基于FME的MapInfo地形数据库的建立

通过对CASS ,MapInfo数据格式的分析,采用FME数据转换机制,阐述一种基于FME实现CASS数据到MapInfo数据的无损转换技术。以一幅1∶10000的CASS地形图为原数据,进行实例论证,结果表明转换模型实现了CASS与MapInfo数据间的无损转换。     

SV300到CASS地形图数据转换研究

分析了SV300与CASS各自交换文件的数据类型和特点,介绍了数据转换思路和转换流程,制定标准的转换关系配置文件,并以VB.Net语言编写了转换程序,实现SV300到CASS地形图数据无损失转换。     

ArcGIS格式数据向CASS格式数据的转换方法

简要介绍ArcGIS和CASS数据格式,结合实际数据,重点研究由ArcGIS格式的mdb数据向南方CASS图件转换的过程,并对转换结果做了分析。     

浅析JX4全数字摄影测量工作站向量测图数据向CASS数据的转换

本文分析了JX4向量测图与南方CASS数据的存贮格式,利用图形交换文件(DXF)及两种软件提供的数据接口,解决了JX4向量测图数据向南方CASS软件数据的图层、符号等的自动转换问题,并提出了时JX4与CASS软件间数据相互转换的思路。     

MapGIS文件到CASS格式转换关键技术研究

传统将MapGIS数据转换为CASS格式的方法包括将MapGIS数据利用FME转换为AutoCAD格式,或利用MapGIS格式转换系统的功能进行转换等,这两种方法都需要将DWG或DXF文件在CASS中进行逐层匹配CASS码来实现到CASS格式的转换,工作量较大。因此,提出将MapGIS点、线明码文件转换为*.cas文件,将区文件转换为DXF文件的转换方法,相比传统方法,工作量得到很大的缩减。     

CASS到MapInfo数据转换的探讨及实现

本文在综合分析CASS和MapInfo数据交换文件结构特点的基础上,通过VB开发数据转换程序实现了AutoCAD环境下的地形图数据向MapInfo数据的转换,并解决了CASS数据转换成没有属性信息的GIS数据问题,降低了地理信息系统开发过程中数据采集的费用,对实际生产具有一定的参考意义。     

浅谈南方CASS向WALKFIELD数据转换研究

WALKFIELD地籍建库管理软件在各地市广泛应用,而其基础资料基本上以南方CASS数据为主,必须将CASS数据完整转换成WALKFIELD格式数据,笔者主要介绍使用VBA语言完成数据的转换及转换后的后续加工处理。     

清华山维EPS到南方CASS地形数据无损转换研究

分析了EPS与CASS各自的数据结构特点及它们之间的联系,论证了无损转换的可行性;利用EPS软件提供的特定机制,探索了数据结构与属性在不同的异构数据之间传递的方法,最终实现了EPS到CASS的地形数据无损转换。     

CASS数据向GEOWAY的无损转换

分析了CASS和GEOWAY的图形属性、数据交换格式及符号库,并总结出一套CASS数据转入GEOWAY的方法与作业流程。此方法能够保证高质量的数据转换,提高工作效率。     

基于DWGdirect.NET与ArcGIS Engine的CAD地形图转换

根据AutoCAD及ESRI ArcGIS数据的特点,采用结合DWGDirect.NET与ArcGIS Engine编写系统实现CAD地形图到GIS数据的转换,并就早期AutoCAD成图与当前CASS成图提出不同的转换方案.     

Teragons for Testing Implementations of Point Reduction Algorithms

There are several open source and commercial implementations of the Visvalingam algorithm for line generalization. The algorithm provides scope for implementation-specific interpretations, with different outcomes. This is inevitable and sometimes necessary and, it does not imply that an implementation is flawed. The only restriction is that the output must not be so inconsistent with the intent of the algorithm that it becomes inappropriate. The aim of this paper is to place the algorithm within the literature, and demonstrate the value of the teragon-test for evaluating the appropriateness of implementations; Mapshaper v 0.2.28 and earlier versions are used for illustrative purposes. Data pertaining to natural features, such as coastlines, are insufficient for establishing whether deviations in output are significant. The teragon-test revealed an unexpected loss of symmetry from both the Visvalingam and Douglas-Peucker options, making the tested versions unsuitable for some applications, especially outside of cartography. This paper describes the causes, and discusses their implications. Mapshaper 0.3.17 passes the teragon test. Other developers and users should check their implementations using contrived geometric data, such as the teragon data used in this paper, especially when the source code is not available for inspection. The teragon-test is also useful for evaluating other point reduction algorithms.     

