基于CityGML的城市建筑物三维建模研究

城市建筑物三维建模是虚拟3D城市建模的基础和重要组成部分。本文对基于CityGML1.0（City Geography Markup Language 1.0,城市地理标记语言）的城市建筑物三维建模技术进行了深入的研究,主要内容包含了CityGML1.0的简介、城市建筑物三维建模的方法和内容等,并给出了一个实际建模的例...     

基于语义映射的BIM与3D GIS集成方法研究

BIM与3D GIS技术的结合可以连接室内室外,实现城市精准三维建模,更好地推进智慧城市的建设。IFC与CityGML分别作为BIM与3DGIS的通用标准,利用本文提出的基于语义映射的方法,可以实现IFC到CityGML几何与语义信息的转换,并以标准模型进行了验证。     

对城市地理标记语言(CityGML)的探讨

虚拟3D城市模型是三维城市GIS研究的基础。本文对CityGML1.0(City Geography Markup Language1.0,城市地理标记语言)的发展和核心技术进行了深入的研究,其主要内容包含了CityGML1.0的5层LOD模型、空间数据模型、CityGML模块、应用领域扩展等,还给出了基于CityGML1.0开发的系统实例,最后对CityGML的应用和发展进行了预测。     

基于ArcGIS的三维场景自动化精细建模

主要研究将ArcGIS强大的图形、属性数据组织和管理能力与CityEngine基于CGA规则的建模思想相结合,进行大面积三维场景的自动化精细建模,高效实现三维可视化.不但能够实现GIS数据中各种属性的快速、自动建模,还能实时修改规则,调整模型显示,降低了三维GIS建模的成本,缩短了三维建模的周期,同时也扩展了参数化精细建模的应用领域.     

三维地理信息建模典型的三种方法探索与实践

三维地理信息建模是测绘地理信息行业近年来发展的新技术,其建立的三维城市模型已经是数字城市、智慧城市地理空间框架数据的核心内容之一。本文主要介绍了三维地理信息建模的3种典型建模方法及其建模步骤,并以具体图片展示其建模结果,最后结合3种方法的各自特点分析了其优缺点及其适合的建模应用领域。     

顾及建筑物多细节层次的IFC和CityGML模型转换研究

针对现有三维地籍管理中难以有效利用已有建筑信息模型(BIM)数据的问题,提出一种顾及建筑物多细节层次的模型转换方法,结合三维地籍管理的应用需求,建立工业基础类(IFC)到城市地理标记语言(CityGML)的模型转换流程,解决转换过程中语义信息匹配、几何模型转换、要素关系构建的技术难点。实验表明,该方法能够兼顾三维不动产模型的精细化表达及产权信息展示,为三维不动产的多层次集成可视化及应用提供有效可靠的方法。     

基于共形几何代数的三维地理场景建模与表达

以共形几何代数对几何体的多维统一表达为基础,构建基于多重向量的三维地理场景建模与表达流程。对CityGML数据进行解析,应用本模型对其加以组织和管理,并实现场景的可视化与交互。德国Waldbruecke村的实例验证结果显示,基于共形几何代数的三维场景建模与表达可以较好地支撑复杂地理场景的表达、重建与检索,并可实现多维度对象的统一管理与维护,有助于支撑大规模地理数据及场景的分析及应用。     

一种基于CityGML的三维模型单体化方法

实景三维中国建设应满足自然资源管理与社会经济发展需求,因此需要对基础地理信息产品进行实体化改造,三维模型单体化正是实体化改造的关键环节。本文提出了一种基于CityGML的三维模型单体化方法,首先根据地物实体轮廓的二维矢量面提供的顶点坐标及高程信息,构造墙面、屋顶等多边形平面组成地物的简单三维表达,然后配合渲染到纹理技术（RTT）进行纹理贴图,基于CityGML为每个二维矢量面对应的地物重构出有语义、有LOD层级的三维模型。该方法能够高效地实现三维模型单体化,且成果模型容量小,可满足各种实景三维应用需求。     

