Identification Of System Design Features That Affect Sickness In Virtual Environments

The terms simulator and VR are typically used to refer to specific types of virtual environments (VEs) which differ in the technology used to display the simulated environment. While simulators and VR devices may offer advantages such as low cost training, numerous studies on the effects to humans of exposure to different VEs indicate that motion sickness-like symptoms are often produced during or after exposure to the simulated environment. These deleterious side effects have the potential to limit the utilization of VE systems if they jeopardize the health and/or safety of the user and create liability issues for the manufacturer. The most widely used method for assessing the adverse symptoms of VE exposure is the Simulator Sickness Questionnaire (SSQ). The method of scoring the symptoms reported by VE users permits the different sickness symptoms to be clustered into three general types of effects or subscales and the distribution or pattern of the three SSQ subscales provides a profile for a given VE device. In the current research, several different statistical analyses were conducted on the SSQ data obtained from 21 different simulator studies and 16 different VR studies in order to identify an underlying symptom structure (i.e., SSQ profile) or severity difference for various types of VE systems. The results of the research showed statistically significant differences in the SSQ profiles and the overall severity of sickness between simulator and VR systems, which provide evidence that simulator sickness and VR sickness represent distinct forms of motion sickness. Analyses on three types of simulators (i.e., Fixed- and Rotary-Wing flight simulators and Driving simulators) also found significant differences in the sickness profiles as well as the overall severity of sickness within different types of simulator systems. Analyses on three types of VR systems (i.e., HMD, BOOM, and CAVE) revealed that BOOM and CAVE systems have similar sickness profiles, which are different than the HMD system profile. Moreover, the results showed that the overall severity of sickness was greater in HMD systems than in BOOM and CAVE systems. Recommendations for future research included additional psychophysical studies to evaluate the relationship between various engineering characteristics of VE systems and the specific types of sickness symptoms that are produced from exposure to them

Human factors in the perception of stereoscopic images

Research into stereoscopic displays is largely divided into how stereo 3D content looks, a field concerned with distortion, and how such content feels to the viewer, that is, comfort. However, seldom are these measures presented simultaneously. Both comfortable displays with unacceptable 3D and uncomfortable displays with great 3D are undesirable. These two scenarios can render conclusions based on research into these measures both moot and impractical. Furthermore, there is a consensus that more disparity correlates directly with greater viewer discomfort. These experiments, and the dissertation thereof, challenge this notion and argue for a more nuanced argument related to acquisition factors such as interaxial distance (IA) and post processing in the form of horizontal image translation (HIT). Indeed, this research seeks to measure tolerance limits for viewing comfort and perceptual distortions across different camera separations. In the experiments, HIT and IA were altered together. Following Banks et al. (2009), our stimuli were simple stereoscopic hinges, and we measured the perceived angle as a function of camera separation. We compared the predictions based on a ray-tracing model with the perceived 3D shape obtained psychophysically. Participants were asked to judge the angles of 250 hinges at different camera separations (IA and HIT remained linked across a 20 to 100mm range, but the angles ranged between 50° and 130°). In turn, comfort data was obtained using a five-point Likert scale for each trial. Stimuli were presented in orthoscopic conditions with screen and observer field of view (FOV) matched at 45°. The 3D hinge and experimental parameters were run across three distinct series of experiments. The first series involved replicating a typical laboratory scenario where screen position was unchanged (Experiment I), the other presenting scenarios representative of real-world applications for a single viewer (Experiments II, III, and IV), and the last presenting real-world applications for multiple viewers (Experiment V). While the laboratory scenario revealed greatest viewer comfort occurred when a virtual hinge was placed on the screen plane, the single-viewer experiment revealed into-the-screen stereo stimuli was judged flatter while out-of-screen content was perceived more veridically. The multi-viewer scenario revealed a marked decline in comfort for off-axis viewing, but no commensurate effect on distortion; importantly, hinge angles were judged as being the same regardless of off-axis viewing for angles of up to 45. More specifically, the main results are as follows. 1) Increased viewing distance enhances viewer comfort for stereoscopic perception. 2) The amount of disparity present was not correlated with comfort. Comfort is not correlated with angular distortion. 3) Distortion is affected by hinge placement on-screen. There is only a significant effect on comfort when the Camera Separation is at 60mm. 4) A perceptual bias between into the depth orientation of the screen stimuli, in to the screen stimuli were judged as flatter than out of the screen stimuli. 5) Perceived distortion not being affected by oblique viewing. Oblique viewing does not affect perceived comfort. In conclusion, the laboratory experiment highlights the limitations of extrapolating a controlled empirical stimulus into a less controlled “real world” environment. The typical usage scenarios consistently reveal no correlation between the amount of screen disparity (parallax) in the stimulus and the comfort rating. The final usage scenario reveals a perceptual constancy in off-axis viewer conditions for angles of up to 45, which, as reported, is not reflected by a typical ray-tracing model. Stereoscopic presentation with non-orthoscopic HIT may give comfortable 3D. However, there is good reason to believe that this 3D is not being perceived veridically. Comfortable 3D is often incorrectly converged due to the differences between distances specified by disparity and monocular cues. This conflict between monocular and stereo cues in the presentation of S3D content leads to loss of veridicality i.e. a perception of flatness. Therefore, correct HIT is recommended as the starting point for creating realistic and comfortable 3D, and this factor is shown by data to be far more important than limiting screen disparity (i.e. parallax). Based on these findings, this study proposes a predictive model of stereoscopic space for 3D content generators who require flexibility in acquisition parameters. This is important as there is no data for viewing conditions where the acquisition parameters are changed

