三维造型设计与工程图学的有效融合

随着计算机软硬件技术的普及和飞速发展以及制造业对二维计算机绘图以及三维设计造型技术日益增长的需求,在工程图学教学中有效地融入二维计算机绘图以及三维设计造型技术已显得尤为重要。论文介绍了北京理工大学在工程图学和三维造型创新设计方面“外挂式、分段式和融合式”三种模式的教学改革实践,并着重对如何将三维造型设计与工程图学有效地融合进行了论述。     

A Survey Of Free-Form Object Representation and Recognition Techniques

Advances in computer speed, memory capacity, and hardware graphics acceleration have made the interactive manipulation and visualization of complex, detailed (and therefore large) three-dimensional models feasible. These models are either painstakingly designed through an elaborate CAD process or reverse engineered from sculpted prototypes using modern scanning technologies and integration methods. The availability of detailed data describing the shape of an object offers the computer vision practitioner new ways to recognize and localize free-form objects. This survey reviews recent literature on both the 3D model building process and techniques used to match and identify free-form objects from imagery.     

Exploring the relationship between presence and enjoyment in a virtual museum

The Augmented Representation of Cultural Objects (ARCO) system, developed as a part of an EU ICT project, provides museum curators with software and interface tools to develop web-based virtual museum exhibitions by integrating augmented reality (AR) and 3D computer graphics. ARCO technologies could also be deployed in order to implement educational kiosks placed in real-world museums. The main purpose of the system is to offer an entertaining, informative and enjoyable experience to virtual museum visitors. This paper presents a formal usability study that has been undertaken in order to explore participants’ perceived ‘sense of being there’ and enjoyment while exposed to a virtual museum exhibition in relation to real-world visits. The virtual museum implemented was based on an existing gallery in the Victoria and Albert Museum, London, UK. It is of interest to determine whether a high level of presence results in enhanced enjoyment. After exposure to the system, participants completed standardized presence questionnaires related to the perceived realism of cultural artifacts referred to as AR objects’ presence, as well as to participants’ generic perceived presence in the virtual museum referred to as VR presence. The studies conducted indicate that previous experience with ICTs (Information and Communication Technologies) did not correlate with perceived AR objects’ presence or VR presence while exposed to a virtual heritage environment. Enjoyment and both AR objects’ presence and VR presence were found to be positively correlated. Therefore, a high level of perceived presence could be closely associated with satisfaction and gratification which contribute towards an appealing experience while interacting with a museum simulation system.     

Virtual reality technology and its industrial applications

Virtual reality (VR) is well known and is currently being investigated for practical use in various industrial fields. Using three-dimensional computer graphics, interactive devices, and a high-resolution display, a virtual world can be realized in which imaginary objects can be picked up as if they were in the physical world. Using VR technology, Matsushita Electric Works, Ltd. has been developing application systems for industrial use since 1990. This paper details four VR application systems: a relax/refresh system, a horseback riding therapy simulator, a VR-supported kitchen layout design system, as well as an urban planning VR system.     

An Application of Computer Graphics and Networks to Anatomic Model and Prosthesis Manufacturing

Computer graphics has now matured in medical applications from 2D and 3D presentations for diagnosis and the planning of surgery and therapy to become the key step in making hand-held models of custom prostheses. The system described here delivers 3D shape information to create skeletal models, plan corrective surgery, and directly manufacture prostheses. Implants and anatomic models are manufactured using computed tomography (CT) image data and a system to generate Instructions for numerically controlled machines. The system combines clinical imaging, an algorithm for 3D edge detection, computer communications, and computer-aided and manufacturing (CAD/CAM). This integration of technologies brings recent advances in computer-aided design and manufacturing to the local community CT scanning clinic in a cost-effective manner. Via computer communications, several hundred remote medical imaging centers can have their CT scanners connected on-line to CAD/CAM facilities that one could not support alone. Operators of the remote CT scanners bear only the cost of computer communications equipment to being their patients this service. We use the clinical course of several patients in whom prostheses have been implanted to describe this technology.     

Effective virtual reality based building navigation using dynamic loading and path optimization

Although computer capabilities have been improved significantly, a large-scale virtual reality (VR) system demands much more in terms of memory and computation than the current computer systems can offer. This paper discusses two important issues related to VR performance and applications in building navigation. These are dynamic loading of models based on cell segmentation for the optimal VR operation, and the route optimization based on path planning for easy navigation. The VR model of engineering and information technology complex (EITC) building at the University of Manitoba is built as an example to show the feasibility of the proposed methods. The reality, enhanced by three-dimensional (3D) real-time interactivity and visualization, leads navigators into a state of the virtual building immersion.     

