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In military aviation helmet-mounted displays (HMDs) or head-up displays, light from the ambient scene is added to the symbology to create a complex mixture of colors, textures, and luminances. In the case of color mixing, the color of the transparent symbology symbols shifts toward the colors of the ambient background that the symbology overlays. The magnitude of the shift depends on the contrast of the symbology against the background. Against a darkened background, there is negligible shifting of symbology color. However, during daylight conditions, symbology colors shift toward the background hue. Using CIELAB distances between symbology colors as a measure of color discrimination, confusion contrast thresholds are calculated for each of seven symbology colors mixed with fourteen different background colors over a wide range of luminance contrasts. Confusion contrast thresholds are calculated for color normal and color vision deficient (CVD) observers. For CVD observers, colors are filtered using the RGB coefficients developed by Machado. Using the color discrimination data presented here as well as previous assessments of HMD luminance requirements based on observer ratings of the quality of symbology, luminance guidelines for see-through displays are presented, which correct for a calculation error made previously. [ABSTRACT FROM AUTHOR]

We assessed the effect of wearing a junior-high-school helmet when the frontal or lateral part of a helmet impacted the upper part and lower part of the A-pillar of a vehicle at 35 km/h (212 J). The head injury criterions (HICs) of the headform impactor without a helmet were respectively 4530 and 4937. In the case of the headform impactor wearing a junior-high-school helmet, the helmet reduced the HIC by 17.5 % and 9.9 % for impacts of the frontal part of the helmet and by 15.0 % and 4.0 % for impacts of the lateral part of the helmet. We also assessed the effect of wearing a junior-high-school helmet when the frontal part of the helmet impacted a road surface from a height of 1.5 m (66 J). The HIC of the headform impactor without a helmet was 6525. The HIC was reduced by 82.7 % when wearing a junior-high-school helmet. Both experiments show that, under a relatively low impact energy condition such as a road surface impact, wearing a junior-highschool helmet greatly reduces the head injury level. Meanwhile, under a relatively high-impact-energy condition such as impact against an A-pillar, wearing a junior-high-school helmet is ineffective in reducing the head injury level. [ABSTRACT FROM AUTHOR]

Addressing vergence-accommodation conflict in head-mounted displays (HMDs) requires resolving two interrelated problems. First, the hardware must support viewing sharp imagery over the full accommodation range of the user. Second, HMDs should accurately reproduce retinal defocus blur to correctly drive accommodation. A multitude of accommodation-supporting HMDs have been proposed, with three architectures receiving particular attention: varifocal, multifocal, and light field displays. These designs all extend depth of focus, but rely on computationally expensive rendering and optimization algorithms to reproduce accurate defocus blur (often limiting content complexity and interactive applications). To date, no unified framework has been proposed to support driving these emerging HMDs using commodity content. In this paper, we introduce DeepFocus, a generic, end-to-end convolutional neural network designed to efficiently solve the full range of computational tasks for accommodation-supporting HMDs. This network is demonstrated to accurately synthesize defocus blur, focal stacks, multilayer decompositions, and multiview imagery using only commonly available RGB-D images, enabling real-time, near-correct depictions of retinal blur with a broad set of accommodation-supporting HMDs. [ABSTRACT FROM AUTHOR]

All-terrain vehicle (ATV) safety laws, including helmet use, vary by state and are sporadically enforced. Kentucky state laws require safety helmets only for younger riders. We hypothesized that ATV riders injured in Kentucky and seen at a Tennessee trauma center would more likely be unhelmeted, have more severe head injuries, and have higher mortality rates than those injured in Virginia or Tennessee. A Trauma Registry review of 750 injured ATV riders from June 1, 2005, through June 1, 2015 examined state location of accident, helmet use, markers of injury severity, and outcomes. Multiple logistic regression analysis examined predictors of severe head injuries and death with P < 0.05 significant. Unhelmeted ATV rider status predicted more severe head injuries (relative risk 23.5, P < 0.001) and death (relative risk 4.6, P < 0.001). ATV riders injured in the state of Kentucky were twice as numerous. In addition, they were more likely than ATV riders injured in Tennessee or Virginia to be unhelmeted, to have severe head injuries, and to sustain fatal injuries (all P < 0.001). This single trauma center study lends support for maintaining and enforcing current universal helmet laws for ATV riders of all ages in states where they are in effect and highlights the need to upgrade helmet laws that apply only to some riders. [ABSTRACT FROM AUTHOR]

