基于Cityengine平台的CGA规则室内三维建模方法研究

随着三维数字城市建设的兴起和不断发展,3D GIS技术逐渐被人们所重视,多种三维建模软件也已被大量应用在三维数字城市的设计和创建中。首先通过与传统建模软件的对比,分析了Cityengine城市引擎软件在快速批量建模和与GIS软件数据交互方面的优点,同时也指出了Cityengine在建筑物室内场景方面缺乏对建模规则的研究。因此本文利用二维GIS几何数据作为模型的底面基础数据,借助Cityengine软件特有的CGA语法编写规则文件,对Cityengine平台下创建建筑物室内三维场景的方法进行了初步探究。通过对该方法的研究旨在使三维室内外场景形成良好的整体,弥补之前Cityengine只能对大场景进行外部批量建模而缺乏对内部模型研究的不足,扩展Cityengine在三维建模领域的应用范围,为智慧城市的创建设计以及可视化分析提供了新的手段。     

城市3维景观模型重建技术研究

3维景观模型越来越广泛地应用于城市建设和管理之中,如何高效快速地构建城市3维景观模型成为一个关键技术问题。地形与地物分层建模法是城市3维景观模型重建领域中的一个热门方法,它采用地形数据叠加建筑物实体来构建3维景观。该方法已成功应用于惠州市3维建模,实践证明该方法建模速度快、操作简单、具有广阔的应用前景。     

Visualization and level-of-detail of metadata for interactive exploration of Sensor Web

There are several issues with Web-based search interfaces on a Sensor Web data infrastructure. It can be difficult to (1) find the proper keywords for the formulation of queries and (2) explore the information if the user does not have previous knowledge about the particular sensor systems providing the information. We investigate how the visualization of sensor resources on a 3D Web-based Digital Earth globe organized by level-of-detail (LOD) can enhance search and exploration of information by easing the formulation of geospatial queries against the metadata of sensor systems. Our case study provides an approach inspired by geographical mashups in which freely available functionality and data are flexibly combined. We use PostgreSQL, PostGIS, PHP, and X3D-Earth technologies to allow the Web3D standard and its geospatial component to be used for visual exploration and LOD control of a dynamic scene. Our goal is to facilitate the dynamic exploration of the Sensor Web and to allow the user to seamlessly focus in on a particular sensor system from a set of registered sensor networks deployed across the globe. We present a prototype metadata exploration system featuring LOD for a multiscaled Sensor Web as a Digital Earth application.     

Improved Cubemap model for 3D navigation in geo-virtual reality

Due to advances in rendering techniques and hardware capability, stereoscopic 3D (s3D) visualization is becoming increasingly common in daily life. However, this does not change the fact that stereo effects and visual comfort depend greatly on how the related parameters are controlled during the production of the s3D images. In geo-virtual reality systems, which are important browsers for Digital Earth, the maintenance of these parameters is deeply related to the navigation process. Therefore, the navigation method in such systems requires special care. This paper presents a new flying method based on a Cubemap structure. The method defines a Vehicle model and modifies the original Cubemap structure by adding a front view camera during the navigation; it allows the users to fly through a virtual geographic environment with automatic speed control, smooth collision resolution, and dynamic adjustment of the s3D-related parameters. A user test was conducted to compare this new method with the original method based on the Cubemap structure. The results show that the new method performs better than the former one for it provides a convenient interaction experience with improved stereoscopic effect, and diminishes visual discomfort.     

一种便捷的城市三维景观可视化方法

本文提出了基于城市CAD地形图和高分辨率遥感影像的城市景观三维建模方法。利用建筑物的多边形和层数属性,在二维GIS软件中以建筑物多边形为底、层数乘以每层高度为高,生成立柱体。再把立柱体和正射影像投影到DEM上,得到城市三维景观模型。本研究以南京市新街口地区为例,实验结果表明,该方法是一条经济而高效的城市景观三维可视化途径,可广泛应用在城市GIS的相关研究中。     

基于OGRE的高精度三维城市建模技术分析

三维城市模型作为城市三维地理信息系统的重要组成部分,已广泛应用于城市规划、城市建设、建筑设计等领域。随着计算机图形学技术以及虚拟现实技术的不断发展,为快速、自动化生成高精度的三维城市模型提供了条件。本文基于OGRE引擎,阐述了三维城市建模技术的整体架构及关键技术,开发了自动化建模工具及三维可视化平台,实现了城市建筑自动建模及模型实时渲染显示。     

Cartography-Oriented Design of 3D Geospatial Information Visualization – Overview and Techniques

