......................................................................................................................................................................................... FUNDAMENTALS OF ......................................................................................................................................................................................... GEOGRAPHIC ......................................................................................................................................................................................... INFORMATION ......................................................................................................................................................................................... SYSTEMS ......................................................................................................................................................................................... FOURTH EDITION Michael N. DeMers New Mexico State University JOHN WILEY & SONS, INC. VICEPRESIDENTANDPUBLISHER JayO’Callaghan EXECUTIVEEDITOR RyanFlahive ASSISTANTEDITOR CourtneyNelson SENIORPRODUCTIONEDITOR NicoleRepasky MARKETINGMANAGER DanielleTorio DESIGNER MichaelSt.Martine PRODUCTIONMANAGEMENTSERVICES KatieBoilard/PineTreeComposition,Inc. PHOTOEDITOR HilaryNewman EDITORIALASSISTANT ErinGrattan MEDIAEDITOR LynnPearlman ImageprovidedbyUSGSEROSDataCenterSatelliteSystemsBranch.CourtesyNASA. Thisbookwassetin10/12CheltenhambyLaserwordsPrivateLimited,Chennaiandprintedandbound byHamiltonPrinting.ThecoverwasprintedbyPhoenixColor. Thisbookisprintedonacidfreepaper. Copyright©2009JohnWiley&Sons,Inc.Allrightsreserved. Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmittedinanyformorbyany means,electronic,mechanical,photocopying,recording,scanningorotherwise,exceptaspermittedunder Sections107or108ofthe1976UnitedStatesCopyrightAct,withouteitherthepriorwrittenpermissionofthe Publisher,orauthorizationthroughpaymentoftheappropriateper-copyfeetotheCopyrightClearanceCenter, Inc.222RosewoodDrive,Danvers,MA01923,websitewww.copyright.com.RequeststothePublisherfor permissionshouldbeaddressedtothePermissionsDepartment,JohnWiley&Sons,Inc.,111RiverStreet, Hoboken,NJ07030-5774,(201)748-6011,fax(201)748-6008,websitehttp://www.wiley.com/go/permissions. Toorderbooksorforcustomerserviceplease,call1-800-CALLWILEY(225-5945). LibraryofCongressCataloging-in-PublicationData DeMers,MichaelN. Fundamentalsofgeographicinformationsystems/MichaelN.DeMers.—4thed. p.cm. Includesbibliographicalreferences. ISBN978-0-470-12906-7(alk.paper) 1.Geographicinformationsystems—Textbooks.I.Title. G70.212.D462009 910.285—dc22 2007038332 PrintedintheUnitedStatesofAmerica 10 9 8 7 6 5 4 3 2 1 P R E F A C E GISoncemeantonlygeographicinformationsystems.Todayitisevolvingintoa morecomprehensivedisciplineinitsownrightandthetermnowrepresentsnot only thesystemitself, buttheunderlying science and technology foundations. It has even acquiring a new acronym: GIS&T, meaning Geographic Information ScienceandTechnology.Justthisyearwehavecompletedamajorundertaking with the publication of the first edition of what is hoped will be an ongoing set of editions of the GIS&T Body of Knowledge (Dibiase, et. al. 2006). Afer the culmination of almost seven years of work involving geographers, computer scientists, researchers, academics, and industry participants, this document represents a first approximation definition of the discipline as it stands today. Beyond setting the standards and outlining some 1,660 learning objectives within ten knowledge areas, it suggests what a student completing a four-year university degree emphasizing GIS&T would be expected to know. This also providedbothanincentiveandasetofguidelinesforthe4th editionofthetext youarenowreading. When l wrote the first edition of this text over ten years ago there were few guidelines for content or learning objectives. I was forced to glean what I could from personal mentors, my own class notes and teaching experiences, discussions with other GIS faculty teaching GIS, student responses and a gut