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CITIZENSASSENSORS:THEWORLDOFVOLUNTEEREDGEOGRAPHY
MichaelF.Goodchild1
ABSTRACT
InrecentmonthstherehasbeenanexplosionofinterestinusingtheWebtocreate,assemble,anddisseminategeographicinformationprovidedvoluntarilybyindividuals.SitessuchasWikimapiaandOpenStreetMapareempoweringcitizenstocreateaglobalpatchworkofgeographicinformation,whileGoogleEarth andothervirtualglobesareencouragingvolunteerstodevelopinterestingapplicationsusingtheirowndata.Ireviewthisphenomenon,andexamineassociatedissues:whatdrivespeopletodothis,howaccuratearetheresults,willtheythreatenindividualprivacy,andhowcantheyaugmentmoreconventionalsources?Icomparethisnewphenomenontomoretraditionalcitizenscienceandtheroleoftheamateurin geographicobservation.
INTRODUCTION
In1507inStDidesVosges,MartinWaldseemllerdrewanoutlineofanewcontinentandlabeleditAmerica(Figure1).ItappearsthathewasinfluencedbynewbooksbeingcirculatedinEuropeatthetime,andparticularlybytheSoderiniLetteranditspurportedauthorAmerigoVespucci,andthelattersclaimstothecontinentsdiscovery.AlthoughWaldseemllerwithdrewthenameonalatermap,andalthoughmanyscholarsandanewbiographybyFelipeFernndezArmesto(2006)castdoubtontheauthenticityoftheLetter,thefeminineformofVespuccisfirstnamestuck,andwaseventuallyadoptedastheauthoritativenameofnotonebuttwocontinents.
Bytodaysstandardsthisactofnamingbyanobscurecartographerwouldattractlittleornoattention.ModernnamingindevelopedcountriesiscloselyregulatedbyahierarchyofcommitteesthatintheU.S.extendfromthelocaltothenationallevel(Monmonier,2006).TheBoardonGeographicNameswasestablishedin
1NationalCenterforGeographicInformationandAnalysis,and DepartmentofGeography,UniversityofCalifornia,SantaBarbara,CA931064060,USA.Phone+18058938049,FAX+18058933146,[email protected]
Figure1.AnextractfromtheWaldseemllermapof1507.
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1890forthepurposeofstandardizingtheuseofnameswithinthefederalgovernment,andthuswithinthenationalmappingagencies.InEnglishtheterm gazetteer,thecommontermforaplacenameindex,isitselfrootedinofficialauthority,andrenamingofgeographicfeaturesrequiresalengthyprocessofreview,andisvirtuallyimpossibleexceptinspecialcircumstances.Geographicnaminghasbeencentralizedandstandardized,andassignsnoroleto obscureindividualslikeWaldseemller,whowouldcertainlybeamazedtolearnthathismapwasrecentlyacquiredbytheU.S.LibraryofCongressfor$10million.
Nevertheless,theeventsof1507provideanearlyechoofaremarkablephenomenonthathasbecomeevidentinrecentmonths:thewidespreadengagementoflargenumbersofprivatecitizens,oftenwithlittleinthewayofformalqualifications,inthecreationofgeographicinformation,afunctionthatforcenturieshasbeen reservedtoofficialagencies.Theyarelargelyuntrainedandtheiractionsarealmostalwaysvoluntary,andtheresultsmayormaynotbeaccurate.Butcollectively,theyrepresentadramaticinnovationthatwillcertainlyhaveprofoundimpactsongeographicinformationsystems(GIS)andmoregenerallyonthedisciplineofgeographyanditsrelationshiptothegeneralpublic.Itermthisvolunteeredgeographicinformation (VGI),aspecialcaseofthemoregeneralWebphenomenonof usergeneratedcontent,anditisthesubjectofthispaper.
