大型虚拟博览会场景的优化方法研究

随着人们对信息需求的不断攀升,大型展览会都开始同期设立网上展馆.为了解决不断扩大的场景规模和访问者对场景的高精度要求之间的矛盾,采用了合理的建模方法,如优化模型、LOD技术和预渲染方法,简化的碰撞检测模型和天气仿真模型等对大型虚拟博览会场景进行了有效优化.在不影响场景质量的前提上,有效地减少了系统硬件设备运算量,降低网上博览会的运营成本,同时增强了系统的互动性,使大型虚拟博览会的体验更加真实和生动.     

一种用于在线搭建的虚拟展览馆拆分及检索方法*

以“2010年中国上海网上世博会”为研究背景,针对网页中用户在线拖动搭建虚拟展览馆的动态生成和个性化定制要求,从虚拟展览馆的组件特征、数据构成和应用网络方面进行了分析,提出了以具像特征体描述为原则的组件化拆分方法,建立了基于基因特征的展览馆组件编码规则和B/S架构下的二次检索机制,由实验导出了组件传输时间和场景构建响应速度的关系及优化方法。通过应用于网上博览会在线拖动搭建系统,证明了该方法有效解决了网页中动态构建虚拟展览馆的元素组合和重构问题。     

基于SketchUp虚拟场景快速建模

随着虚拟城市、虚拟旅游、虚拟建造等虚拟现实设计的迅速崛起,传统的三维建模方式已无法满足大批量场景建模的需求。文章通过对虚拟场景的数据采集、建模流程和模型优化深入研究,提出一种基于SketchUp平台快速、高效的建模方法,旨在为大型复杂虚拟场景的构建提供借鉴与参考。     

大规模虚拟场景渐进式传输的研究进展

随着网上三维虚拟场景的急剧扩张,来自用户端的即时下载请求和有限带宽之间的矛盾亦变得日益突出。现已有大量研究者致力于通过渐进式传输来实现网上大规模虚拟场景的快速下载,因此有必要对现有研究成果进行综述。首先介绍了渐进式传输的基本原理和过程,给出了一个用于评价不同传输策略的公式,接下来分别从(1)潜在可视场景集及潜在可视场景集增量的判定,(2)三维物体模型的简化技术和流式编码,(3)不同体系结构的分布式虚拟环境中的场景传输机制,(4)虚拟场景的预下载策略等方面论述了针对大规模虚拟场景的渐进式传输策略,最后展望了网上大规模虚拟场景渐进式下载技术的未来研究方向。     

基于3dsMax的建筑虚拟场景建模及优化技术研究

虚拟场景的建模是建筑效果图制作以及虚拟场景漫游系统实现的重要基础。本文重点阐述了使用3ds Max软件创建建筑及其周边环境模型以及进行模型优化的技术和方法。     

基于Creator的复杂场景建立方法的研究与实现

内含大量设备模型的场景是虚拟现实应用的典型场景.文章阐述了在虚拟场景构造中大规模复杂场景的建模与优化、场景数据库优化、CAD模型显示与优化、数据格式优化等关键技术问题,实现了整个系统的设计与开发.实验证明该系统具有良好的交互性与实时性.     

基于MultiGen的虚拟场景真实感研究

虚拟校园是数字城市的缩影.以北京交通大学的真实校园场景为研究对象,采用模块化、层次结构和纹理映射技术相融合的方法,通过运用实时可视化三维建模软件系统MultiGen Greator进行建模,创建了较为逼真的校园虚拟场景模型,并从数据库结构和组成模型的面片数两方面对其进行了优化,最后利用仿真系统Vega实现了校园虚拟场景的驱动显示.对于校园虚拟现实系统关键技术的研究与实现成为完成逼真合理的大规模虚拟场景的基础.     