In economy, society and personal life map-based interactive geospatial visualization becomes a natural element of a growing number of applications and systems. The visualization of 3D geospatial information, however, raises the question how to represent the information in an effective way. Considerable research has been done in technology-driven directions in the fields of cartography and computer graphics (e.g., design principles, visualization techniques). Here, non-photorealistic rendering (NPR) represents a promising visualization category – situated between both fields – that offers a large number of degrees for the cartography-oriented visual design of complex 2D and 3D geospatial information for a given application context. Still today, however, specifications and techniques for mapping cartographic design principles to the state-of-the-art rendering pipeline of 3D computer graphics remain to be explored. This paper revisits cartographic design principles for 3D geospatial visualization and introduces an extended 3D semiotic model that complies with the general, interactive visualization pipeline. Based on this model, we propose NPR techniques to interactively synthesize cartographic renditions of basic feature types, such as terrain, water, and buildings. In particular, it includes a novel iconification concept to seamlessly interpolate between photorealistic and cartographic representations of 3D landmarks. Our work concludes with a discussion of open challenges in this field of research, including topics, such as user interaction and evaluation.     

On strategies and automation in upgrading 2D to 3D landscape representations

3D scenes within all media indicate a societal preference shift toward 3D presentations. In spite of wide data availability and successful standardization efforts in 3D modeling, it is not a standard practice to offer large-scale topographic references to the end user in the form of 3D models. This motivates to propose automated strategies for the generation of closed 3D representations of a complete urban landscape, which at the same time account for capabilities of consumer-class devices. The campus of Dresden University of Technology served as a test case. The final appearance of the 3D model will be steered directly by the original geographic information system (GIS) data source. Such a “schematic model” displays source classes and attributes by nonphotorealistic rendering. A tested generic workflow can be presented, which programmatically integrates attributed 2D GIS entities and digital elevation model data, checks for compliancy with consistency rules and generates a slim geometric model. Only detailed GIS references can be considered to allow close-range visualization as needed in virtual walks. In delegating the geometric processing to automated workflows, playing room is gained for as well innovative as expressive texturing and, thus, design of the final 3D model.     

基于3ds MAX的三维数字城市可视化模型构建方法

随着地理空间信息技术发展与应用的不断进步,数字城市建设已从二维向三维发展,数字城市可视化模型的构建是数字城市的重要工作。本文分析三维数字城市的数据需求,结合3ds Max软件实现三维地形模型、三维建筑模型、三维小品模型技术,构建三维数字城市可视化综合模型。     

城区大比例尺影像三维景观重建

本文利用目标提取技术,根据近似点位进行房屋角点的自动定位,自动搜索同名点,然后建立一个尽可能多地包含房顶面的目标窗口,取代传统的以房角为中心的窗口进行房顶角点影像匹配,提高了房顶角点匹配的可靠性,实现了航空影像房屋三维数据的半自动量测。进而在地面与建筑物表面二维半不规则三角网和原始数字影像的基础上,实现了建筑物可见表面纹理的恢复,重建了城市真实三维景观。     

Sentinel-2和AW3D30相结合的湿地提取

为了实现大范围湿地动态监测,本文以辽河入海口附近的盘锦湿地为研究区,基于Sentinel2-L1C和AW3D30 DSM数据,在随机森林分类的基础上,结合地形数字特征和多边形形状特征对研究区进行湿地信息提取。通过人工目视解译对该分类方法进行精度验证,结果表明：该方法的自动化程度较高,能够在较少的人工干预下提取湿地覆盖范围。提取结果精度较高,制图精度和总体精度分别为91.04%和82.65%,Kappa系数为0.599 7,说明本文所采用的计算机分类方法与人工目视解译方法具有较好的一致性。     

Shell model representation as a substitute of LoD3 for 3D modeling in CityGML

The OGC standard for 3D city modeling is widely used in an increasing number of applications.It defines five consecutive Levels of Detail(LoD0 to LoD4 with increasing accuracy and structural complexity),in which LoD3 includes all exterior appearances and geometrical details and subsequently requires much storage space.A new LoD is introduced as shell model with the exterior shell of the LoD3 model and the opening objects like windows,doors as well as smaller faade objects are projected onto walls.In this paper,a user survey is presented.The results of this survey show that the shell model can give users almost the same visual impression as the LoD3 model.Furthermroe,algorithms are developed to extract the shell model from LoD3 model.Experiments show that this shell model can reduce up to 90% storage of the original LoD3 model.Therefore,on one hand it can be used as a substitute for a LoD3 model for the visualization on small displays.On the other hand,it can be treated as a sub-level of detail(SLoD3) in CityGML,since it retains almost the same amount of information but requires much less storage space.     