THEEVOLVINGWORLDOFVGI
OneofthemorecompellingexamplesofVGIisWikimapia,which adaptssomeof theproceduresthathavebeensosuccessfulinthecreationoftheWikipediaencyclopediaandappliesthemtothecreationofagazetteer.AnyonewithanInternetconnectioncanselectanareaontheEarthssurfaceandprovideitwithadescription,includinglinkstoothersources.Anyonecaneditentries,andvolunteerreviewersmonitortheresults,checkingforaccuracyandsignificance.AttimeofwritingWikimapiahad4.8millionentriescomparedtoWikipedias7million,describingfeaturesranginginsizefromentirecitiestoindividualbuildings(eachentrysgeographicextentisdefinedbyrangesoflatitudeandlongitude).Somedescriptionsareextensiveandincludehyperlinksforexample,theentryforMadinah(SaudiArabia)includesapicture of theMasjideNabawiandalinktothecitysWikipediaentry.Otherentriesdescribefeatureswithinthecity(Figure2)orinthesurroundingarea.
SimilarinsomerespectsistheFlickrsite,whichallowsuserstouploadandlocatephotographsontheEarthssurfacebylatitudeandlongitude.Attimeofwritingroughly2.8millionphotographswerebeingcontributedeachmonthtothesite.Figure3showsoneofthemorethan2,500volunteeredphotographsofUluru(AyersRock)incentralAustralia.
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Figure2InformationfromtheFlickrsitefortheareaofUluru(AyersRock)incentralAustralia.Eachsymboldenotestheavailabilityofaphotographattimeofwritingthereweremorethan2,500availablefortheareashown.Descriptiveinformation
AtaratherdifferentlevelofsophisticationisMissPronouncer,asitecreatedbyJackieJohnsontohelppeoplepronouncesomeofthemoredistinctiveWisconsinplacenames.Afulltimeradiobroadcaster,MsJohnsondevelopedthesiteinhersparetime,andoffersaudiorecordingsof thecorrectpronunciationofalmost2,000placesinthestate.Phonicrepresentationsofplacenameshavetheadvantagethattheyarenotsubjecttoproblemsoverdifferencesofalphabet(Beijingversus, Baghdadversus),thoughthephonicrenderingofcommonplacenamesmayvaryfromonelanguagetoanother(e.g,Paris,Moscow).
OtherVGIactivitiesfocusonthecreationofmoreelaboraterepresentationsoftheEarthssurface.OpenStreetMapisaninternationalefforttocreateafreesourceofmapdatathroughvolunteereffort.Figure4showsthemapforpartofDublinattimeofwriting.Notetheincompletenatureof themap,withmajorstreets,railways,andparksshownbutwithminorstreetdetailinsomeareasbutnotothers,andsomestreetsnamedbutnotothers.Dublinfamouslylacksacheap,readilyavailabledigitalstreetmap,asdomanyothercitiesaroundtheworld,sothisvolunteereffortcanpotentiallyfillayawninggapintheavailabilityofdigitalgeographicinformation.
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Figure3.TheWikimapiacoverageofMadinah,SaudiArabia.Eachboxdenotestheavailabilityofinformationdescribingthefeatureoutlinedbythebox.
WhenGoogleacquiredthesoftwarepreviouslyknownasEarthviewer,rebrandedit,redesignedtheuserinterface,andpublishedanapplicationprograminterface,itcreatedaservicethathadimmediateappealtomillions.IhavedescribedtheGoogleEarthphenomenonasthedemocratizationofGIS(Butler,2006),becauseithasopenedsomeofthemorestraightforwardcapabilitiesofGIStothegeneralpublic.WhereasthecreationofaflybywaspreviouslyoneofthemoresophisticatedGIStasks,itisnowpossibleforachildoftentocreateoneintenminutes.GoogleEarthandGoogleMapspopularizedtheterm mashup,theabilitytosuperimposegeographicinformationfromsourcesdistributedovertheWeb,manyofthemcreatedbyamateurs.Forexample,Figure5showsaGoogleEarthmashupoftheSohoareaofLondon duringthe1854choleraoutbreakmadefamousbyDrJohnSnow(Johnson,2006).ItcombinesastreetmapofLondonfrom1843(fromtheonlineprivatecollectionofDavidRumsey,aSanFranciscomapcollector)with onlinedataonthewatersourcesandcholeradeathsfrommyownWebsite.Readilyavailablesoftwaremakesthiskindofmashupremarkablyeasy (see,forexample,Brown,2006) andwellwithinthecapabilitiesofthegeneralpublic.Asaresult,thenumberofavailablemashupshasreportedly reachedthehundredsofthousands,andthenumberofdownloadsoftheGoogleEarthsoftwareexceedsahundredmillion.
