Table Of ContentEncyclopediaofGIS
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Shashi Shekar Hui Xiong (Eds.)
Encyclopedia of GIS
With723Figuresand90Tables
123
SHASHISHEKHAR
McKnightDistinguishedUniversityProfessor
FacultyofComputerScienceandEngineering
UniversityofMinnesota
Minneapolis,MN55455
USA
HUIXIONG
AssistantProfessor
ManagementScienceandInformationSystemsDepartment
RutgersBusinessSchool
NewarkandNewBrunswickRutgers,theStateUniversityofNewJersey
Newark,NJ07102
USA
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Foreword by Brian Berry
ThepublicationofadefinitiveEncyclopediaofGISthatlaysoutmanyofthecomputerscience/mathematicsfoundations
ofthefieldisamajorevent,theculminationofahalfcenturyofdevelopment.Iwaspartoftheearlieststirringsinthe
mid-1950s.AsmallgroupofgeographygraduatestudentsattheUniversityofWashington,WilliamGarrison’s“space
cadets,”begantoassemblewhatbecamethefoundationsofcontemporaryspatialanalysisandtorefocusmathematical
cartographywhileworkingwithcivilengineerEdgarHorwoodonhisattemptstousetheprintersofthetimetoproduce
grey-shadedmaps.OurattentionwascapturedbySputnik,however,wedidn’tanticipatethattheUS’sresponse,therapid
developmentofNASAandsatellitesystems,wouldbethekeytotheequallyrapiddevelopment ofremotesensing,or
thatglobalpositioningwouldrewritecartography.AmongtheinnovationsofthetimewereTorstenHägerstrand’sfirst
simulation models of space-time diffusion processes and early econometric interest in spatial autocorrelation. Both
themesarenowcentraltospatialanalysis.
TheGISfocus shiftedwhenGarrison, MarbleandIrelocatedtotheChicagoregion. GarrisonandIhelpedfundcivil
engineer Howard Fisher’s first generation computer graphics software, SYMAP I, and Marble and I organized NSF
workshops to spread the word and drew together an initial overview of the field in Spatial Analysis. Fisher took his
ideas to the Ford Foundation and a subsequent grant to Harvard University, where he established the Laboratory for
Computer Graphics. The Lab served as the focus for research in the field well into the 1970s, providing the spark
to such innovators as Jack Dangermond, who subsequently established ESRI and created what became the world’s
mostwidelyusedcomputergraphicssoftware.Meanwhile,hardwaredevelopmentproceededapace,asdidimagingand
positioningcapabilitiescreatedbytheDepartmentofDefenseandNASA,facilitatingtheresultingemergenceofdigital
cartography and the establishment of the first large-scale Geographic Information Systems such as the Canada Land
Inventory.Therest,astheysay,ishistory–albeitgivenanewdynamicbytheInternetandthecontinuedevolutionof
computingcapabilitiesbothonthedesktopandinthesupercomputer.
Fiftyyearsafterthesebeginnings,theresultisalargeandcomplexfieldspanningmanydisciplines,continuingtogrow
andtoexpandintoanexpandingarrayofapplications.Cartographershaveeschewedtheirpen-and-ink,andrudimentary
mapmakingisatthefingertipsofeveryonewithInternetaccess.Roadatlasesarefastgivingwaytosatellitenavigation
systems.Congresscontinuestobeconcernedwiththeprivacyissuesraisedbygeographicinformationsystemcapabil-
ities, yet police and fire departments can no longer function effectively without GIS and Homeland Security without
moderndatabaseanddataminingcapabilities.Fromcityplanningtostorelocation,propertytaxationtohighwaybuild-
ing,disasterresponsetoenvironmentalmanagement,therearefewarenasinwhichGISisnotplayingasignificantrole.
