杭州市DLG数据更新若干问题的研究与讨论

随着杭州市城市规模的日益扩大和城市建设的迅速发展，地物要素变化频繁，为了保证杭州市DLG数据的现势性，必须对杭州市的DLG数据进行及时的维护和更新，使数据相对处于最新状态。本文对DLC数据更新的方法、技术路线、关键技术等问题进行了分析和讨论，为杭州市DLG数据维护更新机制的建立提供了技术上的参考。     

1∶10000DLG数据的更新方法

总结了1∶10 000 DLG数据更新的一般方法,分析了1∶10 000 DLG数据更新的相关问题;结合项目实例探讨了1∶10 000 DLG更新方法的具体应用,对制订1∶10 000 DLG数据更新方法的技术路线有参考价值。     

1∶10000DLG数据的更新方法

总结了1∶10 000 DLG数据更新的一般方法,分析了1∶10 000 DLG数据更新的相关问题;结合项目实例探讨了1∶10 000 DLG更新方法的具体应用,对制订1∶10 000 DLG数据更新方法的技术路线有参考价值。     

利用DLG数据高效高质量生成DEM的方法研究

通过对DLG数据的分析,研究了一套基于ArcGIS平台快速自动加密高程点的方法。提出了利用DLG数据高效高质量生成DEM的工艺流程,对大面积区域的DEM快速制作与更新有较好的借鉴作用。     

基于GIS的DLG数据快速三维建模方法研究

本文分析了三维模型不同构建方式的优缺点,探讨了三维场景模型地理要素的取舍问题,以及利用DLG数据快速构建城市三维模型的方法,并对城市复杂结构地物的快速建模及与场景的融合也进行了研究。最后以赣州市老城区为例,进行了城市三维场景的快速构建,结果证实,DLG数据快速构建三维模型效率高,渲染速度快,成本低,精度相对高。     

浅谈数字线划图的编绘

本文阐述了在MicroStation V8环境下的1：10000数字线划图（DLG）的编绘，着重讲述了交通、水系等地物要素，通过对误差的分析处理，确保数据质量的准确性、统一性、系统性、完整性，满足全省范围内数据建库和管理。     

基于单片数字微分纠正技术的1：1万地形图修测生产方案的探讨

本文结合浙江省1：10000地形图更新与航测技术改造的研究与试生产,介绍一种较为经济、灵活、快捷的数字成图法：将1：10000老地形图的地貌要素扫描矢量化建立DEM;再以单张像片数字微分纠正的方法获取剃;然后用屏幕数字化法,并辅以数字或解析测图法的立体修测,采集地物数据;最后编辑图形和符号化生成DLG。文章研究分析了单片数字微分纠正成图法的精度、效率和实用性。     

LiDAR数据用于1∶10000 DLG更新生产分析

目前,福建省级基础测绘产品1∶10 000 DLG是通过年度更新的方式来维持数据的现势性,主要方法是基于遥感影像对地物进行更新,由于无法及时获取到地面高程信息,因而无法实施地形更新。本文对比分析了LiDAR成果数据,提出了利用LiDAR点云数据成果和基于同时相的点云成果纠正而成的DOM对1∶10 000 DLG进行年度更新的技术路线,为1∶10 000 DLG更新工作开辟了一条行之有效的新道路。     

利用DOM更新1：10000地形图平面精度的探讨

针对基础地理信息数据更新的现状,综合分析了利用数字正射影像图进行矢量化数据采集以更新DLG的误差源、未变要素在DLG与DOM中的偏差,并进行了更新成果精度分析,实例表明,分析结果合理、可行。     

基于地理国情普查数据更新1∶10000 DLG的方法

首先比较了地理国情普查数据与1︰10 000 DLG的差异,然后分析了利用地理国情普查数据更新1∶10 000 DLG的关键技术;最后提出了一套快速更新流程。该套流程能够实现部分要素的快速更新,节约了成本,为今后1∶10 000 DLG的更新提供了新思路。     