In see-through helmet-mounted displays (HMDs), image-intensifier tubes are located on the sides of the helmet. This HMD design increases the effective interpupillary distance and exposes the observer to hyperstereopsis. The modification of three-dimensional space perception by hyperstereopsis in laboratory studies is well known. Little is known, however, about its effects in real, operational conditions. The present study investigated the effects of hyperstereopsis on visual perception in helicopter pilots during the first flight of a night-flight training program using a see-through HMD. Fifteen pilots’ percepts of distance and height under hyperstereoscopic viewing were assessed using a double-distance estimation task in standard flight circuits. In addition, two questionnaires were used to characterize the perceptual effects induced by hyperstereoscopic viewing during the first night flight, and to determine whether any aftereffects were still present during the 24-h period following the flight. Height and distance estimation errors were observed. On average, pilots tended to underestimate the near plane relative to the farther plane in the double-distance estimation task; this is the inverse of what is commonly observed under natural viewing. We ascribed this effect to a non-linear decrease in the hyperstereopsis effect with viewing distance. Six pilots experienced sensory illusions resembling a distortion of apparent visual space: the impression of “sinking into a hole” when landing, of objects appearing closer than they actually were, and reduced in size. Four pilots cited landing as the most difficult situation encountered during the flight. Only minor complaints were reported for the 24-h period following the flight. The results of this field study represent a step towards characterizing the perceptual and operational impact of this display technology in helicopter pilots during initial exposure. [ABSTRACT FROM AUTHOR]

The paper presents selected results of analytical and construction works executed at the Air Force Institute of Technology (AFIT) in the context of possibilities of supporting the actions of a helicopter crew, i.e., pilot-crew commander, pilot-operator of on-board systems, and on-board technician participating in aviation/maritime search and rescue missions. Such support is based on using the helmet-mounted display systems SWPL1 "Cyklop" and NSC1 "Orion" for information from the observation-targeting heads and verbal communication with the survivor. Selected imaging and verbal communication devices installed on aircraft operated by the Polish Armed Forces, which are used in aviation/maritime search and rescue actions, are discussed. Particular attention is drawn to the problems associated with the integrated avionics systems of helmet-mounted imaging of piloting-navigation parameters and the helmet-mounted imaging of information from the observation-targeting heads, i.e., the on-board radio direction finder system and emergency radio, which are part of the integrated communication system. Sample structural solutions for such systems and the possibilities of their application in search and rescue missions are presented. [ABSTRACT FROM AUTHOR]

See-through distortion can occur when a pilot looks through a curved aircraft transparency because of a weak lens effect. A helmet-mounted display (HMD) system must either compensate for this distortion or incur a distortion error in its total error budget. We describe a method for characterization of and compensation for aircraft transparency distortion, allowing for increased targeting accuracy and reduced binocular vergence errors from any position within a large head box. We present techniques for compensating for transparency distortion for the entire HMD head box and implications observed based on applying these techniques for A-10 and F-16 aircraft transparencies. [ABSTRACT FROM AUTHOR]

NASA Langley Research Center (LaRC) has conducted research in the area of helmet-mounted display (HMD)/head-worn display (HWD) over the past 30 years. Initially, NASA LaRC’s research focused on military applications, but recently NASA has conducted a line of research in the area of HWD for commercial and business aircraft. This work revolved around numerous simulation experiments as well as flight tests to develop technology and data for industry and regulatory guidance. This paper summarizes the results of NASA’s HMD/HWD research. Of note, the work tracks progress in wearable collimated optics, head tracking, latency reduction, and weight. The research lends credence to a small, sunglasses-type form factor of the HWD being acceptable to commercial pilots, and this goal is now becoming technologically feasible. The research further suggests that an HWD may serve as an “equivalent” head-up display (HUD) with safety, operational, and cost benefits. “HUD equivalence” appears to be the economic avenue by which HWDs can become mainstream on the commercial and business aircraft flight deck. If this happens, NASA’s research suggests that additional operational benefits using the unique capabilities of the HWD can open up new operational paradigms [ABSTRACT FROM AUTHOR]