What is important is the cross-cutting capability that was recognized when the NSF funded the Center for Spatially-
IntegratedSocialScience(CSICC)attheUniversityofCalifornia,SantaBarbara,ormyownuniversity’sPh.D.program,
ajointventureoftheSchoolofEconomic,PoliticalandPolicySciences,theSchoolofNaturalSciencesandMathemat-
ics,andtheSchoolofEngineeringandComputerSciences.
I like to tell my colleagues that there are three levels of GIS education: “Driver’s Ed,” “Mr. Goodwrench,” and
“Design Team.” Driver’s Ed provides essential skills to the broad base of software users, the Mr. Goodwrenches of
theworldlearnhowtoputtogetherandmaintainworkingsoftware-hardware installations,whileDesignTeamscreate
new and improved GIS capabilities. Most of the new data handling capabilities reside in the arenas of computer sci-
ence/mathematics,whileadvancesininferencearecomingfrominnovationsintheabilitytohandlespace-timedynamics
whilesimultaneouslyaccountingforserialandspatialdependence.
TheEncyclopediaofGISprovidesanessentialreferenceworkforallthreecategoriesofusers.Incontrasttothecurrent
textbooksinthefield,whicharekeyedtoDriver’sEd,theEncyclopediaalsoprovidesahandysourcebookfortheMr.
GoodwrencheswhiledefiningtheplatformonwhichfutureDesignTeamswillbuildbyfocusing–morethanexisting
VIII ForewordbyBrianBerry
works–onthecomputerscience/mathematicalfoundationsofthefield.IknowthattheGIScommunitywillvaluethis
importantreferenceandguide,andIwillcherishitasamilestone.Itmarkshowfarwehavecome–farbeyondwhat
ourgroupofpioneersdreamedmightbepossibleahalfcenturyago.ProfessorsShekharandXiongandtheconsiderable
communityofcontributors tothecollectionhaveprovideduswithacomprehensiveandauthoritativetreatmentofthe
field,extensivelycross-referencedwithkeycitationsandfurtherreadings.Importantly,itisavailableinbothprintedand
XMLonlineeditions,thelatterwithhyperlinkedcitations.TheGISworldwillbeindebtedtothem.NoGISbookshelf
should,astheysay,bewithoutit.
McKinney,Texas BrianJ.L.Berry
August,2007 SchoolofEconomic,PoliticalandPolicySciences
TheUniversityofTexas,Dallas
Dallas,TX
USA
Foreword by Michael Goodchild
GeographicInformationSystemsdatefromthe1960s,whencomputersweremostlyseenasdevicesformassivecom-
putation.Verysignificanttechnicalproblemshadtobesolvedinthoseearlydays:howdidoneconvertthecontentsof
apapermaptodigitalform(bybuildinganopticalscannerfromscratch);howdidonestoretheresultonmagnetictape
(intheformofalinearsequenceofrecordsrepresentingthegeometryofeachboundarylineassequencesofvertices);
andhowdidonecomputetheareasofpatches(usinganelegantalgorithminvolvingtrapezia).Mostoftheearlyresearch
wasaboutalgorithms,datastructures,andindexingschemes,and,thus,hadstronglinkstoemergingresearchagendas
incomputerscience.
Over the years, however, the research agenda of GIS expanded away from computer science. Many of the technical
problems of computation were solved, and attention shifted to issues of data quality and uncertainty; the cognitive
principles ofuserinterfacedesign; thecostsandbenefitsofGIS;andthesocialimpactsofthetechnology. Academic
computerscientistsinterestedinGISwonderediftheirresearchwouldberegardedbytheircolleaguesasperipheral–
amarginallyinterestingapplication–threateningtheirchancesofgettingtenure.Repeatedeffortsweremadetohave
GIS recognized as an ACM Special Interest Group, without success, though the ACM GIS conferences continue to
attractexcellentresearch.
Theentriesinthisencyclopediashouldfinallylayanylingeringdoubtstorestaboutthecentralroleofcomputerscience
inGIS. Someresearchareas,suchasspatiotemporal databases,have continued togrow inimportance becauseofthe
fundamentalproblemsofcomputersciencethattheyaddress,andarethesubjectofseveralrespectedconferenceseries.