Thesearejustafewexamplesofaphenomenonthathastakentheworldof geographicinformationbystorm andhasthepotentialtoredefinethetraditionalrolesofmappingagenciesandcompanies.InthenextsectionIexaminesomeofthetechnologiesthathave
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combinedtomakethispossible.Thisisthenfollowedbyadiscussionofrelevantconceptsandissues,andthenbyananalysisoftheusefulnessofVGI.
Figure4.PartoftheOpenStreetMapcoverageofDublin,Ireland.Notethemissingstreetnamesandareaswherenocoverageisavailable.
ENABLINGTECHNOLOGIES
Web2.0TounderstandVGI,wemustfirstaskaboutthetechnologiesthatmakeitpossible.EarlyconceptsoftheWebstressedtheabilityofuserstoaccessremotesitesthroughsimpleinterfacesknownasbrowsers(Mosaic,launchedin1992,wasthefirstwidelyavailablebrowser).OnecouldsurftheWebbyfollowinghyperlinks,typicallyhighlightedwordsthatwhen clickedwouldinitiateadownloadfromanotherpageorsite.Webpagesconsistedprimarilyoftext,butgraphicimagescouldalsobeincluded,takingadvantageoftherecentlyexpandedgraphicscapabilitiesofpersonalcomputers.Inallofthis,however,therelationshipbetweenuser(client)andWebpage(locatedonaserver)wasessentiallyonewaytheusersonlyrolewastoinitiatethedownloadingofcontent.
Intimeitbecamepossiblefortheusersroletoextendsomewhat.Protocolsweredevelopedthatalloweduserstoaccessinformationstoredinaserversdatabases,andeventoaddrecordstosuchdatabasesby completingforms.Airlinereservationsites(e.g.,
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Expedia), eBay,andCraigsListallexploitthiscapability.Bytheearly2000sthisabilityofuserstosupplycontenttoWebsiteshadgrowninsophisticationtothepointwhereitbecamepossibletoconstructsitesthatwerealmostentirelypopulatedbyusergeneratedcontent,withverylittlemoderationorcontrolbythesitesownersandverylittlerestrictiononthenatureofcontent.Insomecasesuserscouldeveneditthecontentcreatedbyothers. BlogsandWikisfallintothiscategory,asdo thesitesreviewedintheprevioussection.Collectively,theyhavebeentermedWeb2.0.Firstandforemost,then,VGIisaresultofthegrowingrangeofinteractionsenabledbytheevolvingWeb.
Figure5.AGoogleEarthmashupoftheareaofSoho,London.Thecontemporaryimagerybasehasbeenobscuredbyan1843mapfromtheDavidRumseycollection.Superimposedonthisarethedeaths(green)fromcholeraintheoutbreakof1854,andthewatersources
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Georeferencing
GISreliesontheabilitytospecifylocationontheEarthssurfaceusingasmallnumberofwelldefinedandinteroperablesystems,ofwhichlatitudeandlongitudeisbyfarthemostuniversal.Mostcountrieshavesomeformofnationalgridthatprovidesanalternativelocalcoordinatesystem,andtheUniversalTransverseMercator (UTM)systemhasbeenadoptedforthegeographiccoordinatesneededbymanymilitaryagencies.Allofthesearespecialized,however,andinnormalhumandiscourseitisplacenamesthatprovidethebasisofgeographicreferencing.Veryfewpeopleknowthelatitudeandlongitudeoftheirhome,letaloneitsUTMcoordinates.Toenablethecreationofgeographicdatabythegeneralpublic,therefore,itisnecessarytohavearangeofreadilyavailabletoolsforidentifyingthecoordinatesoflocationsontheEarthssurface.
