Table of Contents
Introduction
About This Book
Conventions Used in This Book
What You’re Not to Read
Foolish Assumptions
How This Book Is Organized
Part I: GIS: Geography on Steroids
Part II: Geography Goes Digital
Part III: Retrieving, Counting, and Characterizing Geography
Part IV: Analyzing Geographic Patterns
Part V: GIS Output and Application
Part VI: The Part of Tens
Icons Used in This Book
Where to Go from Here
Part I: GIS: Geography on Steroids
Chapter 1: Seeing the Scope of GIS
Getting a Feel for GIS
Meeting the GIS Collective
Accumulating geographic data
Adding the right computing power
Providing display and representation
Working with people
Knowing How to Think Spatially
Recognizing the spatial nature of questions
Discovering what’s so special about spatial data
At Least 101 Uses of GIS
Managing business activities
Planning city operations and expansion
Providing protection and emergency services
Land management and conservation
Military and defense-related tasks
A treasure chest of possibilities
Chapter 2: Recognizing How Maps Show Information
Knowing How Maps Represent Geography
Understanding scale
Interpreting symbols
Incorporating symbols into your map
Recognizing the Different Types of Maps
Reading reference maps
Using thematic maps
Grasping the importance of scale
Working with Projections and Datums
Picking the right projections
Good projections depend on accurate datums
Working with Coordinate Systems and Land Subdivisions
Meeting the Universal Transverse Mercator (I know you want to)
Measuring the land
Chapter 3: Reading, Analyzing, and Interpreting Maps
Making Sense of Symbols
Categorizing the space on a map
Understanding levels of measurement
Understanding the relationship between symbology and data measurement
Recognizing Patterns
Identifying random distributional patterns
Finding clustered distributional patterns
Observing uniform distributional patterns
Seeing patterns among dissimilar features
Describing patterns with linear features
Understanding the repeated sequence of shapes
Analyzing and Quantifying Patterns
Knowing your geometry and patterns
Using GIS software for the analysis
Determining the type of pattern
Identifying even more patterns
Interpreting the Results and Making Decisions
Part II: Geography Goes Digital
Chapter 4: Creating a Conceptual Model
Helping Computers Read Maps
Embracing the Model-Creation Process
Defining Your Map’s Contents
Choosing a theme to map
Applying the methodology to any GIS project
Breaking down the data you want to include
Verifying your data’s characteristics
Converting from Map to Computer
Deciding how to represent your map
Weighing the benefits: Raster versus vector
Chapter 5: Understanding the GIS Data Models
Examining Raster Models and Structure
Representing dimension when everything is square
Making a quality difference with resolution
Finding objects by coordinates
Finding grid cells by category
Working with map layers
Linking objects and descriptions
Exploring Vector Representation
Simple forms of vector representation
Complex forms of vector representation
Dealing with Surfaces
Storing surface data in a raster model
Representing surfaces in a vector model
Chapter 6: Keeping Track of Data Descriptions
Knowing the Simple Systems for Tracking Descriptions
Understanding computer-assisted cartography
Using computer-aided design
Exploring raster systems
Working with Tables and Database Management Systems
Structuring simple relational data
Getting more complex with relational joins
Managing data in Vector GIS
Storing data in Raster GIS
Searching with SQL in any GIS
Understanding Object-Oriented Systems
Storing attributes with object-oriented systems
Using object orientation to enhance descriptive information
Knowing the packaging descriptions for different objects
Chapter 7: Managing Multiple Maps
Layering Data in GIS Models
Comparing the Map-Handling Capabilities of GIS System Models
Checking out a hybrid system model
Eliminating pointers with integrated system models
Getting better control with object-oriented system models
Opting for an Object-Oriented Model
Chapter 8: Gathering and Digitizing Geographic Data
Identifying Quality Data
Importing Statistical and Sensory Data
Getting information from GPS data
Using remote sensing to create maps
Collecting field data
Working with census data
Getting Existing Map Data into the Computer
Forms of digitizing
Preparing your map for digitizing
Deciding what to digitize
Cleaning up after digitizing
Building the metadata
Part III: Retrieving, Counting, and Characterizing Geography
Chapter 9: Finding Information in Raster Systems
Creating a Search Strategy
Locating objects on a map
Searching for linear features
Searching for areas and distributions
Using the Software to Perform a Search
Searching in simple raster systems
Searching DBMS-supported raster systems
Counting and Tabulating the Search Results
Getting simple statistics
Interpreting the results
Chapter 10: Finding Features in Vector Systems
Getting Explicit with Vector Data
Seeing How Data Structure Affects Retrieval
Deciding How to Search the Systems
Targeting the right data source
Keeping the expected result in mind
Locating Specific Features with SQL
Getting to the point(s)
Keeping your searches
What’s my line?
