Depending upon their nature, Outdoor AR applications can be deployed on head mounted displays (HMD) like Google glass or handheld Displays (HHD) like smartphones. This master’s thesis investigates novel gesture-based interaction techniques and applications for a HMD-HHD hybrid system that account for advantages presented by each platform. Prior research in HMD-HHD hybrid systems and gestures used in VR and surface computing were taken into account while designing the applications and interaction techniques. A prototype system combining a HMD and HHD was developed and four applications were created for the system. For evaluating the gestures, an application that compared four of the proposed gestures for selection tasks was developed. The results showed a significant difference between the different gestures and that the choice of gesture for selection tasks using a hybrid system depended upon application requirements like speed and accuracy.

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Graduation date: 1997

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Approved for public release; distribution is unlimited / This study compares the effects of a visual and a 3-dimensional auditory display on primary and secondary task performance, mood, and mental workload at incremental levels of sleep deprivation. It is based on a study conducted by the Army Research Laboratory, Cognitive Science Branch, Aberdeen, Maryland, from 12 Marines performing land navigational tasks in two helmet-mounted display (HMD) modes; visual and 3-dimensional auditory, for a 48 hour period. The results indicate that performance under sleep deprivation is significantly impacted in both modalities; however, performance in the primary task was more degraded in the 3-D auditory modality. Additionally, Marines were more likely to experience degraded performance in the secondary task with increased sleep deprivation. The recommendations address the need to design HMDs that will not overburden sensory channels and the concern for military leaders to understand the additional demands imposed on solders in a HMD environment. / Captain, Signal Corps, United States Army

Virtual environment (VE) design for cognitive rehabilitation necessitates a new methodology to ensure the validity of the resulting rehabilitation assessment. We propose that benchmarking the VE system technology utilizing a user-centered approach should precede the VE construction. Further, user performance baselines should be measured throughout testing as a control for adaptive effects that may confound the metrics chosen to evaluate the rehabilitation treatment. To support these claims we present data obtained from two modules of a user-centered head-mounted display (HMD) assessment battery, specifically resolution visual acuity and stereoacuity. Resolution visual acuity and stereoacuity assessments provide information about the image quality achieved by an HMD based upon its unique system parameters. When applying a user-centered approach, we were able to quantify limitations in the VE system components (e.g., low microdisplay resolution) and separately point to user characteristics (e.g., changes in dark focus) that may introduce error in the evaluation of VE based rehabilitation protocols. Based on these results, we provide guidelines for calibrating and benchmarking HMDs. In addition, we discuss potential extensions of the assessment to address higher level usability issues. We intend to test the proposed framework within the Human Experience Modeler (HEM), a testbed created at the University of Central Florida to evaluate technologies that may enhance cognitive rehabilitation effectiveness. Preliminary results of a feasibility pilot study conducted with a memory impaired participant showed that the HEM provides the control and repeatability needed to conduct such technology comparisons. Further, the HEM affords the opportunity to integrate new brain imaging technologies (i.e., functional Near Infrared Imaging) to evaluate brain plasticity associated with VE based cognitive rehabilitation.

The purpose of this thesis was to evaluate currently commercially available head mounted virtual reality displays for potential use in pilot training simulators. For this purpose acommercial simulator was modified to display the virtual environment in an Oculus RiftDK2 headset. A typical monitor based setup was used to provide a set of hardware requirements which the VR implementation had to meet or exceed to be considered potentially usable for pilot training simulators. User tests were then performed with a group of users representative of those normally using pilot training simulators, including both pilots and engineers working with simulator development. The main focus of the user tests was to evaluate some potential weaknesses found in the technical comparison (such as when a measured parameter was close to the lower limit defined by the monitor based setup) and to make a measurement of the usability of the VR implementation. The results from the technical comparison showed that the technical requirements were met and in most cases also exceeded. There were however some potential weaknesses revealed during the user tests, which included screen resolution and the field of view. There was one main critical deficiency found during the user tests. This was the lack of interaction with the aircraft as users were only able to interact with the flight stick and throttle lever. While this enabled the users to control many aspects of the aircraft (by using buttons and other controls fitted on the flight stick/throttle) in a training scenario a user also has to be able to interact with other switches and/or monitors in the cockpit. This was however a known limitation of the implementation and thus didn’t affect the tested parts of the simulator. The user tests also confirmed that the resolution was a potential problem, but that the overall usability was high. Thus the VR implementation had potential for use in a pilot training simulator, if the critical issues found during the user tests were solved.