reaction.AsIlookattheGIS&TBodyofKnowledgeImustsaythatIwasnottoo faroffthemark.But,thedisciplineischangingconstantly,andthemanypeople involvedincreatingthedisciplinarystandardrepresentaninterestingmixofthe disciplinary historical roots and the future advances in cutting edge research. AsaresultofworkingwiththisawesomesetofparticipantsandadvisorsIhave rethoughtsomemajorportionsofthistexttoreflectthenewstandard. At first blush the structure of the text doesn’t look all that different from its initial inception, but the content, particularly with regard to the computer science, cartographic visualization, and design are considerably more robust. These are meant to reflect both the Body of Knowledge Standard and the changing level of computer expertise of the students. The percentage of tech savvystudentsthatIhaveseenoverthepastdecadehasgrownlogarithmically. This is fortunate because the industry itself is adapting to acknowledge both a need for new concepts and geographical constructs to include in the toolkit andnewwaystoimplementthem.ThiseditionofFundamentalsofGeographic InformationSystemsismeanttotargetstudentswhoarecomfortablewithe-mail and text messaging, digital file formats(mp3,mp4,jpeg), computer games and visualizations, and a host of technologies that did not exist ten years ago. Some educators are now referring to this new generation of students as the neomillenials, not because of when they were born, but because of their daily immersioninatechnology-richenvironment. AtthesametimeIhaveaddedapre-GISchapter(Chapter0)called‘‘ASpatial Learner’s Permit.’’ This chapter is a reaction to the ever increasing diversity of student who enters the field of GIS, often with little or no knowledge of iii iv Preface geographicterminology,explicittrainingingeographicprincipals,orexperience inspatialcognitionandspatialanalysis.Theconcepthereisthatofapermitting processwherethosestudentswhoarenewtothefieldofGIS,orthosewhowish torenewtheirbackground,haveanopportunitytodosowithoutbeingthrown in head first and watching to see who survives and who doesn’t. There is no reason why everyone, no matter what their discipline, cannot fully appreciate andsuccessfullyemploythetoolsandtechniquesofGISaslongastheyhavea chancetogetthisnecessarybackground. Beyond their growing technological sophistication, my own students are increasingly entering my GIS classes from disciplines outside of geography. They are coming from departments you might expect such as criminal justice, geology,biology,surveying,wildlife,andanthropology.Morerecentlytheyhave startedarrivingfromeconomics,history,engineering,publichealth,hospitality, agronomy, and a host of others. This has made the teaching of GIS and the production of this supporting text both exciting and difficult. It is stimulating getting the often wildly different perspectives these students bring to the classroom but it also highlights a fundamental difficulty with the current state ofGISeducation.Howdoweteachstudentswithasolidgeographyandmapping skillsbackgroundwiththesameclass,orthesametextbook,asthosewithlittle or no background in the spatial sciences? This is an on-going topic of GIS educational research,but Ihavemadeastabat apartial solution in thisbook. For geographers and others well versed in spatial tools I suggest they review Chapters 1–3 and begin studying in earnest with Chapter 4. For the neophyte I often recommend that they think of the first three chapters, especially 2 and 3, as a GIS Bootcamp. Many GIS software companies provide a set of pre-GIS exercises as a part of their software training. This has proven successful and mightprovideamodelforacademicinstructionaswell. The pressure from students to get more software exposure and less theory andconceptscontinuestomount.AndasIstatedinthethirdedition,Icontinue toresist.Itisgettingevenmoredifficultwiththeneomillenialsbecausetheyare soinextricablylinkedtotechnology.Sowhatdoweinstructorsdo?Myapproach has been to increase the complexity of the hands-on problems and force the students to ask questions about the underlying concepts that are required for them to answer them. My lab components are becoming