虚拟工厂现实场景系统平台设计与实现

随着现代化工业不断发展,模拟过程工业真实环境,并在此基础上进行地理信息显示与空间分析等成为当前的研究热点。构建基于虚拟现实(VR)和地理信息系统的(GIS)的虚拟工厂现实场景系统是进行工业生产仿真的一条有效途径,为此,设计开发一个三维的、可维护性强并具有一定扩展性的虚拟工厂现实场景系统具有重要的实用价值。本文通过数据准备、数据生成、系统扩展及客户端设计,实现了虚拟工厂现实场景系统开发过程。通过应用分析与对比,结果表明,该平台化系统具有更高的可扩展性且开发成本低,为虚拟工厂现实场景系统平台设计提供了一个良好的、可扩展的开发途径。     

A hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality environment

This article proposes a hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality (VR) environment. The data model integrates a high level constraint-based model for intuitive and precise manipulation, a middle level solid model for complete and precise representation and a low-level polygon mesh model for real-time interactions and visualization in a VR environment. The solid model is based on a hybrid B-rep/CSG data structure. Constraints are embedded in the solid model and are organized at hierarchical levels as feature constraints among internal feature elements, part constraints among internal features and assembly constraints between individual parts. In addition to providing a complete and precise model representation and the support for real-time visualization, the proposed data model permits intuitive and precise interaction through constraint-based manipulations for solid modeling in a VR environment. This is a critical issue for product design in a VR environment due to the limited resolutions of today's VR input and output devices.     

Using virtual reality for industrial design learning: a methodological proposal

ABSTRACT

Nowadays, the different computer tools available enable designers to create complex industrial prototypes. The use of these tools is constrained by the limitations imposed by common devices, such as screens and displays. Recently emerged virtual and augmented reality techniques have started being used as supports in many learning and industrial environments. Beyond the new possibilities that these tools offer for designing industrial objects, the underlying question is whether these new technologies could improve the creativity of designers to enable them to get a better understanding of the designing process itself. This paper presents a methodological proposal for the deployment of an industrial design engineering course aimed not only at learning different design techniques, but also at assessing the creativity skills of students. The practical contents include the use of virtual reality devices, to help the designer overcome the limitations of prototype visualisation and make better designing decisions. Moreover, a creativity test will be performed at the beginning and at the end of the course to assess the changes in creativity skills taking place within the experiment group versus the changes in a traditional learning (control) group.     

Head-mounted display versus desktop for 3D navigation in virtual reality: a user study

Virtual Reality (VR) has been constantly evolving since its early days, and is now a fundamental technology in different application areas. User evaluation is a crucial step in the design and development of VR systems that do respond to users’ needs, as well as for identifying applications that indeed gain from the use of such technology. Yet, there is not much work reported concerning usability evaluation and validation of VR systems, when compared with the traditional desktop setup. The paper presents a user study performed, as a first step, for the evaluation of a low-cost VR system using a Head-Mounted Display (HMD). That system was compared to a traditional desktop setup through an experiment that assessed user performance, when carrying out navigation tasks in a game scenario for a short period. The results show that, although users were generally satisfied with the VR system, and found the HMD interaction intuitive and natural, most performed better with the desktop setup.

ClinicaVR: Classroom-CPT: A virtual reality tool for assessing attention and inhibition in children and adolescents

Having garnered interest both in clinic and research areas, the Virtual Classroom (Rizzo et al., 2000) assesses children's attention in a virtual context. The Digital MediaWorks team (www.dmw.ca) has evolved the original basic classroom concept over a number of iterations to form the ClinicaVR Suite containing the Classroom-CPT as one of its components. The present study has three aims: investigate certain validity and reliability aspects of the tool; examine the relationship between performance in the virtual test and the attendant sense of presence and cybersickness experienced by participants; assess potential effects of gender and age on performance in the test. The study was conducted with 102 children and adolescents from Grade 2 to Grade 10. All participants were enrolled in a regular school program. Results support both concurrent and construct validity as well as temporal stability of ClinicaVR: Classroom-Continuous Performance Test (CPT). Gender exerted no effect on performance, while age did. The test did not cause much cybersickness. We recommend ClinicaVR: Classroom-CPT as an assessment tool for selective and sustained attention, and inhibition, in clinic and research domains.     

A virtual reality cognitive health screening tool for aviation: Managing accident risk for older pilots

To address elevated risk for older pilots, we examined the efficacy of a virtual reality (VR) cognitive health screening tool (integrated into simulated flight scenarios) in identifying general aviation pilots who experienced a critical incident during flight in a full-scale Cessna 172 simulator. Performance data were obtained from 51 certified pilots (17–71 years). Machine learning classification algorithms, based on key data from the VR flight, were used to validate the utility of the screening tool for identifying pilot risk. The results showed that aviation-relevant cognitive factors obtained in the VR screening tool, including situation awareness and prospective memory, predicted risk of a critical incident with good sensitivity (0.83) and specificity (0.85), AUC = 0.82. These results support VR-based cognitive screening to identify at-risk older pilots. The present findings inform procedures for optimizing safety and reducing critical incidents at any point in the pilot lifespan and are timely in view of the impending pilot workforce shortage.     