When color is implemented in helmet-mounted displays (HMDs) that are eyes-out, see-through displays, visual perception issues become an increased concern. A major confound with HMDs is their inherent see-through (transparent) property. The result is color in the displayed image that combines with color from the outside (or in-cockpit) world, producing an image with additive color. As luminance of the HMD imagery is reduced, the color separation between the HMD imagery and the background is also reduced. It is because of this additive effect that luminance contrast is so vitally important in developing HMD standards for color symbology. As a result, this paper identifies luminance requirements for full-color HMDs based upon two lines of investigation. The first is based on a study of white symbology against natural static backgrounds, where the quality of symbology was judged to be a function of not only the background luminance but also of the background complexity as well. The second is based on an evaluation of the complexity inherent in natural backgrounds and from this investigation, a predictive curve was found that describes the complexity of natural backgrounds as a function of ambient luminance. [ABSTRACT FROM AUTHOR]

In the past couple of years, research on display content for helicopter operations headed in a new direction. The already reached goals could evolve into a paradigm change for information visualization. Technology advancements allow implementing three-dimensional and conformal content on a helmet-mounted see-through device. This superimposed imagery inherits the same optical flow as the environment. It is supposed to ease switching between display information and environmental cues. The concept is neither pathbreaking nor new, but it has not been successfully established in aviation yet. Nevertheless, there are certainly some advantages to expect—at least from perspective of a human-centered system design. Within the following pages, the next generation displays will be presented and discussed with a focus on human factors. Beginning with recalling some human factor related research facts, an experiment comparing the former two-dimensional research displays will be presented. Before introducing the DLR conformal symbol set and the three experiments about an innovative drift, indication related research activities toward conformal symbol sets will be addressed. [ABSTRACT FROM AUTHOR]

A head-worn display combined with accurate head-tracking allows one to show synthetically generated symbols in a way that they appear as a part of the real world. Depending on the specific research context, different terms have been used for the ability to show display elements as parts of the outside world. These include contact analog, scene linked, augmented reality, and outside conformal. While the famous highway in the sky was one of the first applications in avionics, over the years more and more conformal counterparts have been devised for aircraft-related instruments. Among them are routing information, navigation aids, specialized landing displays, obstacle warnings, drift indicators, and many more. Conformal displays have been developed for more than 40 years. We present a review of some results, as well as look ahead to research trends for the next years. We suggest that naturalism is not the best choice for the design of conformal displays. Instead, more abstract representations often yield better pilot acceptance. [ABSTRACT FROM AUTHOR]

Virtual Reality is a computer-generated, mock environment that can allow people to interact with it in a seemingly real way by using certain types of specialized equipment. It is mainly used for training or educational purposes and allows for "real-life" training in a safe and monitored environment. Virtual training can be used in many different fields such as medical, military, biomedical research, aviation, and many others. However, this paper reviews the most cited publications related to the application of virtual reality for training in the United States Military. As a result, researchers can find research venues based on the challenges, risk, and infrastructures. [ABSTRACT FROM AUTHOR]

In this paper, we attempt to get a better understanding of command and control practices of incident commanders from Dutch fire services (battalion chiefs, BCs) by examining the recordings made by helmet-mounted cameras during 55 real incidents. The aim is to examine the degree to which the BCs issued orders to front-line workers and the degree to which these orders were carried out appropriately. The results indicate that incident commanders were able to influence the work at the front line, but were generally not in control of what happened at the front line. [ABSTRACT FROM AUTHOR]