Searching Vector Systems using Geography
Counting, Tabulation, and Summary Statistics
Validating the Results
Chapter 11: Searching for Geographic Objects, Distributions, and Groups
Searching Polygons in a GIS
Searching for the Right Objects
Extracting specific information
Knowing the size of each polygon
Working with concentrations of point objects
Reorganizing data
Locating 2-D Map Objects
Searching based on category
Finding polygons based on level
Looking for polygons based on value
Locating polygons based on size, shape, and orientation
Finding polygons based on location and position
Defining the Groups You Want to Find
Looking for common properties
Looking for common positioning
Grouping by what you already know
Part IV: Analyzing Geographic Patterns
Chapter 12: Measuring Distance
Taking Absolute Measurement
Finding the shortest straight-line path
Measuring Manhattan distance
Calculating distance along networks
Working with buffers
Establishing Relative Measurement
Adjacency and nearness
Separation and isolation
Containment and surroundedness
Measuring Functional Distance
Anisotropy (whew!) — non-uniformity
Accounting for physical parameters
Based on intangibles
Creating the functional surface
Calculating the functional distance
Chapter 13: Working with Statistical Surfaces
Examining the Character of Statistical Surfaces
Understanding discrete and continuous surfaces
Exploring rugged and smooth surfaces
Climbing steep surfaces
Determining slope and orientation
Working with Surface Data
Collecting surface data for entire areas
Sampling statistical surfaces
Displaying and analyzing Z values
Ignoring the rules
Predicting Values with Interpolation
Determining values with linear interpolation
Using non-linear interpolation
Estimating values with distance-weighted interpolation
Knowing the other exact interpolation methods
Chapter 14: Exploring Topographical Surfaces
Modeling Visibility with Viewsheds
The importance of viewshed analysis
Using ray tracing
Finding and Using Basins
Knowing how basins work
Working with basins in your GIS
Characterizing Flow
Knowing the importance of flow
Modeling and using flow
Defining Streams
Finding and quantifying streams
Identifying methods that work for you
Chapter 15: Working with Networks
Measuring Connectivity
Recognizing the importance of connectivity
Measuring and using connectivity
Working with Impedance Values
Knowing when your paths are fast or slow
Modeling impedance for traffic flow
Working with One-Way Paths
Understanding unidirectional paths
Modeling unidirectional paths
Characterizing Circuitry
Knowing when lines create circuits
Measuring and modeling circuits
Working with Turns and Intersections
Recognizing the importance of turns and intersections
Encoding and using turns and intersections
Directing Traffic and Exploiting Networks
Finding the shortest path, or route
Finding the fastest path
Finding the nicest path
Finding the service areas
Chapter 16: Comparing Multiple Maps
Exploring Methods of Map Overlay
Finding points in polygons
Finding lines on polygons
Using Logical Overlay to Compare Polygons
Searching with union overlay
Using intersection overlay
Understanding complement or symmetrical difference overlay
Using identity overlay
Comparing geometry with clip overlay
Understanding Raster Overlay
Comparing Features with Selective Overlay
Chapter 17: Map Algebra and Model Building
Creating Cartographic Models
Understanding Map Algebra
The Language of Map Algebra
Performing Functions with Map Algebra
Exercising control
Using local functions
Using focal functions
Exploring zonal functions
Understanding block functions
Using global functions
Formulating a Model
Making a formulation flowchart
Basing your database on your flowchart
Implementing a Model
Testing a Model
Determining whether the software is working correctly
Assessing whether the model gives adequate results
Gauging whether your model makes sense
Ensuring that your model satisfies the user
Part V: GIS Output and Application
Chapter 18: Producing Cartographic Output
Exploring Traditional Maps
Mapping qualitative data
Mapping quantitative data
Creating classes
Using map elements
Factoring in graphic map design
Understanding Cartograms
Attracting attention with area cartograms