Geospatialdatamininghasattractedsignificantattentionfromcomputerscientistsaswellasspatialstatisticians,anditis
clearthattheacquisition,storage,manipulation,andvisualizationofgeospatialdataarespecial,requiringsubstantially
differentapproachesandassumptionsfromthoseinotherdomains.
Atthesametime,GIShasgrowntobecomeaverysignificant applicationofcomputing. Sometimearound 1995, the
earlier view of GIS as an assistant performing tasks that the user found too difficult, complex, tedious, or expensive
todobyhand,wasreplacedbyoneinwhichGISbecamethemeansbywhichhumanscommunicatewhattheyknow
aboutthesurfaceofEarth,withwhichtheycollectivelymakedecisionsabout themanagement ofland,andbywhich
theyexploretheeffectsofalternativeplans.Ahostofnewissuessuddenlybecameimportant:howtosupportprocesses
ofsearch,assessment,andretrievalofgeospatialdata;howtoovercomelackofinteroperabilitybetweensystems;how
tomanagelargenetworksoffixedormobilesensorsprovidingflowsofreal-timegeographic data;howtoofferuseful
servicesontheverylimitedplatformofacellphone;andhowtoadaptandevolvethetechnologyinordertorespondto
emergenciesandtoprovideusefulintelligence.Arevitalizedresearchagendaforcomputerscienceemergedthatshows
nosignofdiminishing,andisreflectedinmanyofthetopicsaddressedinthisencyclopedia.
Forexample,computerscientistsareengagedinthedevelopmentofdatastructures,algorithms,andindexingschemes
tosupportthehugelypopularvirtualglobes(GoogleEarth,Microsoft’sVirtualEarth,NASA’sWorldWinds)thathave
emerged in the past few years and are stimulating a whole new generation of applications of geospatial technology.
Researchisongoing onsensornetworks, andthecomplexprotocols thatareneededtohandle flowsofreal-timedata
frommassivenumbersofdevicesdistributedovertheEarth’ssurface,inareasofscientificinterestsuchastheseafloor,
invehiclesacquiringdataontrafficmovement,andinbattlefields.Semanticinteroperability,ortheabilityofsystemsto
sharenotonlydatabutthemeaningofdata,remainsathornyproblemthatwillchallengetheresearchcommunityfor
manyyearstocome.
As a collection of well-written articles on this expanding field, this encyclopedia is a welcomed addition to the GIS
bookshelf.ThefactthatitscompilershavechosentoemphasizethelinksbetweenGISandcomputerscienceisespecially
welcome.GISisinmanywaysaboundaryobject,touseatermcommoninthecommunityofsciencehistorians:afield
X ForewordbyMichaelGoodchild
thathasemergedbetweentwoexistingandrecognizedfields,inthiscasecomputerscienceandgeography,andwhich
hasslowlyestablisheditsownidentity.Asitdoesso,contributions suchasthiswillhelptokeepthoselinksalive,and
toensurethatGIScontinuestoattracttheinterestofleadingresearchersincomputerscience.
MichaelF.Goodchild
NationalCenterforGeographicInformationandAnalysis
andDepartmentofGeography
UniversityofCalifornia
SantaBarbara,CA
USA
Preface
Interest in Geographic Information Systems, Science, and Services (GIS) has tremendously grown in recent years in
many different ways. Researchers from a variety of academic disciplines are using spatial thinking and GIS tools to
develop spatially-explicit models. Broad public interest in this subject is being fuelled by popular applications like
Googlemaps,personal navigation devices,MapQuest,etc.Web-basedsoftware developers areincreasinglyexploring
“mash-ups”integratingdifferentinformationsourcestoweb-basedmaps,suchasGoogleEarthandMSVirtualEarth.
