三维场景中查询功能的设计与实现

【作者】 吕成姝；

【导师】 迟忠先；

【作者基本信息】 大连理工大学 ， 系统工程， 2003， 硕士

【摘要】 查询是各种决策分析中用户最经常使用的功能。三维地理信息系统中查询功能的设计与实现对于用数字化的方式定量描述和研究人类所处的真实场景，并以此为基础进行各种辅助性决策分析，具有关键性的意义。三维场景是三维地理信息系统中人机交互的主界面，本文以实际应用为背景，结合用户的实际需求，对三维场景中查询功能的实现机制进行了研究。 论文首先针对自主开发的三维地理信息系统中三维场景的特点，提出了实体模型概念，将三维场景空间信息和属性信息有机地结合在一起，为查询功能的实现奠定了基础。 论文重点讨论了查询功能的设计与实现。通过分析三维场景的数据特点和用户需求，建立了三维场景中查询功能的组成模块。将三维场景的查询分为对地形的查询及对地物的查询。地形的查询建立在DEM数据结构的基础上。对地物的查询采用了ActiveX组件技术，使得原有二维地理信息系统的已有成果可以在三维系统中重用，同时根据三维场景的特点新增加了三维实体拾取等模块，共同完成对地物的空间-属性交互查询。运用组件技术进行开发，可以有效地保护已有投资，显著提高开发效率。同时由于该查询组件的功能设计建立在实体模型的基础上，因此可以将其应用到森林覆盖率分析等其他众多应用领域，以及用于网络环境下WebGis的开发中。 本文最后对下一步工作进行了展望。更多还原

【Abstract】 This thesis concentrates on the realization of enquiry function in 3D scene, the main interactive interface of 3D GIS. As in most decision supporting systems, enquiry function is fundamental to a true 3D GIS. It helps to describe the real space in a quantitative and digital way, so the system can support decision-makings in a variety of engineering fields.The thesis makes an analysis of the features of the 3D scene. The entity model is then proposed, which combines spatial information with attributes information of the 3D scene. This forms the basis for the realization of enquiry function.The thesis puts an emphasis on the design and implementation of the enquiry function in 3D scene. The structure of the enquiry functions is designed after the client’s demands and the features of the data are analyzed. In this way, enquiries in 3D scene are classified into two types: enquiries to terrain and those to spatial objects. Enquiries to terrain are implemented on the basis of DEM data structure. Enquiries to spatial objects are implemented by calling a component which has been developed by utilizing useful modules and information in the existing two-dimension system. The component is developed in Delphi using ActiveX component technology. The other modules of the whole enquiry functions, which have the features to deal with three-dimensional data, for example the three-dimensional entity pick module, are developed by Visual C++. It is concluded that by using component technology, enquiry functions in 3D GIS can be realized while making full use of the exiting two-dimension ones. Moreover, it can be widely used in other fields, forest coverage rate analysis for example, as the component is based on the entity model, and it can also be used in the development of WebGis.更多还原