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Implementing digital technologies, such as augmented reality and 3D modeling, to various cultural sectors is an ongoing procedure, especially favorable after the COVID-19 pandemic. Even though such technologies are common to museums, galleries and archaeological places all over the world, little research or practical cases have been developed when it comes to theaters and theatrical costumes. The proposed research article describes the methodology of both reference material collection and application development, while an analysis of functions and aesthetic results are described, especially when it comes to 3D modeling. This paper’s aim is to reveal that theatrical operations (as part of the cultural sector) as well as structured parts (such as acts, performances and costumes) can be preserved and served to larger audiences via technological means, such as an augmented reality application.

The use of Augmented Reality glasses opens up many possibilities in hospital care, as they facilitate treatments and their documentation. In this paper, we present a prototype for the HoloLens 2 supporting wound care and documentation. It was developed in a participatory process with nurses using the positive computing paradigm, with a focus on the improvement of the working conditions of nursing staff. In a qualitative study with 14 participants, the factors of autonomy, competence and connectedness were examined in particular. It was shown that good individual adaptability and flexibility of the system with respect to the work task and personal preferences lead to a high degree of autonomy. The availability of the right information at the right time strengthens the feeling of competence. On the one hand, the connection to patients is increased by the additional information in the glasses, but on the other hand, it is hindered by the unusual appearance of the device and the lack of eye contact. In summary, the potential of Augmented Reality glasses in care was confirmed, and approaches for a well-being-centered system design were identified but, at the same time, a number of future research questions, including the effects on patients, were also identified.

The holistic growth and psychological well-being of people with special needs and disabilities remain high on the priority agenda for sustainable and inclusive education. Digital well-being technologies and especially “smart technologies”, are ready to revolutionize mental health interventions by meeting trainees’ needs and providing them with more positive and transformative mental, emotional, and social experiences. Μeta-skills refer to a set of consciousness-raising competences that incorporate meta-cognitive, social–emotional, and motivational attributes, allowing individuals to intentionally achieve a state of optimal functioning. Although positive psychology and well-being technologies are considered promising intervention approaches, there is less knowledge regarding the effectiveness of such interventions among people with special needs and disabilities, especially in the crucial domain of meta-skills development. Thus, the current systematic review aims to examine positive psychology strategies as well as the synergy with well-being technologies in the development of metacognition, emotional intelligence, and motivation meta-skills in populations with special training needs and disabilities. The PRISMA methodology was utilized to answer the research questions. A total of forty-nine studies met the inclusion criteria. The results indicated that positive psychology strategies improved a wide range of meta-skills, including self-regulation, emotional control, behavioral control, inhibition control, self-awareness, intrapersonal skills, interpersonal skills, adaptation, goal setting, and self-compassion. Artificial intelligence tools, wearables, smart applications, immersive technologies (virtual and augmented reality), neurofeedback and biofeedback technologies, as well as digital games were found to effectively assist such training programs. The results of the current review may provide positive feedback in the discussion about digitally-aided mental health interventions for training the meta-skills of mental and emotional health.

Critical care injuries, such as burn trauma, require specialized skillsets and knowledge. A clinical decision support system to aid clinicians in providing burn patient management can increase proficiency and provide knowledge content for specific interventions. In austere environments, decision support tools can be used to aid in decision making and task guidance when skilled personnel or resources are limited. Therefore, we developed a novel software system that utilizes augmented reality (AR) capabilities to provide enhanced step-by-step instructions based on best practices for managing burn patients. To better understand how new technologies, such as AR, can be used for burn care management, we developed a burn care application for use on a heads-up display. We developed four sub-set applications for documenting and conducting burn wound mapping, fluid resuscitation, medication calculations, and an escharotomy. After development, we conducted a usability study utilizing the System Usability Scale, pre- and post- simulation surveys, and after-action reviews to evaluate the AR-based software application in a simulation scenario. Results of the study indicate that the decision support tool has generalized usability and subjects were able to use the software as intended. Here we present the first use case of a comprehensive burn management system utilizing augmented reality capabilities to deliver care.

Augmented reality (AR) applications are currently used in many fields for communication and educational purposes. Tourism is also a sector where augmented reality is used for destination marketing and cultural heritage promotion. This study will focus on mobile location-based AR applications and their potential in tourism. Such applications can guide tourists to places of interest and enhance their overall experience. The aim of this paper is to present a mobile application that was created for tourists visiting the region of Western Macedonia, Greece. The application was developed in order to guide the users in the region, entertain them, and educate them about the region’s sights, cultural heritage, and other special characteristics. The paper also aims to present a large set of features that are present in the application, including various types of AR (marker-based, markerless, and location-based) in order to provide designers who wish to create AR applications for tourism with new ideas. The application was validated by a usability test, and its features were evaluated by 39 participants who completed a questionnaire with 29 Likert-scale items. This procedure revealed the level of acceptance for the application features, and valuable feedback was also received during a discussion with the participants about how the application could be upgraded in the future.

This study aspires to contribute some initial results to the growing area of research regarding technology potential in the field of early foreign language literacy. An experiment was conducted to examine very young learners’ alphabet and vocabulary learning and retention in an early foreign language (FL) learning context when implementing augmented reality (AR) applications, while very young learners’ motivation was also assessed. A pilot intervention was implemented in a state school in northern Greece. The participants (n = 26) were primary school first-graders (5.5–6 years old) and were assigned into two groups, experimental (13) and control (13). To examine the effects of the intervention, this current study employed two instruments: (a) a pre-test–post-test model to assess young learners’ alphabet and vocabulary learning during three phases and (b) a questionnaire to assess their motivation during the learning process. The findings of this study reveal that both groups displayed significant improvements in FL alphabet and vocabulary learning; however, there are statistical differences in favor of the experimental group regarding long-term alphabet and vocabulary learning and retention. Furthermore, qualitative results regarding children’s perceptions of the technology used indicate that AR was highly appealing and motivating to participating students.

The structural characteristics of biomolecules are a major focus in the field of structural biology. Molecular visualization plays a crucial role in displaying structural information in an intuitive manner, aiding in the understanding of molecular properties. This paper provides a comprehensive overview of core concepts, key techniques, and tools in molecular visualization. Additionally, it presents the latest research findings to uncover emerging trends and highlights the challenges and potential directions for the development of the field.