Therefore, thereisaneed tobring keyGIS concepts andresults toadiverseaudience ascurrent GIS literature(e.g.,
textbooks,journals,conference-proceedings,trade-books)largelycaterstoeitherGISspecialistsorend-usersofpopular
GISsoftware.
TheGISresearchcommunityisenthusiasticallyembracingencyclopedias,i.e.,collectionsofarticlesonnumeroustop-
icsinafield,asatooltobringkeyideasfromafieldtoageneralaudience.Thisisnotonlyevidentfromthepreparation
of multiple encyclopedias of GIS in the 2007–2008 time-frame, but also from the generous time commitments from
GISresearcherscontributingtotheencyclopediaprojectsasauthors,fieldeditorsandreviewers.Theconcurrentdevel-
opment of multiple GIS encyclopedias helped us define afocus, given the multi-disciplinary nature of thefield. This
encyclopedia focuses on computational aspects of a variety of GIS concepts for a variety of reasons. First, computa-
tionaladvancesaremakingGISavailabletoawidevarietyofend-users,softwaredevelopersandresearchers.Second,
manygeo-spatial datasetsarelargeandgrowingrapidly duetoadvances incyber-infrastructure, includingsensorand
data management technologies. This will make computational issues even more critical in the coming years. Finally,
computational technologies are advancing at a rapid pace, making new capabilities possible every few years. While
therecentadvances,e.g.,GoogleEarthandMicrosoftVirtualEarth,lookimpressive,wearelikelytoseeevenbigger
advancesduetogrowingcomputingpowerintheyearstocome.
Despitethefocusoncomputational aspectsofGIS,itwasstillchallengingtonarrowdownthelistofpossiblearticles
inorder toexplain the key software, datasets, and processes used by geographers and computational scientists.After
all, our goal was to provide a comprehensive and authoritative treatment of GIS, providing easy access to the field.
Wereviewedthetopicsincalls-for-papersforconferencesandjournalsalongwiththekeywordsinrelevantbooksand
modelcurricula. Wealsoconsultedvarious leadersintheGISarea.Additionally, wetriedtobalancethesetoftopics
to reflect the interests of industry, government and academia. For example, topics such as GIS standards as well as
examplesofGISsoftwarefromindustryandthepublicdomainwereincludedinthetopiclist.Similarly,weincluded
topics like crime mapping, evacuation planning and location-based services. Naturally, the list includes a variety of
academictopicsrangingfrom“SpatialCognition”to“StatisticalModeling.”
Thenext major challenge was to identify suitable field editors and authors representing the world leaders inselected
topicareas.Manyresearchersusuallyfocusonconferenceandjournalpapers.Yet,wewerepleasantlysurprisedbythe
generosityoftimeandexpertisereceivedfromsomanyenthusiasticGIScolleaguesforthisencyclopediaproject.Field
editorswentbeyondtheircallofdutytoidentifyandinvitepotentialauthors,andreviewcontributionsinordertoensure
technical quality while working with Springer project managers tokeep the project on schedule. This is awonderful
signoftheenergyandcollegialityofthecomputationalGISresearchcommunity.
Springer’sencyclopedia groupprovidedthoughtful guidelinesfortheentries.Typicalentriesare3000wordsandpro-
vide balance among definition, scientific fundamentals, application domains, and future trends. Many include short
definitionalentriescross-referencedtorelatedregularentriesinordertodiscussspecifictermsandconceptssuchasthe
GlobalPositioningSystem,DigitalElevation/TerrainModel,andRemoteSensing.Regularentriesincludekeycitations
andalistofrecommended readingregardingtheliterature,and(online)internal hyperlinks todefinitional entriesand
XII Preface
current standards. This Encyclopedia is also simultaneously available as an XML online reference with hyperlinked
citations,cross-references,four-colorart,linkstoWeb-basedmaps,andotherinteractivefeatures.