基于虚拟现实技术的矿山三维建模、显示及漫游系统

介绍了虚拟现实技术建模、漫游的方法,并结合矿山的具体情况,建立了矿山三维模型,包括巷道和工业广场等三维实体建模,并实现了场景实时漫游系统的设计。     

Application of the Fisher's “Horizon Viewshed” to a proposed power transmission line in Nozzano (Italy)

Visibility algorithms have progressed very little since early GIS software, and today the typical approach is still based on the simple binary logic (visible – not visible). Specialized packages, such as Esri's 3DAnalyst, provide tools able only to identify the cells from which an observer can see the evaluated target object. This technical note presents an experimental approach to combining different Esri tools into a model in order to return the visibility analysis based on the Fisher's “horizon viewshed” approach (Fisher, 1996 ). The latter consists in evaluating whether an object in the landscape rises above the skyline or remains below it. The model has been applied to study the visual impact of an High Voltage Power line in the area of Nozzano Castle, Lucca (Italy).     

地勘工程3维空间数据模型及其数据结构设计

3维现象随着研究领域的不同，描述空间实体的方法存在较大差异，不可能设计一种数据模型来适合所有的应用领域，应根据研究领域空间实体分布特征，设计出专用的3维空间数据模型。本文对传统的3维数据模型进行了分析，以地质勘探工程的各种3维空间对象为研究背景，提出了适合地质勘探工程的矢量与栅格集成的面向对象混合数据模型，以复杂体－体－面－线－点对象之间的逻辑关系来建立对象之间的拓扑关系，设计了部分对象的数据结构，并以一玢岩型铁矿床为例，对数据结构进行了描述。     

基于OpenGL的3维弯管线的衔接方法

三维管线的显示问题已取得了不少进展,直线部分已经成熟,但弯管的显示还不够光滑。从三维管线衔接处的光滑出发,借助OpenGL中的几何转换技术及剪切变换技术,巧妙地利用四串同直线上的圆台衔接两直线管。该方法不仅实现起来比较简单,而且视觉效果较好,不论从哪个角度观察,衔接处都很光滑。     

GIS技术在景观视觉分析中的应用

探索应用地理信息系统空间分析技术,通过三维数字高程模型修正模拟规划在建大型建筑群的“地形”表面,并对观察点和目标点之间视觉的通视、可视域分析,采用定性和定量相结合的方法,形象直观分析评价未来重庆科技馆的景观视觉效果,     

Automated reconstruction of 3D scenes from sequences of images

Modelling of 3D objects from image sequences is a challenging problem and has been an important research topic in the areas of photogrammetry and computer vision for many years. In this paper, a system is presented which automatically extracts a textured 3D surface model from a sequence of images of a scene. The system can deal with unknown camera settings. In addition, the parameters of this camera are allowed to change during acquisition (e.g., by zooming or focusing). No prior knowledge about the scene is necessary to build the 3D models. Therefore, this system offers a high degree of flexibility. The system is based on state-of-the-art algorithms recently developed in computer vision. The 3D modelling task is decomposed into a number of successive steps. Gradually, more knowledge of the scene and the camera setup is retrieved. At this point, the obtained accuracy is not yet at the level required for most metrology applications, but the visual quality is very convincing. This system has been applied to a number of applications in archaeology. The Roman site of Sagalassos (southwest Turkey) was used as a test case to illustrate the potential of this new approach.     

Automated reconstruction of 3D models from real environments

This paper describes an integrated approach to the construction of textured 3D scene models of building interiors from laser range data and visual images. This approach has been implemented in a collection of algorithms and sensors within a prototype device for 3D reconstruction, known as the EST (Environmental Sensor for Telepresence). The EST can take the form of a push trolley or of an autonomous mobile platform. The Autonomous EST (AEST) has been designed to provide an integrated solution for automating the creation of complete models. Embedded software performs several functions, including triangulation of the range data, registration of video texture, registration and integration of data acquired from different capture points. Potential applications include facilities management for the construction industry and creating reality models to be used in general areas of virtual reality, for example, virtual studios, virtualised reality for content-related applications (e.g., CD-ROMs), social telepresence, architecture and others. The paper presents the main components of the EST/AEST, and presents some example results obtained from the prototypes. The reconstructed model is encoded in VRML format so that it is possible to access and view the model via the World Wide Web.     

基于VirtuoZo等平台数字水库3维景观图建设思路

3维景观图是地理信息可视化表达和虚拟仿真的有效表现形式,它的应用涉及到各行各业.水库是水利设施建设的重要组成部分,水库3维景观图的制作是数字水库地理信息建设的一部分.Virtuozo是比较具有代表性的数字摄影系统,本文简述数字水库的3维景观可视化建设思路.