Designing virtual characters that are capable of reflecting a sense of personality is a key goal in research and applications in virtual reality and computer graphics. More and more research efforts are dedicated to investigating approaches to construct a diverse, equitable, and inclusive metaverse by infusing expressive personalities and styles into virtual avatars. While most previous work focused on exploring variations in virtual characters’ dynamic behaviors, characters’ visual appearance plays a crucial role in affecting their perceived personalities. This paper presents a series of experiments evaluating the effect of virtual characters’ outfits on their perceived personality. Based on the related psychology research conducted in the real world, we determined a set of outfit factors likely to reflect personality in virtual characters: color, design, and type. As a framework for our study, we used the “Big Five” personality model for evaluating personality traits. To test our hypothesis, we conducted three perceptual experiments to evaluate the outfit parameters’ contributions to the characters’ personality. In our first experiment, we studied the color factor by varying color hue, saturation, and value; in the second experiment, we evaluated the impact of different neckline, waistline, and sleeve designs; and in our third experiment, we examined the personality perception of five outfit types: professional, casual, fashionable, outdoor, and indoor. Significant results offer guidance to avatar designers on how to create virtual characters with specific personality profiles. We further conducted a verification test to extend the application of our findings to animated virtual characters in augmented reality (AR) and virtual reality (VR) settings. Results confirmed that our findings can be broadly applied to both static and animated virtual characters in VR and AR environments that are commonly used in games, entertainment, and social networking scenarios.

The article discusses the modeling of the use of digital twin technologies (a digital twin) for the task of organizing long-term storage of various types of documents. A digital twin in this respect differs from a digital copy, which has no connection with the real original object. A review of the problem was carried out. We argue that, despite the active use of digital twin technology in various areas, its applications in the area of long-term storage of documents remain limited. At the same time, the task of increasing the durability of documents during long-term storage remains important and largely unresolved. The complexity of solving the problem of long-term storage of documents is considered, and a formal statement of the problem of long-term storage using digital twin technologies is carried out. Destructive factors that affect long-term storage documents and significantly reduce their durability have been identified. A system of indicators has been developed to assess the durability (preservation) of documents. The modeling of the use of digital twin technology in the organization of long-term preservation within the framework of Industry 4.0 was carried out. In the course of modeling, the goals and the strategies of long-term storage were established. Primary mathematical models for controlling destructive factors as well as technological solutions for digital twin long-term storage are proposed. It is assumed that the key part of this technology is the Industrial Internet of Things. The effectiveness of the use of digital twin technologies for solving the problem was assessed. The spheres of application and further ways of research are determined.

This study aims to identify and analyze existing gaps in the integration of immersive approaches for collaborative processes with Building Information Modeling (BIM) in the Architecture, Engineering, and Construction (AEC) sector. Using a systematic approach that includes metadata analysis and review procedures, we have formulated specific research questions aimed at guiding future investigations into these gaps. Additionally, the analysis generates insights that could guide future research directions and improvements in the field. The methodology involves a comprehensive review of the literature, focusing on the interaction between immersiveness, BIM methodology, and collaborative processes. Data from 2010 to 2023 have been analyzed to ensure relevance and completeness. Our findings reveal current limitations in the field, such as the need for fully integrated prototypes and the execution of empirical studies to clarify operational processes. These limitations serve as the basis for our research questions. The study offers actionable insights that could guide future research and improvements in the AEC sector, particularly in the adoption of immersive technologies. The research underscores the urgency of addressing these challenges to facilitate ongoing development and greater adoption of immersive technologies in the AEC sector.

This study investigates how virtual and augmented reality role games impact self-learning in higher education settings. A qualitative research–action approach that involved creating augmented reality micro-stories to encourage creativity and critical thinking was used. Through role-playing, students collaborated and gained a deeper understanding of the course, improving their self-learning abilities. The findings indicate that incorporating virtual and augmented reality into higher education positively affects self-learning, promoting active student engagement and meaningful learning experiences. Additionally, students perceive these immersive educational methods as bridging the gap between virtual and in-person learning environments, ultimately leading to enhanced educational results.

Metaverse is an upcoming transformative technology that will impact our future society with immersive experiences. The recent surge in the adoption of new technologies and innovations in connectivity, interaction technology, and artificial realities can fundamentally change the digital world. The Metaverse concept is the most recent trend to encapsulate and define the potential new digital landscape. However, with the introduction of 5G with high speed and low latency advancements in the hardware and software with the graphics power to display millions of polygons in 3D and blockchain technology, this concept is no longer fiction. This transition from today’s Internet to a spatially embodied Internet is, at its core, a transition from 2D to 3D interactions taking place in multiple virtual universes. In recent years, augmented virtual reality has created possibilities in the private and professional spheres. The new Virtual Reality (VR) headsets and Augmented Reality (AR) glasses can provide immersion in the physical sense. Technology must offer realistic experiences for users to turn this concept into reality. This paper focuses on the potential use cases and benefits of the Metaverse as a tech for good. The research paper outlines the potential areas where a positive impact could occur, highlights recent progress, and discusses the issues around trust, ethics, and cognitive load.

The air spring for railway vehicles uses the air pressure inside the bellows to absorb vibration and shock to improve ride comfort and adjust the height of the underframe with a leveling valve to control stable driving of the train. This study developed augmented reality content that proposes a novel visual technology to effectively support the training of air spring maintenance tasks. In this study, a special effect algorithm that displays the dispersion and diffusion of fluid, and an algorithm that allows objects to be rotated at various angles, were proposed to increase the visual learning effect of fluid flow for maintenance. The FDG algorithm can increase the training effect by visualizing the leakage of air at a specific location when the air spring is damaged. In addition, the OAR algorithm allows an axisymmetric model, which is difficult to rotate by gestures, to be rotated at various angles, using a touch cube. Using these algorithms, maintenance personnel can effectively learn complex maintenance tasks. The UMUX and CSUQ surveys were conducted with 40 railway maintenance workers to evaluate the effectiveness of the developed educational content. The results showed that the UMUX, across 4 items, averaged as score of 81.56. Likewise, the CSUQ survey score, consisting of 19 questions in 4 categories, was very high, at 80.83. These results show that this AR content is usable for air spring maintenance and field training support.