基于VR 技术的工程图学移动学习系统

基于虚拟现实(VR)技术,利用JPCT-AE 三维引擎、3DsMAX 以及 OpenGL ES 2.0 等工具,开发出应用于Android 平台移动终端的工程图学移动学习系统,详细描述了系统的底 层结构、功能及技术开发方案。针对工程图学课程的认知规律开发了分屏功能,使多媒体影音 讲解与立体虚拟模型同屏展示,同时实现了对虚拟模型的交互控制。     

A desktop VR prototype for industrial training applications

The recent advances in computer graphics has spurred interest from both academics and industries in virtual reality (VR) enabled training applications. This paper presents a desktop VR prototype for industrial training applications. It is designed and implemented as a general shell by providing the data interface to import both the virtual environment models and specific domain knowledge. The geometric models of the virtual environment are constructed using feature-based modelling and assembly function by external CAD tools, and then transferred into the prototype through a conversion module. A hierarchical structure is proposed to partition and organise these imported virtual environment models. Based on this structure, a visibility culling approach is developed for fast rendering and user interaction. The case study has demonstrated the functionality of the proposed prototype system by applying it to a maintenance training application for a refinery bump system, which, in general, has a large number of polygons and a certain depth complexity. Significant speedup in both context rendering and response to user manipulations has been achieved to provide the user with a fast system response within the desktop virtual environment. Compared with the immersive VR system, the proposed system has offered an affordable and portable training media for industrial applications.The work was done in Nanyang Technological University.     

基于图像绘制的虚拟环境构建与漫游技术研究

虚拟现实是一个重要目标是用计算机构建逼真的视觉世界,使参与者漫游虚拟世界。传统上,其实现是用3D图形学进行几何建模和绘制,但有诸多不足,而基于图像绘制的实现虚拟实现系统的新方法,它克服了3D图形方法的缺点,本文提出了一个实现基于图像绘制的虚拟环境的构建与漫游系统框架模型。     

一个协作式虚拟学习环境的设计与实现

当今网络技术以及虚拟现实技术将会把计算机辅助学习带入一个新的领域———协作式虚拟学习环境。文中根据建构主义和认知科学理论提出了一个基于Web的协作式虚拟学习系统的设计方法,并以一种工业产品作为学习对象开发了一个原型系统,旨在通过先进的学习理念和计算机技术提高学习者的认知效率。通过实践测试和评估,证明效果良好。     

基于VR技术的三维射击游戏开发研究

目前三维游戏中利用了虚拟场景,以便捷的人机交互,为游戏者提供最佳的游戏体验.三维游戏的衍生在很大程度上推动了虚拟现实(VR)技术的更新优化,其涵盖了虚拟现实所有技术.本文基于VR技术设计开发三维射击游戏.首先分析游戏开发需求,其次设计三维VR系统结构与游戏开发流程,再次详细规划三维射击游戏功能模块,最后进行游戏人物、场...     

Future standards for immersive VR: report on the IEEE Virtual Reality 2007 workshop.

The future standards for immersive VR workshop at the IEEE Virtual Reality 2007 Conference aimed to foster an understanding between the VR and Web3D communities. Although the fields of VR and Web-based 3D graphics tend to view their technologies as different beasts, the technologies share many requirements regarding virtual world content: modeling, lighting, animation, interaction, and direct manipulation. This workshop focused on the common interests around the seamless access and delivery of interactive, network-based VR content and resources.     

Virtual orthopedic surgery training

Medicine is one of the most promising areas for emerging computer graphics and virtual reality techniques. VR training simulators let surgeons practice on virtual body tissue and get the same feedback they would experience in performing a real operation. Hybrid VR systems permit medical practitioners to view the patient overlaid with 3D data sets derived from 3D scanners, thus providing doctors and surgeons with pseudo X-ray vision. While currently available immersive VR surgery systems usually require expensive hardware and software, we developed a desktop VR orthopedic surgery training system that can run on commonly available personal computers     

Solid model reconstruction from engineering paper drawings using Genetic Algorithms

The wide applications of CAD/CAM technologies have promoted the development and application of many advanced technologies, such as digital manufacturing, rapid prototyping, enterprise resources planning, computer integrated manufacturing, concurrent engineering, virtual reality, and mass customization. These advanced technologies all need to be supported by three-dimensional (3D) solid models of products. Most enterprises, however, still organize their production using 2D paper drawings, which makes difficulties for the application of these advanced technologies. It is needed to convert engineering paper drawings into 3D solid models for applications. Based on holo-extraction of information from paper drawings, this paper develops a systematic 3D reconstruction method, which simulates an experienced human designer's thinking mode in transforming inaccurate outlines with inaccurate projection relationships in 2D drawings into 3D image, with the aid of Genetic Algorithms.     

