前言
All geographic information systems (GIS) are built using formal models that describe how things are located in space. A formal model is an abstract and well-defined system of concepts. It defines the vocabulary that we can use to describe and reason about things. A geographic data model defines the vocabulary for describing and reasoning about the things that are located on the earth. Geographic data models serve as the foundation on which all geographic information systems are built.
GIS系统是使用模型建立的。数据模型是GIS系统的基础。
We are all familiar with one model for geographic information—the map. A map is a scale model of reality that we build, using a set of conventions and rules (for example, map projections, line symbols, text). Once we construct a map, we can use it to answer questions about the reality it represents. For example, how far is it from Los Angeles to San Diego? Or, what cities lie along the Mississippi River? The map model also serves as a tool for communicating facts about geography visually: Is the terrain rough? Which way is north? In fact, when we see a map, we often understand things that might not even occur to us as specific questions.
我们都熟悉一个地理数据模型——地图。地图就是采用一些约定而建立起来的。
Maps work because we know the “rules” of conventional map reading: blue lines are rivers, North is toward the top of the page, and so on. In a similar way, geographic data models define their own set of concepts and relationships, which must be understood before you can expect to create or interpret your own data model. These concepts relate to how you can represent geographic information in a computer system, rather than, as in the map example, on paper.
地图之所以能够工作，是因为我们知道这些约定：蓝色的线条表示河流，北方指的是上方，等等。数据模型定义了它们自己的一套概念和关系，这些东西必须理解透彻好之后，你才能期望建立起一套你自己的数据模型。这些概念涉及如何在计算机系统中表示地理信息，而不是像地图示例中那样在纸上表示。
In Modeling Our World, Michael Zeiler has written an excellent primer for understanding the various models used to represent geographic information in ArcInfo™ 8 software. He presents, using straightforward text and excellent illustrations, the concepts and vocabulary employed in the design, implementation, and use of the ArcInfo 8 geographic database. In addition to explaining the ArcInfo data model (objects, features, surfaces, networks, images, and so forth) in detail, Michael also provides good insight into how to use this framework to design useful information models that fit your particular needs.
在《为我们的世界建模》中，Michael Zeiler编写了一本优秀的入门书。他用简单明了的文字和出色的插图介绍了Arcinfo8地理数据库的设计、实现和使用中使用的概念和词汇。除了详细解释ArcInfo数据模型（对象、特征、曲面、网络、图像等等），Michael还提供了如何使用这个框架来设计适合您特定需求的有用信息模型的深刻见解。
This book serves a variety of different purposes. For the geographer or scientist, it defines a conceptual context for representing geographic information. For the GIS specialist, it serves as a guidebook in designing and using geographic databases. Finally, it introduces database concepts to a geographic audience, and geographic concepts to the database specialist.
这本书有各种不同的用途。对于地理学家或科学家来说，它定义了表示地理信息的概念上下文。对于地理信息系统专家来说，它是设计和使用地理数据库的指南。最后，它向地理受众介绍数据库概念，并向数据库专家介绍地理概念。
ArcInfo 8 defines a unified framework for representing geographic information in a database. Several different generic data models are supported within this framework:
arcinfo8定义了在数据库中表示地理信息的统一框架。此框架支持几种不同的通用数据模型：
• cell-based or raster representation 基于单元或光栅的表示
• object-based or feature-based representation 基于对象或基于特征的表示
• network or graph-element representation网络或图元素的表示法
• finite-element or TIN representation有限元或三角网表示法
Each of these generic models has its own vocabulary used to define and reason about geographic information. When we decide to represent roads, rivers, terrain, or any sort of phenomena in a GIS, we need to decide exactly how we define information in terms of these generic models. As chapter 1 points out, there are many ways that information can be modeled in a GIS. The representation you choose for the data model will affect how you sample and measure geographic information, how you display it visually, and which relationships between elements can be represented, as well as query and analysis operations that can be applied to the information.
每个通用模型都有自己的词汇表，用于定义和推理地理信息。当我们决定在GIS中表示道路、河流、地形或任何类型的现象时，我们需要准确地决定如何根据这些通用模型定义信息。正如第一章所指出的，有许多方法可以在GIS中对信息进行建模。为数据模型选择的表示方式将影响如何对地理信息进行采样和测量、如何直观地显示地理信息、可以表示哪些元素之间的关系，以及可以应用于信息的查询和分析操作。
Some have asserted that we should hide representational models for geographic information (features, geometry, rasters, surfaces, and so on)from the users of geographic information systems. Somehow, these representational concepts are considered “implementation details.” In this view, a single real-world thing, such as the Mississippi River, should be modeled as a single thing within the GIS. Perhaps, behind the scenes, the system could automatically use multiple representations for these real-world things. If you ask “What is upstream?” it could use a network representation of the river. If you ask “What is the surface area of the water?” it could use a polygon feature representation. If you ask “What area does it drain?” it could use a surface or terrain representation, and so on. While it may be desirable to hide these concepts from some consumers of geographic information, I believe that a strong understanding of geographic data models and representations is crucial to the correct design and use of geographic information systems. Geographic data models act as the lens or filter through which we perceive and interpret the infinite complexity of the real world. It is only in the context of representations of the Mississippi River, for example, that we can define specific properties, behavior, or even its identity as a “thing of interest.” Understanding geographic data model concepts is central to knowing how to define and collect geographic information. It is also crucial for correctly interpreting the results derived from the analysis of geographic information. This is similar to the role that statistics and sampling theory play in the natural sciences.
