With recent advancements in augmented reality (AR) display technologies, various head-mounted AR displays are now on the consumer market (e.g., Microsoft HoloLens 2, Meta Quest 3). However, there is limited knowledge on how these modern displays impact depth perception. Moreover, understanding the significance of occlusion's effects on action-space distance perception in AR is important, particularly for practical applications such as AR-assisted search-and-rescue operations. However, to our knowledge, no prior research has examined how varying occluder surfaces affect action-space distance estimation across head-mounted AR devices (optical see-through (OST) and video see-through (VST)). In this paper, we present the first research to examine how different occluding surfaces affect action-space distance estimation using OST and VST head-mounted AR devices. With 28 participants across two experiments, we examined verbal estimates and blind walking distance estimation methods. Three occluding surfaces: a checkerboard (high-salient), a black surface (low-salient), and a realistic brick wall texture were considered. Five action-space distances, ranging from 1m to 5m, were evaluated using two commercial AR devices: Microsoft HoloLens 2 (OST) and Meta Quest 3 (VST). Our findings suggest that occluders do not impact AR object action-space distance estimations through blind walking and verbal distance estimation tasks with two modern AR devices. Blind walking distance estimations varied between the HoloLens 2 and Meta Quest 3, with the HoloLens 2 (OST) achieving higher accuracy (distance error: 0.4cm to 3m), than the Meta Quest 3 (VST) (distance error: 24cm to 3m), regardless of occlusion. For AR objects placed on or behind an occluder, distance estimations were overestimated with Meta Quest 3, while the HoloLens 2 either achieved close to accurate or underestimated of depth perception via blind walking.

A replication attempts to confirm outcomes of earlier research, which is critical in validating and generalizing scientific findings. Yet, its prevalence and practices remain underexplored in Augmented and Virtual Reality (AR/VR) research. To address this, we present a scoping literature review of replication studies within IEEE ISMAR and IEEE VR, spanning 15 years from 2010 to 2024. Our analysis revealed that replication in AR/VR research is rare. Of 2167 total papers reviewed, less than 4 % were identified as replication studies. Of these, conceptual replications were the predominant type (57 %). Most of those were studies in VR (67 %) and within-subject designs (66 %). Complementing the literature survey results, we conducted an online survey with 61 participants about their experiences with replication studies and found that 39 % of them had conducted a replication study. However, limited resources and external motivation hamper the execution of replication studies among these AR/VR researchers. Combining the findings from our literature review and online survey, we discuss the current state of replication research and the factors contributing to its infrequency. We provide recommendations to improve AR/VR research replication practices, focusing on research culture and reporting, and discuss ongoing challenges.

Current smoke opacity certification methods are environmentally harmful and logistically inefficient, requiring real emissions, travel, and time off work. In this study, we present a Virtual Reality (VR) training and assessment system that simulates black and white smoke emissions in an immersive, controlled environment, designed to mirror real-world training and testing standards. Participants in the VR group completed two training sessions and a standardized test adapted from an official certification exam. Their performance was compared to a control group that received traditional lecture-based training and paper-based testing. Certification required a test score below 37 for both smoke colors. The VR group achieved mean scores of 33.44 (black smoke) and 57.75 (white smoke), outperforming the control group, which scored 46.00 and 72.00 respectively. The VR group significantly outperformed the control on black smoke$(p<0.05)$achieving passing scores on nearly all tested opacities ($<3$points (15%) deviation per reading). Subjectively, VR participants reported feeling more confident, better prepared, and found the application enjoyable. These results suggest VR is an effective, scalable alternative to traditional training, enhancing performance, increasing user satisfaction, and reducing environmental impact.

A primary objective of optical see-through (OST) Augmented Reality (AR) systems is to enable users to perceive the depth of AR objects with the same accuracy as they perceive the depth of realworld objects. Previous studies have shown that individuals often make depth judgments that either underestimate or overestimate the depth of AR objects compared to real-world objects. Recently, OST AR devices have incorporated eye-tracking technology, offering the opportunity to objectively measure and investigate the depth-dependent components of the human visual system (e.g., eye vergence angle) while perceiving the depth of real and AR objects. This paper measures and examines the eye vergence angle (EVA) for both real and AR objects at four different depths (0.35 m, 0.75 m, 1.5 m, and 4.0 m) using integrated eye-tracking systems of the two commercial devices: Microsoft HoloLens 2 and Magic Leap 2. The experiment considered a four-alternative forced-choice visual discrimination task with a repeated-measures design, involving 24 participants. Our findings showed that subjective (verbal estimation) and objective (EVA) measures of depth perception were consistent with the depth of both real and AR objects in both OST AR devices. The results demonstrated individual differences in EVA for each device across various depths. No difference in EVA was identified between real and AR objects. Additionally, the EVA range differs between the OST AR devices for each depth. These findings indicate that objective EVA measurements can not be generalized across different OST AR devices and individuals.

In an optical see-through augmented reality system, virtual and real information can be viewed at different distances. This requires users to frequently change their eye focus from one distance to another, and only one piece of information is in sharp focus while the other is out of focus. Previous studies have found that due to out-of-focus virtual information, when integrating information between the distances, users suffer fatigue and miss important information. Therefore, this paper introduces a novel font, termed a SharpView font, which looks sharper and more legible than standard fonts when seen out of focus. Our method models out-of-focus blur with Zernike polynomials and coefficients, develops a focus correction algorithm based on constrained total variation optimization, and proposes a novel gradient-based algorithm to quantify the sharpness of textual information. We have evaluated the SharpView font through simulation and optically viewed camera-based measurement. When seen out of focus, our proposed font are significantly sharper than standard fonts, as assessed both visually and quantitatively through simulation (40%-44%), as well as the optics of an augmented reality display (24%-32%).