Severaltoolsnowsupplythisneed,andcollectivelyenableVGI.TheGlobalPositioningSystem(GPS)canbeaccessedbyawiderangeofconsumerproducts,allowinglocationtobemeasuredinmanystandardcoordinatesystems.CamerascanbeenabledwithGPS,sothatdigitalphotographscanbeautomatically taggedwithcoordinates.SomeGPSreceiversstoreentiretracksthatcanlaterbeuploadedindigitalform,andsimilarcapabilitiescanbebuiltintomobilephones.Coordinatescanalsobeobtainedthroughaprocessknownasgeocoding.AnyrecognizedstreetaddresscanbematchedtoadigitalstreetfileinaserviceavailableinmostGISsoftwareaswellasontheWeb.
AtechnicallysimpleroptionistousetheimageryavailablethroughGoogleEarth,GoogleMapsorsimilarservicestoselectalocationvisually,andtorecorditscoordinatesbyclicking.Severalservicesallowthisapproachtobeusedtocreatedigitalrecordsofentirestreetsandotherfeaturesbyfollowing(digitizing) thefeaturesonthescreentheresultsarethen uploadedandcompiledintocompositedigitalmaps.OpenStreetMaphasalreadybeencitedasanexampleofthisapproach.
Geotags
A geotagisastandardizedcodethatcanbeinsertedintoinformationinordertonoteitsappropriategeographiclocation.GeotagshavebeeninsertedintomanyWikipediaentries,whenthecontentsrelatetoaspecificlocationontheEarthssurface,andseveralsitesallowsuchentriestobeaccessedfrommaps.Forexample,Figure6showstheresultof searchingtheGeonamessiteforWikipediaentriesinFrenchintheregionofAlsaceLorraineclickingonthesymbolbesideStDidesVosgesbringsupthetownsWikipediadescription.Attimeofwritingtherewereover60,000geotaggedentriesintheWikipediaFrenchlanguageresourcealone.
GPS
TheGlobalPositioningSystemisarguablythefirstsysteminhumanhistorytoallowdirectmeasurementofpositionontheEarthssurface.GPSreceiversareeasytouse,andprovidevirtuallyinstantaneousestimatesoflocation,oftentobetterthan10maccuracy.
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Incorporatedinincarnavigationsystems,GPSallowsthecurrentlocationofthevehicletobecomparedtothecontentsofadigitalstreetmap.Asastandalonedevice,areceiveristhebasisofthepopularsportof geocaching,whichengagesparticipantsinfindinghiddendestinationsbasedonlyontheircoordinates.GPShassparkedanumberofinterestingVGIactivities,suchasthecreationofmapsbywalking,cycling,ordriving.Figure7showstheinterestingmapcreatedbymycolleagueValNoronha,whohasinstalledaGPSinhiscartokeeptrackofhisdailytravelsaroundhisneighborhoodinGoleta,California.Thecolorsdenotehisaveragespeed.
Figure6.TheGeonamessiteshowsthegeographiclocationgeotaggedinWikipediaentries,allowingtheencyclopediatobeaccessedviamaps.
Graphics
Itiseasytoforgetthathighqualitygraphicsareacomparativelyrecentinnovationinthehistoryofcomputing.Dynamicvisualizationofthreedimensionalobjects,suchasoccurswithGoogleEarth,requiredahighlysophisticatedandexpensivecomputerasrecentlyas1995,andwhenEarthviewerappearedin2000onlyafewpersonalcomputershadthepowerfulgraphicshardwareneededtorunit.Today,ofcourse,lowlyhouseholdcomputershavesufficientpower,thoughdevicesbuiltforvideogames,suchasWii,oftenhaveevengreaterpower.
Broadbandcommunication
Finally,VGIwouldbeimpossiblewithoutwidespreadaccesstotheInternet,preferablyviaahighcapacityconnection.Manyhouseholdsindevelopedcountriesnowhavesuchbroadbandconnections,usingarangeofsatellite,cable,andphonelinetechnologies.