Our laboratory has developed a skill learning support environment “Motion Navigator”, by which a learner can train himself/herself for a motion just by following model motion displayed on his/her HMD with AR. we have developed a golf learning support environment by improving “Motion Navigator”, which takes the necessary elements into account for a learner to mimic and to practice golf swing. By displaying learner's operation superimposed with the model motion simultaneously, the system can give the learner awareness of mistake of his/her motion. [ABSTRACT FROM AUTHOR]

This study aims to evaluate three commercial virtual reality (VR) display devices on the market via a 3D Fitts's task. In addition, a symptom questionnaire was used to assess the severity of cybersickness symptoms induced by these displays. Ten participants performed repetitive pointing tasks over different conditions of varying display devices, movement directions, and indices of difficulty. On the basis of the results, the projection display obtained the best task performance with the lowest movement time and the highest throughput. It had the least symptoms among the three display devices. The HMD gave the worst results in all criteria. The 3D TV could be considered as good as the projection display in task performance but induced slight level of discomfort, fatigue, and eyestrain. These findings not only provided an initial understanding of differences between the 3D TV and the other two familiar display devices in human performance when interacting within a 3D VE but also pointed a direction to effectively improve future VR display technique. [ABSTRACT FROM AUTHOR]

BACKGROUND: During approach and departure in rotary wing aircraft, a sudden loss of external visual reference precipitates spatial disorientation. METHODS: There were 10 Royal Canadian Air Force (RCAF) Griffon pilots who participated in an in-flight investigation of a 3-dimensional conformal Helmet Display Tracking System (HDTS) and the BrownOut Symbology System (BOSS) aboard an Advanced System Research Aircraft. For each symbology system, pilots performed a two-stage departure followed by a single-stage approach. The presentation order of the two symbology systems was randomized across the pilots. Subjective measurements included situation awareness, mental effort, perceived performance, perceptual cue rating, NASA Task Load Index, and physiological response. Objective performance included aircraft speed, altitude, attitude, and distance from the landing point, control position, and control activity. Repeated measures analysis of variance and planned comparison tests for the subjective and objective responses were performed. RESULTS: For both maneuvers, the HDTS system afforded better situation awareness, lower workload, better perceptual cueing in attitude, horizontal and vertical translation, and lower overall workload index. During the two-stage departure, HDTS achieved less lateral drift from initial takeoff and hover, lower root mean square error (RMSE) in altitude during hover, and lower track error during the acceleration to forward flight. During the single-stage approach, HDTS achieved less error in lateral and longitudinal position offset from the landing point and lower RMSE in heading. DISCUSSION: In both maneuvers, pilots exhibited higher control activity when using HDTS, which suggested that more pertinent information was available to the pilots. Pilots preferred the HDTS system. [ABSTRACT FROM AUTHOR]

The relationship between the occurrence of simulator sickness (SS) and varying latency in a helmet-mounted display (HMD) was explored in this study. Previous work has always considered latency to be a constant. The aim of this research was to determine if a latency that varied over time would impact the experience of SS for HMD users. An object location task was used while viewing real, live video scenes via HMD. A planned comparisons approach was utilized with four experimental conditions, 2 of them having constant latency (0 ms added to system baseline, 200 ms added to system baseline) and 2 of them having sinusoidally varying latency (100 ms amplitude at 0.2 Hz frequency, and 20–100 ms varying amplitude at 0.2 Hz frequency). These conditions allowed for the assessment of the effects of constant latency vs. varying latency on the experience of SS. The results indicated that a varying latency is associated with greater experience of SS among HMD users than constant latency. Results also indicated, as has other recent research, that added constant latency on its own does not appear to be associated with the experience of higher levels of SS in an HMD. [ABSTRACT FROM AUTHOR]