Distorting distance with linear cartograms
Mapping sequence with routed line cartograms
Chapter 19: Generating Non-Cartographic Output
Looking for Routings and Travel Directions
Getting Customer Lists and Statistical Data
Producing Alarms and Signals (Audio and Video)
Benefiting from Virtual Output
Animating your maps
Getting the most from flythroughs
Chapter 20: GIS in Organizations
Understanding How Your Organization’s Interactions Change
Categorizing the Types of Organizations That Use GIS
Private/commercial
Government
Non-profit/educational
Designing and Introducing a GIS for Your Organization
Understanding how technology affects organizations
Managing people problems
Planning for integration
Looking Before You Leap (And Afterwards, Too)
Performing needs analysis
Performing a cost/benefit analysis
Understanding initial versus ongoing analysis
Using Change Detection
Technological change
Institutional change
Part VI: The Part of Tens
Chapter 21: Ten GIS Software Vendors
Environmental Systems Research Institute
PitneyBowes MapInfo Incorporated
Intergraph
Clark Laboratories
Autodesk, Inc.
GE Smallworld
PCI Geomatics
Leica Geosystems
Bentley GIS
GRASS GIS
Chapter 22: Ten Questions to Ask Potential Vendors
What Services Do You Offer?
Can You Show How Your Product Will Meet My Needs?
What Data Formats Does Your Product Support?
How Do You Handle Communications and Change Requests?
What Hardware Expertise Do You Have?
What Does the Price Include?
How Long Until the System Is Operational?
What Happens If the System Crashes?
What Are Your Quality-Control Procedures?
Chapter 23: Ten GIS Data Sources
GIS Data Depot
Environmental Systems Research Institute
National Geospatial Data Clearinghouse
Center for International Earth Science Information Network (CIESIN)
Go-Geo!
Instituto National de Estadistica Geographia e Informatica (INEGI)
CGIAR Consortium for Spatial Information (CGIAR-CSI)
Australian Consortium for the Asian Spatial Information and Analysis Network (ACASIAN)
Geoscience Australia
Canada Geospatial Data Infrastructure
by Michael N. DeMers
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To all who have taught me, including my teachers, my students, my colleagues, and those I have known only through their writings.
I am grateful to Katie Feltman and Andy Cummings for having the faith in me to write this book. Both gratitude and high praise are due to Colleen Totz Diamond and Laura Miller for their Herculean efforts to make sense of the often vague and always technical GIS ideas and terms. I thank Karen Kemp for her diligent efforts to keep me from technical blunders. My deepest thanks go to Leah Cameron who endured, persevered, and worked tirelessly, all with wonderful humor and constant encouragement. Thanks to all of you in composition, proofreading, page layout, and graphics who convert words and sketches into a polished document.
Thanks to Caliper Corporation, Clarke Laboratories, and Intergraph Corporation for providing me with complementary copies of their software (Maptitude, IDRISI, and GeoMedia Professional, respectively) for the production of this book.
Finally, thanks to all those I love so dearly who have supported me on this journey.
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Introduction
Do you plan to purchase a geographic information system (GIS) in the near future? Are you curious about what it can do for you and how you can get the most out of it? Do you need to use the software, or do you need to supervise others who use it? Do you have concerns about how GIS might change the way your organization functions?
If you answered yes to any of these questions, GIS For Dummies is the right book for you. GIS is some of the most exciting software to come along in ages, and I want to get you as excited about the possibilities GIS offers as I am. This book can help you start thinking about how you can use maps and harness the awesome power of this new technology.
About This Book
Unlike many books on GIS, this one isn’t meant to keep you spellbound for days or weeks. Instead, you can use this book when you need to answer basic questions or figure out what questions to ask your GIS-specialist friends. Think of this book as a reference you can use to find what you need when you need it.
