Movement In Virtual Environment Research Articles

User elicited gesture-based locomotion techniques for immersive VEs in a seated position: a comparative evaluation

Locomotion is a fundamental task for exploring and interacting in virtual environments (VEs), and numerous locomotion techniques have been developed to improve the perceived realism and efficiency of movement in VEs. Gesture-based locomotion techniques have emerged as a more natural and intuitive mode of interaction than controller-based methods of travel in VEs. In this paper, we investigate the intuitiveness, comfort, ease of use, performance, presence, simulation sickness, and user preference of three user-elicited body-based gestures: the Calling gesture, Deictic Pointing gesture, and Mirror Leaning gesture. These gestures are intended to be used in three different seated multitasking scenarios involving virtual travel and various levels of hand engagement in selection. In the first study, participants compared the Calling gesture with the Tapping and Teleportation gestures for Scenario 1, which involved virtual travel only. The Calling gesture was found to be the most intuitive, with increased presence, while the Teleportation gesture was the preferred travel technique. The second study involved participants comparing the Deictic Pointing gesture with the Tapping and Teleportation gestures for Scenario 2, which involved virtual travel and one hand engaged in selection. The Deictic Pointing gesture was found to be more intuitive than the other gestures in terms of performance, comfort, ease of use, and presence. The third study introduced a new group of participants who compared the Mirror Leaning gesture with the Tapping and Teleportation gestures for Scenario 3, which involved virtual travel and both hands engaged in selection. The Mirror Leaning gesture was found to be the most intuitive, with increased presence and performance compared to the other gestures. We compared the gestures of the scenarios in three complementary search tasks: traveling in a straight-line path, moving in a directed path, and moving in an undirected path. We believe that the qualitative and quantitative measures obtained from our studies will help researchers and interaction design experts to design efficient and effective gesture-based locomotion techniques for traveling in a seated position in multitasking VEs.

The Role of the Precuneus in Human Spatial Updating in a Real Environment Setting-A cTBS Study.

As we move through an environment, we update positions of our body relative to other objects, even when some objects temporarily or permanently leave our field of view—this ability is termed egocentric spatial updating and plays an important role in everyday life. Still, our knowledge about its representation in the brain is still scarce, with previous studies using virtual movements in virtual environments or patients with brain lesions suggesting that the precuneus might play an important role. However, whether this assumption is also true when healthy humans move in real environments where full body-based cues are available in addition to the visual cues typically used in many VR studies is unclear. Therefore, in this study we investigated the role of the precuneus in egocentric spatial updating in a real environment setting in 20 healthy young participants who underwent two conditions in a cross-over design: (a) stimulation, achieved through applying continuous theta-burst stimulation (cTBS) to inhibit the precuneus and (b) sham condition (activated coil turned upside down). In both conditions, participants had to walk back with blindfolded eyes to objects they had previously memorized while walking with open eyes. Simplified trials (without spatial updating) were used as control condition, to make sure the participants were not affected by factors such as walking blindfolded, vestibular or working memory deficits. A significant interaction was found, with participants performing better in the sham condition compared to real stimulation, showing smaller errors both in distance and angle. The results of our study reveal evidence of an important role of the precuneus in a real-environment egocentric spatial updating; studies on larger samples are necessary to confirm and further investigate this finding.

Effect of Physical and Virtual Feedback on Reach-to-Grasp Movements in Virtual Environments

Object grabbing is a common interaction task in virtual environments, where the virtual and physical feedback of both the hand and the targeted object may impact its performance. To investigate these effects, we first designed a comparative study where subjects were required to reach and grasp a physical cylinder under four conditions: 1) no virtual hand and no virtual cylinder; 2) virtual cylinder without virtual hand; 3) virtual hand and cylinder; and 4) real environment. The results showed that the subjects performed with different kinematic patterns in all three virtual conditions compared to the real environment. Additionally, we found that this difference is not due to the environment or depth illusion. We performed another experiment to examine the effects of physical cylinder feedback on reach-to-grasp movement. We found that the subjects performed similarly to the physical environment only in the condition with a virtual hand and a virtual cylinder. These results suggest that feedback with virtual hand and virtual targeted object would result in similar kinematic patterns in virtual environments as in physical environments, which implies design guidelines in virtual environments for rehabilitation in patients with motor deficits.

Development of a Hybrid Method to Generate Gravito-Inertial Cues for Motion Platforms in Highly Immersive Environments.