3D Multi-user interactive visualization with a shared large-scale display

When the multiple users interact with a virtual environment on a largescale display there are several issues that need to be addressed to facilitate the interaction. In the thesis, three main topics for collaborative visualization are discussed; display setup, interactive visualization, and visual fatigue. The problems that the author is trying to address in this thesis are how multiple users can interact with a shared large-scale display depending on the display setups and how they can interact with the shared visualization in a way that doesn’t lead to visual fatigue. The first user study (Chapter 3) explores the display setups for multi-user interaction with a shared large-display. The author describes the design of the three main display setups (a shared view, a split screen, and a split screen with navigation information) and a demonstration using these setups. The user study found that the split screen and the split screen with navigation information can improve users’ confidence and reduce frustration level and are more preferred than a shared view. However, a shared view can still provide effective interaction and collaboration and the display setups cannot have a large impact on usability and workload. From the first study, the author employed a shared view for multi-user interactive visualization with a shared large-scale display due to the advantages of the shared view. To improve interactive visualization with a shared view for multiple users, the author designed and conducted the second user study (Chapter 4). A conventional interaction technique, the mean tracking method, was not effective for more than three users. In order to overcome the limitation of the current multi-user interactive visualization techniques, two interactive visualization techniques (the Object Shift Technique and Activity-based Weighted Mean Tracking method) were developed and were evaluated in the second user study. The Object Shift Technique translates the virtual objects in the opposite direction of movement of the Point of View (PoV) and the Activity-based Weighted Mean Tracking method assigns the higher weight to active users in comparison with stationary users to determine the location of the PoV. The results of the user study showed that these techniques can support collaboration, improve interactivity, and provide similar visual discomfort compared to the conventional method. The third study (Chapter 5) describes how to reduce visual fatigue for 3D stereoscopic visualization with a single point of view (PoV). When multiple users interact with 3D stereoscopic VR using multi-user interactive visualization techniques and they are close to the virtual objects, they can perceive 3D visual fatigue from the large disparity. To reduce the 3D visual fatigue, an Adaptive Interpupillary Distance (Adaptive IPD) adjustment technique was developed. To evaluate the Adaptive IPD method, the author compared to traditional 3D stereoscopic and the monoscopic visualization techniques. Through the user experiments, the author was able to confirm that the proposed method can reduce visual discomfort, yet maintain compelling depth perception as the result provided the most preferable 3D stereoscopic visualization experience. For these studies, the author developed a software framework and designed a set of experiments (Chapter 6). The framework architecture that contains the three main ideas are described. A demonstration application for multidimensional decision making was developed using the framework. The primary contributions of this thesis include a literature review of multiuser interaction with a shared large-scale display, deeper insights into three display setups for multi-user interaction, development of the Object Shift Techniques, the Activity-based Weighted Mean Tracking method, and the Adaptive Interpupillary Distance Adjustment technique, the evaluation of the three novel interaction techniques, development of a framework for supporting a multi-user interaction with a shared large-scale display and its application to multi-dimensional decision making VR system

Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

no abstrac

Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

no abstrac

Detection of changes through visual alerts and comparisons using a multi-layered display.

The Multi-Layered Displays (MLD) comprise two LCD screens mounted one in front of the other, allowing the presentation of information on both screens. This physical separation produces depth without requiring glasses. This research evaluated the utility of the MLD for change detection tasks, particularly in operational environments. Change Blindness refers to the failure to detect changes when the change happens during a visual disruption. The literature equates these visual disruptions with the types of interruptions that occur regularly in work situations. Change blindness is more likely to occur when operators monitor dynamic situations spread over several screens, when there are popup messages, and when there are frequent interruptions which are likely to block the visual transients that signal a change. Four laboratory experiments were conducted to evaluate the utility of the MLD for change detection tasks. The results from the experiments revealed that, when depth is used as a visual cue, the depth of the MLD has a different effect on the detection of expected changes and unexpected events. When the depth of the MLD is used as a comparison tool, the detection of differences is limited to translation differences in simple stimuli with a white background. These results call into question previous claims made for the MLD regarding operational change detection. In addition, observations and interviews were used to explore whether change blindness occurred in an operational command room. The results suggested that operators develop strategies to recover from interruptions and multitasking. These results call into doubt the wisdom of applying change detection theories to real world operational settings. More importantly, the research serves as a reminder that cognitive limitations found in the laboratory are not always found in real world environments

Detection of changes through visual alerts and comparisons using a multi-layered display

The Multi-Layered Displays (MLD) comprise two LCD screens mounted one in front of the other, allowing the presentation of information on both screens. This physical separation produces depth without requiring glasses. This research evaluated the utility of the MLD for change detection tasks, particularly in operational environments. Change Blindness refers to the failure to detect changes when the change happens during a visual disruption. The literature equates these visual disruptions with the types of interruptions that occur regularly in work situations. Change blindness is more likely to occur when operators monitor dynamic situations spread over several screens, when there are popup messages, and when there are frequent interruptions which are likely to block the visual transients that signal a change. Four laboratory experiments were conducted to evaluate the utility of the MLD for change detection tasks. The results from the experiments revealed that, when depth is used as a visual cue, the depth of the MLD has a different effect on the detection of expected changes and unexpected events. When the depth of the MLD is used as a comparison tool, the detection of differences is limited to translation differences in simple stimuli with a white background. These results call into question previous claims made for the MLD regarding operational change detection. In addition, observations and interviews were used to explore whether change blindness occurred in an operational command room. The results suggested that operators develop strategies to recover from interruptions and multitasking. These results call into doubt the wisdom of applying change detection theories to real world operational settings. More importantly, the research serves as a reminder that cognitive limitations found in the laboratory are not always found in real world environments

Human factors aspects of control room design: Guidelines and annotated bibliography

A human factors analysis of the workstation design for the Earth Radiation Budget Satellite mission operation room is discussed. The relevance of anthropometry, design rules, environmental design goals, and the social-psychological environment are discussed