A general framework for error analysis in measurement-based GIS Part 2: The algebra-based probability model for point-in-polygon analysis

This is the second paper of a four-part series of papers on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we discuss the problem of point-in-polygon analysis under randomness, i.e., with random measurement error (ME). It is well known that overlay is one of the most important operations in GIS, and point-in-polygon analysis is a basic class of overlay and query problems. Though it is a classic problem, it has, however, not been addressed appropriately. With ME in the location of the vertices of a polygon, the resulting random polygons may undergo complex changes, so that the point-in-polygon problem may become theoretically and practically ill-defined. That is, there is a possibility that we cannot answer whether a random point is inside a random polygon if the polygon is not simple and cannot form a region. For the point-in-triangle problem, however, such a case need not be considered since any triangle always forms an interior or region. To formulate the general point-in-polygon problem in a suitable way, a conditional probability mechanism is first introduced in order to accurately characterize the nature of the problem and establish the basis for further analysis. For the point-in-triangle problem, four quadratic forms in the joint coordinate vectors of a point and the vertices of the triangle are constructed. The probability model for the point-in-triangle problem is then established by the identification of signs of these quadratic form variables. Our basic idea for solving a general point-in-polygon (concave or convex) problem is to convert it into several point-in-triangle problems under a certain condition. By solving each point-in-triangle problem and summing the solutions, the probability model for a general point-in-polygon analysis is constructed. The simplicity of the algebra-based approach is that from using these quadratic forms, we can circumvent the complex geometrical relations between a random point and a random polygon (convex or concave) that one has to deal with in any geometric method when probability is computed. The theoretical arguments are substantiated by simulation experiments.This project was supported by the earmarked grant CUHK 4362/00H of the Hong Kong Research grants Council.     

虚拟加工环境中的工件动态建模方法研究

提出并实现了基于平面纹理映射的基元立方体构造方法，以之为动态结点建立了动态八叉树结构，实现了支持变精度动态建模的自相似递归算法。该算法确保离正在加工的部位更近的区域有更高的精度，并采用C^ Builder和OpenGL构造了一个集成于虚拟加工环境的可加工工件模型。     

Thesaurus and Domain Ontology of Geoinformatics

Geoinformatics is a comparatively new interdisciplinary science and as a part of space informatics uses methods and terminology of informatics and many natural sciences. An ontology of geoinformatics is discussed in the paper, especially concerning its structure, relationships with other ontologies, resources for development and utilization. The ontology of geoinformatics is a kind of domain ontology and has a layered structure consisting of syntactic and semantic layers. The corpus of this ontology is an existing multilingual dictionary of geographical information systems (GIS) enriched with terminology from other external sources. The building of the ontology is preceded by the development of a taxonomy and thesaurus of geoinformatics. The thesaurus database is converted into an OWL ontology by a Visual Basic application. The reusing of the ontology is proposed by its transformation in application ontologies for geoinformatics education.     

用差商代替导数的非线性最小二乘估计

针对不同类型观测值的非线性最小二乘平差，介绍一种不使用导的解析方法。在这种解算中，由于只使用函数值，避免了二阶和二阶偏导数的计算，使原本复杂的计算得以简化。实例验证了本方法的有效性和可靠性。     

Photogrammetry and geographic information systems for quick assessment, documentation and analysis of earthquakes

After a catastrophe like an earthquake, one on the most important problems is to provide shelter and housing for the homeless. To this end, it is necessary to decide if a building is still habitable, or if it is has to be renovated or even torn down. A prerequisite for such decisions is the detailed knowledge about the status of the building. Earlier earthquakes revealed problems in the processes of documenting and analysing the building damage, as they demanded much effort in terms of time and manpower. The main difficulties appeared to be because of the analogue damage assessments which created a great variety of unstructured information that had to be put in a line to allow further analysis. Apart from that, documentation of damage effects was not detailed and could only be carried out on the spot of a disaster. The aim of this study is to make an improvement, using combination of Geographic Information Systems (GIS) as a management and data analysis tool and photogrammetry as a documentation method. Photogrammetric data acquisition is achieved using a CCD camera and the digital photogrammetric software package PICTRAN by Technet. The information system part is the GIS package ArcView by ESRI. The combination of rapid data acquisition and GIS offers a quick assessment of the situation and the possibility of its objective and holistic analysis. This is the prerequisite for a quick initiation of appropriate measures to help people.     

