A photogrammetric application in virtual sport training

The paper discusses an application of close range photogrammetry for the development of a virtual training system for rugby football, and the use of the technique for the evaluation of rugby players' performance. NuView, a stereo-imaging device, and a digital high-definition video (HDV) camera were used to capture stereoscopic video footage of players during field training. The left view and the right view were colour-tinted cyan and red, respectively. The tinted stereo (anaglyph) views were projected onto a white screen, and players were instructed to practise ball-throwing at the screen. A custom-built laser device (TAM) measured the accuracy of the virtual throws. In addition, a photogrammetric system was used to track the movement of body segments, for example, the angle of shoulder orientation and the trunk flexion of the thrower. The measurements determined the parameters needed for an accurate throw and these parameters would be used in the training of new players. The study shows statistically significant differences in the values of these parameters between experienced and inexperienced players.     

网络环境下数据简化与数据调度的若干关键技术

网络环境下进行二维电子地图与三维虚拟场景集成,关键问题之一是数据快速、有效地传输与表达。为了解决网络电子地图与三维虚拟场景集成过程中数据快速传输问题,该文讨论了空间数据多级存储、网络数据流压缩、矢栅数据有机结合、纹理模型及原型模型库等网络传输瓶颈解决方案和模型数据简化方法,为后续网络电子地图和三维虚拟场景集成系统的开发奠定基础。     

Analysis on Buckling Performance of Submarine Pipelines During Deepwater Pipe-Laying Operation

Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formalas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear rcsponse of elliptical collapse of steel circular tubes for different ratios of diameter to thickness (D/t) under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.     

基于Multigen Creator和Vega的大型场馆虚拟仿真技术

以大型场馆虚拟仿真开发为背景,对采用MultiGen Creator/Vega实现视景仿真开发进行了探讨,论述了Creator的建模方法,以及Vega的应用环境、碰撞检测、视景仿真软件的开发过程和整体系统实现等关键技术。     

东北三省城市拟态与现实人居环境时空耦合协调特征与机制

单一形态的现实人居环境研究,不能合理诠释人地关系地域系统下日益变化的人居环境现象.目前,不同形态人居环境相互作用的理论基础、实践探索以及科学决策等问题并不清晰.建构城市拟态与现实人居环境耦合协调的理论框架,运用耦合协调模型、空间趋势分析、地理探测器等实证分析2011-2017年东北三省34个地级市耦合协调的时空规律,并...     

基于FLASH的湛江虚拟旅游全景漫游与导航系统

探讨了基于FLASH的湛江虚拟旅游网上导航与全景漫游系统的构建以及各项关键技术,设计并实现了基于PV3D的全景浏览器,提出了基于Flash的旅游交通导航机制,对经典的A*算法作了改进,能够在网页上快速地计算出任意两个景点之间的最短路径,从而为自架车游客提供了最短路径导航服务;开发了管理维护性后台,对全景漫游、自驾车导航和公交车导航模块提供有效的增加、修改,删除信息。实际应用表明,该系统具有很好的跨平台、免插件、高效、扩展性和维护性。     

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基于虚拟GIS和空间分析的小流域泥石流地质灾害遥感解译——以嵊州市为例

介绍了基于虚拟GIS和空间分析技术在小流域泥石流地质灾害遥感解译中的方法及其应用,提出了基于数字高程模型(DEM)、遥感影像和各类地质环境要素创建遥感解译环境,并以嵊州市小流域泥石流地质灾害调查与评价项目为例,阐述了小流域泥石流调查分级、泥石流沟谷与地质环境要素提取等工作的技术方案.该方案有效地改善了遥感解译环境,提高了解译精度与工作效率,获得了丰富的地质环境信息,成为区域性泥石流调查的有效手段.     

虚拟仿真平台下摄影测量实践教学模式探索

摄影测量学课程理论抽象、实践环节多,因实验设备缺乏,部分实验无法开展,影响实践教学质量及学生综合能力的提高。虚拟仿真技术为摄影测量实践提供了解决途径,通过研发仿真软件,整合课程资源,充分利用虚拟仿真平台的技术优势,为学生提供直观的学习体验环境,可以更好地理解课程内容,提高学生实践动手及创新能力,培养高素质的摄影测量技术人才。     

虚拟地理环境在智慧城市中的研究与应用

智慧城市是数字城市的升级版,其管理服务的动态实现与虚拟地理环境联系紧密。本文首先综述了虚拟地理环境的概况;然后对虚拟地理环境运用在智慧城市中的关键技术作了归纳,分析了三维动态仿真、虚实交互、多智能体、数字孪生技术的特点及其在智慧城市管理中的适用范围;进而从应用的角度分析了虚拟地理环境在智慧城市中的研究现状与存在的挑战;最后总结出在人工智能和VR新时代下,虚拟地理环境在智慧城市中实时显示、高效算法、虚实交互等方面的发展前景。