A heuristic multi-criteria classification approach incorporating data quality information for choropleth mapping

ABSTRACT

Despite conceptual and technology advancements in cartography over the decades, choropleth map design and classification fail to address a fundamental issue: estimates that are statistically indifferent may be assigned to different classes on maps or vice versa. Recently, the class separability concept was introduced as a map classification criterion to evaluate the likelihood that estimates in two classes are statistical different. Unfortunately, choropleth maps created according to the separability criterion usually have highly unbalanced classes. To produce reasonably separable but more balanced classes, we propose a heuristic classification approach to consider not just the class separability criterion but also other classification criteria such as evenness and intra-class variability. A geovisual-analytic package was developed to support the heuristic mapping process to evaluate the trade-off between relevant criteria and to select the most preferable classification. Class break values can be adjusted to improve the performance of a classification.     

交互式地图综合过程中的符号可视化问题

针对计算机地图综合仍然以人机交互的方式为主的现状,本文根据地图综合操作中的符号可视化的四个特点,提出了建立以单套比例尺符号库适宜多套比例尺地形图数据的可视化方案。通过定义不同比例尺之间符号的衰减系数,讨论了单套比例尺可视化多套比例尺数据的实现方式,并结合1:1万地形图缩编至1:5万地形图进行了模拟实验。     

地图数据缩编更新中的道路自动选取研究

总结道路选取的研究现状,分析在道路的缩编更新过程中,道路要素选取需要考虑的要素指标.介绍一种道路选取方法,综合考虑道路的等级、长度、网眼面积、区域道路密度、是否是悬挂链等几何、语义和拓扑信息,模拟人类在缩编更新时的思维过程,实现道路的自动选取,并进行试验,验证方法的有效性.     

土地利用现状图斑的自动综合

本文针对土地利用现状数据中图斑的自动综合,采用语义与空间相结合的方法,分析了影响图斑综合的因素,根据这些因素的影响对土地利用多边形进行合并、融合及聚合操作。并以长沙市宁乡县的土地利用数据为例进行实验,结果表明,该方法较好地保持了宁乡县综合前后各地类的结构布局,能够较好地反映土地利用现状布局,节省了人机交互合并的工作量。     

Interactive generalization on large-scale topographical map supported by a database platform

This paper makes a study on the interactive digital generalization, where map generalization can be divided into intellective reasoning procedure and operational procedure, which are done by human and computer, respectively. And an interactive map generalization environment for large scale topographic map is then designed and realized. This research focuses on: ① the significance of researching an interactive map generalization environment,② the features of large scale topographic map and interactive map generalization, ③ the construction of map generalization-oriented database platform.     

Interactive generalization on large-scale topographical map supported by a database platform

This paper makes a study on the interactive digital generalization, where map generalization can be divided into intellective reasoning procedure and operational procedure, which are done by human and computer, respectively. And an interactive map generalization environment for large scale topographic map is then designed and realized. This research focuses on: ¹ the significance of researching an interactive map generalization environment, ² the features of large scale topographic map and interactive map generalization, ³ the construction of map generalization-oriented database platform.     

Model generalization of two different drainage patterns by self-organizing maps

In this study, we develop a new method using self-organizing maps (SOMs) for the selection of hydrographic model generalization. The most suitable attributes of the stream objects are used as input variables to the SOM. The attributes were weighted using Pearson’s chi-square independence test. We used the Radical Law to determine how many features should be selected, and an incremental approach was developed to determine which clusters should be selected from the SOM. Two drainage patterns (dendritic and modified basic) were obtained from the National Hydrography Datasets of United States Geological Survey at 1:24,000-scale (high resolution) and used in order to derive stream networks at 1:100,000-scale (medium resolution). The 1:100,000-scale stream networks, derived in accordance with the proposed approach, are similar to those in the original maps in both quantity and visual aspects. Stream density and pattern were maintained in each subunit, and continuous and semantically correct networks were obtained.     

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.     

地图内容质量特征和数量特征概括的数学模型

在分类的定义下,根据概念外延的包含关系,给出了质量特征概括的数学模型。在定义数量的基础上,推导出级距概念,并根据两个不同级距的偏序集中大级距子集包含多个小级距子集的关系,给出了数量特征概括的数学模型。本文给出的地物质量特征和数量特征概括的数学模型,可对地图编制过程中诸如随地图比例尺缩小而缩减分类,扩大级差等经验事实,作出定量的描述和理论阐释。     

大比例尺数字地形图缩编方法的探讨

本文针对大比例尺地形图全自动化制图综合所存在的难点,分析了影响制图综合实现的主要因素.通过生产实践提出基于规则库的一致性制图综合和交互式制图综合相结合的方法,提高计算机的人工智能水平,从而形成完善而高效的制图综合工作流程.实践证明,基于规则库的一致性制图综合和交互式制图综合方法作业效率比较高,可以顺利地完成地图缩编工作...     

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.     