Previous research has demonstrated a loss of helmet-mounted display (HMD) legibility for users exposed to whole body vibration. A pair of human factors studies was conducted to evaluate the effect of whole body vibration on eye, head, and helmet movements for seated users of a HMD while conducting simple fixation and smooth pursuit tracking tasks. These experiments confirmed that vertical eye motion can be demonstrated, that is consistent with the human visual systems' response to the vestibular-ocular reflex (VOR). Helmet slippage was also shown to occur, which could exacerbate loss of display legibility. The largest amplitudes in eye movements were observed during exposure to sinusoidal vibration in the 4-6 Hz range, which is consistent with the frequencies that past research has associated with whole-body resonance and the largest decrease in display legibility. Further, the measured eye movements appeared to be correlated with both the angular acceleration of the user's head and the angular slippage of the user's helmet. This research demonstrates that the loss of legibility while wearing HMDs likely results from a combination of VOR-triggered eye movements and movement of the display. Future compensation algorithms should consider adjusting the display in response to both VOR-triggered eye and HMD motion. [ABSTRACT FROM AUTHOR]

This paper documents the development of a prototype binocular, see-through, monochrome holographic waveguide helmet mounted display (HWVD). The optical system couples a commercial high resolution 1440 times 1080 pixel (1.5Mpixel) 12mm diagonal LCOS microdisplay with a state of the art holographic waveguide. Utilization of the waveguide gives a wide 40-degree field of view (FOV), while having a large 30times30 mm eyebox. With the advantages obtained by use of the holographic waveguide and the small LCOS microdisplay, the HWVD system enables significant cost, volume, and weight reductions as compared to existing CRT type designs. The design will also address power and efficiency requirements consistent with a pilot HMD system. [ABSTRACT FROM AUTHOR]

Visually coupled systems such as helmet mounted displays are designed to improve aircrew situational awareness by providing timely flight, targeting and other information overlaid on real or sensor-derived views of the external environment. Data can be presented in monocular, biocular or binocular fashion and are associated with visual conflicts and potential ophthalmic problems. Restricted sensor spectrum, limits of resolution, inherent system latency, the displaced visual input from remote sensors and restricted field of view may contribute to ophthalmic symptoms in aircrew. Disruption to binocularity and reliance on monocular cues for depth perception and hyperstereopsis from sensor-induced convergence disparity may cause distance estimation problems, whereas inappropriate accommodative stimuli and ocular dominance factors are common causes of eyestrain. Binocular rivalry from discordant imagery to each eye may compromise visual performance via several mechanisms. This article discusses the potential visual problems associated with visually coupled systems and the challenges of integrating complex systems with the aircrew interface. [ABSTRACT FROM AUTHOR]

With the development of new concepts and principles over the past century, helmet-mounted displays (HMDs) have been widely applied. This paper presents a review of avionic HMDs and shows some areas of active and intensive research. This review is focused on the optical design aspects and is divided into three sections to explore new optical design methods, which include an off-axis design, design with freeform optical surface, and design with holographic optical waveguide technology. Building on the fundamentals of optical design and engineering, the principles section primarily expounds on the five optical system parameters, which include weight, field of view, modulation transfer function, exit pupil size, and eye relief. We summarized the previous design works using new components to achieve compact and lightweight HMDs. Moreover, the paper presents a partial summary of the more notable experimental, prototype, fielded, and future HMD fixed-wing and rotary-wing programs. [ABSTRACT FROM AUTHOR]

Abstract: The sodium salts of the conjugated bases of uracils undergo highly chemoselective O4-monoalkylation when treated with various alkyl halides in dry DMF, while the use of methyl iodide results in N1+N3-dimethylation. Theoretical evaluations of the chemo- and regioselectivity along with X-ray crystallographic data are presented. [Copyright &y& Elsevier]

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Abstract: Head-mounted displays (HMDs) allow users to immerse in a virtual environment (VE) in which the user’s viewpoint can be changed according to the tracked movements in real space. Because the size of the virtual world often differs from the size of the tracked lab space, a straightforward implementation of omni-directional and unlimited walking is not generally possible. In this article we review and discuss a set of techniques that use known perceptual limitations and illusions to support seemingly natural walking through a large virtual environment in a confined lab space. The concept behind these techniques is called redirected walking. With redirected walking, users are guided unnoticeably on a physical path that differs from the path the user perceives in the virtual world by manipulating the transformations from real to virtual movements. For example, virtually rotating the view in the HMD to one side with every step causes the user to unknowingly compensate by walking a circular arc in the opposite direction, while having the illusion of walking on a straight trajectory. We describe a number of perceptual illusions that exploit perceptual limitations of motion detectors to manipulate the user’s perception of the speed and direction of his motion. We describe how gains of locomotor speed, rotation, and curvature can gradually alter the physical trajectory without the users observing any discrepancy, and discuss studies that investigated perceptual thresholds for these manipulations. We discuss the potential of self-motion illusions to shift or widen the applicable ranges for gain manipulations and to compensate for over- or underestimations of speed or travel distance in VEs. Finally, we identify a number of key issues for future research on this topic. [Copyright &y& Elsevier]