KeyFeaturesataGlance
• Immediatepointofentryintothefieldforresearchers
• A–Zformatallowseasy,intuitiveaccessfornewcomerstothefield
• Manyheadersforeasyskimmingandnavigationoftopics
• IncludescoverageofGISstandardsindevelopmentbyISO
• Cross-referencedentries
• Internationallyrenownededitorialboard,bothscientificallyandgeographicallydiverse
• Hundredsofcontributorsensurebalancedcoverage
• Interactivefeaturesaddtoconvenience,easeofuseandunderstanding
• Peer-reviewedentriesassureresearchersthatinformationisvetted
• eReferenceisavailableatspringerlink.com
ContentOrganization
The encyclopedia is divided into 41 fields, each one an important sub-area within GIS. These fields include: Basic
Concepts;BasicStorageandRetrievalStructure;CartographyandVisualization;CommercialGIS;CommercialSpatial
Databases;CriticalEvaluationofStandardProposals;DataExchangeandInteroperability;DigitalRoadMap;Emergen-
cyEvacuations;EvacuationPlanningandOperations;GeosensorNetworks;GeoSpatialSemanticWeb;GISinBusiness
Intelligence,Routing;GISIssuesandApplications;IndoorPositioning;InformationCollectionUsingSensorNetwork;
OpenSourceGISSoftware;Photogrammetry;RepresentationofInexactSpatialInformation;RoadNetworkDatabases;
SecurityandPrivacyinGeospatial Information Systems;Spatial Analysis;Spatial AspectsofBioinformatics; Spatial
AspectsofDistributedComputing; SpatialAspectsofMobileComputing; SpatialAssociationDiscovery;SpatialCo-
locationRuleMining;SpatialConstraintDatabases;SpatialDataWarehousingandDecisionSupport;SpatialDatabase
Modeling for Applications; Spatial Indexing; Spatial Outlier Detection; Spatial Prediction; Spatial Thinking; Spatial
TimeSeries;Spatial Uncertaintyand Imprecision; Spatio-Temporal DataModeling; Spatio-Temporal Databases;Sta-
tisticalModelingforSpatialData;TesselationDataModels;andUseofSpatialDataforSimulation.
Acknowledgements
Many people have played a part in the production of this book and we are extremely grateful to them. In particular,
field editors who have made excellent efforts include Vijay Atluri, Sudipto Banerjee, Yvan Bedard, Sanjay Chawla,
RobertDenaro,LipingDi,FredericoFonseca,AndrewFrank,OscarFranzese,DimitriosGunopulos,ErikHoel,Kath-
leen Hornsby, Yan Huang, Robert Kauffman, Baris Kazar, Sangho Kim, Ravi Kothuri, Phaedon Kyriakidis, Xinrong
Li,HenryLiu,Chang-TienLu,NikosMamoulis,HelmutMayer,LiqiuMeng,MohamedMokbel,AndreasNeumann,
SilviaNittel,LeonOsborne,Sudhanshu SekharPanda,SrinivasanParthasarathy,PeterRevesz,AshokSamal,Markus
Schneider,CyrusShahabi,JayantSharma,YufeiTao,VassilisTsotras,OuriWolfson,ChaoweiYang,PushengZhang,
andNaijunZhou.
WewouldliketothankthemembersofthespatialdatabaseresearchgroupintheComputerScienceDepartmentatthe
University of Minnesota. They contributed in many different ways including providing literature surveys, organizing
topics,andreviewingarticles.WewouldalsoliketothanksomeofthestudentsenrolledinCsci8701andCsci8715for
contributingarticles.
Finally,specialthanksareduetomanypeopleatSpringerfortheirenthusiasm,advice,andsupport. Inparticular, we
wouldliketothankSusanLagerstrom-Fife,OonaSchmid,JenniferCarlson,AndreaSchmidt,SimoneTavenrath,Sharon
Palleschi,andYanaLambert,whoatdifferenttimeshaveplayedkeyrolesinthedevelopmentofthisbook.
August,2007 ShashiShekharandHuiXiong