Virtual Reality (VR) technology has advanced to include eye-tracking, allowing novel research, such as investigating how our visual system coordinates eye movements with changes in perceptual depth. The purpose of this study was to examine whether eye tracking could track perceptual depth changes during a visual discrimination task. We derived two depth-dependent variables from eye tracker data: eye vergence angle (EVA) and interpupillary distance (IPD). As hypothesized, our results revealed that shifting gaze from near-to-far depth significantly decreased EVA and increased IPD, while the opposite pattern was observed while shifting from far-to-near. Importantly, the amount of change in these variables tracked closely with relative changes in perceptual depth, and supported the hypothesis that eye tracker data may be used to infer real-time changes in perceptual depth in VR. Our method could be used as a new tool to adaptively render information based on depth and improve the VR user experience.

In optical see-through augmented reality (AR), information is often distributed between real and virtual contexts, and often appears at different distances from the user. To integrate information, users must repeatedly switch context and change focal distance. If the user's task is conducted under time pressure, they may attempt to integrate information while their eye is still changing focal distance, a phenomenon we term transient focal blur. Previously, Gabbard, Mehra, and Swan (2018) examined these issues, using a text-based visual search task on a one-eye optical see-through AR display. This paper reports an experiment that partially replicates and extends this task on a custom-built AR Haploscope. The experiment examined the effects of context switching, focal switching distance, binocular and monocular viewing, and transient focal blur on task performance and eye fatigue. Context switching increased eye fatigue but did not decrease performance. Increasing focal switching distance increased eye fatigue and decreased performance. Monocular viewing also increased eye fatigue and decreased performance. The transient focal blur effect resulted in additional performance decrements, and is an addition to knowledge about AR user interface design issues.

For optical see-through augmented reality (AR), a new method for measuring the perceived three-dimensional location of virtual objects is presented, where participants verbally report a virtual object’s location relative to both a vertical and horizontal grid. The method is tested with a small (1.95 × 1.95 × 1.95 cm) virtual object at distances of 50 to 80 cm, viewed through a Microsoft HoloLens 1stgeneration AR display. Two experiments examine two different virtual object designs, whether turning in a circle between reported object locations disrupts HoloLens tracking, and whether accuracy errors, including a rightward bias and underestimated depth, might be due to systematic errors that are restricted to a particular display. Turning in a circle did not disrupt HoloLens tracking, and testing with a second display did not suggest systematic errors restricted to a particular display. Instead, the experiments are consistent with the hypothesis that, when looking downwards at a horizontal plane, HoloLens 1stgeneration displays exhibit a systematic rightward perceptual bias. Precision analysis suggests that the method could measure the perceived location of a virtual object within an accuracy of less than 1 mm.

A haploscope is an optical system which produces a carefully controlled virtual image. Since the development of Wheatstone's original stereoscope in 1838, haploscopes have been used to measure perceptual properties of human stereoscopic vision. This paper presents an augmented reality (AR) haploscope, which allows the viewing of virtual objects superimposed against the real world. Our lab has used generations of this device to make a careful series of perceptual measurements of AR phenomena, which have been described in publications over the previous 8 years. This paper systematically describes the design, assembly, calibration, and measurement of our AR haploscope. These methods have been developed and improved in our lab over the past 10 years. Despite the fact that 180 years have elapsed since the original report of Wheatstone's stereoscope, we have not previously found a paper that describes these kinds of details.

The use of Optical See-Through (OST) technology for presenting Augmented Reality (AR) experiences is becoming more common. However, OST-AR displays require a calibration procedure, in order to determine the location of the users eyes. Currently, the predominantly cited manual calibration technique is the Single Point Active Alignment Method (SPAAM). However, with the SPAAM technique, there remains uncertainty about the causes of poor calibration results. This paper reports an experiment which examined the influence of two factors on SPAAM accuracy and precision: alignment point distribution, and user posture. Alignment point distribution is examined at user-centered reaching distances, 0.15 to 0.3 meters, as well as environment-centered room-scale distances, 0.5 to 2.0 meters. User posture likely contributes to misalignment error, and is examined at the levels of sitting and standing. In addition, a control condition replaces the user with a rigidly-mounted camera, and mounts the OST display on a precisely-adjustable tripod. The experiment finds that user-centric distributions are more accurate than environment-centric distributions, and, somewhat surprisingly, that the users posture has no effect. The control condition replicates these findings. The implication is that alignment point distribution is the predominant mode for induction of calibration error for SPAAM calibration procedures.

The use of Optical See-Through Head-Mounted Displays (OST-HMDs) for presenting Augmented Reality experiences has become more common, due to the increasing availability of lower cost head-worn device options. Despite this growth, commercially available OST hardware remains devoid of the integrated eye-tracking cameras necessary for automatically calibrating user-specific view parameters, leaving manual calibration methods as the most consistently viable option across display types. The Single Point Active Alignment Method (SPAAM) is currently the most-cited manual calibration technique, due to the relaxation of user constraints with respect to allowable motion during the calibration process. This work presents the first formal study directly investigating the effects that alignment point distribution imposes on SPAAM calibration accuracy and precision. A user experiment, employing a single expert user, is presented, in which SPAAM calibrations are performed under each of five conditions. Four of the conditions cross alignment distance (arm length, room scale) with user pose (sitting, standing). The fifth condition is a control condition, in which the user is replaced with a rigidly mounted camera; the control condition removes the effect of noise from uncontrollable postural sway. The final experimental results show no significant impact on calibration due to user pose (sitting, standing). The control condition also did not differ from the user produced calibration results, suggesting that posture sway was not a significant factor. However, both the user and control conditions show significant improvement using arm's length alignment points over room scale alignments, with an order of magnitude difference in eye location estimate error between conditions.