Motion platforms have been widely used in Virtual Reality (VR) systems for decades to simulate motion in virtual environments, and they have several applications in emerging fields such as driving assistance systems, vehicle automation and road risk management. Currently, the development of new VR immersive systems faces unique challenges to respond to the user’s requirements, such as introducing high-resolution 360° panoramic images and videos. With this type of visual information, it is much more complicated to apply the traditional methods of generating motion cues, since it is generally not possible to calculate the necessary corresponding motion properties that are needed to feed the motion cueing algorithms. For this reason, this paper aims to present a new method for generating non-real-time gravito-inertial cues with motion platforms using a system fed both with computer-generated—simulation-based—images and video imagery. It is a hybrid method where part of the gravito-inertial cues—those with acceleration information—are generated using a classical approach through the application of physical modeling in a VR scene utilizing washout filters, and part of the gravito-inertial cues—the ones coming from recorded images and video, without acceleration information—were generated ad hoc in a semi-manual way. The resulting motion cues generated were further modified according to the contributions of different experts based on a successive approximation—Wideband Delphi-inspired—method. The subjective evaluation of the proposed method showed that the motion signals refined with this method were significantly better than the original non-refined ones in terms of user perception. The final system, developed as part of an international road safety education campaign, could be useful for developing further VR-based applications for key fields such as driving assistance, vehicle automation and road crash prevention.

Camera keyframing with style and control

We present a novel technique that enables 3D artists to synthesize camera motions in virtual environments following a camera style , while enforcing user-designed camera keyframes as constraints along the sequence. To solve this constrained motion in-betweening problem, we design and train a camera motion generator from a collection of temporal cinematic features (camera and actor motions) using a conditioning on target keyframes. We further condition the generator with a style code to control how to perform the interpolation between the keyframes. Style codes are generated by training a second network that encodes different camera behaviors in a compact latent space, the camera style space. Camera behaviors are defined as temporal correlations between actor features and camera motions and can be extracted from real or synthetic film clips. We further extend the system by incorporating a fine control of camera speed and direction via a hidden state mapping technique. We evaluate our method on two aspects: i) the capacity to synthesize style-aware camera trajectories with user defined keyframes; and ii) the capacity to ensure that in-between motions still comply with the reference camera style while satisfying the keyframe constraints. As a result, our system is the first style-aware keyframe in-betweening technique for camera control that balances style-driven automation with precise and interactive control of keyframes.

The impact of different navigation speeds on cybersickness and stress level in VR

The aim of this research was to determine if the speed of movement in virtual environments has an impact on cybersickness as potentially experienced by an end user of the system. Cybersickness is a common side effect in virtual reality (VR) systems, shown to have a negative influence on user experience. It can be described as a mismatch between vestibular and oculomotor sensors, where a person has a feeling of movement even though there is none. In this research, we study the impact of different navigation speeds in VR on cybersickness, relying on both subjective ratings indicating cybersickness symptoms, and objective measures of stress level. We wanted to find out if there is a correlation between objective and subjective metrics used. For test purposes, we used the HTC Vive VR headset and scenery from the Talos Principle VR game (where subjects can easily shift between three different movement speeds). Subjective ratings were collected using a questionnaire involving 11 questions used to evaluate cybersickness symptoms. Objective metrics were collected using the Pip Biosensor. A total of 28 participants took part in the study, while 2 participants withdrew due to physical discomfort. Results obtained from the Pip device show no statistically significant difference between navigation speeds for relaxed, stressed, and steady states. Some statistically significant correlations were found between gender and stomach ache, need to vomit, and physical discomfort while wearing HMD. Furthermore, correlation was found between age and variables of nausea in transport vehicles and vertigo. Other correlations found are described in the results section of the paper.

How to Observe Users' Movements in Virtual Environments: Viewpoint Control in a Power Wheelchair Simulator.

We describe a networked, two-user virtual reality (VR) power wheelchair (PWC) simulator system in which an actor (client) and an observer (clinician) meet. We then present a study with 15 observers (expert clinicians) evaluating the effect of three principal forms of viewpoint control (egocentric-egomotion, egocentric-tethered, and client-centric) on the observer's assessment of driving tasks in a virtual environment (VE). VR allows for the simulation and assessment of real-world tasks in a controlled, safe, and repeatable environment. Observing users' movement behavior in such a VE requires appropriate viewpoint control for the observer. The VR viewpoint user interface should allow an observer to make judgments equivalent or even superior to real-world situations. A purpose-built VR PWC simulator was developed. In a series of PWC driving tasks, we measured the perceived ease of use and sense of presence of the observers and compared the virtual assessment with real-world "gold standard" scores, including confidence levels in judgments. Findings suggest that with more immersive techniques, such as egomotion and tethered egocentric viewpoints, judgments are both more accurate and more confident. The ability to walk and/or orbit around the view significantly affected the observers' sense of presence. Incorporating the observer into the VE, through egomotion, is an effective method for assessing users' behavior in VR with implications for the transferability of virtual experiences to the real world. Our application domain serves as a representative example for tasks where the movement of users through a VE needs to be evaluated.