State-of-the-art augmented reality (AR) glasses record their 3D pose in space, enabling measurements and analyses of clinical gait and balance tests. This study’s objective was to evaluate concurrent validity and test–retest reliability for common clinical gait and balance tests in people with Parkinson’s disease: Five Times Sit To Stand (FTSTS) and Timed Up and Go (TUG) tests. Position and orientation data were collected in 22 participants with Parkinson’s disease using HoloLens 2 and Magic Leap 2 AR glasses, from which test completion durations and durations of distinct sub-parts (e.g., sit to stand, turning) were derived and compared to reference systems and over test repetitions. Regarding concurrent validity, for both tests, an excellent between-systems agreement was found for position and orientation time series (ICC(C,1) > 0.933) and test completion durations (ICC(A,1) > 0.984). Between-systems agreement for FTSTS (sub-)durations were all excellent (ICC(A,1) > 0.921). TUG turning sub-durations were excellent (turn 1, ICC(A,1) = 0.913) and moderate (turn 2, ICC(A,1) = 0.589). Regarding test–retest reliability, the within-system test–retest variation in test completion times and sub-durations was always much greater than the between-systems variation, implying that (sub-)durations may be derived interchangeably from AR and reference system data. In conclusion, AR data are of sufficient quality to evaluate gait and balance aspects in people with Parkinson’s disease, with valid quantification of test completion durations and sub-durations of distinct FTSTS and TUG sub-parts.

Gait speed is increasingly recognized as an important health indicator. However, gait analysis in clinical settings often encounters inconsistencies due to methodological variability and resource constraints. To address these challenges, GaitKeeper uses artificial intelligence (AI) and augmented reality (AR) to standardize gait speed assessments. In laboratory conditions, GaitKeeper demonstrates close alignment with the Vicon system and, in clinical environments, it strongly correlates with the Gaitrite system. The integration of a cloud-based processing platform and robust data security positions GaitKeeper as an accurate, cost-effective, and user-friendly tool for gait assessment in diverse clinical settings.

This literature review presents a comprehensive and systematic account of research on the experiences of children with extended reality (XR), including VR, AR, and other types of immersive technologies that enhance and augment children’s activities. The search on Scopus and Web of Science produced 531 outputs. Content analysis with inter-rater reliability (Krippendorff’s α) and Leximancer, a software for text mining, were used for analyzing the material. Four research strands were identified: (1) interventions, treatments, and medical procedures in clinical contexts; (2) teaching and learning enhanced by XR; (3) children’s adoption and user experiences; (4) design and prototyping of XR hardware and software for children. The results showed the following findings: (a) studies on children’s clinical interventions and treatments using HMD-supported immersive virtual reality comprise the most substantial strand of studies; (b) research in this area, and in teaching and learning studies, has grown dramatically since 2017, while the other areas have been stagnant over the years; (c) AR research is still limited and is mainly applied in educational contexts for design and prototyping; (d) few studies have considered children’s perspectives on XR safety issues; (e) research on the use of XR for enhancing social and emotional skills development is underrepresented. Future research should focus on the potential of XR technologies for interventions to enhance children’s psychosocial wellbeing and health more broadly. The further implications and study limitations for the fast-developing nature of this transdisciplinary research field are also discussed.

Strawberry production has been continually increasing worldwide, but this growth has often resulted in a lack of taste, favoring yield and plant adaptability instead. However, in recent decades, consumer focus has shifted towards more flavorful fruits. Consequently, the application of new sensory methodologies for consumers in strawberry breeding programs is becoming essential. This review provides an overview of new rapid consumer-based sensory methodologies and a brief summary of their potential applications when combined with Augmented Reality technology. These advancements aim to better understand and meet consumer needs, offering breeders valuable tools for their future work.

People with disorders of consciousness, either as a consequence of an acquired brain injury or a traumatic brain injury, may pose serious challenges to medical and/or rehabilitative centers with an increased burden on caregivers and families. The objectives of this study were as follows: to explore the use of extended reality as a critical means of rehabilitative support in people with disorders of consciousness and brain injuries; to evaluate its impact on recovery processes; to assess the improvements in the participants’ quality of life, and to reduce the burden on families and caregivers by using extended reality and artificial-intelligence-based programs. A selective review of the newest empirical studies on the use of extended reality and artificial-intelligence-based interventions in patients with brain injuries and disorders of consciousness was conducted over the last decade. The potential for bias in this selective review is acknowledged. A conceptual framework was detailed. The data showed that extended reality and artificial-intelligence-based programs successfully enhanced the adaptive responding of the participants involved, and improved their quality of life. The burden on caregivers and families was reduced accordingly. Extended reality and artificial intelligence may be viewed as crucial means of recovery in people with disorders of consciousness and brain injuries.

For nearly three decades, researchers have explored the use of augmented reality for facilitating collaboration between humans and robots. In this survey paper, we review the prominent, relevant literature published since 2008, the last date that a similar review article was published. We begin with a look at the various forms of the augmented reality (AR) technology itself, as utilized for human–robot collaboration (HRC). We then highlight specific application areas of AR for HRC, as well as the main technological contributions of the literature. Next, we present commonly used methods of evaluation with suggestions for implementation. We end with a look towards future research directions for this burgeoning field. This review serves as a primer and comprehensive reference for those whose work involves the combination of augmented reality with any kind of human–robot collaboration.

This study evaluates an innovative control approach to assistive robotics by integrating brain–computer interface (BCI) technology and eye tracking into a shared control system for a mobile augmented reality user interface. Aimed at enhancing the autonomy of individuals with physical disabilities, particularly those with impaired motor function due to conditions such as stroke, the system utilizes BCI to interpret user intentions from electroencephalography signals and eye tracking to identify the object of focus, thus refining control commands. This integration seeks to create a more intuitive and responsive assistive robot control strategy. The real-world usability was evaluated, demonstrating significant potential to improve autonomy for individuals with severe motor impairments. The control system was compared with an eye-tracking-based alternative to identify areas needing improvement. Although BCI achieved an acceptable success rate of 0.83 in the final phase, eye tracking was more effective with a perfect success rate and consistently lower completion times (p<0.001). The user experience responses favored eye tracking in 11 out of 26 questions, with no significant differences in the remaining questions, and subjective fatigue was higher with BCI use (p=0.04). While BCI performance lagged behind eye tracking, the user evaluation supports the validity of our control strategy, showing that it could be deployed in real-world conditions and suggesting a pathway for further advancements.

