The method of graphic simplification of area feature boundary with right angles

Some rules of simplification of area feature boundary and the method of acquiring spatial knowledge, such as maintaining area and shape of area feature, are discussed. This paper focuses on the progressive method of graphic simplification of area feature boundary with right angles based on its characteristics.     

以直角方式转折的面状要素图形简化方法

讨论了面状要素图形轮廓简化的一些规则以及面的空间知识获取方法,结合以直角方式转折的面状要素图形轮廓的特点,重点讨论了其图形渐进式简化方法。     

The Spatial Characteristics of a Line and Their Application to Line Simplification

This paper discusses the spatial knowledge related to a line,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line points are presented.These characteristic points are used to improve the algorithms of line generalization.An algorithm for identifying bends is shown.In this paper,improved algorithms based on those by Douglas-Peucker,Visvalingam and Whyatt are shown.In this test,the progressive process of line generalization is emphasized.     

Progressive graphic simplification of contours based on spatial reasoning

This paper discusses the rules representing relief with contour lines and methods for automatically constructing relation of contour lines. Mean-while, the improvement of existent methods for extracting the topographic characteristic points and lines is described. On the basis of this analysis, we propose a series of practicable progressive graphic simplification ideas of contour lines and concrete algorithms for the exception’s handling. In this way, graphic generalizations of contour lines at different scales are integrated into one model that is convenient to implement, and in which contour lines’ intersection in generalization can be controlled.     

Progressive graphic simplification of contours based on spatial reasoning

This paper discusses the rules representing relief with contour lines and methods for automatically constructing relation of contour lines.Meanwhile,the improvement of existent methods for extracting the topographic characteristic points and lines is described.On the basis of this analysis,we propose a series of practicable progressive graphic simplification ideas of contour lines and concrete algorithms for the exception's handling.In this way,graphic generalizations of contour lines at different scales are integrated into one model that is convenient to implement,and in which contour lines' intersection in generalization can be controlled.     

A progressive line simplification algorithm

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A progressive line simplification algorithm

An application of line simplification considering spatial knowledge is described. A method for identifying potential conflict regions, in order to avoid the self-intersection of generalized, lines, is also discussed. Further-more, a new progressive line simplification algorithm is presented. From the view point of spatial cognition, a spatial hierarchical structure is proposed, and its application to construction of spatial knowledge related to a line is explained.     

道路网示意性地图的渐进式综合研究

研究并总结了示意性道路网地图的制图规则,量化了约束条件,提出了一种道路网渐进式图形简化方法和移位方法,并研究了拓扑关系检查方法。在具体实验中,通过对道路网上点的分类,依据约束条件,快速生成有效的道路网示意性地图,同时保证了原始道路图与示意性道路图之间的拓扑关系一致性。     

Schematic road network map progressive generalization based on multiple constraints

Multiple constraints for schematic road network map cartographic design are analyzed and summarized. Based on this, a set of quantitative criteria are set up and a new road network generalization method including progressive selection and displacement is proposed. Furthermore, topological checking methods for road networks are researched. Based on these constraints, the points in a road network are classified, and a satisfactory and effective schematic map is designed in a concrete experiment while maintaining topological consistency of the road network between the original and the schematic map.     

多约束条件下示意性道路网地图渐进式综合

Multiple constraints for schematic road network map cartographic design are analyzed and summarized. Based on this, a set of quantitative criteria are set up and a new road network generalization method including progressive selection and displacement is proposed. Furthermore, topological checking methods for road networks are researched. Based on these constraints, the points in a road network are classified, and a satisfactory and effective schematic map is designed in a con- crete experiment while maintaining topological consistency of the road network between the original and the schematic map     

等高线的空间关系规则和渐进式图形简化方法

详细讨论了等高线表达地形的规则和以此为基础自动建立等高线关系的方法,对地形特征点、线的提取改进了已有较成熟的方法,建立了一套实用的等高线图形简化的渐进式方法,并对其特殊情况的处理提 出了具体的算法。这种方法把不同比例尺跨度的等高线图形综合融为一体,易于实现,等高线图形简化时的等高线相交可在综合过程中控制。     

图形简化过程中空间拓扑关系抽象的规律

以局域基本拓扑关系的抽象为基础,着重阐述了线与线之间局域拓扑关系抽象的规则,并研究了相邻两类局域基本空间拓扑关系合并的规律,提出了在空间抽象过程中渐进式删除局域拓扑关系的方法。     