基于MultiGen的虚拟场景真实感研究

虚拟校园是数字城市的缩影。以北京交通大学的真实校园场景为研究对象,采用模块化、层次结构和纹理映射技术相融合的方法,通过运用实时可视化三维建模软件系统MultiGen Creator进行建模,创建了较为逼真的校园虚拟场景模型,并从数据库结构和组成模型的面片数两方面对其进行了优化,最后利用仿真系统Vega实现了校园虚拟场景的驱动显示。对于校园虚拟现实系统关键技术的研究与实现成为完成逼真合理的大规模虚拟场景的基础。     

Web环境下产品虚拟展示系统的场景优化

在Web环境下,由于较慢的网络传输速度和过大的虚拟展示系统场景文件问题,导致展示场景首次加载时间长,场景漫游时出现卡顿和模型闪烁.针对以上情况,提出了双层次细节渐进优化(Gradually Optimize Two Level of Detail)和模型-贴图过渡显示优化方法.GOTLOD技术通过分割场景和异步加载场景文件,使用低精度模型快速搭建展示场景,利用视距远近动态切换不同精度的模型.模型-贴图过渡显示优化技术利用视距改变的差值大小,在模型和贴图间进行多层级切换.实验结果表明,采用GOTLOD和模型-贴图优化技术,场景初次加载时间减少71％,场景漫游时的FPS值提高了3.9倍.该优化技术有效减少了场景加载时间,有效解决了场景高真实度运行时漫游的流畅性问题.     

虚拟场景实时渲染软件优化方法

针对影响虚拟场景实时渲染速度与场景精细度的矛盾,研究了虚拟场景实时渲染的软件优化方法.对虚拟场景构建的设计阶段进行场景分割与预存储,对建模阶段进行模型与贴图的优化处理,对运行控制阶段进行可见性细节层次设置与多线程控制.使用这些优化方法后,在保持视觉效果的同时,有效降低场景的复杂度,减少硬件设备的负担,从而提高实时渲染的速度与交互操作的流畅性.     

网上博览会虚拟要素实时生成技术

在互联网上建立虚拟展馆,能够突破时间和空间的限制,满足世界各地更多的参观人群对参观展会的需求.针对虚拟展馆和现实展馆息息相关的问题,提出了"虚实融合"、"场网联动"的网上博览会设计与构建方法.重点研究了与现实相关联的虚拟展馆中关键要素包括人物和虚拟场景的实时生成技术,符合X3D标准,数据量小,易于网上发布,有效增强了网上博览会的生动性,同时将为现场参观人群提供有效的导览和服务信息.     

程序设计教学中的情境创设

本文结合VB程序设计教学中的具体案例,阐述了基于建构主义的情境创设在教学中的应用,并总结出在教学中进行情境创设时需要注意的问题以及应遵循的原则。     

Study on Recognition Method of Similar Weather Scenes in Terminal Area

Weather is a key factor affecting the control of air traffic. Accurate recognition and classification of similar weather scenes in the terminal area is helpful for rapid decision-making in air traffic flow management. Current researches mostly use traditional machine learning methods to extract features of weather scenes, and clustering algorithms to divide similar scenes. Inspired by the excellent performance of deep learning in image recognition, this paper proposes a terminal area similar weather scene classification method based on improved deep convolution embedded clustering (IDCEC), which uses the combination of the encoding layer and the decoding layer to reduce the dimensionality of the weather image, retaining useful information to the greatest extent, and then uses the combination of the pre-trained encoding layer and the clustering layer to train the clustering model of the similar scenes in the terminal area. Finally, terminal area of Guangzhou Airport is selected as the research object, the method proposed in this article is used to classify historical weather data in similar scenes, and the performance is compared with other state-of-the-art methods. The experimental results show that the proposed IDCEC method can identify similar scenes more accurately based on the spatial distribution characteristics and severity of weather; at the same time, compared with the actual flight volume in the Guangzhou terminal area, IDCEC's recognition results of similar weather scenes are consistent with the recognition of experts in the field.     

An internet based virtual exhibition system: Conceptual deisgn and infrastructure

Virtual reality technology has wide applications in manufacturing, service industry, and medical training. In addition to essential presence, virtual reality provides secure and economical environment for participants to experience the virtual world rather than the corresponding real world. With advent of rapidly developed technology, there are numerous new products and projects to be introduced in exhibition shows over the world everyday and it is neither prudent nor possible to attend all of them. There have been overwhelming amount of virtual exhibitions available on the Internet; however, most of them are not satisfactory in terms of performance and users cannot get a full understanding on the product interested due to low sense of presence. Information coordination, other than information share and distribution, between the participants is crucial but not yet well defined in the current virtual exhibitions. It is prominent to develop Internet based virtual reality exhibition systems that agglomerate the advantages of efficiency/accessibility on the Internet and high sense of presence in virtual environment. The Internet based virtual exhibition systems are not only as informative as traditional exhibitions but also more flexible to relax temporal and spatial constraints to allow users attend exhibitions anytime and anywhere.     