Display technologies influence user experience, not only through the perception of product features but also due to their own usage properties. In this work, 12 functional, usable, pleasuring, and media usage properties were analysed for five display technologies: image rendering, 360° rotation, and augmented, immersive, and non-immersive virtual reality. The perception of their importance and their assessment for the chosen technologies were studied by taking two different household products. Two variables for studying decision and expectations were also considered. The results showed that 360° rotation was well-valued in various properties, mainly related to functionality and usability, while the immersive virtual technology stood out in media properties and also in the most important feature: realism. It was also seen that the results could depend on the displayed product. These results provide a deeper insight for user experience optimisation because they complement the information to choose the most appropriate display technology based on the properties to be prioritised.

Surgical education demands extensive knowledge and skill acquisition within limited time frames, often limited by reduced training opportunities and high-pressure environments. This review evaluates the effectiveness of extended reality-based head-mounted display (ExR-HMD) technology in surgical education, examining its impact on educational outcomes and exploring its strengths and limitations. Data from PubMed, Cochrane Library, Web of Science, ScienceDirect, Scopus, ACM Digital Library, IEEE Xplore, WorldCat, and Google Scholar (Year: 2014–2024) were synthesized. After screening, 32 studies comparing ExR-HMD and traditional surgical training methods for medical students or residents were identified. Quality and bias were assessed using the Medical Education Research Study Quality Instrument, Newcastle–Ottawa Scale-Education, and Cochrane Risk of Bias Tools. Results indicate that ExR-HMD offers benefits such as increased immersion, spatial awareness, and interaction and supports motor skill acquisition theory and constructivist educational theories. However, challenges such as system fidelity, operational inconvenience, and physical discomfort were noted. Nearly half the studies reported outcomes comparable or superior to traditional methods, emphasizing the importance of social interaction. Limitations include study heterogeneity and English-only publications. ExR-HMD shows promise but needs educational theory integration and social interaction. Future research should address technical and economic barriers to global accessibility.

This review explores the transformative applications of augmented reality (AR) and mixed reality (MR) technologies in interventional cardiology. The integration of these cutting-edge systems offers unprecedented potential to enhance visualization, guidance, and outcomes during complex cardiac interventional procedures. This review examines four key domains: (1) medical AR/MR systems and technological foundations; (2) clinical applications across procedures like TAVI, PCI, and electrophysiology mapping; (3) ongoing technology development and validation efforts; and (4) educational and training applications for fostering essential skills. By providing an in-depth analysis of the benefits, challenges, and future directions, this work elucidates the paradigm shift catalyzed by AR and MR in advancing interventional cardiology practices. Through meticulous exploration of technological, clinical, and educational implications, this review underscores the pivotal role of these innovative technologies in optimizing procedural guidance, improving patient outcomes, and driving innovation in cardiovascular care.

In the global context, advancements in technology and science have rendered virtual, augmented, and mixed-reality technologies capable of transforming clinical care and medical environments by offering enhanced features and improved healthcare services. This paper aims to present a mixed reality-based system to control a robotic wheelchair for people with limited mobility. The test group comprised 11 healthy subjects (six male, five female, mean age 35.2 ± 11.7 years). A novel platform that integrates a smart wheelchair and an eye-tracking-enabled head-mounted display was proposed to reduce the cognitive requirements needed for wheelchair movement and control. The approach’s effectiveness was demonstrated by evaluating our system in realistic scenarios. The demonstration of the proposed AR head-mounted display user interface for controlling a smart wheelchair and the results provided in this paper could highlight the potential of the HoloLens 2-based innovative solutions and bring focus to emerging research topics, such as remote control, cognitive rehabilitation, the implementation of patient autonomy with severe disabilities, and telemedicine.

Extended reality (XR) is one of the most important technologies in developing a new generation of human–machine interfaces (HMIs). In this study, the design and implementation of a standalone interactive XR-supported industrial robot programming system using the Unity game engine is presented. The presented research aims to achieve a cross-platform solution that enables novel tools for robot programming, trajectory validation, and robot programming debugging within an extended reality environment. From a robotics perspective, key design tasks include modeling in the Unity environment based on robot CAD models and control design, which include inverse kinematics solution, trajectory planner development, and motion controller set-up. Furthermore, the integration of real-time vision, touchscreen interaction, and AR/VR headset interaction are involved within the overall system development. A comprehensive approach to integrating Unity with established industrial robot modeling conventions and control strategies is presented. The proposed modeling, control, and programming concepts, procedures, and algorithms are verified using a 6DoF robot with revolute joints. The benefits and challenges of using a standalone XR-supported interactive industrial robot programming system compared to integrated Unity–robotics development frameworks are discussed.

Recent advancements in communication technology have catalyzed the widespread adoption of realistic content, with augmented reality (AR) emerging as a pivotal tool for seamlessly integrating virtual elements into real-world environments. In construction, architecture, and urban design, the integration of mixed reality (MR) technology enables rapid interior spatial mapping, providing clients with immersive experiences to envision their desires. The rapid advancement of MR devices, or devices that integrate MR capabilities, offers users numerous opportunities for enhanced entertainment experiences. However, to support designers at a high level of expertise, it is crucial to ensure the accuracy and reliability of the data provided by these devices. This study explored the potential of utilizing spatial mapping within various methodologies for surveying architectural interiors. The objective was to identify optimized spatial mapping procedures and determine the most effective applications for their use. Experiments were conducted to evaluate the interior survey performance, using HoloLens 2, an iPhone 13 Pro for spatial mapping, and photogrammetry. The findings indicate that HoloLens 2 is most suited for the tasks examined in the scope of these experiments. Nonetheless, based on the acquired parameters, the author also proposes approaches to apply the other technologies in specific real-world scenarios.

Periacetabular osteotomy (PAO) is an effective approach for the surgical treatment of developmental dysplasia of the hip (DDH). However, due to the complex anatomical structure around the hip joint and the limited field of view (FoV) during the surgery, it is challenging for surgeons to perform a PAO surgery. To solve this challenge, we propose a robot-assisted, augmented reality (AR)-guided surgical navigation system for PAO. The system mainly consists of a robot arm, an optical tracker, and a Microsoft HoloLens 2 headset, which is a state-of-the-art (SOTA) optical see-through (OST) head-mounted display (HMD). For AR guidance, we propose an optical marker-based AR registration method to estimate a transformation from the optical tracker coordinate system (COS) to the virtual space COS such that the virtual models can be superimposed on the corresponding physical counterparts. Furthermore, to guide the osteotomy, the developed system automatically aligns a bone saw with osteotomy planes planned in preoperative images. Then, it provides surgeons with not only virtual constraints to restrict movement of the bone saw but also AR guidance for visual feedback without sight diversion, leading to higher surgical accuracy and improved surgical safety. Comprehensive experiments were conducted to evaluate both the AR registration accuracy and osteotomy accuracy of the developed navigation system. The proposed AR registration method achieved an average mean absolute distance error (mADE) of 1.96 ± 0.43 mm. The robotic system achieved an average center translation error of 0.96 ± 0.23 mm, an average maximum distance of 1.31 ± 0.20 mm, and an average angular deviation of 3.77 ± 0.85°. Experimental results demonstrated both the AR registration accuracy and the osteotomy accuracy of the developed system.

