Motion platforms are integral to enhancing user immersion in vehicle simulators by reproducing vehicle accelerations through virtual reality. A key challenge in this domain is ensuring that users perceive critical motion cues accurately. Due to the physical limitations of motion platforms, Motion Cueing algorithms (MCA) often fail to transmit specific acceleration signals that are important for the purpose of the simulator (e.g., training), leading to a loss in motion fidelity. This gap, widely acknowledged but insufficiently addressed in prior research, directly impacts the user’s perception of realism. To address this issue, we propose a heuristic-based enhancement to the classical washout algorithm (CWA) that prioritizes the retention of these critical signals while maintaining system stability. To evaluate the effectiveness of this approach, an experimental study was conducted with 40 participants who tested the system with and without the proposed heuristics. Participants provided real-time feedback and completed post-test questionnaires. The results indicate that the heuristic-enhanced CWA significantly improves users’ ability to perceive signals that were previously lost, thus bridging the identified research gap and advancing the state of motion simulation.

Research on alternative ways to provide anatomy learning and training has increased over the past few years, especially since the COVID-19 pandemic. Virtual reality (VR) and augmented reality (AR) represent two promising alternatives in this regard. For this reason, in this work, we analyze the suitability of applying VR and AR for anatomy training, comparing an optical-based AR setup and a semi-immersive setup based on a VR table, using the same anatomy training software and the same interaction system. The AR-based setup uses a Magic Leap One, whereas the VR table is configured through the use of stereoscopic TV displays and a motion-capture system. This experiment builds on a previous one (Vergel et al., 2020) on which we have improved the AR-based setup and increased the complexity of one of the two tasks. The goal of this new experiment is to confirm whether the changes made in the setups modify the previous conclusions. Our hypothesis is that the improved AR-based setup will be more suitable, for anatomy training, than the VR-based setup. For this reason, we conducted an experimental research with 45 participants, comparing the use of an anatomy training software. Objective and subjective data were collected. The results show that the AR-based setup is the preferred choice. The differences in measurable performance were small but also favorable to the AR setup. In addition, participants provided better subjective ratings for the AR-based setup, confirming our initial hypothesis. Nevertheless, both setups offer a similar overall performance and provide excellent results in the subjective measures, with both systems approaching the highest possible values.

Abstract Human-computer interaction based on hand gesture tracking is not uncommon in Augmented Reality. In fact, the most recent optical Augmented Reality devices include this type of natural interaction. However, due to hardware and system limitations, these devices, more often than not, settle for semi-natural interaction techniques, which may not always be appropriate for some of the tasks needed in Augmented Reality applications. For this reason, we compare two different optical Augmented Reality setups equipped with hand tracking. The first one is based on a Microsoft HoloLens (released in 2016) and the other one is based on a Magic Leap One (released more than two years later). Both devices offer similar solutions for the visualization and registration problems but differ in the hand tracking approach, since the former uses a metaphoric hand-gesture tracking and the latter relies on an isomorphic approach. We raise seven research questions regarding these two setups, which we answer after performing two task-based experiments using virtual elements, of different sizes, that are moved using natural hand interaction. The questions deal with the accuracy and performance achieved with these setups and also with user preference, recommendation and perceived usefulness. For this purpose, we collect both subjective and objective data about the completion of these tasks. Our initial hypothesis was that there would be differences, in favor of the isomorphic and newer setup, in the use of hand interaction. However, the results surprisingly show that there are very small objective differences between these setups, and the isomorphic approach is not significantly better in terms of accuracy and mistakes, although it allows a faster completion of one of the tasks. In addition, no remarkable statistically significant differences can be found between the two setups in the subjective datasets gathered through a specific questionnaire. We also analyze the opinions of the participants in terms of usefulness, preference and recommendation. The results show that, although the Magic Leap-based system gets more support, the differences are not statistically significant.