Dialogue and carnival: understanding visitors' engagement in design museums

Abstract

As the role of museums has shifted from collection-driven institutions to experience-centred environments, researchers in museology have felt a growing need to understand how visitors experience and engage in exhibitions. Defining design museums as sites of meaning-making through diverse interactions and co-creative experiences, we examine dialogue as a means of encouraging visitors' active participation and creative engagement in design exhibitions. This article presents a theoretical framework based on Mikhail Bakhtin's concept of dialogism and carnival theory. Four kinds of dialogic engagement are identified to illustrate different ways of engagement and co-creation in design museums through the analysis of example exhibitions.     

绘制大规模场景的可见性计算技术

高效的可见性计算可大量节省关于场景中不可见部分的计算．较系统地介绍了各种可见性计算技术。首先讨论可见性计算的基础方法；然后讨论可见性计算的高效实现和运用方法，以及一些能很好地提高绘制效率的可见性计算系统．     

风场作用下大规模草地场景动态模拟*

草体作为自然场景的一种重要元素,其数量众多、覆盖范围广,很难实现实时动态模拟。针对已有方法存在的问题,提出了一种风场作用下大规模草地场景动态模拟方法,首先利用混合式表达方法构建出大规模静态草地场景,通过二维向量建立风场模型,采用混合动力学方程以及移动布告板上端顶点的方法,分别模拟出离视点不同距离的草体在风场作用下的形变。实验结果表明,该方法不仅能绘制出风场中草体随风摆动的逼真效果,同时对可变风场有很好的支持。     

域间路由系统自组织特性

域间路由系统与Internet一样是一个复杂巨系统.自组织理论是当前对于复杂性系统研究的重要成果,是研究复杂系统的有效工具.所以,从自组织特性的角度分析了域间路由系统的内在规律和外在表现,并且评价了为了改善域间路由系统的扩展性、收敛性、稳定性和安全性而对BGP协议进行改进的各种方法.在对BGP的发展趋势进行预测的基础上,给出了利用自组织特性解决域间路由系统问题的指导原则和几种可行的方法.     

Extrinsic and intrinsic motivation for using a booth recommender system service on exhibition attendees’ unplanned visit behavior

Our study on unplanned behavior theory examines the effect of the booth recommender system (BRS) service on exhibitions arising from either extrinsic or intrinsic motivation. Previous studies have ignored the importance of the unplanned behavioral effectiveness through a BRS service that joins extrinsic and intrinsic motivations to deliver unexpected outcomes at exhibitions. In this paper, we propose a model for the impact of BRS service in which the perception of usefulness and the threats to freedom of choice mediate the effect of both extrinsic and intrinsic motivation on unplanned booth visit behavior. We collected data from 101 exhibition visitors and analyzed the data using the partial least squares (PLS) method. Our findings indicate that intrinsic motivations (escape, event attractions) are significantly related to both the perceived usefulness of the BRS service and the threats to freedom of choice, while extrinsic motivation (information gain) were not significantly related to those characteristics. The perceived usefulness of the BRS service directly mediates the effect of escape and event attractions on unplanned booth visit behavior. The results and implications of these findings are further discussed in the paper.     

以蚁群优化为基础的组播路由算法优化

分析组播路由算法和蚁群优化算法,并通过仿真实验评价了以蚁群优化为基础的组播路由算法的优化方法。当路由计算的规模较大时,信息中未搜索到的数量能够减少并趋近0,将路由算法的全局搜索能力降低。蚁群算法中,蚂蚁的数量与算法的全局搜索能力呈正相关,但蚂蚁的数量在增加的过程中会影响其收敛速度。通过蚁群优化组播路由算法,能够在规模的限定下,提高算法的搜索能力。