Real-world understanding serves as a medium that bridges the information world and the physical world, enabling the realization of virtual–real mapping and interaction. However, scene understanding based solely on 2D images faces problems such as a lack of geometric information and limited robustness against occlusion. The depth sensor brings new opportunities, but there are still challenges in fusing depth with geometric and semantic priors. To address these concerns, our method considers the repeatability of video stream data and the sparsity of newly generated data. We introduce a sparsely correlated network architecture (SCN) designed explicitly for online RGBD instance segmentation. Additionally, we leverage the power of object-level RGB-D SLAM systems, thereby transcending the limitations of conventional approaches that solely emphasize geometry or semantics. We establish correlation over time and leverage this correlation to develop rules and generate sparse data. We thoroughly evaluate the system’s performance on the NYU Depth V2 and ScanNet V2 datasets, demonstrating that incorporating frame-to-frame correlation leads to significantly improved accuracy and consistency in instance segmentation compared to existing state-of-the-art alternatives. Moreover, using sparse data reduces data complexity while ensuring the real-time requirement of 18 fps. Furthermore, by utilizing prior knowledge of object layout understanding, we showcase a promising application of augmented reality, showcasing its potential and practicality.

With the rapid development of science and technology, the integration and complexity of aerospace vehicles, weaponry, and large-scale chemical equipment are becoming higher and higher. PHM plays an important role in realizing reductions in equipment loss due to failures in many fields. In order to systematically sort through the research history of PHM and deeply analyze the development status of AR and DT technologies in the field of PHM, to clarify the current technical challenges and future development directions and to provide valuable references and insights for researchers, engineers, and decision-makers in the related fields, this paper summarizes the development of PHM in the engineering field. This paper summarizes the development of PHM in the field of engineering, from the initial PHM used in aerospace to the current PHM systems supported by various advanced technologies; analyzes the advantages and shortcomings of the digital twin and augmented reality technologies used for PHM; and organizes and summarizes the future directions and future research focuses of PHM research based on the existing technologies (mainly digital twins and augmented reality). After systematic research and study, we found that the integration of augmented reality and digital twin technologies will provide superb simulation capabilities and immersive operation and bring new challenges and opportunities. Therefore, it is also imperative to address the challenges and limitations that hinder the seamless integration of the new technologies.

The construction industry is undergoing a digital transformation, with the digital twin serving as a core system for project information. This digital twin provides an opportunity to utilize AR technology for real-time verification of on-site project information. Although many AR developments for construction sites have been attempted, they have been limited to accessing information on stationary components via Building Information Models. There have been no attempts to access information on dynamically changing resources, such as personnel and equipment. This paper addresses this gap by presenting an AR framework that enables site managers to verify real-time information on specific personnel or equipment. It introduces a matching algorithm for retrieving the necessary information from the digital twin. This algorithm is pivotal in identifying and retrieving the specific information needed from the vast dataset within the digital twin. The matching process integrates object detection and tracking algorithms applied to video frames from AR devices, along with GPS and IMU sensor data. Experimental results demonstrate the potential of this matching algorithm to streamline on-site management and reduce the effort required to interact with digital twin information. This paper highlights the transformative potential of AR and digital twin technologies in revolutionizing construction site operations.

In this study, we report on a case study of two Swedish preschool teachers’ first experiences of teaching sustainable development goals through the innovative use of augmented reality. Their statements about thematic work, children’s agency, teachers’ perspective, and augmented reality were analysed qualitatively through a theoretical framework based on transduction and place. The innovative use of augmented reality related to the importance of children’s agency in their exploration of local places associated with sustainable development goals is elaborated on, especially with the value of treating augmented reality as a ‘what’, or content, in teaching before it can be used as a ‘how’, or tool, for teaching sustainable development. It is seen in this exploratory study that transducing meaning between different representations such as physical places and the sustainable development goals in augmented reality applications opens up fruitful discussions regarding, for example, democracy aspects and source criticism between children and preschool teachers. Results indicate that the introduction of augmented reality technology is also worth pursuing in early-year teaching.

With the rapid growth of Augmented Reality (AR) in e-commerce, it is necessary to conduct in-depth studies related to the integration of AR with Artificial Intelligence (AI) technology to improve personalization in product recommendations. AI and AR are expected to work together, where AI systems analyze consumer data to provide more suitable product recommendations, while AR helps consumers visualize these recommendations in the real world. This research explores the influence of AI and AR technology integration in personalized recommendations on customer usage intention, with a focus on the cosmetics industry on the e-commerce platform Shopee. Adopting the Technology Acceptance Model (TAM) and the Theory of Planned Behavior (TPB), this research uses quantitative methods with the try-on feature of cosmetic products as the main focus. With a total number of 387 respondents, the results of the PLS-SEM analysis revealed factors impacting the intention to use, such as perceived ease of use, perceived usefulness, and users’ perceived trust, on the intention to use personalized recommendations. This research contributes to the understanding of AI–AR technology acceptance in the context of online shopping, particularly in the cosmetics sector.

It is well-recognized that online experience can carry profound impacts on health and well-being, particularly for young people. Research has already documented influences from cyberbullying, heightened feelings of inadequacy, and the relative decline of face-to-face interactions and active lifestyles. Less attention has been given to the health impacts of aesthetic experiences of online users, particularly gamers and other users of immersive virtual reality (VR) technologies. However, a significant body of research has begun to document the surprisingly strong yet previously unrecognized impacts of aesthetic experiences on health and well-being in other arenas of life. Other researchers have used both fixed laboratory and wearable sensors and, to a lesser extent, user surveys to measure indicators of activation level, mood, and stress level, which detect physiological markers for health. In this study, we assessed the evidence that online sensorial experience is no less important than in the physical world, with the capacity for both harmful effects and salutogenic benefits. We explore the implications for online design and propose an outline for further research.