Web环境下房产测绘信息三维可视化技术研究

Web环境下的三维可视化技术存在诸多技术难点。相对单机及局域网环境,Web环境下的网络响应时间将很大程度上影响着三维可视化的实际效果。文章围绕这一问题,从三维建模效率和三维模型数据量两方面入手,在分析现有方法不足的基础上,结合房产测绘信息特点,提出了基于模型库的房产测绘信息三维场景实时构建方法、基于模块化和参考复用的三维建模方法,进而提出一套行之有效的解决方案,使Web环境下房产测绘信息三维可视化技术得以实用化。实验系统证明了该方法的有效性、实用性。     

基于Google Map的测量数据可视化研究

三维建模是数字化城市建设过程中重要的环节,但是传统的三维建模软件如3d Max、Sketch Up、Skyline等在建模过程中不仅对数据质量要求很高,而且耗费大量的人力资源和时间资源,无法做到快速批量建模。本文的目的是对测量数据进行三维可视化管理,并不要求精细建模及纹理映射,只需要快速地建立几何模型。本文提出了基于Google Map的测量数据可视化研究,以Google Maps API作为开发工具,在谷歌地图上实现控制点信息和建筑物的三维可视化管理。     

UML‐Based Approach to Developing a CityGML Application Domain Extension

Recently a national 3D standard was established in the Netherlands as a CityGML Application Domain Extension (called IMGeo). In line with the Dutch practice of modeling geo‐information, the ADE is developed using a model driven approach. The classes are designed in UML and automatically mapped to GML schema. The current OGC CityGML specification does not provide rules or guidance on correctly modeling an ADE in UML. This article fills this gap by studying how CityGML can be extended for specific applications starting from the UML diagrams. Six alternatives for modeling ADEs in UML are introduced and compared. The optimal alternative is selected and applied to obtain the national 3D standard. The approach was extensively discussed with international experts, who were members of both SIG3D and other working groups. As a consequence the approach was adopted by the SIG3D, the Special Interest Group 3D which, among other things, work on the 3D standard CityGML in cooperation with OGC. Therefore the approach contains many issues that can be generalized and reused by future domain extensions of CityGML. To further support this, the article formulates a model‐driven framework to model CityGML ADEs. Open issues are described in the conclusions.     

Utilities of Virtual 3D City Models Based on CityGML: Various Use Cases

Virtual 3D city models are increasingly being used to model the realms of the real world for utilization in a number of applications related to environmental simulations including, urban planning, mapping the energy characteristics of buildings, noise mapping, flood modelling, etc. Apart from geometric and appearance/textural information, these applications have a requirement for complex urban semantics. Currently, a number of 3D standards are available in CAD, BIM and GIS related domains for the storage, visualization and transfer of 3D geospatial datasets. Initially, the 3D data models (such as COLLADA, VRML, X3D, etc.) were purely graphical/geometrical in nature and mainly used for visualization purposes. With the inclusion of thematic modules in OGC CityGML, the integration of geometry and semantics in a single data model paved the way for better sharing of virtual 3D city models. In spite of the availability of a wide range of 3D data standards, there are certain differences with respect to geometry, topology, semantics, LODs, etc., which complicates the integration of 3D geodata from heterogeneous sources. This paper serves to highlights the need for the innovative solutions with respect to the urban environmental related simulations primarily based on the use of virtual 3D city models. Four use cases are studied in this context namely, (1) urban solar potential estimation using CityGML models, (2) simulation of traffic noise level mapped on building walls from the urban road segments, (3) CityGML based 3D data models interoperability, and (4) 3D indoor logistics and subsurface utilities. However, for modelling majority of use cases, CityGML does not provide explicit thematic representations but provides support for extending the CityGML schema using Application Domain Extensions. In a nutshell, the study explores the semantic modelling capabilities of the CityGML for the transformation of native 3D virtual city models to one satisfying capabilities like semantic information and support towards interoperability.     