The fight against sexism is nowadays one of the flagship social movements in western countries. Adolescence is a crucial period, and some empirical studies have focused on the socialization of teenagers, proving that the socialization with the surrounding environment prevent sexist practices. In a previous work, we developed and tested the effectiveness of a mobile app, called Liad@s , with the goals of helping teenagers to prevent sexism and build healthy couple relationships. In this article, we carry out a study where (using a real situation) we compare the effectiveness of the Liad@s app in front of traditional interventions like a workshop about sexism for teenagers. Also, we evaluate the usability of the app and the user satisfaction with this application. In this study, our primary hypothesis is that the effectiveness of using our mobile application, in terms of knowledge acquired about sexism, would be at least as good as attending the workshop. Our secondary hypothesis is that the user satisfaction with the mobile application would be higher than the one with the workshop, causing a preference for the app. The results of this study show significant differences in learning appeared between gender and between the two different procedures when separately evaluating the data collected from both hostile sexism (HS) and benevolent sexism (BS) questionnaires. These results validate our primary hypothesis. Also, most of the population under study preferred the mobile app in front of the traditional workshop, validating also our secondary hypothesis.

Motion-based simulators are used for a variety of applications, such as research, education, entertainment and training. In fact, motion cues are required to achieve the highest regulatory certifications in training vehicle simulators. Nonetheless, the reproduction of self-motion cues presents technological and economic limitations that are not present in the generation of audiovisual cues. For this reason, the generated motion does not generally match the expected one. Therefore, it is necessary to define means to assess the suitability/fidelity of the generated motion cues. After more than 50 years of motion-based vehicle simulation, no mechanism has been universally accepted as the standard solution for the evaluation of motion cues. This paper reviews the mechanisms for obtaining measures of motion fidelity, focusing on those based on objective methods. Since the design of the Objective Motion Cueing Test in 2006, researchers have shown a renewed interest in identifying objective methods to evaluate motion cueing, as the number of works following this approach in recent years reveals. Objective motion fidelity systems allow also performing automatic tuning of MCA by means of optimization techniques, which addresses one of the other main problems of these algorithms. Nevertheless, a universally accepted objective method to assess perceptual motion fidelity in vehicle simulators has not been proposed yet. For this reason, this review work frames and classifies the existing methods. In addition, the authors propose a series of features that an ideal evaluation method for assessing perceptual motion fidelity should include and provide future research guidelines for this complex topic.

Anatomy training with real cadavers poses many practical problems for which new training and educational solutions have been developed making use of technologies based on real-time 3-D graphics. Although virtual reality (VR) and augmented reality (AR) have been previously used in the medical field, it is not easy to select the right 3-D technology or setup for each particular problem. For this reason, this article presents a comprehensive comparative study with 82 participants between two different 3-D interactive setups: an optical-based AR setup, implemented with a Microsoft HoloLens device, and a semi-immersive setup based on a VR Table. Both setups are tested using an anatomy training software application. Our primary hypothesis is that there would be statistically significant differences between the use of the AR application and the use of the VR Table. Our secondary hypothesis is that user preference and recommendation for the VR setup would be higher than for the HoloLens-based system. After completing two different tasks with both setups, the participants filled two questionnaires about the use of the anatomy training application. Three objective measures are also recorded (time, number of movements, and a score). The results of the experiments show that more than two-thirds of the users prefer, recommend, and find more useful the VR setup. The results also show that there are statistically significant differences in the use of both systems in favor of the VR Table.

Collaborative Augmented Reality (CAR) systems allow multiple users to share a real world environment including computer generated images in real time. Currently, the hardware features of most mobile phones not only provide excellent multimedia services, but it also includes wireless network capabilities that provides a natural platform for CAR systems. However, the wide variety of these hardware features can have important effects on the performance of the mobile CAR applications. This paper presents the experimental characterization of CAR applications for mobile phones in regard to well-known performance metrics in distributed systems. Characterization results show that the most time consuming stage in a CAR application is the marker detection stage. Moreover, the rendering stage is decoupled on some devices. This decoupling process allows avoiding low refresh rate, facilitating the collaborative work. These results can be used as the basis for an efficient design of CAR systems and applications.

