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。     

空间线要素综合算法的不确定性讨论

简述了几种曲线综合算法思路,从综合算法阈值的计算,综合算例数据等方面对综合算法及其不确定性进行了量化的评价,并进一步总结了综合算法不确定的各种表现.     

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。     

基于遗传算法的线要素自动化简模型

线划要素是地图上大量存在的最基本的地图要素，作为自动综合的一个重要方面，它的化简受到了极大的关注。在分析总结现有线划要素化简方法的基础上，依据遗传算法的基本原理和方法，建立了地图上线划要素的化简模型，并讨论了基于遗传算法的线要素自动化简方法中的关键问题，给出了具体的操作步骤和实验结果。结果表明，利用遗传算法对线要素进行化简能够比较好地保持线要素的整体形状，同时还对点具有很高的压缩率。     

Subdivision of polygon parcel in land-use data generalization

In land-use data generalization, the removal of insignificant parcel with small size is the most frequently used operator. Traditionally for the generalization method, the small parcel is assigned completely to one of its neighbors. This study tries to improve the generalization by separating the insignificant parcel into parts around the weighted skeleton and assigning these parts to different neighbors. The distribution of the weighted skeleton depends on the compatibility between the removed object and its neighbor, which considers not only topological relationship but also distance relationship and semantic similarity. This process is based on the Delaunay triangulation model. This paper gives the detailed geometric algorithms for this operation.     

Subdivision of polygon parcel in land-use data generalization

In land-use data general-ization, the removal of insignificant parcel with small size is the most fre-quently used operator. Traditionally for the generalization method, the small parcel is assigned completely to one of its neighbors. This study tries to improve the generalization by sepa-rating the insignificant parcel into parts around the weighted skeleton and assigning these parts to different neighbors. The distribution of the weighted skeleton depends on the com-patibility between the removed object and its neighbor, which considers not only topological relationship but also distance relationship and semantic sim-ilarity. This process is based on the Delaunay triangulation model. This paper gives the detailed geometric al-gorithms for this operation.     

基于OpenMP的Li-Openshaw算法并行计算方法

随着网络地图、移动地图的发展,对地图自动综合效率的要求不断提高;并行计算技术已经在遥感图像处理、计算几何等方面显示出优势。本文尝试将地图综合算法与并行计算方法相结合,探讨地图综合算法效率提高的方法;并通过对Li-Openshaw线要素简化算法的分析,探讨了在多核处理器环境下该算法的并行计算策略,基于OpenMP实现了Li-Openshaw算法的并行计算,最后通过实验验证了基于OpenMP的Li-Openshaw线要素化简算法在效率上的提高。     

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.     

采用3D D-P算法的等高线三维综合实验研究

将等高线看作是由高程点以特定形式组织得到的空间三维线段,采用3维Douglas-Peucker算法从三维空间提取等高线上的主要特征点。根据等高线数据特点,对该算法进行等高线综合的几种方案进行实验讨论。实验结果和运算速度表明,采用3维Douglas-Peucker算法综合等高线具有广阔的研究前景。     

支持地图综合的面状目标约束Delaunay三角网剖分

针对多边形面状目标的综合问题,建立了二维空间中约束Ｄｅｌａｕｎａｙ三角网剖分结构,融入多边形的环、岛屿、边界、顶点的描述,通过形式化条件检索,在该结构上提取二维空间中各种感兴趣的由剖分三角形组成的区域,用于支持地图综合中邻近多边形的搜索、多边形弯曲部位的识别、冲突关系探测、多边形合并等操作。并对基于骨架线的图结构建立、分枝宽度计算等几何问题进行了详细讨论,指出了其在诸如双线河中轴化、街道中轴线网络模型建立、多边形合并中的邻近关系分析、面状目标注记自动定位领域的支持作用。     

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.     

地图自动综合知识的分类及其形式化描述

在分析了已有地图综合知识的分类和表示方法的基础上 ,提出了一种新的地图综合知识的分类方法和形式化方法 ,这种分类方法易于系统开发 ,其形式化方法便于同地图综合模型和空间数据管理相结合。     

曲线弯曲深度层次结构的二叉树表达

地图综合要顾及目标的几何特征、语义特征和拓扑特征，其中地理意义是控制综合算子系统、参量调整的决定性因素。就线状要素而言，单从角度、距离、矢高等几何特征出发设计的曲线化简算法只能算作对曲线坐标串的几何压缩，不是真正意义上的地图综合。由于曲线的弯曲特征在表达线状地物地理特征上具有重要意义，对弯曲特征的识别、结构描述及操作分析成为目前线要素制图综合的研究热点。本文基于约束Delaunay三角网模型提出一种方法描述曲线弯曲特征在深度上的层次结构，对曲线上的矢量点构建三角网，在三角网覆盖区域里，由外向内进行三角形的“剥皮”操作，根据“剥皮”操作，根据“剥皮”进行过程中遇到的特征三角形构建二叉树，实现大弯曲套小弯曲层次结构的表达。该方法基于Gestalt对称性、连续性原则、对二叉树结点进行考察，可提取认知意义上的真正弯曲。本文同时给出了弯曲特征二叉树在多边形（闭合曲线）综合化简中的算法设计及实验结果。     