有人断言，我们应该对地理信息系统的用户隐藏地理信息的表示模型（特征、几何、光栅、曲面等）。不知何故，这些代表性概念被认为是“实现细节”。在这种观点下，一个单一的现实世界的东西，如密西西比河，应该建模为一个单一的东西在地理信息系统。也许，在幕后，系统可以自动为这些真实世界的事物使用多种表示。如果你问“上游是什么？”它可以使用河流的网络表示。如果你问“水的表面积是多少？”它可以使用多边形特征表示法。如果你问“它在哪个区域排水？”它可以使用曲面或地形表示，等等。虽然对地理信息的某些消费者隐藏这些概念可能是可取的，但我认为，对地理数据模型和表示的深刻理解对地理信息系统的正确设计和使用至关重要。地理数据模型是我们感知和解释现实世界无限复杂性的透镜或过滤器。例如，只有在密西西比河表示的上下文中，我们才能定义特定的属性、行为，甚至它作为“感兴趣的事物”的身份。理解地理数据模型概念对于了解如何定义和收集地理信息至关重要。这对于正确解释地理信息分析的结果也至关重要。这类似于统计学和抽样理论在自然科学中所起的作用。
For the GIS specialist, this book serves as an introduction to a new object-relational model for representing features, spatial relationships between features, and other thematic relationships. This new model is significantly richer in its ability to represent features with associated behavior, relationships, and properties than the current coverage or shapefile model. If you are already familiar with coverages, shapefiles, and database tables, the new model is a dramatic extension of concepts and capabilities with which you are already familiar. Our goal in building the new feature data model has been to move as much specialized application logic (for example, maintaining connectivity or relational integrity between objects) as possible into the scope of the data model itself. This allows more of the GIS application to be defined using rules in the data model, rather than custom application logic written for each application. For other aspects of the data model, which may already be familiar to the reader, the specific jargon and concepts used in ArcInfo 8 (for topics like image data, as an example) are clearly introduced and defined.
对于地理信息系统专家，这本书作为一个新的对象关系模型的介绍，用于表示特征、特征之间的空间关系和其他专题关系。与当前的覆盖率或shapefile模型相比，这个新模型在表示具有相关行为、关系和属性的功能方面更加丰富。如果您已经熟悉coverage、shapefile和数据库表，那么新模型是您已经熟悉的概念和功能的一个显著扩展。我们构建新特性数据模型的目标是将尽可能多的专用应用程序逻辑（例如，维护对象之间的连接或关系完整性）移动到数据模型本身的范围内。这允许使用数据模型中的规则来定义更多的GIS应用程序，而不是为每个应用程序编写自定义应用程序逻辑。对于读者可能已经熟悉的数据模型的其他方面，arcinfo8中使用的特定术语和概念（例如，对于图像数据之类的主题）被清楚地介绍和定义。
This book also connects the specialized world of geographic information systems and the broader world of object-relational databases. ArcInfo now supports the direct use of standard relational database technology as an integral part of the GIS. This introduces some new concepts to the GIS community. Topics such as transaction models for simultaneous editing of a shared, seamless database are described in detail. For the GIS specialist, this provides a good introduction to standard database concepts. For the database specialist, this book serves as a good answer to the question “what is so special about spatial?”
本书还连接了地理信息系统的专业世界和对象关系数据库的更广泛世界。ArcInfo现在支持直接使用标准关系数据库技术作为GIS的一个组成部分。这为GIS社区引入了一些新概念。本文详细描述了用于同时编辑共享无缝数据库的事务模型等主题。对于GIS专家来说，这为标准数据库概念提供了一个很好的介绍。对于数据库专家来说，这本书很好地回答了“空间有什么特别之处？”
Working with geographic information systems is fun for me because it serves to integrate concepts and ideas from a variety of different disciplines— geometry and networks from applied mathematics, sampling and measurement theory from remote sensing and physics, information modeling and multiuser database issues from information technology. In working with GIS, we get to integrate all of this in a single, useful framework for building real systems. This book presents that synthesis, based on our work with ArcInfo 8. I hope you find this book useful and stimulating as a basis for your own work in geographic information systems.