This paper presents the development of a 3D digital model of end-of-service-life buildings to facilitate a step change in preparation of pre-demolition protocols that can eliminate problems of inadequate documentation and extensive time spent in preparing pre-demolition audits. The 3D digital model consists of the following four main components: (i) digitization of paper-based drawings and their conversion to CAD; (ii) automated generation of a 3D digital model from CAD; (iii) corrections to the 3D digital model to account for changes in the lifetime of a building; (iv) a sub-model for performing pre-demolition audit. This paper proposes the innovative approaches of incorporating a minimal amount of human intervention to overcome numerous difficulties in automated drawing analysis, application of augmented reality (AR) in corrections to the 3D digital model, and data compatibility for pre-demolition audit. These processes are demonstrated using one building as case study. Using the digital model, a pre-demolition audit can be prepared in minutes rather than the many days required in current practice without a digital model. The accurate quantification of the quantities and locations of different demolition waste materials and products in buildings to be demolished will enable a systematic and quantitative evaluation of potentials of material and product reuse and eliminate contamination of different demolition waste streams (which may contain hazardous waste), which is the main cause of environmental degradation and downcycling of demolition waste materials.

In response to the evolving landscape of maritime operations, new technologies are on the horizon as mixed reality (MR), which shall enhance navigation safety and efficiency during remote assistance as, e.g., in the remote pilotage use case. However, up to now, it is uncertain if this technology can provide benefits in terms of usability and situational awareness (SA) compared with screen-based visualizations, which are established in maritime navigation. Thus, this paper initially tests and assesses novel approaches to pilotage in the congested maritime environment, which integrates augmented reality (AR) for ship captains and virtual reality (VR) and desktop applications for pilots. The tested prototype employs AR glasses, notably the Hololens 2, to superimpose the Automatic Identification System (AIS) data directly into the captain’s field of view, while pilots on land receive identical information alongside live 360-degree video feeds from cameras installed on the ship. Additional minimum functionalities include waypoint setting, bearing indicators, and voice communication. The efficiency and usability of these technologies are evaluated through in situ tests conducted with experienced pilots on a real ship using the System Usability Scale, the Situational Awareness Rating Technique, as well as Simulator Sickness Questionnaires during the assessment. This includes a first indicative comparison of VR and desktop applications for the given use case.

The integration of interactive technology into magic performances was explored in this study, with a focus on leveraging virtual user interfacing and interactive video projection techniques to enhance the entertainment effects. A thorough literature review identified transformation techniques between virtual and real forms in the magic performance, along with various digital magic effects. Design principles derived from the review were applied in constructing a magic show system named “FUI Magic”, where FUI stands for fantasy user interface. The system is based on virtual user interfacing, implemented via laser range-finding and video projection techniques. The “FUI Magic” system facilitated the development and presentation of a digital-multimedia magic show titled “Fantasy Doves”, publicly showcased in an exhibition. Statistical evaluation of the feedback from expert interviews and a questionnaire survey revealed positive audience impressions and confirmed the effectiveness of incorporating virtual user-interfacing technology for captivating entertainment. This study affirms the significance of visual design through virtual user interfacing in enhancing technological ambiance and magic effects, suggesting its practicality for further exploration in diverse applications.

This study delves into the transformative potential of integrating augmented reality (AR) within imaging technologies, shedding light on this evolving landscape. Through a comprehensive narrative review, this research uncovers a wealth of literature exploring the intersection between AR and medical imaging, highlighting its growing prominence in healthcare. AR’s integration offers a host of potential opportunities to enhance surgical precision, bolster patient engagement, and customize medical interventions. Moreover, when combined with technologies like virtual reality (VR), artificial intelligence (AI), and robotics, AR opens up new avenues for innovation in clinical practice, education, and training. However, amidst these promising prospects lie numerous unanswered questions and areas ripe for exploration. This study emphasizes the need for rigorous research to elucidate the clinical efficacy of AR-integrated interventions, optimize surgical workflows, and address technological challenges. As the healthcare landscape continues to evolve, sustained research efforts are crucial to fully realizing AR’s transformative impact in medical imaging. Systematic reviews on AR in healthcare also overlook regulatory and developmental factors, particularly in regard to medical devices. These include compliance with standards, safety regulations, risk management, clinical validation, and developmental processes. Addressing these aspects will provide a comprehensive understanding of the challenges and opportunities in integrating AR into clinical settings, informing stakeholders about crucial regulatory and developmental considerations for successful implementation. Moreover, navigating the regulatory approval process requires substantial financial resources and expertise, presenting barriers to entry for smaller innovators. Collaboration across disciplines and concerted efforts to overcome barriers will be essential in navigating this frontier and harnessing the potential of AR to revolutionize healthcare delivery.

(1) Background: This study aimed to integrate an augmented reality (AR) image-guided surgery (IGS) system, based on preoperative cone beam computed tomography (CBCT) scans, into clinical practice. (2) Methods: In preclinical and clinical surgical setups, an AR-guided visualization system based on Microsoft’s HoloLens 2 was assessed for complex lower third molar (LTM) extractions. In this study, the system’s potential intraoperative feasibility and usability is described first. Preparation and operating times for each procedure were measured, as well as the system’s usability, using the System Usability Scale (SUS). (3) Results: A total of six LTMs (n = 6) were analyzed, two extracted from human cadaver head specimens (n = 2) and four from clinical patients (n = 4). The average preparation time was 166 ± 44 s, while the operation time averaged 21 ± 5.9 min. The overall mean SUS score was 79.1 ± 9.3. When analyzed separately, the usability score categorized the AR-guidance system as “good” in clinical patients and “best imaginable” in human cadaver head procedures. (4) Conclusions: This translational study analyzed the first successful and functionally stable application of the HoloLens technology for complex LTM extraction in clinical patients. Further research is needed to refine the technology’s integration into clinical practice to improve patient outcomes.

