三维地下管线建模及系统实现研究

城市地下管线探测成图已由二维进入三维时代,但是目前探测使用的数据标准仍然沿用传统数据标准,难以满足管线三维成图需求。本文分析了原数据标准在三维成图方面的不足,在传统管线数据标准的基础上,针对管线点数据方面的不足进行了设计和扩充,特别是对井室数据的调查和建模进行了详细探讨,最后通过软件开发,实现基于规则的三维地下管线模型自动建立,真实再现三维地下管线场景。     

基于二维地下管线数据快速建立地下管网三维场景

随着地下空间应用的不断深入,二维信息不能准确表达管线之间的空间关系,三维空间信息系统更加适合地下空间数据的表达。本文主要论述了二维地下管线数据向地下管网三维场景的快速建立,以及在建立过程中出现的各种问题,经反复实验解决问题,最终实现了地下管网三维场景的快速构建、三维管线浏览、信息查询等功能。     

基于skyline的城市地下三维管线建立研究

传统二维管线系统难以直观地反映各管线之间的立体空间位置关系。旧管线更新、新管线规划、管线设计施工、土建工程的破土动工等都需要准确掌握地下管线的现状信息,如果盲目开挖就可能引起自来水管爆裂、煤气泄露、停电、通信信号中断等事故。以地下管线为研究对象,以skyline为平台,C#为开发语言建立城市三维管网系统,在地下错综复杂的条件下,展现各管线之间以及管线与周边地物之间的空间位置关系,实现管线的查询和分析功能,有利于决策者做出更好的决定。     

城市地下管线三维快速建模技术研究及应用

随着城市建设的日新月异,地下管线空间分布越来越复杂,地下管线探测成果的二维图形已无法表达管线之间的复杂空间关系,而三维管线的直观明了正好可以弥补二维成果的不足。在此背景下,提出在AutoCAD平台下利用其自身的三维模块,通过二次开发进行三维地下管线快速建模研究。并将开发成果应用于地铁建设工程,取得较好的实用效果。     

城市地下管线三维建模工具开发及应用

首先对常用的管线三维建模方法进行了归纳总结;在分析不同方法的应用范围、综合考虑各种建模方法优缺点的基础上,基于Direct X9.0、.NET Framework3.5运行环境,采用C++语言,集成开发了管线三维建模工具。以广州市现有二维管线数据库为例,该工具通过对编码、字段、材质、特征、附属物等信息的映射设置,能快速、高效地实现管线的三维建模。     

三维仿真技术在地下管线成果中的应用

随着科技创新,三维仿真技术逐步应用到各行各业,得到社会的广泛肯定。三维仿真技术和传统的管线信息系统有机结合,构建了三维化、立体化和精细化的三维管线信息系统,具有直观展示、地上地下整合应用、提升管线规划水平、适应大数据展示的良好效果。     

城市地下管线三维建模关键技术研究

随着城市地下管线信息化管理、表达和应用从二维向三维延伸,本文结合武汉市地下管线三维模型建设工作,在开展了大量研究与实践的基础上,针对地下管线三维建模的高精度自动化、局部更新快速化和地上地下一体化等关键技术提出了一些新的方法与思路,为国内其他城市开展类似工作提供了参考。     

利用地下管线探测点进行区域三维模拟

作为一种直观的成果展示方式,三维模拟已经成为地下管线信息系统的必备工具。但是良好的三维显示效果需要高成本的DEM数据支撑,导致三维模拟的实施存在困难。文中探索以道路为参考依据,利用地下管线的点位探测数据进行概略内插计算,以最小代价实现小区域范围的地下管线、道路甚至地面构筑物的三维模拟显示和数据集成。     

地下管线的三维可视化研究

介绍了管线管理的现状,阐述了管线数据的层次模型和组织方式,建立了地下管线的三维模型,提出了分段渐次推算的模型计算方法,并介绍了基于Visual C⁺⁺和OpengGL技术开发的三维管线系统。     

城市地下管线三维模型的实现

本文阐述了地下管线的数据模型和数据结构,介绍了地下管线三维几何实体模型的构建方法,提出了由管线数据库快速建模的新思路,基于Autodesk Map利用Visual LISP和VBA编程,实现了地下管线三维实体模型的自动生成,取得了较好的效果.     