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Figure7.AveragedrivingspeedloggedbyonecaroveranextendedperiodaroundanareaofGoleta,California.
CONCEPTS
Spatialdatainfrastructurepatchworks
Itiseasytobelievethattheworldiswellmapped.Mostcountrieshavenationalmappingagenciesthatproduceandupdatecartographicrepresentationsoftheirsurfaces,andremotesensingsatellitesprovideregularlyupdatedimages.Butinrealityworldmappinghasbeenindeclineforseveraldecades(EstesandMooneyhan,1994).TheU.S.GeologicalSurveynolongerattemptstoupdateitsmapsonaregularbasis,andmanydevelopingcountriesnolongersustainnationalmappingenterprises.
Thedeclineofmappinghasmanycauses(Goodchild,Fu,andRich,2007).Governmentsarenolongerwillingtopaytheincreasingcostsofmapping,andoftenlooktomapusersassourcesofincome.Remotesensinghasreplacedmappingformanypurposes,butsatellitesareunabletosensemanyofthephenomenatraditionallyrepresentedonmaps,includingthenamesofplaces.Intheearly1990stheMappingScienceCommitteeoftheU.S.NationalResearchCouncilissuedareportdescribingtheconceptofspatialdatainfrastructure(NRC,1993),whichitdefinedastheaggregateofagencies,technologies,people,anddatathattogetherconstitutedanationsmappingenterprise.
Amongthemanyconceptsintroducedinthereportwasthatof patchwork,thenotionthatnationalmappingagenciesshouldnolongerattempttoprovideuniformcoverageoftheentireextentofthecountry,butinsteadshouldprovidethestandardsandprotocolsunderwhichnumerousgroupsandindividualsmightcreateacompositecoveragethatwouldvaryinscaleandcurrencydependingonneed.ThecreationoftheNationalSpatialDataInfrastructure (NSDI)wasauthorizedbyPresidentClinton underExecutiveOrder12906
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in1994,andhasprovidedthepolicyumbrellaforgeographicinformationintheU.S.forthepast13years.
VGIclearlyfitsthemodelofNSDI.Acollectionofindividualsactingindependently,andrespondingtotheneedsoflocalcommunities,cantogethercreateapatchworkcoverage.Given aserverwith appropriatetools,thevariouspiecesofthepatchworkcanbefittedtogether,removingany obviousinconsistencies,anddistributedovertheWeb.Theaccuracyofeachpieceofthepatchwork,andthefrequencywithwhichitisupdated,canbedeterminedbylocalneed.
Humansassensors
Recentlyagreatdealofattentionhasbeendevotedtotheconceptofsensornetworks.TheobservationalobjectivesofEarthscience,aswellastheobjectivesofsecurityandsurveillance,canbeaddressedatleastinpartbytheinstallationofnetworksofsensorsacrossthegeographiclandscape.Commonlycitedexamplesincludethenetworkofvidoemonitorsinmanymajorcities,proposalstoinstrumenttheoceanandseabedwithsensorsintheinterestsofscienceandearlywarningoftsunamis,andnetworksoftrafficsensorsthatcanprovideusefulinformationtoplanners,aswellasrealtimepicturesofcongestion.
Itisusefultodistinguishthreetypesofsensornetworks.Mostexamplesfitthefirst,anetworkofstatic,inertsensorsdesignedtocapturespecificmeasurementsoftheirlocalenvironments.Lesscommonlycitedaresensorscarriedbyhumans,vehicles,oranimals.Forexample,muchusefulresearchisemergingfromprojectsthathaveequippedchildrenwithsensorsofairpollution,inanefforttounderstandthefactorsaffectingasthma.Athirdtypeofsensornetwork,andinmanywaysthemostinteresting,consistsofhumansthemselves,eachequippedwithsomeworkingsubsetofthefivesensesandwith theintelligencetocompileandinterpretwhattheysense,andeachfreetorovethesurfaceoftheplanet.