SQL Server Spatial应用开发研究

空间数据库是近年来GIS研究领域的热点之一,SQL Server 2005及其后续版本提供了空间数据扩展模块,能管理海量的矢量数据,基于OGC的标准,将矢量数据的存储、分析等功能与其内核结合,并且支持T-SQL,极大地简化了GIS的程序开发.本文简单研究了SQL Server Spatial的基本功能,并且基于它开发了简单的GIS应用系统.     

矢量空间数据版本管理插件

本文在不改变原有矢量空间数据库结构和内容的条件下,设计了矢量空间数据版本库,并基于GIS平台实现了数据版本管理插件。该插件截获GIS平台软件发出的矢量要素编辑消息并进行处理,在不改变已有软件和原始矢量空间数据的前提下,实现了矢量空间数据库版本管理的功能,能够记录对矢量数据的增删改操作和每个图层的版本历史,并且能够进行版本回溯。本插件具有开发工作量小、即插即用和对其他GIS功能透明的优点。     

Adapting Generalization Tools to Physiographic Diversity for the United States National Hydrography Dataset

This paper reports on generalization and data modeling to create reduced scale versions of the National Hydrographic Dataset (NHD) for dissemination through The National Map, the primary data delivery portal for USGS. Our approach distinguishes local differences in physiographic factors, to demonstrate that knowledge about varying terrain (mountainous, hilly or flat) and varying climate (dry or humid) can support decisions about algorithms, parameters, and processing sequences to create generalized, smaller scale data versions which preserve distinct hydrographic patterns in these regions. We work with multiple subbasins of the NHD that provide a range of terrain and climate characteristics. Specifically tailored generalization sequences are used to create simplified versions of the high resolution data, which was compiled for 1:24,000 scale mapping. Results are evaluated cartographically and metrically against a medium resolution benchmark version compiled for 1:100,000, developing coefficients of linear and areal correspondence.     

GQL: Extending Xquery to query GML documents

GML is becoming the de facto standard for electronic data exchange among the applications of Web and distributed geographic information systems. However, the conventional query languages (e.g. SQL and its extended versions) are not suitable for direct querying and updating of GML documents. Even the effective approaches working well with XML could not guarantee good results when applied to GML documents. Although XQuery is a powerful standard query language for XML, it is not proposed for queryings spatial features, which constitute the most important components in GML documents. We proposes GQL, a query language specification to support spatial queries over GML documents by extending XQuery. The data model, algebra, and formal semantics as well as various spatial functions and operations of GQL are presented in detail.     

GQL： Extending XQuery to Query GML Documents

IntroductionThe geography markup language (GML)[1]is anXML encoding in compliance with ISO 19118 forthe transport and storage of geographic informationmodel according to the conceptual modeling frame-work used in the ISO 19100 series and includingboth the…     

用于虚拟现实的分区漫游

为了加快对三维可视化中海量数据浏览的速度，提出了分区漫游的思想，并通过虚拟现实建模语言和Java的结合来实现。     

对空间数据多尺度表达有关问题的思考

多尺度空间数据表达及数据库建立在流媒体网络数据传输、自适应动态可视化、空间认知导航、互操作尺度匹配多个领域都有贡献，但实现该技术面临着数据存储量大、操作响应慢、横向空间一致关系难以维护、尺度变化难以达到真正的连续性等诸多问题。针对这些问题，提出了多级尺度显式存储、初级尺度变化累积、关键尺度函数演变和初级尺度自动综合四种技术策略。     

LAS格式解析与信息提取

结合LAS1.0,从公共文件头区、变长记录区和点集记录区3个方面,对LAS格式的各个版本进行了分析比较,并利用Matlab语言实现对各个版本LAS数据的读取、显示以及激光脚点的三维坐标、回波、强度等信息的提取,为后续LAS格式数据的处理奠定了基础。     

DEVELOPMENTS WITH THE COBLO BLOCK ADJUSTMENT PROGRAM

In spite of the striking progress in block adjustment techniques, it is widely assumed that their application continues to be out of reach for a large part of the photogrammetric community that cannot afford expensive computer systems. The COBLO program performs rigorous block adjustment with models and can be implemented even on inexpensive microcomputers. The first COBLO versions are in operation in several places in South America and Europe and the latest versions, which are considerably more efficient, are now being introduced. This paper describes the main features of different COBLO versions and presents the experience of some users.