An empirical examination of factors affecting college students’ proactive stickiness with a web-based English learning environment

Drawing on the Social Cognitive Theory (SCT) and Uses and Gratifications (U&G) theory, this study develops a conceptual model to investigate the determinants of college students’ proactive “stickiness” with a web-based English learning (WBEL) environment. The model was validated using a cross-sectional survey of 306 college students. The partial least squares (PLS) method was applied to validate the measurement properties and proposed hypotheses. Overall, the empirical results show that computer self-efficacy, system characteristics, digital material features, interaction, learning outcome expectations and learning climate are critical affecting factors in determining student learning gratifications with WBEL, which is crucial to a college student’s proactive stickiness with the WBEL system. This study demonstrates the value in integrating findings from cognitive science and mass communication research to understand the WBEL processes involved. The findings provide initial insights into those factors that are likely critical antecedents for promoting college students’ English learning effectiveness through web-based technologies.     

A transatlantic research and development environment [3D virtualgraphics]

Distributed 3D virtual environments can help researchers conduct experiments globally with remotely located participants. We discuss challenges and opportunities for the shared work environment. Our world is entering an age where our current understanding of telecommunications and graphics computing is constantly challenged. With the availability of global information highways, 3D graphical intercontinental collaboration will become a part of our daily work routine. Already, world class auto makers are attempting to reduce car development time to two-year cycles, enlisting global engineering teams. However, this process requires new tools such as shared 3D CAD and distributed product data management systems. The Fraunhofer Center for Research in Computer Graphics (CRCG) in the United States and the Fraunhofer Institute for Computer Graphics (IGD) in Germany, are looking ahead into this new age by establishing a transcontinental computer graphics research effort and a proposed G-7 testbed. We are studying how 3D computer graphics and virtual environments can aid global collaborative work. We have focused our research efforts on determining how computer networks can transform the distributed workplace into a shared environment, allowing real time interaction among people and processes without regard to their location     

凡口铅锌矿地测工程信息化技术研究与应用

阐述凡口矿地测部门在数据库、CAD系统开发、网络及三维可视化技术等领域近年来取得的成果。分别开发电子测量导线簿、矿化模型CAD管理系统、地质测量绘图系统和地质测量信息管理系统,建立地质数据库、水文地质数据库和矿床三维模型,组建地测采FTP电子图件服务器,采用空区激光探测系统对3个大爆破采场实施精密探测,建立采场三维可视化模型,准确计算采场各项回采指标。研究表明,凡口矿地测工程信息化技术的广泛应用对于加快我国数字矿山建设具有重要意义。     

一种具有精确位姿的飞机CAD模型投影图像库设计方法

近年来,随着CAD技术和3D场景理解等方面研究的发展,基于目标3D CAD模型进行精确位姿估计成为了一种重要方法。然而,直接使用CAD模型时往往需要在编程中调用商用CAD软件,这不仅需要配置大量兼容性文件而且对计算机图形硬件要求较高,同时软件层次数据频繁交互导致效率低下。因此,可以通过对CAD模型进行投影得到其带有位姿真值的图像库,从而将三维问题转化为二维问题,使其大大简化。考虑到程序的集成性,选用OpenGL作为CAD模型的显示工具。首先标定虚拟相机内外参数,考虑到运动的相对性,保持虚拟相机不动,按设定距离将目标模型以1°为步长,俯仰和方位各旋转0～90°和0～360°进行投影,从而得到具有精确位姿的目标投影图像库。     

分布式同步协同包装纸盒CAD/CAM系统的设计与实现

采用Java技术开发了基于Web的分布式同步协同包装纸盒CAD／CAM系统．研究了纸盒CAD／CAM系统的体系结构、系统功能的分配、分布式同步协同设计、并发控制、协同感知、负载均衡、3D可视化技术、参数化设计以及系统安全性的保证等关键技术．