地理相关数据模型 基于对象数据模型
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4.1 Georelational Data Model 地理相关数据模型
• Geographically referenced data: 地理参照数据：
• Vector data model 矢量数据模型 – Uses x, y coordinates of points to represent points, lines, areas 用点的 x, y 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
复合要素数据模型
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How does a computer “see” map features? 计算机如何“看”地图要素？(请看课本第72页)
Vector Data Model 矢量数据模型
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CHAPTER 4: VECTOR DATA MODEL 第 4 章 矢量数据模型
– Uses geometric objects of point, line, area to represent spatial features
– 用点、线、面等几何对象表示空间要素
Figure 3.3 Point, line, and area features.
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– Spatial and attribute components 空间和属性组分
• Georelational data model 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
Figure 3.2 Based on the georelational data model, an ArcInfo coverage has two components: graphic files for spatial data and INFO files for attribute data. The label connects the two components.
例如：井、建筑物、测量标记
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Line
• One-dimensional • Properties of length and location • Defined by x, y coordinates of its end
• 4.1 Georelational data model 地理关系数据模型
• 4.2 Representation of Simple Features 简单要素的表示
4.3 Topology 拓扑 • 4.4 Nontopological Vector Data 非拓扑矢量数据 • 4.5 Data Models for Composite Features
– Called relational database 所谓关系数据库
• Object-based data model stores spatial 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
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Point
• Zero dimensions • No length, width or height, only location
implied • Defined by x, y coordinates • Also called a node or vertex • Examples: wells, buildings, survey markers
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Evolution of Vector Data Model 矢量数据模型的演变
• ESRI, Inc.
– Arc/Info: coverages – ArcView: shapefiles – ArcGIS: geodMcGraw Hill Companies, Inc. Permission required for reproduction or display.
4.2 Representation of Simple Features
简单要素的表示
• Vector data model 矢量数据模型