We report a WUXGA (1920 × 1200) resolution head mounted OLED microdisplay with luminance of 2000cd/m in monochrome and 240cd/m2 in full color. We believe this is the highest resolution OLED microdisplay based headset ever reported. The sub-pixel size for this 0.86-inch diagonal microdisplay is 2.45 μm × 8.5 μm. [ABSTRACT FROM AUTHOR]

This paper describes the design and the setup of a novel interactive binocular see-through head-mounted display (HMD) based on OLED microdisplays. In contradistinction to previous reported bulky monocular eyetracking HMDs based on the OLED-on-CMOS technology, the presented system meets the requirements of lightweight eyeglasses with a high functionality. [ABSTRACT FROM AUTHOR]

Abstract: While virtual reality environments have been shown to reduce pain, the precise mechanism that produces the pain attenuating effect has not been established. It has been suggested that it may be the ability to command attentional resources with the use of head mounted displays (HMDs) or the interactivity of the environment. Two experiments compared participants’ pain ratings to high and low levels of electrical stimulation while engaging in interactive gaming with an HMD. In the first, gaming with the HMD was compared to a positive emotion induction condition; and in the second experiment the HMD was compared to a condition in which the game was projected onto a wall. Interactive gaming significantly reduced numerical ratings of painful stimuli when compared to the baseline and affect condition. However, when the two gaming conditions were directly compared, they equally reduced participants’ pain ratings. These data are consistent with past research showing that interactive gaming can attenuate experimentally induced pain and its effects are comparable whether presented in a head mounted display or projected on a wall. [Copyright &y& Elsevier]

Abstract: We report a head-mountable CMOS camera for recording rapid neuronal activity in freely moving rodents using fluorescent activity reporters. This small, lightweight camera is capable of detecting small changes in light intensity (0.2% ΔI/I) at 500fps. The camera has a resolution of 32×32, sensitivity of 0.62V/lxs, conversion gain of 0.52μV/e− and well capacity of 2.1Me−. The camera, containing intensity offset subtraction circuitry within the imaging chip, is part of a miniaturized epi-fluorescent microscope and represents a first generation, mobile scientific-grade, physiology imaging camera. [Copyright &y& Elsevier]

Abstract: The experience of simulator sickness (SS) during head-mounted display (HMD) exposure continues to be a problem. The aim of these two experiments was to examine the effect of delay on SS while viewing a real, live video scene via an HMD. An object search task was performed in both experiments. Experiment 1 examined 0 and 200ms of delay and Experiment 2 examined 0, 145, and 300ms of delay. SS did not differ as a function of delay. However, SS increased as duration exposure increased in both experiments. In Experiment 1, SS was greater during the first experimental session than the second. SS did not differ between those who donned an HMD and a No HMD control condition in Experiment 2. It is possible that this is due to adaptation to repeated exposure to the sickening stimulus. This adaptation could have confounded the delay effects from Experiment 1. For this reason, a second experiment with an increased intersession interval was conducted. Intersession intervals for Experiment 2 were increased to 11–14days from 7days in Experiment 1. However, no effect of delay or session was found in Experiment 2. These results suggested that SS does not increase as a function of delay, but exposure duration increases SS. Also, performing repetitive head movements alone may have elicited symptoms of SS. As reported by other researchers, it appears that adaptation can occur to motion sickness stimuli with intersession intervals of up to 7days, but not with 11–14days. Other characteristics of HMD VEs need to be examined because SS occurs and delay does not appear to be as strong of a causal factor as once thought. [Copyright &y& Elsevier]