Investigating learners’ attitudes toward virtual reality learning environments: Based on a constructivist approach

The use of animation and multimedia for learning is now further extended by the provision of entire Virtual Reality Learning Environments (VRLE). This highlights a shift in Web-based learning from a conventional multimedia to a more immersive, interactive, intuitive and exciting VR learning environment. VRLEs simulate the real world through the application of 3D models that initiates interaction, immersion and trigger the imagination of the learner. The question of good pedagogy and use of technology innovations comes into focus once again. Educators attempt to find theoretical guidelines or instructional principles that could assist them in developing and applying a novel VR learning environment intelligently. This paper introduces the educational use of Web-based 3D technologies and highlights in particular VR features. It then identifies constructivist learning as the pedagogical engine driving the construction of VRLE and discusses five constructivist learning approaches. Furthermore, the authors provide two case studies to investigate VRLEs for learning purposes. The authors conclude with formulating some guidelines for the effective use of VRLEs, including discussion of the limitations and implications for the future study of VRLEs.     

A Comparison of learning gains when using a 2D simulation tool versus a 3D virtual world: An experiment to find the right representation involving the Marginal Value Theorem

The use of three-dimensional Virtual Worlds in the classroom offers the promise of engaging and authentic learning experiences. Given the effort and investment involved in the creation of these worlds, more studies are needed which measure the learning gains. In particular, greater understanding is needed concerning what aspects of the technology are beneficial for learning what sort of content and in what context. We conducted two experimental studies involving 129 biology students over a two-year period that sought to make a contribution towards this understanding. Our study compared the knowledge of students after a traditional classroom lecture about a biological theorem known as Marginal Value Theorem, with their knowledge after they were exposed to simulations of two-dimensional models developed in NetLogo and three-dimensional models developed in Unity3D. Perhaps due to cognitive overload and distractors in the virtual world, it appears that the two-dimensional NetLogo model delivered better learning outcomes.     

基于3D虚拟现实技术的弹药检测虚拟训练系统设计

目前提出的弹药检测虚拟训练系统接收检测信号接收率较低,检测虚拟训练成功率较低。基于3D虚拟现实技术设计一种新的弹药检测虚拟训练系统,硬件由主控操作机、检测总线接口以及资源测试器组成,软件部分在3D虚拟现实技术下构建虚拟空间,在开放式软件结构构建的基础上进行检测指标划分,对用户界面的文件进行整改,按照弹药检测的指标数据提升整改的方向正确性,选用自检公式对检测的信息进行系统自检,依据检测到的问题的发生形式判断下一次问题发生的触发机制,由此避免下一次问题的产生,从而实现软件流程。实验结果表明,基于3D虚拟现实技术的弹药检测虚拟训练系统能有效提高信号接收率,增强虚拟训练接收成功率,具有较强的应用性。     

RMAP: a system for visualizing data in multidimensional relevance space

exact relevance measures of the objects are not significant. We flatten the multidimensionality of the feature space into a 2D relevance map, capturing the inter-relations among the features. The prototype, extract information from the World Wide Web from query engines, automatically categorizes and clusters the information and allow the user to visualize.     

Learning science in a virtual reality application: The impacts of animated-virtual actors’ visual complexity

As the technology in computer graphics advances, Animated-Virtual Actors (AVAs) in Virtual Reality (VR) applications become increasingly rich and complex. Cognitive Theory of Multimedia Learning (CTML) suggests that complex visual materials could hinder novice learners from attending to the lesson properly. On the other hand, previous studies have shown that visual complexity correlates with presence and may increase the perceived affective quality of the virtual world, towards an optimal experience or flow. Increasing these in VR applications may promote enjoyment and higher cognitive engagement for better learning outcomes. While visually complex materials could be motivating and pleasing to attend to, would they affect learning adversely? We developed a series of VR presentations to teach second-year psychology students about the navigational behaviour of Cataglyphis ants with flat, cartoon, or lifelike AVAs. To assess learning outcomes, we used Program Ratings, which measured perception of learning and perceived difficulty, and retention and transfer tests. The results from 200 students did not reveal any significant differences in presence, perceived affective quality, or learning outcomes as a function of the AVA’s visual complexity. While the results showed positive correlations between presence, perceived affective quality and perception of learning, none of these correlates with perceived difficulty, retention, or transfer scores. Nevertheless, our simulation produced significant improvements on retention and transfer scores in all conditions. We discuss possible explanations and future research directions.     

