【作者】 苏加强；

【导师】 石奋谡；

【作者基本信息】 西北第二民族学院 ， 计算机应用技术， 2007， 硕士

【摘要】 首先介绍了GIS理论和组件式技术的基础,然后依据宁夏中部干旱带的实际状况,以Visual Basic作为前端开发工具,结合MapObjects、GeoLod 4.0等控件技术,将计算机数据库技术、多媒体技术、组件式GIS技术、VR技术等进行集成,给出宁夏中部干旱带荒漠化系统的实现细节。开发过程中,针对GIS研究和应用的难点三维数据模型和海量数据大范围动态漫游问题,提出了自己的解决方案。三维数据模型和数据结构一直是GIS理论研究的难点和焦点之一,针对这一问题提出了基于对象级的虚拟现实技术与GIS整合,并共享一样的数据结构。设计的数据模型,采用了矢量数据和栅格数据混合管理的数据结构,并将数字高程模型DEM、数字正射影像DOM、三维模型、虚拟对象、属性、多媒体等各种信息统一进行管理,避免了将二者分开进行处理的弊端。海量数据大范围动态漫游是当前GIS应用的瓶颈,我们分别采用金字塔数据结构和数据的动态装载和渐进描绘,根据显示范围的大小可以灵活方便地自动调入不同层次的数据,目前已经圆满地解决了对海量三维数据的大范围多尺度无缝漫游问题。多重细节层次LOD(Levels of Detail)是实现海量数据大范围实时漫游的关键技术之一,对LOD处理的好坏直接影响漫游的速度。针对LOD技术的实现,在面向对象的层次建模和实时模型简化能力方面提出了独有的机制。将所有相关的数据有效地组织起来,并根据其地理分布建立统一的空间索引,进而可以快速调度数据库中任意范围的数据、达到对整个地形的无缝漫游。更多还原

【Abstract】 Firstly,this paper introduces GIS theory and component-based technology, then gives the detail of Central dry area desertification system was actualized accoding to the central dry area condition in NingXia. this system use Visual Basic as front development tool , integrate database、multimedia、virtual reality、component technology , combinate MapObjects and GeoLod 4.0 control technique etc. In the process of development,this paper propose some solutions to solve the issues of three-dimensional data model and large-scale dynamic 3 D roaming of Massive Data in allution to GIS research and application.Three-dimensional data model and data structure are one of foucses and difficulties for GIS theory research and application. This system solve this problem through integrating virtual reality based on object and GIS technology which sharing the same data structure. This data model adopt a data structure that can manage vector data and the grid data.. In order to avoid the trouble of disposal for separating both, this model also take a centralization of management to these data, such as DEM,DOM,CGS,virtual object,multimedia,etc.Nowadays the bottleneck of GIS applicaion is large-scale dynamic 3 D roaming of Massive Data. this system solve perfectly large range multi-scale seamless roaming problem by using pyramid data structure and dynamic loading and gradual descripting data technology. Thus system can autoload diffirent level’s data in according to scope for display.LOD technology is one critical technology for implementing large-scale dynamic 3 D roaming of Massive Data .System organize availably all kinds of relative datas and create a uniform spatial index according to geographic distribution to achive the purpose of quicking the survey of the large range multi-scale seamless roaming.更多还原