The book gives you a big picture look at GIS — everything from the parts that make up the systems (see Chapter 1) to the spatial information products (see Chapter 20) that the systems produce. So wherever your interests in GIS point you, find those topics in the Table of Contents or Index and jump right in.
Conventions Used in This Book
GIS terminology can get a bit confusing, especially with computer terms. I use the term raster to represent both a GIS data structure (composed of square grid cells) and the software based on that structure. When I talk about vector, I’m also referring to both the data structure (based on points, lines, and polygons) and software that uses the structure.
When I define a term for you, that term appears in italics. Also, I show URLs in monofont typeface to set them apart from the regular text.
What You’re Not to Read
You may feel the urge, every now and then, to explore some of the more advanced features of the GIS software. The GIS crowd might recognize these features and understand the details, but I don’t expect everyone to have (or want to have) that specialized knowledge. Most GIS analysis is based on pretty basic ideas about how things work in geographic space. Sometimes, GIS gets technical and uses fancier methods including mathematical procedures that you probably don’t need to understand in depth. So, keep an eye out for the Technical Stuff icons and skip them if you want.
Also, I like to illustrate certain points with extra examples that appear in the book as sidebars. I think you’ll find the examples interesting, but they’re not essential to your understanding of the basics.
Foolish Assumptions
I’m going to assume that you’ve heard about GIS but don’t know all that much about its inner workings and hidden mechanisms. Many people think GIS (geographic information system) means GPS (global positioning system) because more people have heard the term GPS. In reality, GPS is just a part of GIS, and I tell you about that in Chapter 8. I assume you have something more than a casual interest in GIS, so I explain what GIS is, what it does, and how it can help you with what you do in your organization. Here are a few other assumptions I make:
You know what a map is. GIS relies heavily on maps and map-related data. I assume that you have used a map of some kind, but aren’t an expert in either making or using maps. I provide all the background you need to become familiar with how maps represent the real-world geography.
You know what geography is. I assume that you’ve taken a geography class at some point in your life, but I don’t assume that you’re a geographer or that you think like a geographer. So I guide you on that path, as well. After you figure out how to think like a geographer (in mapping terms), GIS can become your friend and ally. You might even find it fun to use.
You use some form of computer from time to time. GIS relies on computers. I don’t expect that you’re a computer technician, but I do assume that you know what data files and software programs are and how to use a computer interface. Beyond that, I explain some of the inner workings of the GIS software and databases so that you can ask intelligent questions of the GIS experts.
How This Book Is Organized
GIS For Dummies contains six parts. They move from general background in geography and mapping in Part I, to the use of computers for maps in Part II, GIS data retrieval in Parts III, pattern identification and analysis in Part IV, a look at GIS output in Part V, and some helpful info about GIS vendors and data sources in the Part of Tens (Part VI).
Part I: GIS: Geography on Steroids
If you’re brand new to GIS, you may want to start here. Part I provides a general overview of the book, explains the basic geography background needed to understand how maps represent the real world, and introduces you to some of the mapping terminology that you need to know to understand GIS-speak. It covers map reading, symbolism, projections (moving from 3-D to 2-D), datums (starting points for measurement), scale issues, and generalization. You can see the power of map data and how getting them into your computer really improves your ability to make use of information contain in maps.
Part II: Geography Goes Digital
Part II deals with how you get data from your paper maps into the computer. If you’re unsure about how GIS data work inside the computer, this part can give you the answers. In this part, I show you the two basic models used for digital map representation (grids, called raster; and points, lines, and polygons, called vector). You find out how these different models enable you to keep track of the geographic features you include in your GIS and how the models link these features to the descriptive information that eventually winds up in your GIS output (such as a map legend).
Part III: Retrieving, Counting, and Characterizing Geography
Part III is for people who want to know how to use GIS to answer questions. It includes information about how to find the geographic features that you put in your GIS database, different ways of searching for features, how to count them up when you find them, and how you can describe what you find. In this part, you discover how to locate and characterize features by type or category, by their sizes and shapes, by measurements that describe them, and even by where they’re located relative to each other in geographic space.