Thisnetworkofhumansensorshasover6billion components,eachanintelligentsynthesizerandinterpreteroflocalinformation.OnecanseeVGIasaneffectiveuseofthisnetwork,enabledbyWeb2.0andthetechnologyofbroadbandcommunication.
Citizenscience
Theterm citizenscienceisoftenusedtodescribecommunitiesornetworksofcitizenswhoactasobserversinsomedomainofscience.AperfectU.S.exampleistheChristmasBirdCount,anefforttoenlistamateurornithologistsinconductingamidwintercensusofbirdpopulations.Participantsrequireafairlyhighlevelofskill,andovertheyearsanumberofprotocolshavebeenestablishedtoensurethattheresultingdatahavehighquality.AninternationalexampleisProjectGLOBE,anefforttoenlistschoolchildrenandtheirteachersinprovidingaworldwidesourceofhighqualityatmosphericobservations.AswiththeChristmasBirdCount,anumberofprotocolsandtraining
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programshavebeenestablishedtoensurequality,andtocollect,synthesize,andredistributetheresults.
Bothoftheseprojectsrequireafairdegreeoftrainingandexpertise.ThisneedforexpertisewouldbealimitingfactorinanyefforttoextendVGItosuchcomparativelysophisticatedmappingthemesaslanduse,landcover,orsoilclass.OtherformsofVGIaremuchlessdemanding,however,particularlythoseassociatedwithplacenames,streets,andotherwelldefinedgeographicfeatures.
Participantpopulations
SitessuchasWikimapiaareopentoall,asaremanyotherVGIefforts.TheChristmasBirdCountandProjectGLOBE,ontheotherhand,placerestrictionsonparticipationinordertoensureadequateexpertise.Thequestionofwhomayvolunteerhasmuchtodowiththequalityoftheresultinginformation,andarangeofpossibilitiesexist.Formanyyearscompaniesproducingdigitalstreetmapshavereliedonnetworksoflocalobserverstoproviderapidnoticeofnewstreets,changesofstreetnames,etc.,payingthemasparttimeworkers. Inrixiscollectingtracksfromhundredsofthousandsoftrucksandotherfleets,processingandcompilingtheresultsasasourceofrealtimeinformationonthestateofcongestionandothershorttermfactorsaffectingtravelonroadnetworks.Militarypersonnelareimportantpotentialsourcesofgeographicinformationaboutlocalbattlefieldconditionsthatcanbeusedtoaugmentwhatisavailablefromcentralmappingandimagerysources. Manyfarmersnowhaveelaboratesystemsformappingandmonitoringtheirfieldsandcrops(precisionagriculture),andconstituteapotentialsourceofdatathatisinmanycasesmuchmoredetailedandcurrentthanthatavailablefromcentralagriculturalagencies.Inessence,suchdevelopmentscontributetoagrowingreversalofthetraditional topdownapproachtothecreationanddisseminationofgeographicinformation.
Earlywarning
RecenteventssuchastheIndianOceantsunamiorHurricaneKatrinahavedrawnattentiontotheimportanceofgeographicinformationinallaspectsofemergencymanagement,andtotheproblemsthatariseintheimmediateaftermathoftheeventbeforeadequateoverheadimagerybecomesavailablefordamageassessmentandresponseplanning(NRC,2007).Earthobservingsatellitesmaynotpassovertheaffectedareaforseveraldays.Imagesfromsatellitesandaircraftmaybeobscuredbycloudsandsmoke.Conditionsonthegroundmaypreventtherapiddownloadingofdigitalimagerybecauseofalackofpower,Internetconnections,orcomputerhardwareandsoftware.
Ontheotherhandthehumanpopulationintheaffectedareaisintelligent,familiarwiththearea,andincreasinglyabletoreportconditionsthroughmobilephones,usingvoice,text,orpictures.TodatetherehasbeenverylittleuseofVGIinthesesituations,inpartbecauseofanalmostcompletelackofthetoolsneededtocollect,synthesize,verify,andredistributetheinformation.Howeverthepotentialtoobtainalmostimmediatereports
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fromgeographicallydistributedobserversonthegroundwillsurely driveincreasedeffortstoovercometheseproblemsinthenextfewyears.