Abstract: Motion sickness (MS) can be a debilitating side-effect not just of sea travel, but also when immersed in video games or virtual environments (visually induced MS). To explore the impact of visual display parameters on motion sickness, we presented footage taken on an automobile race track to different groups of observers during three experiments. In Experiment 1, one group watched the movie wearing a head-mounted display (HMD) and a second group looked at a large projection screen with unrestricted view. Resolution and visual angle were equated. In contrast to common assumption, the projection screen produced significantly higher motion sickness scores than the HMD. To understand this rather surprising result, two further groups watched the movie with a limited field of view and reduced display angle, either through a synoptic device or a reduction screen (Experiment 2). Visually induced MS was reduced in both groups to the same extent. In Experiment 3, a fifth group of observers looked at the large screen with a limited field of view, but with unrestricted display angle. Results again showed decreased sickness scores. We conclude that another factor above and beyond display angle is critical to explain visually induced MS, namely the visual surround of the display. If present, the surround increases visually induced MS by causing an additional intra-visual conflict that makes it harder for the visual system to dominate the vestibular information and thus increases the nauseogenic conflict between visual and vestibular information. [Copyright &y& Elsevier]

Objective: We examined the effects of several display characteristics of head-mounted displays (HMDs) on simulator sickness (SS).Background: Technological limitations, such as display delay and reduced field of view (FOV), affect perception when using an HMD and are often thought to be related to SS. Few studies have examined the relationship between FOV and geometric FOV (image scale factor) or how HMD characteristics may interact.Method: Participants made active head movements to locate objects when viewing a live video via an HMD.Results: Compared with no added delay, an additional 200 ms of display delay did not result in increased SS, as measured by the Simulator Sickness Questionnaire. Furthermore, an effect of image scale factor on SS was not revealed. However, SS was greater when peripheral vision was occluded than when it was not. Peripheral vision moderated the effects of image scale factor and delay on head movement velocity.Conclusion: Occluding peripheral vision may subject HMD users to the potential detrimental consequences of HMD characteristics more than when peripheral vision of the external environment is available, resulting in more SS. Future research should investigate to what extent peripheral vision can be occluded without increasing SS and without sacrificing realism and presence.Application: To reduce the occurrence of SS, a degree of peripheral vision of the external world should be provided. Furthermore, users and designers should be aware that head movement behavior may be affected by HMD characteristics. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Lag between head movement and the time to render the visual consequences of the movement during head mounted display (HMD) applications presents challenges in the appearance of a stable image. This appearance of an image to “lag” behind or “swim” about may cause detriments in user performance, lack of user acceptance, and simulator sickness. These known potential consequences of HMD use motivated the current work to explore the human capability to detect display lag. The aim in this study was to gain a better understanding of the threshold for display lag detection and what variables affect this threshold. Methods: Twenty four subjects completed a repeated-measures three field of view (FOV; 10°, 38°, and full monocular) X two psychophysical technique (forced-choice and simple) experimental design. Passive sinusoidal head movements about the yaw axis were generated by an oscillating chair. A visual scene consisting of vertical bars was projected by an optokinetic drum moving in a sinusoidal fashion with the subjects. Subjects reported whether the scene lagged behind head movement. Results: The grand threshold mean for lag detection was 147.64ms (SD =84.91). The median was 130ms and the 25th and 75th percentiles were 84.17ms and 206.25ms, respectively. Lag thresholds were not systematically influenced by either FOV or psychophysical technique. Discussion: Naïve subjects in the current study were less sensitive to lag as compared to thresholds reported in previous HMD studies, which provided lag detection strategies and practice [e.g., 77ms; Ellis, Mania, Adelstein, & Hill, 2004]. Future examinations using the current paradigm should provide detection strategies and more practice. [ABSTRACT FROM AUTHOR]

Abstract: We are presenting the results of a freeform HMD optical system design. The tolerancing and stray light analyses are carried out to analyze the optical performance of this system. Results are discussed in detail. [Copyright &y& Elsevier]