建筑物多边形化简及优化的自动方案研究

针对居民地地图形状化简的一个方面——建筑物多边形的化简,通过对综合规则的研究和居民地几何特征的剖析,提出一种与比例尺相关的切割实现建筑物多边形化简的方法,在Visual Basic6.0环境下实现了该算法,试验结果表明此方法在保持街区的形态特征上效果较好。     

顾及局部特征的线状要素制图综合

针对传统的线状要素化简方法难以准确描述线要素局部结构特征的问题,该文提出了一种顾及局部结构特征的线状要素制图综合方法。引入m阶邻居坐标点概念,分析坐标点对线要素局部结构特征的贡献程度;建立了局部结构特征度量方法,实现了简单线要素的自动化简;基于该化简过程,从拓扑不变性角度顾及线状要素的整体形态及不同线状要素之间的拓扑关系,实现了复合线划网络的自动综合。基于对简单线划目标和复杂线划网络的实验结果表明:通过调整m的取值,可以完成不同尺度下线要素的自动制图综合,且化简结果较好地保持了原始线划要素的整体形态特征。     

平行路段模式识别与简化初探

道路网模式中的平行路段作为一种局部模式,其识别与简化是地图综合研究的重要内容.本文在分析平行路段产生的原因和常见形态后,绐出一种利于简化的平行路段分类方法,并提出基于平头缓冲区搜寻备选平行路段进而利用平行性测度判断路段是否平行的方法.在此基础上,针对3类平行路段分别提出对应的几何化简与连通关系简化方法.实验结果表明,该识别与简化方法能够对路网模式中的平行路段进行有效地综合,具有一定的实用价值,对进一步研究具有参考价值.     

在图形简化中面状目标间拓扑关系渐进式转换的研究

拓扑关系是空间关系中最为重要的关系,在空间抽象中,拓扑关系会发生变化,如何控制这种变化?如何在更抽象的层次上维护空间拓扑关系的一致性,就是一个非常重要的问题。本文以拓扑关系成分抽象的转换方法为基础,研究了面之间拓扑关系的抽象规则,并详细探讨了这些拓扑关系的渐进式转换方法,绘制了相应的面之间基本拓扑关系渐进式转换图。     

多尺度面实体的匹配方法研究

从多尺度面实体匹配的需要出发,分析地图综合所引起的一对多、多对多匹配关系,以及不同地图综合算子给同名实体所造成的差异,将一对一匹配关系的几何相似性度量模型和非一对一匹配关系的基于重叠度的面实体匹配方法相结合,采用指标阈值自动确定方法,建立一种新的适用多尺度变化的面实体匹配方法。最后以多个比例尺的居民地为实验对象,验证本方法的可行性和有效性。     

Constraints of progressive transmission of spatial data on the web

The progressive transmission of map data on the World Wide Web provides the user with a self-adaptive strategy to access remote data. It not only speeds up the web transfer but also offers an efficient navigation guide for information acquisition. The key technology in this transmission is the efficient multiple representation of spatial data and pre-organization on the server site. This paper aims at progressive transmission investigating some constraints from three aspects: data organization on server site, data control in the transmission process and data restore after reaching the client. Two strategies, namely on-line map generalization and off-line map generalization, are examined respectively for this kind of progressive transmission.     

尺度空间中GIS数据表达的生命期模型

以数据量节省和粒度精细为目标,提出了一个面向对象的多尺度概念模型——尺度空间中GIS数据表达的生命期模型。该模型认为,GIS数据在其表达空间中不同的尺度点和尺度段上分别产生突变和缓变的交替变化,其尺度变换过程可描述为三元组Ti:<[si1,si2],fi,{gij}>,其中[si1,si2]为尺度范围,fi为作用于[si1,si2]的变换函数,{gij}为[si1,si2]尺度范围内的表达基态。则任意尺度点的表达可形式化地表达为:Rx=fi({gij},x),x∈[si1,si2]。并总结了4种尺度变换模式:地图综合尺度变换、LOD尺度变换、Morphing尺度变换和等价尺度变换。     

一种GIS共享图形软件符号的方法

针对GIS平台难以共享图形软件符号的问题,该文以AI符号为研究对象,提出了GIS共享AI图形系统点状符号方法。通过研究两类系统地图符号模型差异,分析AI图形符号与基于路径的点状符号结构,对比两类符号模型的几何结构与样式类型,验证了基于路径点状符号结构的通用性;通过设计AI图形符号数据向基于路径点状符号数据的映射方法,提出了GIS共享AI图形系统点状符号方法,实现了GIS平台对AI图形系统符号的共享。实验结果表明,利用基于路径的点状符号能够共享存在于AI图形软件的图形符号,实现GIS平台共享图形符号资源。