less recipe-like and more open ended. For example, it is much more difficult to ask your students to solve a problem where there is no set recipe of GIS commands to follow than it is to just take them through the problem. Such an approach requires morethanjustanabilitytoreadalabmanual,typetheappropriatecommands, and hand in the results. It requires problem solving. These are the skills the GIS industry constantly tells me they need! I’ve found it useful to focus on the learning objectives for each chapter and to ask some of these questions as requiredoutputforlabreportsoraspracticallabexamquestions. So what’s new in this edition? As I mentioned before, for those entering GIS without a substantial background in the geographic underpinnings of the discipline, I have added a short, gentle introduction called A Spatial Learner’s Permit.Thisisnotonlyfornon-geographers,butalsoforthosewhosegeography is a little rusty and would like to brush up a little. Next, I’ve split the old GIS data models chapter (old Chapter 4) into two separate chapters: Chapter 4– GIS:ComputerStructureBasicsandChapter5–GISDatamodels.Thisseemsto havereducedtheconfusionformystudents.Italsoallowsforamorein-depth, Preface v although not comprehensive, examination of the underlying computer science behind GIS, without overwhelming the student with a large single chapter. Another chapter split came in the old Chapter 10 on statistical surfaces is now Chapter 11–Statistical Surfaces and Chapter 12–Terrain Analysis. This suggestion came from a faculty member who used the text and pointed out to me that there is now a pretty robust set of analytical techniques focusing just on the terrain type of statistical surface. As with the other split it allowed me tospend alittle moretimeon techniques that hadbeen neglected before.The reactioninmyclasseswaspositiveregardingthisaswell. Someofthemostmassivechangescameattheendofthetextwheretheold Chapters 16 and 17 dealing with applications and research were eliminated. I receivedfeedbackfrominstructorsthattheywereunabletofindtimetogetto thesechapters,andthattheselectionoftopicsforbothwaslimited.Iwasalso unabletogettothosechaptersandunwillingtorushthroughthematerialtodo so.AsaresultIhaveexpandedandcompletelyupdatedChapter16(Chapter14 in the 3rd edition) to reflect the increasingly robust literature on cartographic visualization.GiventhegraphicalsophisticationofthecurrentstudentIthought this would be a better use of my time. I have also reworked Chapter 17 (old chapter15)toreflectanequallyimprovedbodyofliteratureonGISdesignand management. Both of these major changes are also a direct response to the BodyofKnowledgeDocument. A cautionary note here: neither Fundamentals of Geographic Information Systems,noranyotherintroductorytextIcanenvision,iscapableofcontaining thesumtotalofthe1,660learningobjectivesnorallofthetopicsandknowledge areasfoundintheBodyofKnowledgewithanyreasonablelevel.Anintroductory textismeanttointroduce,notoverwhelm.Insteadthistextfocusesontheideas, concepts,andtechnologiesthatonemightexpectastudenttoencounterinan early exposure to GIS. More detailed topical coverage of the existing material and more selection of topics should be expected in advanced coursework and accompanying textbooks. Still, there is always room for improvement. I look forwardtoyourexperiencesandfeedback,bothmakemyowncoursesbetter. ACKNOWLEDGMENTS Much of this revision came after a long stay in the hospital. There was some doubt about my chances for survival. That I beat the odds is due in large part to the actions and expertise of Renee Williams, Dr. Azhir Zahir, Dr. E. Rhett Jabour,theNMSUemergencyservicespersonnel,thedoctors,nursesandother medicalstaffofMemorialMedicalCenterinLasCruces(especiallythe4th floor, andICU).Iamalsogratefultoallwhoseprayers,visits,gifts,andkindthoughts maintained me during that difficult time, especially Jack Wright, Carol and Jim Campbell, Chris Brown, Bob and Beth Czerniak, Dan and Karla Dugas, David andFrancineMcNeil,JafferHanfoosh,mystudents,andallthosewhosenames I have forgotten. Of course, I am extremely blessed to have had the constant love and