Physical inactivity represents a significant public health challenge globally. Mobile applications, particularly those utilizing augmented reality (AR), have emerged as innovative tools for promoting physical activity. However, a systematic evaluation of their efficacy is essential. This systematic review aims to evaluate and synthesize the evidence regarding the effectiveness and benefits of mobile applications with augmented reality in enhancing physical activity and improving health outcomes. A comprehensive search was conducted in Scopus, PubMed, WOS, and the Cochrane Library databases following PRISMA guidelines. Observational and interventional studies evaluating AR mobile applications for physical exercise were included, without restrictions on publication date or language. The search terms included “Mobile Applications”, “Augmented Reality”, “Physical Fitness”, “Exercise Therapy”, and “Health Behavior”. The methodological quality was assessed using the ROBINS tool. The review identified twelve eligible studies encompassing 5,534,661 participants. The findings indicated significant increases in physical activity and improvements in mental health associated with the use of AR applications, such as Pokémon GO. However, potential risk behaviors were also noted. The evidence suggests that AR interventions can effectively promote physical activity and enhance health. Nonetheless, further research is needed to address limitations and optimize their efficacy. Future interventions should be tailored to diverse cultural contexts to maximize benefits and mitigate risks. AR mobile applications hold promise for promoting physical activity and improving health outcomes. Strategies to optimize their effectiveness and address identified risks should be explored to fully realize their potential.

The widespread adoption of digital technologies in educational systems has been globally reflecting a shift in pedagogic content delivery that seems to fit modern generations of students while tackling relevant challenges faced by the current scholar context, e.g., progress traceability, pedagogic content fair access and intuitive visual representativeness, mobility issue mitigation, and sustainability in crisis situations. Among these technologies, augmented reality (AR) emerges as a particularly promising approach, allowing the visualization of computer-generated interactive data on top of real-world elements, thus enhancing comprehension and intuition regarding educational content, often in mobile settings. While the application of AR to education has been widely addressed, issues related to performance interaction and cognitive performance are commonly addressed, with lesser attention paid to the limitations associated with setup complexity, mostly related to experiences configurating tools, or contextual range, i.e., technical/scientific domain targeting versatility. Therefore, this paper introduces ARPocketLab, a digital, mobile, flexible, and scalable solution designed for the dynamic needs of modern tutorship. With a dual-interface system, it allows both educators and students to interactively design and engage with AR content directly tied to educational outcomes. Moreover, ARPocketLab’s design, aimed at handheld operationalization using a minimal set of physical resources, is particularly relevant in environments where educational materials are scarce or in situations where remote learning becomes necessary. Its versatility stems from the fact that it only requires a marker or a surface (e.g., a table) to function at full capacity. To evaluate the solution, tests were conducted with 8th-grade Portuguese students within the context of Physics and Chemistry subject. Results demonstrate the application’s effectiveness in providing didactic assistance, with positive feedback not only in terms of usability but also regarding learning performance. The participants also reported openness for the adoption of AR in pedagogic contexts.

This paper presents a fully automated experimental setup tailored for evaluating the effectiveness of augmented and virtual reality technologies in healthcare settings for regulatory purposes, with a focus on the characterization of depth sensors. The setup is constructed as a modular benchtop platform that enables quantitative analysis of depth cameras essential for extended reality technologies in a controlled environment. We detail a design concept and considerations for an experimental configuration aimed at simulating realistic scenarios for head-mounted displays. The system includes an observation platform equipped with a three-degree-of-freedom motorized system and a test object stage. To accurately replicate real-world scenarios, we utilized an array of sensors, including commonly available range-sensing cameras and commercial augmented reality headsets, notably the Intel RealSense L515 LiDAR camera, integrated into the motion control system. The paper elaborates on the system architecture and the automated data collection process. We discuss several evaluation studies performed with this setup, examining factors such as spatial resolution, Z-accuracy, and pixel-to-pixel correlation. These studies provide valuable insights into the precision and reliability of these technologies in simulated healthcare environments.

The objective of this study was to examine the effect of augmented-reality picturebooks on enhancing the social skills of students with autism spectrum disorder (ASD). Employing a multiple-probes design across subjects based on the single-subject research design, three students with ASD were engaged, receiving two forty-minute lessons per week, culminating in twelve lessons. This research encompassed a baseline period, an intervention period, and a maintenance period, with analyses conducted using visual analysis and C statistic. The research results found that augmented-reality picturebook courses had immediate and sustained effects on enhancing the “friendship skills” and “conflict management” of students with ASD. Based on the results, the researchers put forward practical suggestions.

A significant percentage of bridges in the United States are serving beyond their 50-year design life, and many of them are in poor condition, making them vulnerable to fatigue cracks that can result in catastrophic failure. However, current fatigue crack inspection practice based on human vision is time-consuming, labor intensive, and prone to error. We present a novel human-centered bridge inspection methodology to enhance the efficiency and accuracy of fatigue crack detection by employing advanced technologies including computer vision and augmented reality (AR). In particular, a computer vision-based algorithm is developed to enable near-real-time fatigue crack detection by analyzing structural surface motion in a short video recorded by a moving camera of the AR headset. The approach monitors structural surfaces by tracking feature points and measuring variations in distances between feature point pairs to recognize the motion pattern associated with the crack opening and closing. Measuring distance changes between feature points, as opposed to their displacement changes before this improvement, eliminates the need of camera motion compensation and enables reliable and computationally efficient fatigue crack detection using the nonstationary AR headset. In addition, an AR environment is created and integrated with the computer vision algorithm. The crack detection results are transmitted to the AR headset worn by the bridge inspector, where they are converted into holograms and anchored on the bridge surface in the 3D real-world environment. The AR environment also provides virtual menus to support human-in-the-loop decision-making to determine optimal crack detection parameters. This human-centered approach with improved visualization and human–machine collaboration aids the inspector in making well-informed decisions in the field in a near-real-time fashion. The proposed crack detection method is comprehensively assessed using two laboratory test setups for both in-plane and out-of-plane fatigue cracks. Finally, using the integrated AR environment, a human-centered bridge inspection is conducted to demonstrate the efficacy and potential of the proposed methodology.

Extended Reality (XR) is increasingly gaining momentum in industries such as retail, health, and education. To protect users’ personal data, establishing a secure authentication system for XR devices becomes essential. Recently, the focus on authentication methods for XR devices has been limited. To further our understanding of this topic, we surveyed authentication schemes, particularly systems and methods deployed in XR settings. In this survey, we focused on reviewing and evaluating papers published during the last decade (between 2014 and 2023). We compared knowledge-based authentication, physical biometrics, behavioral biometrics, and multi-model methods in terms of accuracy, security, and usability. We also highlighted the benefits and drawbacks of those methods. These highlights will direct future Human–computer Interaction (HCI) and security research to develop secure, reliable, and practical authentication systems.