Objective: The aim of this study was to assess how background visual motion and the relative movement of sound affect a head-mounted display (HMD) wearer's performance at a task requiring integration of auditory and visual information. Background: HMD users are often mobile. A commercially available speaker in a fixed location delivers auditory information affordably to the HMD user. However, previous research has shown that mobile HMD users perform poorly at tasks that require integration of visual and auditory information when sound comes from a free-field speaker. The specific cause of the poor task performance is unknown. Method: Participants counted audiovisual events that required integration of sounds delivered via a free-field speaker and vision on an HMD. Participants completed the task while either walking around a room, sitting in the room, or sitting inside a mobile room that allowed separate manipulation of background visual motion and speaker motion. Results: Participants' accuracy at counting target audiovisual events was worse when participants were walking than when sitting at a desk, p = .032. Compared with when they were sitting at a desk, participants' accuracy at counting target audiovisual events showed a trend to be worse when they experienced a combination of background visual motion and the relative movement of sound, p = .058. Conclusion: Multisensory integration performance is least effective when HMD users experience a combination of background visual motion and relative movement of sound. Eye reflexes may play an important role. Application: Results apply to situations in which HMD wearers are mobile when receiving multimodal information, as in health care and military contexts. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to replicate the finding that multisensory integration with a head-mounted display (HMD) is particularly difficult when a person is walking and hearing sound from a free-field speaker, and to extend the finding with a response method intended to reduce workload. Background: HMDs can support the information needs of workers whose work requires mobility, but some low-cost solutions for delivering auditory information may be less effective than others. Method: For the study, 24 participants detected whether shapes moving on the HMD screen made a sound appropriate to their forms when they collided with other shapes. Independent variables were self-motion (participants were mobile or seated), sound delivery (free-field speakers or an earpiece), and response method (noting mismatches via a mental count or via a manual clicker). Results: Unexpectedly, overall mismatch task accuracy was worse with the clicker (p = .027) than without. Participants also reported that it was harder to time-share the mismatch task with clicker responses (p = .033). In the clicker condition, self-motion and sound delivery interacted but in the opposite direction to the previous study. Conclusion: The best way of delivering auditory information to mobile workers performing a multisensory integration task with an HMD may depend on whether responding involves mental load or manual load. Broader theories are needed to capture factors influencing performance. Application: Until more powerful theory is developed, designers should perform careful formative and summative tests of whether the activities to be performed by mobile HMD wearers will make some sound delivery solutions less effective than others. [ABSTRACT FROM AUTHOR]

Background: Unilateral spatial neglect (USN) is most damaging to an older stroke patient who also has a lower performance in their activities of daily living or those elderly who are still working. The purpose of this study was to understand more accurately pathology of USN using a new HMD system. Methods: Two stroke patients (Subject A and B) participated in this study after gaining their informed consent and they all had Left USN as determined by clinical tests. Assessments of USN were performed by using the common clinical test (the line cancellation test) and six special tests by using HMD system in the object-centered coordinates (OC) condition and the egocentric coordinates (EC) condition. OC condition focused the test sheet only by a CCD. EC condition was that CCD can always follow the subject's movement. Moreover, the study focused on the effect of the reduced image condition of real image and the arrows. Results: In Patient A who performed the common test and special tests of OC and EC conditions, the results showed that for the line cancellation test under the common condition, both of the percentage of the correct answers at the right and left sides in the test sheet was 100 percent. However, in the OC condition, the percentage of the correct answers at the left side in the test sheet was 44 percent and the right side was 94 percent. In the EC condition, the left side was 61 percent and the right side was 67 percent. In Patient B, according to the result of the use of reduced image condition and the arrows condition by HMD system, these line cancellation scores more increased than the score of the common test. Conclusions: The results showed that the assessment of USN using an HMD system may clarify the left neglect area which cannot be easily observed in the clinical evaluation for USN. HMD may be able to produce an artificially versatile environment as compared to the common clinical evaluation and treatment. [ABSTRACT FROM AUTHOR]