Technology-assisted learning: a longitudinal field study of knowledge category, learning effectiveness and satisfaction in language learning

Abstract   A field experiment compares the effectiveness and satisfaction associated with technology-assisted learning with that of face-to-face learning. The empirical evidence suggests that technology-assisted learning effectiveness depends on the target knowledge category. Building on Kolb's experiential learning model, we show that technology-assisted learning improves students' acquisition of knowledge that demands abstract conceptualization and reflective observation but adversely affects their ability to obtain knowledge that requires concrete experience. Technology-assisted learning better supports vocabulary learning than face-to-face learning but is comparatively less effective in developing listening comprehension skills. In addition, according to empirical tests, perceived ease of learning and learning community support significantly predict both perceived learning effectiveness and learning satisfaction. Overall, the results support our hypotheses and research model and suggest instructors should consider the target knowledge when considering technology-assisted learning options or designing a Web-based course. In addition, a supportive learning community can make technology-assisted learning easier for students and increase their learning satisfaction.     

On the usability and likeability of virtual reality games for education: The case of VR-ENGAGE

Educational software games aim at increasing the students’ motivation and engagement while they learn. However, if software games are targeted to school classrooms they have to be usable and likeable by all students. Usability of virtual reality games may be a problem because these games tend to have complex user interfaces so that they are more attractive. Moreover, if the games acquire an educational content they may lose the attractiveness and appeal that they have on users who are familiar with commercial games. Consequently, likeability may also be questioned. In this paper, we address the issue of usability and likeability of a virtual reality game that is meant to teach students geography. We describe the evaluation experiments conducted, which involved three categories of students in terms of their level of game-playing expertise: novice, intermediate and expert game players. The evaluation results showed that the game was indeed usable and likeable but there was scope for usability and likeability improvement so that the educational benefits may be maximised for all categories of students. The evaluation studies reported in this paper, revealed important issues about further research on virtual reality educational games.     

Introducing the Wunderkammer as a tool for emotion research: Unconstrained gaze and movement patterns in three emotionally evocative virtual worlds

Here we introduce the “Wunderkammer”, a suite of immersive virtual worlds with different types of emotionally-charged content. We use these worlds to examine the effects of affective context on unconstrained gaze and movement. In the Affect Gallery, participants freely explored a virtual art museum filled with objects that varied in valence and arousal. Participants approached and gazed more at positively valenced objects. This preference was amplified by more arousing objects and was strongest among individuals with resilient emotion regulation tendencies. This bias of avoiding negative valence did not emerge in The Crowded Room, an environment in which participants encountered virtual humans expressing different emotions. Instead, participants gazed more at negative than neutral emotional displays although they physically avoided angry (but not sad or neutral) agents. When placed inside Room 101, an unpredictable environment filled with a series of disturbing events, frightened participants became relatively immobile in terms of both gaze and movement. This freezing-type response was particularly strong among dispositionally resilient individuals. Together these results demonstrate that distinct affective contexts elicit unique patterns in unconstrained gaze and movement. They further illustrate the benefits of using virtual reality to study affect as it naturally emerges.     

A query language for retrieving information from a soil data bank

The paper presents specifications and implementation details of a query language designed for retrieving information from a soil data bank. The commands of the language are based on operations of relational algebra, and can be employed without previous programming experience. The language is part of the ARSIS (A Relational Soil Information System) system that is being developed in Greece.     

2PSM: an efficient framework for searching video information in a limited-bandwidth environment

We present a novel technique, called 2-Phase Service Model, for streaming videos to home users in a limited-bandwidth environment. This scheme first delivers some number of non-adjacent data fragments to the client in Phase 1. The missing fragments are then transmitted in Phase 2 as the client is playing back the video. This approach offers many benefits. The isochronous bandwidth required for Phase 2 can be controlled within the capability of the transport medium. The data fragments received during Phase 1 can be used to provide an excellent preview of the video. They can also be used to facilitate VCR-style operations such as fast-forward and fast-reverse. Systems designed based on this method are less expensive because the fast-forward and fast-reverse versions of the video files are no longer needed. Eliminating these files also improves system performance because mapping between the regular files and their fast-forward and fast-reverse versions is no longer part of the VCR operations. Furthermore, since each client machine handles its own VCR-style interaction, this technique is very scalable. We provide simulation results to show that 2-Phase Service Model is able to handle VCR functions efficiently. We also implement a video player called {\em FRVplayer}. With this prototype, we are able to judge that the visual quality of the previews and VCR-style operations is excellent. These features are essential to many important applications. We discuss the application of FRVplayer in the design of a video management system, called VideoCenter. This system is intended for Internet applications such as digital video libraries.