对我来说，使用地理信息系统很有趣，因为它可以整合各种不同学科的概念和思想——应用数学中的几何学和网络，遥感和物理学中的采样和测量理论，信息技术中的信息建模和多用户数据库问题。在使用GIS时，我们可以将所有这些集成到一个单一的、有用的框架中，以构建真实的系统。这本书基于我们对arcinfo8的工作，呈现了这种综合。我希望你觉得这本书对你自己在地理信息系统方面的工作是有用的和有启发性的。
Contents
PREFACE ........................................................................................................................... vii
ACKNOWLEDGMENTS ............................................................................................. ix
CHAPTER 1: OBJECT MODELING AND GEODATABASES ........................ 1
第1章：对象建模和地理空间数据库
Modeling objects with GIS ...................................................................................... 2
使用GIS进行建模
The progress of geographic data models .............................................................. 4
地理数据模型的过程
The geodatabase, store of geographic data........................................................... 8
地理空间数据库，地理数据的存储
Features in an object-oriented data model ...........................................................10
基于对象的数据模型中的特征
Serving geographic data .........................................................................................12
地理数据服务
Accessing geographic data.....................................................................................14
获取地理数据
Building data models..............................................................................................16
建立数据模型
Guide to reading UML object diagrams ................................................................19
读取UML对象图指南
Technology trends ..................................................................................................21
科技趋势
CHAPTER 2: HOW MAPS INFORM...................................................................... 23
第2章：地图如何提供信息
The utility of maps ..................................................................................................24
How maps present information .............................................................................25
The parts of a map .................................................................................................27
Presenting geography with layers ......................................................................... 28
Drawing features with symbols............................................................................. 30
Drawing feature layers............................................................................................32
Classifying attribute values .....................................................................................36
Displaying thematic, spectral, and picture data....................................................38
Visualizing surfaces with TIN layers .....................................................................41
CHAPTER 3: GIS DATA REPRESENTATIONS ................................................... 45
第3章：GIS数据表示
The fundamentals of a GIS....................................................................................46
The diverse applications of GIS ............................................................................48
Three representations of the world .......................................................................51
Modeling surfaces.................................................................................................. 52
Modeling imaged or sampled data ........................................................................54
Modeling discrete features .....................................................................................56
Comparing spatial data representations ................................................................58
CHAPTER 4: THE STRUCTURE OF GEOGRAPHIC DATA........................ 61
第4章：地理数据结构
The catalog and connections to data....................................................................62
The geodatabase, datasets, and feature classes ...................................................64
ArcInfo workspaces and coverages ..................................................................... 66
Shapefiles and CAD files ........................................................................................68
Maps and layers ......................................................................................................70
Comparing the structure of vector datasets ..........................................................72
Comparing feature geometry in vector datasets ...................................................73
CHAPTER 5: SMART FEATURES ............................................................................. 75
第5章：智能特征
The qualities of features .........................................................................................76
Steps to making features smart ............................................................................. 78
Designing the geodatabase ....................................................................................80
Storing data in tables ..............................................................................................82
The shape and extent of features......................................................................... 84
Attributes: qualities of an object ............................................................................86
Adding simple behavior with subtypes.................................................................88
Validating attributes .................................................................................................90
Relationships among objects .................................................................................92
Extending object classes ........................................................................................96
The geodatabase object model............................................................................. 98
CHAPTER 6: THE SHAPE OF FEATURES ........................................................ 101
第6章：特征的形状
Geometry and features .........................................................................................102
Constructing geometry ..........................................................................................105
Testing spatial relationships .................................................................................110
Applying topological operators............................................................................112
Geometry object model........................................................................................114
CHAPTER 7: MANAGING WORK FLOW WITH VERSIONS ................. 115
第7章：版本化管理流程
Using versions .......................................................................................................116
Long transactions and the geodatabase ..............................................................118
The fundamentals of versions .............................................................................120
Editing versioned geodatabases...........................................................................122
Types of work flows .............................................................................................124
CHAPTER 8: LINEAR MODELING WITH NETWORKS ........................... 127
Modeling infrastructure ........................................................................................128
The network model ..............................................................................................130
How features connect ..........................................................................................132
Network features ...................................................................................................134
Network flow .........................................................................................................139
Analysis on a network ..........................................................................................142
Network object model ..........................................................................................145
CHAPTER 9: CELL-BASED MODELING WITH RASTERS ........................ 147
Representing geography with rasters ...................................................................148
Using raster data....................................................................................................150
Raster data model .................................................................................................152
Raster display and analysis ..................................................................................154
The spatial context of rasters ...............................................................................156
Raster formats ........................................................................................................158
Raster object model ..............................................................................................160
CHAPTER 10: SURFACE MODELING WITH TINS ...................................... 161
Representing surfaces ...........................................................................................162
Structure of a TIN .................................................................................................164
Modeling surface features ....................................................................................166