As wearable computers become more ubiquitous in society and work environments, there are concerns that their use could be negatively impactful in some settings. Previous research indicates that mobile phone and wearable computer use can impair walking and driving performance, but as these technologies are adopted into hazardous work environments it is less clear what the impact will be. The current research investigated the effects that head mounted display use has on high angle climbing, a task representative of the extreme physical demands of some hazardous occupations (such as firefighting or search and rescue work). We explored the effect that introducing a secondary word reading and later recall task has on both climbing performance (holds per meter climbed and distance covered), and word reading and recall (dual-task effects). We found a decrease in both climbing performance and word recall under dual task conditions. Further, we examined participant climbing motion around word presentation and non-word presentation times during the climbing traverse. We found that participants slowed around word presentations, relative to periods without word presentation. Finally, we compared our results to those found in previous research using similar dual-tasking paradigms. These comparisons indicated that physical tasks may be more detrimental to word recall than seated tasks, and that visual stimuli might hinder climbing performance more than audible stimuli. This research has important theoretical implications for the dual-tasking paradigm, as well at important practical implications for emergency response operations and other hazardous working environments.

Head mounted projection display (HMPD) technology, as an alternative to conventional head mounted displays (HMD), offers a potential of designing wide field-of-view (FOV), low distortion optical see-through HMDs (OST-HMDs). Existing HMPD designs, however, suffer from problems of low luminance and low image resolution, which limits the applications of such information displays for the scenarios which require high luminance and high image fidelity. The design of a polarized head mounted projection display (p-HMPD) was recently proposed to overcome the challenge of low luminous efficiency in existing HMPD designs. Polarization management was employed to reduce the light loss caused by beamsplitting in an HMPD.The work in this dissertation focuses on the development and evaluation of an SXGA resolution, high efficiency p-HMPD system. The main contributions are as follows. First, the key elements in the polarization management scheme of a p-HMPD were selected and their polarization performances were characterized by measuring their Mueller matrices, based on which the overall display performance of a p-HMPD was analyzed.Second, based on a pair of ferroelectric liquid-crystal-on-silicon (FLCoS) microdisplays, a compact illumination unit and a light-weight projection system were designed, from which a p-HMPD prototype was built. Following the prototype implementation, a series of calibrations were performed to obtain correct color presentation, desired focusing setting, and optical system characteristics necessary for achieving accurate registration between virtual objects and their counterparts in the real world.Third, the imaging properties of a retroreflective screen which is an essential part of a p-HMPD or HMPD were studied and its effects on the image resolution of an HMPD system were further characterized.Finally, the performance of the system was evaluated through two objective user experiments, including a visual acuity assessment and a depth perception accuracy assessment.

Head-Mounted Displays (HMDs) are increasingly used to support mobile work (Laramee & Ware, 2002). Human operators sometimes require additional auditory support when using an HMD, which raises the question of whether sound is better delivered publicly in free-field or privately via earpiece. A novel experimental procedure was created in which participants had to identify mismatches between auditory information and visual information on an HMD. Different conditions of sound delivery and physical movement were manipulated within-subjects. Participants heard the sound either via earpiece or free-field while they either sat or moved about the test room. Predictions were based on the idea that inconsistent spatial mapping of vision and sound would compromise mismatch detection. First, I predicted a main effect of movement such that participants‟ mismatch detection would be worse when they moved than when they sat. Second, I predicted an interaction between movement and sound delivery. When participants are seated there will be no difference in mismatch detection between the two methods of sound delivery. When participants are walking, however, mismatch detection will be better with an earpiece than with free-field delivery. Results supported the first prediction. For the second prediction, the significant interaction found took a different form than predicted. With the earpiece, participants performed equally well whether sitting or walking, but with free-field sound, participants performed better when sitting than when walking. Results have implications for understanding necessary auditory conditions for effective crossmodal integration and may indicate a cause for concern for people who use HMDs and auditory displays in safety-critical environments.