A necessary condition for providing quality of service to distributed virtual environments (DVEs) is to provide a system response below a maximum threshold to the client computers. In this sense, latency-aware partitioning methods try to provide response times below the threshold to the maximum number of client computers as possible. These partitioning methods should find an assignment of clients to servers that optimizes system throughput, system latency, and partitioning efficiency. In this paper, we present a new algorithm based on greedy randomized adaptive search procedure with memory for finding the best solutions as possible to this problem. We take into account several different alternatives in order to design both the constructive phase and the local search phase of this multistart metaheuristic for combinatorial problems. Additionally, we enhance this basic approach with some intensification strategies that improve the efficiency of the basic search method. Performance evaluation results show that the new algorithm increases the performance provided by other metaheuristics when applied to solve the latency-aware partitioning problem in DVE systems.

Abstract The increasing popularity of multi‐player online games is leading to the widespread use of large‐scale Distributed Virtual Environments (DVEs) nowadays. In these systems, peer‐to‐peer (P2P) architectures have been proposed as an efficient and scalable solution for supporting massively multi‐player applications. However, the main challenge for P2P architectures consists of providing each avatar with updated information about which other avatars are its neighbors. This problem is known as the awareness problem. In this paper, we propose a comparative study of the performance provided by those awareness methods that are supposed to fully solve the awareness problem. This study is performed using well‐known performance metrics in distributed systems. Moreover, while the evaluations shown in the literature are performed by executing P2P simulations on a single (sequential) computer, this paper evaluates the performance of the considered methods on actually distributed systems. The evaluation results show that only a single method actually provides full awareness to avatars. This method also provides the best performance results. Copyright © 2008 John Wiley & Sons, Ltd.

Crowd simulations require both rendering visually plausible images and managing the behavior of autonomous agents. Therefore, these applications need an efficient design that allow them to simultaneously tackle these two requirements. Although several proposals have focused on the software architectures for these systems, no proposals have focused on the computer systems supporting them. In this paper, we analyze the computer architectures used in the literature to support virtual environments. Also, we propose a distributed computer architecture efficient enough to support simulations of thousand of autonomous agents. This proposal consists of a cluster of computers in order to improve flexibility and robustness, as well as a hierarchical software architecture that efficiently provides consistency. Performance evaluation results show that the trade-off between flexibility and consistency allows to effi- ciently manage thousands of autonomous agents.

The current expansion of multi-player online games has promoted the growth of large scale distributed virtual environments (DVEs). In these systems, peer-to-peer architectures have been proved as the most scalable scheme for supporting massively multi-player applications. Nevertheless, the interactions among clients that can take place in this type of systems can lead to the temporal saturation of some of the clients. Since a client saturation has an effect on other clients, these situations limit the performance of peer-topeer DVEs. In this paper, we propose an adaptive technique for avoiding the saturation of the client computers in DVE systems based on peer-to-peer architectures. This technique is based on monitoring the client state and discarding some of the messages received from other clients when the client is close to saturation. The evaluation results show that the proposed method improves the system performance without having an effect on the awareness rate, regardless of the movement pattern that avatars can follow. As a result, both the performance and the scalability of peer-to-peer DVEs are significantly improved.

The current expansion of multi-player online games has promoted the growth of large scale distributed virtual environments (DVEs). In these systems, peer-to-peer architectures have been proved as an efficient scheme for supporting massively multi-player applications. In order to research on this type of architecture, stand-alone simulators do not take into account inconsistencies due to network latency, and it is necessary to develop a distributed tool that allows to simulate large-scale DVEs in an efficient way. In this paper, we propose a distributed platform for simulating the behavior of peer-to-peer DVEs. This simulator is implemented following a modular architecture. It is capable of providing the main performance metrics in distributed systems, and it contains all the elements involved in real DVE simulations like the awareness method and the graphic interface. As a result, this tool can be used in real simulations of peer-to-peer DVEs, becoming an invaluable tool for capturing the behavior of this kind of systems.