利用CityGML模型自动构建三维封闭建筑体

给出了利用CityGML模型自动构建三维封闭建筑体的基本框架和流程。充分利用已有的CityGML数据,分析其与三维封闭建筑体的语义关联和差别,奠定利用CityGML构建三维封闭建筑体的理论基础;从构建三维封闭建筑体所需几何数据出发,根据语义关联从CityGML中提取相应的几何数据,构建符合三维封闭建筑体要求的几何对象,满足三维立体规划和审批、核查的空间数据需要,进而弥补传统地籍数据采集方式的不足。     

CityGML goes mobile: application of large 3D CityGML models on smartphones

CityGML, a semantic information model for digital/virtual city models has become quite popular in various scenarios. While the data format is still actively under development, it is already supported by different software solutions, especially GIS-based desktop applications. Mobile systems on the other hand are still neglected, even though the georeferenced objects of CityGML have many application fields, for example, in the currently popular area of location-based Augmented Reality. In this paper we present an independent multi-platform CityGML viewer, its architecture and specific implementation techniques that we use to realize and optimize the process of visualizing CityGML data for use in Augmented Reality. The main focus lies in improving the implementation on mobile devices, such as smartphones, and assessing its usability and performance in comparison to web-based approaches. Due to the constrained hardware resources of smartphones, it is a particular challenge to handle complex 3D objects and large virtual worlds as provided by CityGML, not only in terms of memory and storage space, but also with respect to mobile processing units and display sizes.     

An Application Domain Extension to CityGML for immovable property taxation: A Turkish case study

It is generally acknowledged that immovable property taxes are one of the main revenue sources for local government. The literature emphasizes that the administration of property taxes needs well-developed inventories or registers that provide complete and accurate records of the taxed properties and their legal-economic attributes. This requirement is generally fulfilled by Spatial Data Infrastructures (SDIs) in which the coordinate exchange and sharing of geo-spatial data is provided by separate registers/information systems such as: cadastral systems, building and address registers. Recently, the Open Geospatial Consortium presented a core component of a 3D SDI in the form of an international domain standard for representing, storing and exchanging 3D city models. The CityGML allows the semantic and 3D geometrical representation of physical objects but does not deal with the legal and administrative aspects of the city objects which are required for the process of property taxation. This paper outlines the development of an Application Domain Extension (ADE) for the immovable property taxation domain that expands the CityGML data model with the legal and administrative concepts defined in Turkish Law. The study shows that this ADE could be a 3D national data model for municipal information systems and facilitate a more efficient taxation process, as well as providing data for urban planning, facility management and other municipal services.     

城市三维管网的可视化及其系统功能

阐明了三维管网几何建模的原理,介绍了基于该技术的城市三维管网的可视化过程及几种加快图形显示的方法和管网系统的功能。该三维管网建模关键技术对于解决复杂的城市三维管网可视化快速建模提供了一种新思路,是建立三维管网系统的前提。     

Development of CityGML Application Domain Extension for Indoor Routing and Positioning

CityGML is an open data model for storage and exchange of 3D city models. It is categorised into thirteen thematic classes, i.e., buildings, tunnels, bridges, etc., lacking the other themes such as indoor routing and positioning. With the amplified use of indoor routing and positioning, the need for prerequisite notion of detailed semantic, as well as geometric information of the 3D building data has grown. We intend to extend the CityGML schema to add attributes of indoor features using the facility of Application Domain Extension (ADE) provided by the OGC CityGML 2.0. In this study, we aim to showcase the formation of Indoor Routing and Positioning ADE along with the process concerning its development, such as the 3D model design, network dataset creation, routing, positioning and Unified Modeling Language based ADE application schema generation. This research would help the users to easily store and exchange 3D city data on which they can perform routing and positioning inside the buildings with enhanced semantic and geometric properties.