【作者】 杨慎欣；

【导师】 傅英亮；

【作者基本信息】 大连海事大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 近几年,基于Web的仿真由于具有使用简单、高访问性和信息共享的优势而受到越来越多的关注,随着高速网络技术的发展使得基于Web的仿真更加切实可行。作者将WWW技术与现有的仿真系统紧密结合,提出了基于Web的训练环境的新使用模式,使更多用户可以随时随地的通过浏览器在线使用。功能完备的大型仿真系统虽然已成为教学和培训有效的实践方式和手段,但由于系统开发周期长、使用周期有限、花费和维护成本高、训练场地、训练人数和训练时间受限制等多方面原因,限制了其应用;而且随着用户数量的逐年增加,难以保证有足够的学习和训练时间。基于Web的仿真系统具有开放性、机动性、灵活性、便于访问性、高交互性、易维护性、可重用性和节省成本等的特点,而且利用仿真这种最有效的在线学习方法,可以有效的弥补传统的远程教育局限于阅读、收听和观看预定的学习程序的不足。但是构建基于Web的仿真系统面临着有限网络带宽限制的巨大挑战,较大的网络延时会严重的影响到仿真训练的结果,甚至使得仿真完全失去意义。如何实现在Web环境下大规模三维场景的实时传输以保证客户端实时显示是该系统的难点。为此,作者在以下几个方面做了重点研究:1.阐述了基于Web的仿真系统的概念和特征。构建了结构开放、兼容能力强的Web三层体系结构,设计了每个模块的具体功能,给出了利用Java+VRML初步构建基于Web的仿真系统的可行性方案。2.对三维场景进行了分类,使用VRML构建了三维视景模型,分析了模型的LOD技术并应用于三维场景的建模。3.通过Java实现了仿真系统客户端用户与三维虚拟环境的交互,包括如何访问三维虚拟环境中的数据以及如何将数据返回给三维虚拟环境。4.实现了基于位移蝶形细分面片的渐进传输技术。通过传输蝶形细分面片的控制网格并进行蝶形细分,使得客户接收端在数据传输的开始就可以获得三维模型的基本几何形状,从而提高了渐进传输的效果。更多还原

【Abstract】 In recent years, Web based simulation has attracted a great deal of attention mainly because of its easy of use, high accessibility, and information sharing potential. Improvements to the information technology infrastructure such as high speed Internet connection make distributed simulation even more feasible. Integration of existed simulation systems and the capabilities of the WWW offer a new training medium—Web Based Simulation System—for expansion of the industry user base. A full mission simulator has been the most effective approach available for education and training. However, there are many problems with most simulation systems today, such as the long development cycle, limited application life, the high expenditure, expensive development cost and the difficult maintenance, the limited accessibility, etc. It cannot ensure that users have enough time to go into training. Web Based Simulation System allows more users pursue training from anywhere, and at any time, via a PC and Web browser. Web Based Simulation System has the characteristics of openness, mobility, flexibility, high accessibility, high interactivity, easy maintenance, high reusability, cost-effectiveness; it also integrates the simulation to effectively make up the limitation of traditional e-Learning, in which users tend to be restricted to a predetermined learning path through reading, listening and observation.However, it is a challenge for constructing the Web Based Simulation System, since the limited bandwidth and the long network delay may greatly affect the efficiency of training, even makes the simulation useless. The difficulty of the research is tring to implement the real-time transmission and display of large-scale 3D scene in Web environment. The key technology research contents and contributions of this dissertation summarized here are:1. The concept and characteristics of a Web-based training environment are presented first; open and strong compatible Web-based three-level architecture and the function of each module are designed. The feasible technical solution of constructing a Web-based maritime training environment with VRML plus Java is proposed. 2. 3D scenes were classified, the VRML was used to construct the port’s three-dimensional visual model, a model of LOD technology was analyzed and applied to the three-dimensional modeling scene.3. Though the Java to achieve the interactive between clients of sea simulation system and 3D virtual environment. It includes how to access the data of 3D virtual environment and how make the data back to the 3D virtual environment.4. Achieve the transmission gradual technology, which based on of the breakdown of film. By the control-grid of transmission of the butterfly displacement and breakdown it butterflies. Make the clients firstly enable to receive the basic geometric models of three-dimensional, so as to enhance the effect of a gradual transference.更多还原