ISSUES
Whydopeopledothis?
Inthemid1990stheU.S.FederalGeographicDataCommitteepublisheditsContentStandardsforDigitalGeospatialMetadata,aformatforthedescriptionofgeographicdatasets.Theprojectwasverytimely,giventherapidincreaseintheavailabilityofgeographicinformationviatheInternetthatoccurredatthattime.Metadatawereseenasthekeytoeffectiveprocessesofsearch,evaluation,anduseofgeographicinformation.Nevertheless,anddespitenumerouseffortsandinducements,itremainsverydifficulttopersuadethoseresponsibleforcreatinggeographicdatasetstoprovideadequatedocumentation.EvensuchapopularserviceasGoogleEarthhasnowayof informingitsusersofthequalityofitsvariousdatalayers,anditisvirtuallyimpossibletodeterminethedatewhenanypartofitsimagebasewasobtained.ArecentnewsreportconcernedtheapparentreplacementofitscoverageofNewOrleanswithpreKatrinaimagery,thoughitscoverageoftheDarfurregionisupdatedalmostdaily.
Giventhisevidentreluctancetoprovidedocumentation,itisperhapssurprisingthattheopportunitytocreateandpublishVGIhasengagedtheinterestsofsomanyindividuals.WhyisitthatcitizenswhohavenoobviousincentiveareneverthelesswillingtospendlargeamountsoftimecreatingthecontentofVGIsites?Whatkindsofpeoplearemorelikelytoparticipate,andwhatdrivesthemtobeaccurate(orinaccurate)?
SelfpromotionisclearlyanimportantmotivatorofInternetactivity,andinitsextremeformcanleadtotheexhibitionismofpersonalwebcams.DespitethevastresourcesoftheWeb,itisstillpossibletobelievethatsomeonewillbeinterestedinonespersonalsite.Thepopularityofsomeblogscanbemisreadassuggestingthatanaudienceexistsforanyblog.
AtadifferentlevelmanyusersvolunteerinformationtoWeb2.0sitesasaconvenientwayofmakingitavailabletofriendsandrelations,irrespectiveofthefactthatitbecomesavailabletoall.ThismayunderliethepopularityofsitessuchasPicasa,whichallowcontributorsof personalphotographstopointotherstothem,butitscarcelyexplainsthepopularityofFlickrorWikimapia,wherecontentiscomparativelyanonymous.ContributorstoOpenStreetMapmayderiveacertain personalsatisfactionfromseeingtheirowncontributionsappearinthepatchwork,andfromwatchingthepatchworkgrowincoverageanddetail,buttherecanbenoquestionofselfpromotioninthisessentiallyanonymousproject.
Authorityandassertion
Thetraditionalmappingagencieshaveelaboratestandardsandspecificationstogoverntheproductionofgeographicinformation,andemploycartographerswithdocumented
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qualifications.Overtheyearstheirproductshaveacquiredanauthoritythatderivesfromeachagencysreputationforquality.Google,on theotherhand,hasnosuchreputationinthegeographicdomain.Neverthelessusersappearwillingtoascribeauthoritytoitsproducts,perhapsbecausecomputerizationcarriesauthority perse,andperhapsbecauseofthecompanyssuccessinotherareas,particularlyitssearchengine.
AttimeofwritingGoogleEarthsimageryoverthecampusoftheUniversityofCalifornia,SantaBarbarawasmisregisteredbyapproximately20meastwest.FurthertotheeastintheCityofSantaBarbarathemisregistrationwasapproximately40meastwestintheoppositedirection,andaswathapproximately60mwiderunningnorthsouthwasmissingfromthecoverage(Figure8).AnylocationsgeoreferencedfromthisimageryandincorporatedintoVGIwillinheritthesepositionalerrors,andifGooglereregisterstheimageryatafuturedatethatVGIwillbeclearlymisplaced.Inessence,GooglehascreatedanewdatumorhorizontalreferencesystemthatissubstantiallydifferentfromthecurrentNorthAmericandatum,butwhichiswidelyacceptedbecauseoftheauthorityofGoogle.TheshiftiscomparableinmagnitudetothatcreatedwhenNorthAmericanmappingagenciesreplacedtheNorthAmericanDatumof1927(NAD27)withthecurrentNAD83.