Quantitative relations between spatial similarity degree and map scale change of individual linear objects in multi-scale map spaces

Quantitative relations between spatial similarity degree and map scale change in multi-scale map spaces play important roles in map generalization and construction of spatial data infrastructure. Nevertheless, no achievements have been made regarding this issue. To fill the gap, this paper firstly proposes a model for calculating spatial similarity degrees between an individual linear object at one scale and its generalized counterpart at the other scale. Then psychological experiments are designed to validate the new model, taking four different individual linear objects at five different scales as test samples. The experiments have shown that spatial similarity degrees calculated by the new model can be accepted by a majority of the subjects. After this, it constructs a formula that can calculate spatial similarity degree using map scale change (and vice versa) for individual linear objects in multi-scale map spaces by the curve fitting method using the point data from the psychological experiments. Both the formula and the model can calculate quantitative relations between spatial similarity degree and map scale change of individual linear objects in multi-scale map spaces, which facilitates automation of map generalization algorithms for linear features.     

数字海图线性特征的识别、量测与综合

图形特征的变化是无究的,只是依据与位移、夸大、化简等相似的综合方法,而不包含图形特征的识别与量测,数字海图的自动综合是无法实现的。只有识别、量测和综合方法的组合,才是数字海图综合概念的全部体现。因而,本文模拟人的综合方法的同时, 点模拟了人的图形特征的识别方式,同时,经过Ｄｏｕｇｌａｓ二叉树方法的引入,给出了图形特征的识别与量测函数,实现了数字海图红性特征的自动综合。     

土地利用图斑综合研究

基于南海市土地利用现状调查与变更系统,进行了一些有关土地利用图斑综合方面的研究,主要包括小地块删除,狭长地物例如河流、道路变线。结合有关制图综合的理论和算法,针对具体问题,采用人机协同的缩编方式,合理进行人机分工,将交互式综合和自动综合结合起来。这种方式可以顺利的完成地图缩编工作,从而减轻了作业强度,提高了作业精度。     

移动环境自适应地图综合方法初探

随着移动定位服务等技术的飞速发展,地图综合在专题内容、综合效率等方面已不能满足移动地图服务的需要。这就要求针对当前的移动环境,发展自适应地图综合方法。在系统分析当今移动环境自适应地图综合研究现状的基础上,指出移动环境自适应地图综合的理论基础与技术背景,提出移动环境自适应地图综合的基本思想、特征与关键问题,并以南京市湖南路商业区居民地为试验数据,实现了自适应于用户位置的居民地简化算法。     

基于多比例尺地图数据的线状要素综合方法

提出了一种基于多比例尺地图数据的线状要素综合方法,若一个顶点在两个不同比例尺的对应线状要素上都存在,则它在中间比例尺线状要素上也应该得到保留。首先,利用不同比例尺线状要素进行同名点识别,并在较大比例尺线状要素上进行标记;然后,以标记的同名点为断点,将大比例尺线状要素分割成多个线段;最后,对分割后的各线段结合Douglas-Peucker算法进行综合。通过实验分析论证了该方法的可行性及有效性。     

编组站线路的综合选取原则及自动化处理方法

编组站是铁路枢纽的核心,是车辆集散和解编基地,线路复杂度极高。囿于编组站数量较少,国内外文献中鲜见探讨其综合选取策略与方法的文章,而大量有关道路的研究成果又不适用。本文在分析编组站结构特性和拓扑特性的基础上,首先精练出6种地图特征：断头弧、同节点弧、相似弧、网眼弧、平行弧和主干弧;提出了适合编组站综合选取的3项基本原则;然后设计了自动化处理方法;最后用实际数据测试验证了这些基本原则的合理性和方法的有效性。     

Terrain generalization with line integral convolution

ABSTRACT

Line integral convolution is a technique originally developed for visualizing vector fields, such as wind or water directions, that places densely packed lines following the direction of movement. Geisthövel and Hurni adapted line integral convolution to terrain generalization in 2018. Their method successfully removes details and retains sharp mountain ridges; it is particularly suited for creating generalized shaded relief. This paper extends line integral convolution generalization with a series of enhancements to reduce spurious artifacts, accentuate mountain ridges, control the level of detail in mountain slopes, and preserve sharp transitions to flat areas. The enhanced line integral convolution generalization effectively removes excessive terrain details without changing the position of terrain features. Sharp mountain ridgelines are accentuated, and transitions to flat waterbodies and valley bottoms are preserved. Shaded relief imagery derived from generalized elevation models is visually pleasing and resembles manually produced shaded relief.