论文总字数：35899字

摘 要

近年来，随着城市化进程的不断加快，城市道路结构愈发复杂，对于导航软件的需求也逐渐提高，对道路模型的需求从二维平面提升到了三维立体。三维导航是未来导航发展的趋势，但是海量数据、计算量大、空间关系错综复杂等因素亟待解决。

Cesium是一个先进的三维WebGIS开发框架，可以在浏览器上展示虚拟的三维地球并进行空间分析。本文结合了WebGIS跨平台、易于扩展、分布计算等优点与三维导航直观性强的特点，研究了基于Cesium的三维导航方法，主要的研究内容如下。

研究Cesium的三维场景管理技术，分析介绍了Cesium支持的三维数据格式和从主流三维数据格式到gltf格式的转换方法，为三维模型加载打下基础。研究了Cesium类库中三维场景管理的关键类及其使用方法。探讨了使用方向传感器控制用户视角的方法，并对不同系统和浏览器的传感器参数进行了统一。研究道路网络模型，根据研究区域特征选择弧段-节点模型，并增加高程字段，将道路网络拓扑扩展到三维。开发三维导航原型系统，选择了Cesium作为开发库、NodeJS搭建服务器端、PostGIS提供数据库支持，完成主要功能的开发，包括三维模型加载与场景漫游、三维场景驱动、位置查询与路径规划功能，并且完成测试。

关键词：Cesium，WebGIS，三维导航，三维场景管理，道路网络模型

Abstract

In recent years, with the continuous acceleration of urbanization, the structure of urban roads has become more and more complex, and the demand for navigation software has gradually increased. The demand for road models has increased from two-dimensional plane to three-dimensional plane. Three-dimensional navigation is the development trend of navigation in the future, but the factors such as massive data, large amount of computation and complicated spatial relations need to be solved urgently.

Cesium is an advanced three-dimensional WebGIS development framework, which can display a virtual three-dimensional earth on a browser and carry out spatial analysis. This paper combines the advantages of WebGIS, such as cross-platform, easy expansion, distributed computation, and strong visualization of three-dimensional navigation, and studies the three-dimensional navigation method based on Cesium. The main research contents are as follows.

This paper studies Cesium's three-dimensional scene management technology, introduces the three-dimensional data formats supported by Cesium, and studies the conversion method from the mainstream three-dimensional data format to gltf format, which lays a foundation for the loading of three-dimensional models. The key classes of 3D scene management in Cesium class library and their usage are studied. The method of using direction sensor to control user's visual angle is studied, and the sensor parameters of different systems and browsers are unified. Research the road network model, select arc segment-node model according to the characteristics of the research area, and add elevation fields to expand the road network topology to three dimensions. The prototype of three-dimensional navigation was developed. Cesium was selected as the development library, NodeJS set up the server side and PostGIS provided database support to complete the development of the main functions, including three-dimensional model loading and scene roaming, three-dimensional scene driving, location query and path planning functions, and the test was completed.

KEY WORDS: Cesium, WebGIS, three-dimensional navigation, three-dimensional scene management, road network mode

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1研究背景 1

1.1.1WebGIS的概述 1

1.1.2三维导航的概述 2

1.2研究意义 2

1.3研究现状 2

1.3.1国外研究现状 2

1.3.2国内研究现状 3

1.4论文主要工作 4

1.5论文章节安排 4

第二章 三维场景管理技术 6

2.1Cesium概述 6

2.2三维数据格式及格式转换方法 7

2.2.1三维数据格式 7

2.2.2格式转换方法 8

2.3Cesium三维场景管理关键类 9

2.3.1影像图层 9

2.3.2实体 9

2.3.3视口照相机 10

2.4用户定位与视角方向 11

2.4.1传感器参数概述 11

2.4.2传感器参数获取与统一 12

2.5本章小结 13

第三章 道路网络数据模型与路径规划算法 14

3.1道路网络数据模型设计 14

3.1.1PostGIS概述 14

3.1.2道路网络数据模型 15

3.1.3道路网络的建立 15

3.2路径规划算法 18

3.2.1路径规划问题描述 18

3.2.2路径规划算法设计 18

3.3本章小结 21

第四章 基于Cesium的三维导航原型的实现 22

4.1架构设计 22

4.2HTTP服务器的搭建 22

4.2.1NodeJS概述 22

4.2.2启动服务器 23

4.2.3实现数据交互 24

4.3主要功能的实现 24

4.3.1数据加载和场景漫游 24

4.3.2三维场景驱动 25

4.3.3位置查询 26

4.3.4路径规划 26

4.4本章小结 28

第五章 总结与展望 29

参考文献 30

致 谢 32

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