VGIissometimestermedassertedgeographicinformation,inthatitscontentisassertedbyitscreatorwithoutcitation,reference,orotherauthority.TheearlydaysoftheInternetwerecharacterizedbyacertainaltruism,abeliefintheessentialgoodnessofusers,andtherewaslittleanticipationofthesubversivephenomenaofspam,viruses,anddenialofserviceattacksthatnowpervadethenetwork.SimilarlymanyVGIeffortsaredrivenbythekindsofaltruisminherentinanykindofvoluntarycommunityeffort.Canweexpect,then,asimilarpatternofdisillusionmentasantisocialelementsrecognizeandexploittheinevitablevulnerabilities?Willtherebeeffortstocreatefictitiouslandscapes,ortoattackandbringdownVGIservers?VGIiscurrentlyasomewhatexoticdomain,butifandwhenusersbegintorelyonitsservicesagrowingpatternofeffortstoundermineitseemsinevitable.
Thedigitaldivide
DespitetheapparentopennessofVGI,itremainslargelythepreserveofthosefortunatetohaveaccesstotheInternetandbroadbandaccessinparticular.Whileagrowingfractionofcitizensindevelopedcountrieshavesuchaccess,itislargelyunavailabletothemajorityoftheworldspopulationwholiveindevelopingcountries.Moreoverissuesoflanguageandalphabetalsoaffectaccessevenforthosewithbroadbandconnections,sincemanyVGIserverssupportonlytheRomanalphabetandEnglish.Inprinciple,muchcouldbeachievedthroughmobilephones,whichoftenhavetheabilitytoconnecttotheInternetandtocaptureimages,butthetoolsneededtoexploitthislimitedenvironmentasasourceforVGIdonotyetexist.SowhileIarguedabovethatsuchlimitedtoolswerepotentiallysignificantinearlywarningandemergencymanagement,significantworkstillneedstobedonetorealizethepotential.
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Figure8. AswathofSantaBarbaraapproximately60mwidehasdisappearedbecauseofmisregistrationofimageryinGoogleEarth.Notetheblurringdownthecenteroftheimage,andthebreakinHighway101,oneofthefewfeaturestocrosstheswathdiagonally.
THEVALUEOFVGI
AsIhopetheexamplesinthispaperillustrate,VGIhasthepotentialtobeasignificantsourceofgeographersunderstandingofthesurfaceoftheEarth.Itcanbetimely,apropertythatwasparticularlystressedinthediscussionofearlywarning.Bymotivatingindividualstoactvoluntarily,itisfarcheaperthananyalternative,anditsproductsarealmostinvariablyavailabletoall(butseetheearlierdiscussionofthedigitaldivide).
InearliersectionsIdiscussedwhypeoplemightbemotivatedtocreateVGI,butnottouseit.WithsitessuchasWikimapiaonecanlearnagreatdealaboutremoteplaces,acquiringthekindsofinformationneededforplannedtouristvisits,ortoprovidebackgroundtotravelogs.SitessuchasOpenStreetMapoftenprovidethecheapestsource
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ofgeographicinformation,andsometimestheonlysource,particularlyinareaswhereaccesstogeographicinformationisregardedasanissueofnationalsecurity.
ItisalreadyclearinmanyfieldsthatsuchinformalsourcesasblogsandVGIcanactasveryusefulsourcesofmilitaryandcommercialintelligence.ThetoolsalreadyexisttoscanWebtextsearchingforreferencestogeographicplaces,andtogeocodetheresults.ThusthemostimportantvalueofVGImaylieinwhatitcantellaboutlocalactivitiesinvariousgeographiclocationsthatgounnoticedbytheworldsmedia,andaboutlifeatalocallevel.ItisinthatareathatVGImayofferthemostinteresting,lasting,andcompellingvaluetogeographers.
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