大范围三维城市立体景观建模系统的研究

建立三维数字城市的立体景观模型 ,是当前地理信息系统技术研究的热点之一。本文根据地理信息系统的自身特点和目前计算机硬件水平的限制 ,结合现有三维可视化技术 ,研究三维城市建模、海量数据的动态调度和快速显示、三维系统的实时交互性和网络化拓展等关键性问题 ,提出实现城市三维可视化及大范围城市景观动态漫游的解决方案     

一种基于嵌入式地形的三维数据建模与调度方法

本文针对嵌入式系统的内存资源及计算能力有限的特点,设计了一种基于线形四叉数结构的静态LOD(Level of Detail)地形,采用分层分块的方法来组织格网的地形数据。在此基础上,对数据动态调度过程中的相关问题进行了分析,实现了基于多分辨率LOD的二维地形数据调度算法,较好地解决了嵌入式系统地形数据的实时可视化问题。     

A new geospatial overlay method for the analysis and visualization of spatial change patterns using object-oriented data modeling concepts

Traditional geographic information system (GIS)-overlay routines usually build on relatively simple data models. Topology is – if at all – calculated on the fly for very specific tasks only. If, for example, a change comparison is conducted between two or more polygon layers, the result leads mostly to a complete and also very complex from–to class intersection. A lot of additional processing steps need to be performed to arrive at aggregated and meaningful results. To overcome this problem a new, automated geospatial overlay method in a topologically enabled (multi-scale) framework is presented. The implementation works with polygon and raster layers and uses a multi-scale vector/raster data model developed in the object-based image analysis software eCognition (Trimble Geospatial Imaging, Munich, Germany). Advantages are the use of the software inherent topological relationships in an object-by-object comparison, addressing some of the basic concepts of object-oriented data modeling such as classification, generalization, and aggregation. Results can easily be aggregated to a change-detection layer; change dependencies and the definition of different change classes are interactively possible through the use of a class hierarchy and its inheritance (parent–child class relationships). Implementation is exemplarily shown for a change comparison of CORINE Land Cover data sets. The result is a flexible and transferable solution which is – if parameterized once – fully automated.     

基于全站仪观测数据的三维平差模型及数据处理

建立基于全站仪多维观测数据的三维网平差模型,用VisualBasic语言编制计算程序,使其自动完成控制网的平差,解决实际应用中全站仪采集数据和成果处理中存在的问题,指导测绘生产,使全站仪更方便地用于地形控制测量、工程控制测量等测绘工程中。     

三维激光扫描技术在建筑立面数字化采集和立面绘制方向应用的可行性研究

利用三维激光扫描技术可对建筑立面进行数据采集,通过对采集的三维点云数据进行拼接、去噪、提取等操作可得到完整的建筑立面点云数据.本文利用三维激光扫描仪快速获取了建筑立面数据,得到高精度的三维点云,将三维点云数据导入CAD中进行绘制,可以将建筑立面各个附属物件的位置、尺寸勾画清楚,保证立面图的准确性和可用性.     

The determination of potential difference by the joint application of measured and synthetical gravity data: a case study in Hungary

In an elementary approach every geometrical height difference between the staff points of a levelling line should have a corresponding average g value for the determination of potential difference in the Earth’s gravity field. In practice this condition requires as many gravity data as the number of staff points if linear variation of g is assumed between them. Because of the expensive fieldwork, the necessary data should be supplied from different sources. This study proposes an alternative solution, which is proved at a test bed located in the Mecsek Mountains, Southwest Hungary, where a detailed gravity survey, as dense as the staff point density (~1 point/34 m), is available along a 4.3-km-long levelling line. In the first part of the paper the effect of point density of gravity data on the accuracy of potential difference is investigated. The average g value is simply derived from two neighbouring g measurements along the levelling line, which are incrementally decimated in the consecutive turns of processing. The results show that the error of the potential difference between the endpoints of the line exceeds 0.1 mm in terms of length unit if the sampling distance is greater than 2 km. Thereafter, a suitable method for the densification of the decimated g measurements is provided. It is based on forward gravity modelling utilising a high-resolution digital terrain model, the normal gravity and the complete Bouguer anomalies. The test shows that the error is only in the order of 10⁻³mm even if the sampling distance of g measurements is 4 km. As a component of the error sources of levelling, the ambiguity of the levelled height difference which is the Euclidean distance between the inclined equipotential surfaces is also investigated. Although its effect accumulated along the test line is almost zero, it reaches 0.15 mm in a 1-km-long intermediate section of the line.     

3D Surface velocity retrieval of mountain glacier using an offset tracking technique applied to ascending and descending SAR constellation data: a case study of the Yiga Glacier

COSMO-SkyMed is a constellation of four X-band high-resolution radar satellites with a minimum revisit period of 12 hours. These satellites can obtain ascending and descending synthetic aperture radar (SAR) images with very similar periods for use in the three-dimensional (3D) inversion of glacier velocities. In this paper, based on ascending and descending COSMO-SkyMed data acquired at nearly the same time, the surface velocity of the Yiga Glacier, located in the Jiali County, Tibet, China, is estimated in four directions using an offset tracking technique during the periods of 16 January to 3 February 2017 and 1 February to 19 February 2017. Through the geometrical relationships between the measurements and the SAR images, the least square method is used to retrieve the 3D components of the glacier surface velocity in the eastward, northward and upward directions. The results show that applying the offset tracking technique to COSMO-SkyMed images can be used to derive the true 3D velocity of a glacier’s surface. During the two periods, the Yiga Glacier had a stable velocity, and the maximum surface velocity, 2.4?m/d, was observed in the middle portion of the glacier, which corresponds to the location of the steepest slope.