The Influence of Affect on the Decision-Making Process in Virtual Simulation

ABSTRACTGames rarely mirror real-life situation – what is more, virtual simulations are often designed as an opened world. Is it possible to predict simple choices regarding movement in virtual environment? The authors decided to test whether it is possible to use affectively laden pictures to influence simple decisions of binomial character. They designed a corridor with a possibility of turning left or right. On the walls of the corridor a different set of affective pictures was presented. Results show that participants not only associated the pictures with the decision about making a turn, but also that it is possible to predict an actual preference of the side. Such results allow to incorporate the predictions regarding affect and choice into simulation development process.

Assessment of human perceptual sensitivity to physically non-conforming motion in virtual environments

Recent advances in neuroscience have shown that the neuropathological disorders are closely related with diseases such as Alzheimers. Those damages are particularly associated with the intermediate visual perceptual processing which can cause the motion perception defects and abnormal visuospatial functions in daily living of patients. In this paper, we propose virtual reality-based assessment tools for measuring human perceptual sensitivity to dynamic erroneous motions, particularly designed to assess possible early stage of brain damages and its associated visual dysfunctions. The main thrust of this paper is on perceptually tuned virtual reality system that can produce realistic natural behavior. The proposed method contains multiple assessment layers to check the awareness of erroneous motion in natural scenes at various severities. Our VR-based game-type environment provides an effective test bed for various dynamic motion-based perceptual sensitivity experiments. Our initial human subject tests show that game-based test environment produces more coherent and consistent data, preferable to survey-based methods.

A Study of Upper Extremity Training for Patients with Stroke Using a Virtual Environment System

[Purpose] A virtual environment (VE) system was designed to facilitate the retraining of motor control by feedback of movement trajectory to patients with neurological impairments, such as stroke victims or those with an acquired brain injury. In this study, we quantitatively assessed motion trajectory of the upper extremity during VE in order to further understand the effect of paralyzed upper extremity movement in VE for each patient as well as the functional clinical evaluations. [Subjects and Methods] Six patients with stroke were participated in this study. The VE system consisted of a computer, an electromagnetic motion tracking device, which monitored and displayed patient movement on the computer, and the VE software, which provided the tools for creating training scenes. This system was used to facilitate motor relearning of the upper extremity for six patients with stroke. [Results] The results showed there were improvements in variability and accuracy of the arm movement in motion trajectory. In addition, the scores of clinical evaluations improved, and VE did not hinder motor relearning of the upper extremity, which is necessary for activities of daily living. [Conclusion] This VE system might be effective at facilitating motor relearning of the upper extremity for stroke patients.

Tuning Self-Motion Perception in Virtual Reality with Visual Illusions

Motion perception in immersive virtual environments significantly differs from the real world. For example, previous work has shown that users tend to underestimate travel distances in virtual environments (VEs). As a solution to this problem, researchers proposed to scale the mapped virtual camera motion relative to the tracked real-world movement of a user until real and virtual motion are perceived as equal, i.e., real-world movements could be mapped with a larger gain to the VE in order to compensate for the underestimation. However, introducing discrepancies between real and virtual motion can become a problem, in particular, due to misalignments of both worlds and distorted space cognition. In this paper, we describe a different approach that introduces apparent self-motion illusions by manipulating optic flow fields during movements in VEs. These manipulations can affect self-motion perception in VEs, but omit a quantitative discrepancy between real and virtual motions. In particular, we consider to which regions of the virtual view these apparent self-motion illusions can be applied, i.e., the ground plane or peripheral vision. Therefore, we introduce four illusions and show in experiments that optic flow manipulation can significantly affect users' self-motion judgments. Furthermore, we show that with such manipulations of optic flow fields the underestimation of travel distances can be compensated.

Computerized task risk assessment using digital human modeling based Job Risk Classification Model

Different from the classical ergonomics analysis, Virtual Interactive Design methodology relies on manikin movements in virtual environment. This platform has been implemented by researchers to accomplish static ergonomic analyses including Rapid Upper Limb Assessment, NIOSH lifting equation and Static Strength Prediction. However, considering only static posture information limits the capacity of ergonomics analysis. In this study, the methodology of performing dynamic ergonomics analysis based on this Virtual Interactive Design platform is proposed. This environment allows velocity and angular velocity of specified body segments/joints calculated for designed tasks to be used to assess the corresponding risk levels based on Job Risk Classification Model. The motion calculation is completed based on the captured interaction between human participants and virtual workplace/mockup. To evaluate the validity and reliability of this upgraded platform, potential errors are analyzed by comparing outputs from several designed experimental conditions.

