矢量数据模型

1、1Vector Data Model矢量数据模型矢量数据模型Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.2CHAPTER 4: VECTOR DATA MODEL第第 4 4 章章 矢量数据模型矢量数据模型4.1 Georelational data model 地理关系数据模型地理关系数据模型4.2 Representation of Simple Features 简单要素的表示简单要素的表示4.3 Topology 拓扑拓扑4.4 Nontopologi

2、cal Vector Data 非拓扑矢量数据非拓扑矢量数据4.5 Data Models for Composite Features 复合要素数据模型复合要素数据模型Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.3How does a computer “see” map features?计算机如何计算机如何“看看”地图要素？地图要素？(请看课本第请看课本第72页页)Vector data model 矢量数据模型矢量数据模型 Uses x, y coor

3、dinates of points to represent points, lines, areas 用点的用点的 x, y 坐标来代表点、线、面坐标来代表点、线、面 Organizes geometric objects thus represented into digital data files 将如此表示的几何对象组织成数字化数据文件将如此表示的几何对象组织成数字化数据文件Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.4Evolution of Ve

4、ctor Data Model矢量数据模型的演变矢量数据模型的演变ESRI, Inc. Arc/Info: coverages ArcView: shapefiles ArcGIS: geodatabase 基于对象数据模型基于对象数据模型地理相关数据模型地理相关数据模型Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.54.1 Georelational Data Model 地理相关数据模型地理相关数据模型Geographically referenced da

5、ta: 地理参照数据地理参照数据： Spatial and attribute components 空间和属性组分空间和属性组分Georelational data model 地理相关数据模型地理相关数据模型 Stores spatial and attribute data separately with a link in a split system 空间数据和属性数据分别贮存在链接的分离系统空间数据和属性数据分别贮存在链接的分离系统 Called relational database 所谓关系数据库所谓关系数据库Object-based data model stores spa

6、tial and attribute data together, not a split system 基于对象数据模型将空间数据和属性数据贮存在一起基于对象数据模型将空间数据和属性数据贮存在一起Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.6Figure 3.2Based on the georelational data model, an ArcInfo coverage has two components: graphic files for spa

7、tial data and INFO files for attribute data. The label connects the two components.Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.74.2 Representation of Simple Features 简单要素的表示简单要素的表示Vector data model 矢量数据模型矢量数据模型 Uses geometric objects of point, line, area

8、 to represent spatial features 用点、线、面等几何对象表示空间要素用点、线、面等几何对象表示空间要素Figure 3.3Point, line, and area features.Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.8PointZero dimensionsNo length, width or height, only location impliedDefined by x, y coordinatesAlso ca

9、lled a node or vertexExamples: wells, buildings, survey markers 例如：井、建筑物、测量标记例如：井、建筑物、测量标记Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.9LineOne-dimensionalProperties of length and locationDefined by x, y coordinates of its end points and (if curved) of po

10、ints along its pathLines also known as edges, linksExamples: roads, streams, contour lines 例如：道路、河流、等高线例如：道路、河流、等高线Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.10AreaTwo-dimensional (length and width)Properties of area and perimeterDefined by its boundary

11、 line (which is defined by its points)Also called polygonExamples: political entities, water bodies 例如：行政区、水体例如：行政区、水体Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.11Map Scale 地图比例尺地图比例尺Representation of map features dependent on map scale 地图要素的表示取决于地图比例尺地

12、图要素的表示取决于地图比例尺A city at 1:1,000,000 may appear as a point, but at 1: 24,000 it will be an area 一个城市在一个城市在 1:1,000,000 地图以一点出现，在地图以一点出现，在1: 24,000 则为一个区域则为一个区域Government mapping standards 政府制图标准政府制图标准Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.124.3 Topol

13、ogy 拓扑（结合课本第拓扑（结合课本第72-75讲解）讲解）Explicit expression of spatial relationship between features 要素空间关系的清晰表达要素空间关系的清晰表达Graph theory Directed lines arcs 弧段弧段 Nodes - points where arcs meet or intersect 结点结点 - 弧段会合点或交叉点弧段会合点或交叉点Copyright The McGraw Hill Companies, Inc. Permission required for reproduction

14、or display.13Figure 3.4The adjacency matrix and incidence matrix for a digraph. Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.144.2 ESRIs Coverage ModelModel introduced in the 1980s to separate CAD from GISSupports three basic topological relationships Con

15、nectivity 联通性联通性 Area definition 面积定义面积定义 Contiguity 邻接性邻接性Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.154. 3 Coverage Data StructureIncorporates topological relationships into data structure 使拓扑关系与数据结构一体化使拓扑关系与数据结构一体化Contains feature IDs and x-y coordin

16、ate pairs 含要素标识号和含要素标识号和 x-y 坐标对坐标对Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.16Figure 3.7The data structure of a point coverage.Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.17Figure 3.8The data structure of

17、a line coverage.Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.18Figure 3.9The data structure of a polygon coverage. Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.194.4 Importance of Topology 拓扑重要性拓扑重要性Assurance o

18、f data quality 保障数据质量保障数据质量 Error detection 查错查错Enhance GIS analysis 增强增强GIS 分析分析 Networks (streets, utilities) 网络（街道、设施）网络（街道、设施）Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.20Figure 3.10A polygon coverage, shown in a, has topological errors. Each small

19、square symbol represents an error caused by lines that do not meet correctly. The shapefile, shown in b, is converted from the polygon coverage. Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display.21Figure 3.12The data structure of a TIN. Copyright The McGraw Hi

20、ll Companies, Inc. Permission required for reproduction or display.223.5.2 Regions 分区分区A geographic area with similar characteristics 具有类似特征的地理范围具有类似特征的地理范围Hierarchical regions 有等级的分区有等级的分区 Progressively smaller subregions of increasingly uniform characteristics随亚区趋于变小，其均一特征递增随亚区趋于变小，其均一特征递增Copyrigh

21、t The McGraw Hill Companies, Inc. Permission required for reproduction or display.23Data Model for Regions 分区数据模型分区数据模型Able to handle overlapping and spatially disjoint polygonsFigure 3.14The regions data model allows overlapped regions (a) and spatially disjoint components (b).可叠置；可叠置；空间不连续空间不连续Copyright The McGraw Hill Com