virtual scene. In addition, the dissertation studied the role of stereopsis in avoiding virtual obstacles while walking by asking participants to step over obstacles and gaps under both stereoscopic and non-stereoscopic viewing conditions in VR experiments. In terms of head motion, the dissertation presented a head gesture interface for interaction in VR that recognizes real-time head gestures on head-mounted displays (HMDs) using Cascaded Hidden Markov Models. Two experiments were conducted to evaluate the proposed approach. The first assessed its offline classification performance while the second estimated the latency of the algorithm to recognize head gestures. The dissertation also conducted a user study that investigated the effects of visual and control latency on teleoperation of a quadcopter using head motion tracked by a head-mounted display. As part of the study, a method for objectively estimating the end-to-end latency in HMDs was presented. For hand motion, the dissertation presented an approach that recognizes dynamic hand gestures to implement a hand gesture interface for VR based on a static head gesture recognition algorithm. The proposed algorithm was evaluated offline in terms of its classification performance. A user study was conducted to compare the performance and the usability of the head gesture interface, the hand gesture interface and a conventional gamepad interface for answering Yes/No questions in VR. Overall, the dissertation has two main contributions towards the improvement of naturalism of interaction in VR systems. Firstly, the interaction techniques presented in the dissertation can be directly integrated into existing VR systems offering more choices for interaction to end users of VR technology. Secondly, the results of the user studies of the presented VR interfaces in the dissertation also serve as guidelines to VR researchers and engineers for designing future VR systems

Virtual reality and body rotation: 2 flight experiences in comparison

Embodied interfaces, represented by devices that incorporate bodily motion and proprioceptive stimulation, are promising for Virtual Reality (VR) because they can improve immersion and user experience while at the same time reducing simulator sickness compared to more traditional handheld interfaces (e.g.,gamepads). The aim of the study is to evaluate a novel embodied interface called VitruvianVR. The machine is composed of two separate rings that allow its users to bodily rotate onto three different axes. The suitability of the VitruvianVR was tested in a Virtual Reality flight scenario. In order to reach the goal we compared the VitruvianVR to a gamepad using perfomance measures (i.e., accuracy, fails), head movements and position of the body. Furthermore, a series of data coming from questionnaires about sense of presence, user experience, cognitive load, usability and cybersickness was retrieved.Embodied interfaces, represented by devices that incorporate bodily motion and proprioceptive stimulation, are promising for Virtual Reality (VR) because they can improve immersion and user experience while at the same time reducing simulator sickness compared to more traditional handheld interfaces (e.g.,gamepads). The aim of the study is to evaluate a novel embodied interface called VitruvianVR. The machine is composed of two separate rings that allow its users to bodily rotate onto three different axes. The suitability of the VitruvianVR was tested in a Virtual Reality flight scenario. In order to reach the goal we compared the VitruvianVR to a gamepad using perfomance measures (i.e., accuracy, fails), head movements and position of the body. Furthermore, a series of data coming from questionnaires about sense of presence, user experience, cognitive load, usability and cybersickness was retrieved