The movement patterns and the experiential components of virtual environments

Human movement in virtual environments (VEs) is a largely unstudied area, and there are no well-established methods of measuring it in VEs. Consequently, it is unclear how movement affects the experiential side of VEs. We introduce a novel method of measuring and modelling human movement. A specific information entropy-based modelling method enabled us to identify different movement patterns and analyse the experiential components related to them. The data was collected by registering the movement patterns of 68 participants who were in a virtual house doing a search task. The experiential side of the VE was measured with the Experimental Virtual Environment Questionnaire (EVEQ). Four movement patterns were identified. In addition, fluent movement in VEs was related to a high sense of presence. Moreover, the participants who moved fluently in the environment assessed their skills high. The results show how movement is related the way in which people experience the VE. The movement analysis method introduced here is applicable to other related research areas as well.

Kinematics of Pointing Movements Made in a Virtual Versus a Physical 3-Dimensional Environment in Healthy and Stroke Subjects

Knaut LA, Subramanian SK, McFadyen BJ, Bourbonnais D, Levin MF. Kinematics of pointing movements made in a virtual versus a physical 3-dimensional environment in healthy and stroke subjects. Objective To compare kinematics of 3-dimensional pointing movements performed in a virtual environment (VE) displayed through a head-mounted display with those made in a physical environment. Design Observational study of movement in poststroke and healthy subjects. Setting Motion analysis laboratory. Participants Adults (n=15; 4 women; 59±15.4y) with chronic poststroke hemiparesis were recruited. Participants had moderate upper-limb impairment with Chedoke-McMaster Arm Scores ranging from 3 to 6 out of 7. Twelve healthy subjects (6 women; 53.3±17.1y) were recruited from the community. Interventions Not applicable. Main Outcome Measures Arm and trunk kinematics were recorded in similar virtual and physical environments with an Optotrak System (6 markers; 100Hz; 5s). Subjects pointed as quickly and as accurately as possible to 6 targets (12 trials/target in a randomized sequence) placed in arm workspace areas requiring different arm movement patterns and levels of difficulty. Movements were analyzed in terms of performance outcome measures (endpoint precision, trajectory, peak velocity) and arm and trunk movement patterns (elbow and shoulder ranges of motion, elbow/shoulder coordination, trunk displacement, rotation). Results For healthy subjects, precision and trajectory straightness were higher in VE when pointing to contralateral targets, and movements were slower for all targets in VE. Stroke participants made less accurate and more curved movements in VE and used less trunk displacement. Elbow/shoulder coordination differed when pointing to the lower ipsilateral target. There were no group-by-environment interactions. Conclusions Movements in both environments were sufficiently similar to consider VE a valid environment for clinical interventions and motor control studies.

Spatial updating of objects after rotational and translational body movements in virtual environments

Spatial reasoning in architectural design can be better understood by considering the factors that affect the spatial updating process of the individual in an environment. This study focuses on the issue of spatial updating of viewed and imagined objects after rotational and translational body movements in a virtual environment (VE). Rotational and translational movements based on an egocentric frame of reference where there is no control of the user are compared in a desktop VE. Moreover, preference in architectural drawing medium and gender are analyzed as the factors that affect the spatial updating of objects in each body movement type. The results indicated that translational movement was more efficient than the rotational movement in judgment of relative directions in viewed objects. Furthermore, the viewed objects were more correctly spatially updated than the imagined ones both in translational and rotational body movements. In comparison of hand, computer and both as the drawing media, findings indicated that preference in computer medium in architectural design drawings was an effective one in spatial updating process in a VE. Contrary to the previous studies, it is found that there was no significant difference between gender and movement types.

Estimation of travel distance from visual motion in virtual environments

Distance estimation of visually simulated self-motion is difficult, because one has to know or make assumptions about scene layout to judge ego speed. Discrimination of the travel distances of two sequentially simulated self-motions in the same scene can be performed quite accurately (Bremmer and Lappe 1999; Frenz et al., 2003). However, the indication of the perceived distance of a single movement in terms of a spatial interval results in a depth scaling error: Intervals are correlated with the true travel distance, but underestimate travel distance by about 25% (Frenz and Lappe, 2005). Here we investigated whether the inclusion of further depth cues (disparity/motion parallax/figural cues) in the virtual environment allows more veridical interval adjustment. Experiments were conducted on a large single projection screen and in a fully immersive computer-animated virtual environment (CAVE). Forward movements in simple virtual environments were simulated with distances between 1.5 and 13 m with varying speeds. Subjects indicated the perceived distance of each movement in terms of a depth interval on the virtual ground plane. We found good correlation between simulated and indicated distances, indicative of an internal representation of the perceived distance. The slopes of the fitted regression lines revealed an underestimation of distance by about 25% under all conditions. We conclude that estimation of travel distance from optic flow is subject to scaling when compared to static intervals in the environment, irrespective of additional depth cues.