prayers of my wife, Dolores, and my brothers James and Dennis, and allmyfamilymembers.Youareallresponsibletosomedegreeforthistext. Thanks to those who taught me and mentored me, especially Bill Dando, Lee Williams, Duane Marble, Kang Tsung Chang, Vince Robinson, Peter Fisher, vi Preface and many others. In this regard I also want to thank all the members of the GIS curriculum project and my Body of Knowledge co-editors for the ideas, knowledge,andinsightsyouprovided.Thestudentswhohadtosufferthrough allthepreviouseditionsdeservethanksfortheirtolerance,and,insomecases, their criticism. Finally, I want to thank thefolks at Pine Tree Composition, Inc. for their editorial services, and at John Wiley and Sons for their continued faith in my work, especially Laura Spence Kelleher, and Ryan Flahive, the production staff, and graphic artists. A special note to all the following who tookthetimeoutoftheirbusyschedulesandtheirownprojectstoreviewthis book: Richard Beck, University of Cincinnati; William Cooke, Mississippi State University;AlisonFeeney, ShippensburgUniversity;ToddFritch,Northeastern University; David Fyfe, Penn State University; Alberto Giordano, Texas State University–San Marcos; Shunfu Hu, Southern Illinois University–Edwardsville; Dorleen Jenson, Salt Lake Community College; Nicholas Kohler, University of Oregon;HelmutKraenzle,JamesMadisonUniversity;DebbieKreitzer,Western Kentucky University; Dean Lambert, San Antonio College; Mark Leipnik, Sam HoustonStateUniversity;ChorPangLo,UniversityofGeorgia;JiaLu,University of Wisconsin–Stevens Point; Yongmei Lu, Texas State University–San Marcos; Robert Martin, Kutztown University; Darrel McDonald, Stephen F. Austin State University;JaewanYoon,OldDominionUniversity;andMayYuan,Universityof Oklahoma.Youallshareinthisproduct. C O N T E N T S Chapter 0 Spatial Learner’s Permit 1 SpatialTerminology 2 ApplyingSpatialTerms 5 SpatialCognition 8 SpatialQuantities 10 SphericalEarth 11 ConcludingRemarks 13 Terms 14 PracticeExercises 14 References 16 UNIT 1 INTRODUCTION 17 ......................................................................................................................................................................................... Chapter 1 Introduction to Digital Geography 19 LearningObjectives 19 GeographicInformationSystemsDefined 19 ABriefHistoryofGeographicInformationSystems 23 GISasaGrowthIndustry 25 SampleApplicationAreasofGIS 26 TheStudyofGIS 29 Terms 31 ReviewQuestions 31 References 31 UNIT 2 DIGITAL GEOGRAPHIC DATA AND MAPS 33 ......................................................................................................................................................................................... Chapter 2 Basic Geographic Concepts 35 LearningObjectives 36 DevelopingSpatialAwareness 37 SpatialMeasurementLevels 40 SpatialLocationandReference 42 SpatialPatterns 45 GeographicDataCollection 47 PopulationsandSamplingSchemes 52 MakingInferencesfromSamples 54 Terms 56 vii viii Contents ReviewQuestions 56 References 57 Chapter 3 Map Basics 58 LearningObjectives 59 AbstractNatureofMaps 59 AParadigmShiftinCartography 60 MapScale 61 MoreMapCharacteristics 63 MapProjections 63 GridSystemsforMapping 66 MapSymbolism 73 MapAbstractionandCartographicDatabases 77 Terms 78 ReviewQuestions 78 References 79 Chapter 4 GIS Computer Structure Basics 81 LearningObjectives 82 AQuickReviewoftheMapasanAbstractionofSpace 82 SomeBasicComputerFileStructures 84 SimpleLists 84 OrderedSequentialFiles 85 IndexedFiles 86 DatabaseManagementStructures 88 HierarchicalDataStructures 88 NetworkSystems 90 RelationalDatabaseManagementSystems 92 SomeBasicComputerTerminology 95 Terms 96 ReviewQuestions 97 References 97 Chapter 5 GIS Data Models 99 LearningObjectives 100 GraphicRepresentationofEntitiesandAttributes 100 GISSystemDataModels 104 RasterModels 105 RasterSurfaceModels 106 CompactStoringofRasterData 108 CommercialRasterCompactionProducts 110 VectorModels 111 AnObject-OrientedDataModel 117 CompactingVectorDataModels 117 AVectorModeltoRepresentSurfaces 118 SystemsModels 119 Terms 123 ReviewQuestions 123 References 124