Part IV: Analyzing Geographic Patterns
GIS does its most powerful work when analyzing the patterns that you identify, and Part IV focuses on that subject. You see how to measure lengths, areas, distances, and volumes; as well as how to work with networks, such as highways and streets. I explain both topographic and non-topographic surfaces, how to analyze rivers and determine where water will flow during flooding, and how to determine places that an observer can and can’t see from a certain point. I even show you how to combine maps and use a powerful map analysis language called map algebra.
This part can’t make you an expert in GIS analysis, but it can help you figure out enough to start your analyses and talk knowledgeably with the experts.
Part V: GIS Output and Application
In Part V, I show you how to make the most of all your GIS queries and analysis. You can find out about the various types of map output, as well as non-map output, that you can use to help explain the results of your work. I tell you how GIS can generate travel directions, customer lists, alarms, and even movies that show maps through time. Finally, I show you how to smoothly incorporate this high-level technology into your organization so that you can quickly take advantage of its power.
Part VI: The Part of Tens
In the Part of Tens, I introduce ten GIS software vendors and explain what other products and services they provide. I also provide a handy list of questions to ask those vendors before you decide where to purchase software, products, and services. Finally, I also provide a list of sources of GIS data from government and private companies — both free and for purchase.
Icons Used in This Book
GIS For Dummies uses little pictures, or icons, that help direct your reading. These little graphics can save you time by letting you find all the high points quickly.
The Tip icon provides a few helpful hints about shortcuts, best practices, and just plain common sense when it comes to GIS. GIS tips help you do the right things at the right time for the right reasons. Each tip comes with an explanation about why it’s a good idea, too.
I use the Warning icon to keep you from making mistakes that are very hard to recover from. Unfortunately, GIS doesn’t come with many built-in safety mechanisms, so I try to point out potential problem points.
The Remember icon is sort of like a summary of important points that you need to focus on. In some cases, I remind you of things I cover recently in the chapter, and in other cases, I highlight material from other parts of the book and explain how it applies to that specific discussion. Think of them like tiny refresher courses.
The Real World GIS icon highlights all the places that you can find out how people use GIS to accomplish real tasks in the real world.
When you see the Technical Stuff icon, you don’t have to read the technical information to understand the surrounding text — but you might want to look at it and get a sense of all the possibilities of GIS.
Where to Go from Here
Because GIS software changes all the time, the user community requires constant updating and retraining. Many fine community colleges, technical schools, colleges, and universities provide formal education in GIS, and some provide continuing education courses to help you keep up with what’s going on. Some vendors offer face-to-face and online courses (largely geared toward their product line, of course).
You can also keep updated by interacting with other users. In the past, you’d make these contacts through professional meetings, trade shows, and user group meetings (which still draw plenty of users). Today’s technology provides you with a supplemental method of keeping current. Blogs, wikis, forums, and RSS feeds now provide a vast array of methods that you can use to obtain just the right answer in a timely fashion without ever having to leave your computer. Even the vendors themselves often provide audio and video podcasts that give updates on the newest software wrinkles. Here are a few prominent Web-based resources that you can use to continue your GIS education:
GIS Café (www.giscafe.com): A general online GIS community that contains all things GIS, including forums, data providers, and much more.
GIS Data Depot (http://data.geocomm.com): Another general online GIS community which is focused mostly on data sharing.
GIS Lounge (http://gislounge.com): Similar to GIS Café, but with a somewhat more educational and informational spin.
Directions Magazine (www.directionsmag.com): A forum and online GIS magazine that focuses on keeping the reader up to date on research, innovations, software, and hardware related to GIS.
VerySpatial (www.veryspatial.com): A podcast that generally covers the larger discipline of geography, but with a large amount of GIS content.
ESRI Podcasts (www.esri.com/news/podcasts/index.html): ESRI’s podcasts include both an instructional series and a speaker series.
GIS forums and podcasts will continue to increase, both in number and in focus. An occasional search on your favorite Internet browser can keep you reading and listening about GIS for a long time to come.