On the spatial distribution of buildings for map generalization

Information on spatial distribution of buildings must be explored as part of the process of map generalization. A new approach is proposed in this article, which combines building classification and clustering to enable the detection of class differences within a pattern, as well as patterns within a class. To do this, an analysis of existing parameters describing building characteristics is performed via principal component analysis (PCA), and four major parameters (i.e. convex hull area, IPQ compactness, number of edges, and smallest minimum bounding rectangle orientation) are selected for further classification based on similarities between building characteristics. A building clustering method based on minimum spanning tree (MST) considering rivers and roads is then applied. Theory and experiments show that use of a relative neighbor graph (RNG) is more effective in detecting linear building patterns than either a nearest neighbor graph (NNG), an MST, or a Gabriel graph (GssG). Building classification and clustering are therefore conducted separately using experimental data extracted from OpenStreetMap (OSM), and linear patterns are then recognized within resultant clusters. Experimental results show that the approach proposed in this article is both reasonable and efficient for mining information on the spatial distribution of buildings for map generalization.     

网络环境下地图自动综合框架模型研究

计算机技术的普及、网络通信技术的迅速发展,不但使地图学发生了深刻的变革,也给制图综合带来了新的机遇和挑战。在分析了网络环境下地图自动综合的现有研究方法及其优缺点的基础上,针对互联网这一特定的信息交换平台,提出了网络环境下地图自动综合的总体设计框架,建立了以实例数据库为核心的用户需求提取模型。同时也讨论了面向无级比例尺的矢量数据的信息压缩。     

FRAMEWORKS FOR GENERALIZATION CONSTRAINTS AND OPERATIONS BASED ON OBJECT-ORIENTED DATA STRUCTURE IN DATABASE GENERALIZATION

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Point grid map: a new type of thematic map for statistical data associated with geographic points

ABSTRACT

Social, economic, and environmental statistical data associated with geographic points are currently globally available in large amounts. When conventional thematic maps, such as proportional symbol maps or point diagram maps, are used to represent these data, the maps appear cluttered if the point data volumes are relatively large or cover a relatively dense region. To overcome these limitations, we propose a new type of thematic map for statistical data associated with geographic points: the point grid map. In a point grid map, an input point data set is transformed into a grid in which each point is represented by a square grid cell of equal size while preserving the relative position of each point, which leads to a clear and uncluttered appearance, and the grid cells can be shaded or patterned with symbols or diagrams according to the attributes of the points. We present an algorithm to construct a point grid map and test it with several simulated and real data sets. Furthermore, we present some variants of the point grid map.     

矢量曲线的视觉清晰度及在网络地图综合中的应用

互联网用户参与的地图制图容易出现视觉冲突、压盖、拥挤等地图表达问题,需要引入地图自动综合协助解决。网络地图中由于原图比例尺和综合后比例尺均难以准确量化,常规地图自动综合基于“原图比例尺-综合后比例尺”判断是否需要综合的方法已不再适用。矢量数据在可视化后会产生视觉粘连,视觉粘连越明显,地图表达效果越差,综合的需求也越强烈。基于此规律,本文提出对视觉粘连进行定量描述并据此判断是否需要综合。首先,从人类视觉感受出发,结合栅格化思想设计了矢量曲线视觉粘连的量化指标——视觉清晰度。然后,基于“金字塔式”的尺度空间计算曲线在多个比例尺表达的清晰度,并拟合了清晰度的变化函数。最后,将该函数应用于众源地理数据的网络地图综合决策。试验结果表明,本文方法可准确判断每条矢量曲线是否需要综合,能有效解决地理数据尺度异质性带来的可视化难题。同时,清晰度变化函数将曲线的尺度描述由静态数值扩展到连续函数,有望更好地支持多尺度空间数据处理及网络地图综合等问题。     

土地利用图中线状要素综合的质量评价

作为土地利用图综合的一个重要组成部分,线状要素综合质量的好坏对于有效提高自动制图综合的正确率具有重要意义。本文基于模糊综合评判理论对土地利用图中线状要素的综合进行了质量评价。首先,基于制图综合约束,确定评价指标体系,组成评价因素集;其次,在确定评判集和权重集的基础上,建立线状要素综合质量评价模型;最后,利用试验验证了评价方法的有效性。该研究为客观评价土地利用图中线状要素的综合质量提供了新的思路。     

交互式基础地理数据制图综合方法的研究

本文对基于地理数据库的制图综合的自动化实现方法作了研究和实践,以期解决基于基础地理数据库的制图综合的生产问题。本文对制图综合的自动化方法实现目前存在的难点作了必要的论述,结合测绘生产单位的实际,提出了基于规则的交互式制图综合方法,并形成了一套较为完整的基于基础地理数据库的制图综合生产工艺流程。     

土地利用面状数据综合组件模块的构建

本文尝试结合土地利用数据的特点,利用组件技术实现扩展ArcG IS的土地利用数据综合功能模块,建立土地利用面状数据综合数学模型,并提出了由对面进行处理转化为对拓扑公共边进行处理的数据模型,较为满意地解决了一般的面状化简算法会产生间隙和重叠的难题。     

基于信息熵的面状要素在地图综合中的量测方法分析

目前,信息熵理论被广泛用于地图信息含量的量测,但对于地图综合的信息量分析评价的研究还不多。介绍信息熵理论及地图综合中的几何信息熵概念,并将其运用到面状要素的地图综合信息量量测中。在实例分析中,通过将不同地类分类,较好地反映了不同地类在地图综合中信息量的变化,说明用几何信息熵表征面状要素在地图综合中的信息量是可行的。并在之后进一步提出几何信息熵的加权理论,为进一步研究提供方向。