Large scale distributed virtual environments (DVEs) have become a major trend in distributed applications, mainly due to the enormous popularity of multi-player online games in the entertainment industry. Since architectures based on networked servers seem to be not scalable enough to support massively multi-player applications, peer-to-peer (P2P) architectures have been proposed as an efficient and truly scalable solution for this kind of systems. However, in order to design efficient DVEs based on peer-to-peer architectures these systems must be characterized, measuring the impact of different client behaviors on system performance. This paper presents the experimental characterization of peer-to-peer distributed virtual environments in regard to well-known performance metrics in distributed systems. Characterization results show that system saturation is inherently avoided due to the peer-to-peer scheme, as it could be expected. Also, these results show that the saturation of a given client exclusively has an effect on the surrounding clients in the virtual world, having no noticeable effect at all on the rest of avatars. Finally, the characterization results show that the response time offered to client computers greatly depends on the number of new connections that these clients have to make when new neighbors appear in the virtual world. These results can be used as the basis for an efficient design of peer-to-peer DVE systems.

Distributed virtual environment (DVE) systems allow multiple users working on different client computer's interconnected through different networks to interact in a shared virtual world. In these systems, latency is crucial for providing an acceptable quality of service (QoS), since it determines how fast client computers are reported about changes in the shared virtual scene produced by other client computers. This paper presents in a unified manner a partitioning approach for providing a latency below a threshold to the maximum number of users as possible in DVE systems. This partitioning approach searches the assignment of avatars, which represents the best trade-off among system latency, system throughput, and partitioning efficiency when solving the partitioning problem. Evaluation results show that the proposed approach not only maximizes system throughput, but also allows the system to satisfy, if possible, any specific latency requirement needed for providing QoS. This improvement is achieved without decreasing either image resolution or quality of animation, and it can be used together with other techniques already proposed. Therefore, it can contribute to provide QoS in DVEs.

In recent years Virtual Reality technologies have enabled astronomers to recreate and explore three dimensional structures of the Universe for scientific purposes. Mars, due to its scientific interest,has been the focal point of numerous research projects using these technologies, however, none of these virtual reality tools have been developed specifically for entertainment purposes.The focus of this paper is to present MarsVR, as an entertainment research project that educates people on the topography and orography of the planet Mars from the perspective of popular science. Some projects have been designed MarsVR for entertainment purposes and include the latest advances in 3D real time applications. However, these applications have underestimated the relevant data necessary for simulating the planet Mars as an interactive virtual environment.

The last years have witnessed a dramatic growth in the number as well as in the variety of distributed virtual environment systems. These systems allow multiple users, working on different client computers that are interconnected through different networks, to interact in a shared virtual world. One of the key issues in the design of scalable and cost-effective DVE systems is the partitioning problem. This problem consists of efficiently assigning the existing clients to the servers in the system and some techniques have been already proposed for solving it. This paper experimentally analyzes the correlation of the quality function proposed in the literature for solving the partitioning problem with the performance of DVE systems. Since the results show an absence of correlation, we also propose the experimental characterization of DVE systems. The results show that the reason for that absence of correlation is the nonlinear behavior of DVE systems with regard to the number of clients in the system. DVE systems reach saturation when any of the servers reaches 100 percent of CPU utilization. The system performance greatly decreases if this limit is exceeded in any server. Also, as a direct application of these results, we present a partitioning method that is targeted to keep all the servers in the system below a certain threshold value of CPU utilization, regardless of the amount of network traffic. Evaluation results show that the proposed partitioning method can improve DVE system performance, regardless of both the movement pattern of clients and the initial distribution of clients in the virtual world.

Computer games follow a scheme of continuous simulation, coupling the rendering phase and the simulation phase. That way of operation has disadvantages that can be avoided using a discrete event simulator as a game kernel. This paper proposes to integrate a discrete event simulator (DESK) to manage the videogames events. The videogame kernel used is Fly3D. The new kernel is called DFlySD. It allows a discrete event simulation scheme and the rendering and simulation phase independence. The integration objective has been to maintain the FlySD main structure and functionality, changing only the events management. The videogames objects behavior and interconnection is modeled by message passing. Maintaining the videogame quality, the videogames created using DFlySD allow reducing the computer power used to execute it. That allows to execute the videogame in computers with less computing power or to improve the game quality