无拓扑关系下GIS图形编辑联动的解决方法

给出了一种解决层内联动以及层间联动的方法，对于实际处理无拓扑关系下编辑联动的问题有较好的利用价值。     

基于瞬时水深模型的最短时间航线自动生成算法

优化的海图航线设计是舰船安全、经济航行的先导和基础。本文提出了一种基于瞬时水深模型的最短时间航线自动生成算法。基于海图静态水深和海域潮位模型,构建瞬时水深模型,动态提取碍航区,并进行航线可行性分析;利用动态规划思想,进行最短时间路径搜索;采用矩形包络分析、相近节点搜索和冗余点删除等策略,进行航线优化。实验表明：本文所提算法,能动态分析航线可行性,搜索最短时间航线; 与传统的最短时间航线算法相比,所提算法可提取航行时间更短的航线;所提取的最短时间航线,与舰船航行的起始时间和舰船航速相关。     

利用断层自动剖分技术的2008年青海大柴旦Mw6．3级地震InSAR反演研究

2008-11-10青海大柴旦地区发生了Mw6．3级地震,其发震断层位于青藏高原东北缘的大柴旦一宗务隆山断裂带。利用欧空局Envisat／ASAR卫星雷达影像数据,采用二通差分干涉技术获得了地震的同震地表形变场,基于1D协方差函数估计InSAR同震形变场的中误差为0．52cm,方差一协方差衰减距离为5．9km。在此基础上,采用弹性半空间矩形位错模型进行断层几何参数反演,并利用断层自动剖分技术确定了地震的最佳同震滑动分布模型。结果表明,该地震的震源机制解为走向107．19°,倾角56．57°,以逆冲为主兼具少量右旋走滑分量;滑动分布主要发生在10-20km深度范围内,最大滑动量为0．51m,释放的能量为4．3×10^18Nm。     

Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

ABSTRACT

Conceptually, the theory and implementation of “map projection” in geographic information system (GIS) technology is difficult to comprehend for most introductory students and novice users. Compounding this difficulty is the concept of a “map projection file” that defines map projection parameters of geo-spatial data. The problem of the “missing projection file” appears ubiquitous for all users, especially in practice where data is widely shared. Another common problem is inadvertent misapplication of the “Define Projection” tool that can result in a GIS dataset with an incorrectly defined map projection file. GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors. A novel pedagogical device is introduced in this paper: the seven possible states of GIS data with respect to map projection and definition. The seven possible states are: (1) a projected coordinate system (PCS) that is correctly defined, (2) a PCS that is incorrectly defined, (3) a PCS that is undefined, (4) a geographic coordinate system (GCS) that is correctly defined, (5) a GCS that is incorrectly defined, (6) a GCS that is undefined, and (7) a non-GCS. Recently created automated troubleshooting tools to determine a missing map projection file are discussed.     

一种利用磁偏角地磁图自动计算磁偏角的方法

磁偏角地磁图是较理想的确定磁偏角的工具。当需要实时跟踪磁偏角时,可以根据地磁图采集数据建立数据库进行实时查询,但是这种方法工作量较大,过程也比较繁琐。因此,文中提出了一种利用磁偏角地磁图基于二维拉格朗日插值多项式的磁偏角自动计算方法,并详细论述了其原理。实验结果表明,这种方法是可行的,精度较高并可大大提高工作效率。