An efficient approach to human motion modeling for the verification of human-centric product design and manufacturing in virtual environments

The efficient and reliable human-integrated design of products and processes is a major goal of the manufacturing industry. Thus, numerous human-related product functionality and manufacturability aspects need to be verified, using simulation, in the context of the product development procedures. The natural representation of human motions in virtual environments is crucial for the reliability of the simulation results. In this context, the paper presents an efficient approach to human motion analysis and modeling with respect to the anthropometric parameters, based on real motion data. Statistical methods employed for the analysis of the data and additive motion models are derived. The models are capable of predicting human motion and driving digital humans in product and worker simulation environments. A specific test case is presented to demonstrate the application of the suggested methodology on a real industrial problem.

화면 움직임과 Cybersickness의 관계에 관한 연구

This paper investigates the effects of scene movements on cybersickness to develop the guidelines of scene movements in virtual environments. The types of scene movements were made for both scene navigations(through the axes of X: lateral, Y: fore & after, and Z: vertical) and scene rotations(by pitch, roll and yaw). And there were each three levels of speed; 2.7, 4.5 and 6.3 /s(for navigation), and 10, 20 and 30 /s(for rotation) were conducted. Twelve participants were exposed to each scene for 15 minutes, and three tests were performed to measure the degree of sickness. Before and after subjects were exposed to virtual environments, they were requested to describe their sickness symptoms by means of answering the Simulator Sickness Questionnaire(SSQ). And the postural stability tests, in which the Center of Pressure(COP) of subjects were traced and recorded by a `force platform`, were conducted. During the exposure on virtual environments, the subjects were requested to rate the degree of nausea. For both navigation and rotation, the effects of speeds and axes were significant in the SSQ scores and the nausea ratings, while it was not in the COP. The correlation between the SSQ scores and the COP data was not found. Therefore, it was inappropriate to use COP as a measure of cybersickness. The degree of sickness increased, except for the case of the yaw, as the speed increased. The sickness was most severe in the scene navigation through the axis X and in the scene rotation by the yaw.

A Spoken Dialogue System for Navigation in Non‐Immersive Virtual Environments

Abstract Navigation is the process by which people control their movement in virtual environments and is a corefunctional requirement for all virtual environment (VE) applications. Users require the ability to move, controllingorientation, direction of movement and speed, in order to achieve a particular goal within a VE. Navigation israrely the end point in itself (which is typically interaction with the visual representations of data) but applicationsoften place a high demand on navigation skills, which in turn means that a high level of support for navigationis required from the application. On desktop systems navigation in non‐immersive systems is usually supportedthrough the usual hardware devices of mouse and keyboard. Previous work by the authors shows that many usersexperience frustration when trying to perform even simple navigation tasks — users complain about getting lost,becoming disorientated and finding the interface `difficult to use'. In this paper we report on work in progressin exploiting natural language processing (NLP) technology to support navigation in non‐immersive virtualenvironments. A multi‐modal system has been developed which supports a range of high‐level (spoken) navigationcommands and indications are that spoken dialogue interaction is an effective alternative to mouse and keyboardinteraction for many tasks. We conclude that multi‐modal interaction, combining technologies such as NLP withmouse and keyboard may offer the most effective interaction with VEs and identify a number of areas where furtherwork is necessary. ACM CSS: I.3.6 Computer Graphics Methodology and Techniques—Interaction and Techniques, I.3.7 Three‐DimensionalGraphics and Realism—Virtual Reality, I.2.7 Natural Language Processing—Speech Recognitionand Synthesis

Path finding for human motion in virtual environments

This paper presents an efficient and robust technique for generating global motion paths for a human model in virtual environments. Initially, a scene is discretized using raster hardware to generate an environment map. An obstacle-free cell path sub-optimal according to Manhattan metric is generated between any two cells. Unlike 2D techniques present in literature, the proposed algorithm works for complex 3D environments suitable for video games and architectural walk-throughs. For obstacle avoidance, the algorithm considers both physical dimensions of the human and actions such as jumping, bending, etc. Path smoothening is carried out to keep the cell path as closely as possible to Euclidean straight-line paths.