Spatial ability (SA) is the mental ability to create, maintain, and manipulate abstract visual representations. Studies have shown that SA is a strong predictor of success in the fields of science, technology, engineering, and mathematics (STEM). More recently, attention has extended to the field of architecture, a discipline where spatial thinking skills are fundamental, yet students in this field have not been extensively examined in terms of their spatial abilities. Therefore, SA skills are essential for students in engineering and architecture during their initial academic phases. This research was conducted within an interdisciplinary academic college and describes in detail a new integrated and hybrid training program that is part of a recent mixed-methods study. This program was built to effectively enhance the SA of first-year undergraduate students in a cost-effective manner, using a multi-method teaching strategy. The training program spanned more than 20 h across four sessions. This article focuses on the training methodology, encompassing four key phases, and serves as a complementary article to the one that was just published separately, describing the effectiveness of this intervention program as measured using SA standard tests. Notably, in certain scenarios, these phases were combined rather than being standalone independent modules. The traditional teaching method (TTM) lays the foundation for SA knowledge via lectures and collaborative interactions. Subsequently, computer-based learning (CBL), using tools such as SketchUp and GeoGebra, facilitates in-depth virtual geometric exploration. Augmented reality (AR) training offers an immersive learning experience, allowing students to interact with 3D objects in real-world environments. Finally, the building real model (BRM) phase transforms 2D designs into tangible 3D structures. This study highlights the comprehensive training approach, emphasizing the robust learning environment facilitated by integrating these phases as part of the full mixed-methods research. The suggested integrated training program was qualitatively explored through post-intervention evaluations to understand participants’ experiences and perceptions.

Precisely estimating the position, diameter at breast height (DBH), and height of trees is essential in forest resource inventory. Augmented reality (AR)-based devices help overcome the issue of inconsistent global point cloud data under thick forest canopies with insufficient Global Navigation Satellite System (GNSS) coverage. Although monocular simultaneous localization and mapping (SLAM) is one of the current mainstream systems, there is still no monocular SLAM solution for forest resource inventories, particularly for the precise measurement of inclined trees. We developed a forest plot survey system based on monocular SLAM that utilizes array cameras and Inertial Measurement Unit (IMU) sensors provided by smartphones, combined with augmented reality technology, to achieve a real-time estimation of the position, DBH, and height of trees within forest plots. Our results from the tested plots showed that the tree position estimation is unbiased, with an RMSE of 0.12 m and 0.11 m in the x-axis and y-axis directions, respectively; the DBH estimation bias is −0.17 cm (−0.65%), with an RMSE of 0.83 cm (3.59%), while the height estimation bias is −0.1 m (−0.95%), with an RMSE of 0.99 m (5.38%). This study will be useful in designing an algorithm to estimate the DBH and position of inclined trees using point clouds constrained by sectional planes at the breast height of the trunk, developing an algorithm to estimate the height of inclined trees utilizing the relationship between rays and plane positions, and providing observers with visual measurement results using augmented reality technology, allowing them to judge the accuracy of the estimates intuitively. Clearly, this system has significant potential applications in forest resource management and ecological research.

Despite advancement in surgical innovation, C1-C2 fixation remains challenging due to risks of screw malposition and vertebral artery (VA) injuries. Traditional image-based navigation, while useful, often demands that surgeons frequently shift their attention to external monitors, potentially causing distractions. In this article, we introduce a microscope-based augmented reality (AR) navigation system that projects both anatomical information and real-time navigation images directly onto the surgical field. In the present case report, we discuss a 37-year-old female who suffered from os odontoideum with C1-C2 subluxation. Employing AR-assisted navigation, the patient underwent the successful posterior instrumentation of C1-C2. The integrated AR system offers direct visualization, potentially minimizing surgical distractions. In our opinion, as AR technology advances, its adoption in surgical practices and education is anticipated to expand.

Augmented Reality (AR) enhances learning by integrating interactive and immersive elements that bring content to life, thus increasing motivation and improving retention. AR also supports personalized learning, allowing learners to interact with content at their own pace and according to their preferred learning styles. This adaptability not only promotes self-directed learning but also empowers learners to take charge of their educational journey. Effective interface design is crucial for these AR applications, requiring careful integration of user interactions and visual cues to blend AR elements seamlessly with reality. This paper explores the impact of AR on user experience within educational settings, examining engagement, motivation, and learning outcomes to determine how AR can enhance the educational experience. Additionally, it addresses design considerations and challenges in developing AR user interfaces, drawing on current research and best practices to propose effective and adaptable solutions for educational AR applications. As AR technology evolves, its potential to transform educational experiences continues to grow, promising significant advancements in how users interact with, personalize, and immerse themselves in learning content.

The emergence of new display technologies can change the perception of product design features and their assessment. Previous studies are limited to comparisons between a few technologies; the real product is considered only occasionally. This work compares the perceptions of 10 design features in two household products, shown by five display technologies (image rendering, 360° rotation, and augmented, immersive, and non-immersive virtual reality), and also with the real product. Results show that the 360° rotation provides the best perception for the most important features. However, the perception of aesthetic features is better achieved with i_VR. Other global results vary depending on the product. Finally, interaction with the real product shows a quite different perception for many features. The results contribute to the understanding of product perceptions influenced by different displays, comparing them with perceptions generated through real interaction. It is expected that the conclusions will be used to optimize the presentation of product features.

In the context of Industry 4.0, industrial environments are at a crossroads, facing the challenge of greater flexibility and significant technical skills gaps. In this situs, Augmented Reality (AR) emerges as a transformative tool, enhancing the synergy between technical staff and emerging technologies. This article focuses on exploring the integration of AR in Industry 4.0, with a particular emphasis on its role in improving technical assistance and training. The research addresses the ways in which AR not only facilitates more efficient processes but also acts as an essential bridge for training and skills development in constantly changing technological environments. It investigates the significant impact of AR on both optimising work processes and training workers to meet the emerging challenges of Industry 4.0. Through a qualitative analysis, the studies are categorised according to their application domains, grouping them into specific thematic areas. Subsequently, a meta-analysis is conducted to determine the actual impact of AR in the sector. The findings reveal a positive and significant correlation between the implementation of AR and its effectiveness in assistance and training in the framework of Industry 4.0. Finally, the article delves into an analysis of current limitations and challenges, providing insights into possible developments and trends in the use of AR for assistance and training in Industry 4.0.