Goodchild VGI2007

1

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.

2

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.

3

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.

4

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

5

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.,

6

Expedia), eBay,andCraigsListallexploitthiscapability.Bytheearly2000sthisabilityofuserstosupplycontenttoWebsiteshadgrowninsophisticationtothepointwhereitbecamepossibletoconstructsitesthatwerealmostentirelypopulatedbyusergeneratedcontent,withverylittlemoderationorcontrolbythesitesownersandverylittlerestrictiononthenatureofcontent.Insomecasesuserscouldeveneditthecontentcreatedbyothers. BlogsandWikisfallintothiscategory,asdo thesitesreviewedintheprevioussection.Collectively,theyhavebeentermedWeb2.0.Firstandforemost,then,VGIisaresultofthegrowingrangeofinteractionsenabledbytheevolvingWeb.

Figure5.AGoogleEarthmashupoftheareaofSoho,London.Thecontemporaryimagerybasehasbeenobscuredbyan1843mapfromtheDavidRumseycollection.Superimposedonthisarethedeaths(green)fromcholeraintheoutbreakof1854,andthewatersources

7

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.

8

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.

9

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

10

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

11

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

12

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

13

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.

14

Figure8. AswathofSantaBarbaraapproximately60mwidehasdisappearedbecauseofmisregistrationofimageryinGoogleEarth.Notetheblurringdownthecenteroftheimage,andthebreakinHighway101,oneofthefewfeaturestocrosstheswathdiagonally.

THEVALUEOFVGI

AsIhopetheexamplesinthispaperillustrate,VGIhasthepotentialtobeasignificantsourceofgeographersunderstandingofthesurfaceoftheEarth.Itcanbetimely,apropertythatwasparticularlystressedinthediscussionofearlywarning.Bymotivatingindividualstoactvoluntarily,itisfarcheaperthananyalternative,anditsproductsarealmostinvariablyavailabletoall(butseetheearlierdiscussionofthedigitaldivide).

InearliersectionsIdiscussedwhypeoplemightbemotivatedtocreateVGI,butnottouseit.WithsitessuchasWikimapiaonecanlearnagreatdealaboutremoteplaces,acquiringthekindsofinformationneededforplannedtouristvisits,ortoprovidebackgroundtotravelogs.SitessuchasOpenStreetMapoftenprovidethecheapestsource

15

ofgeographicinformation,andsometimestheonlysource,particularlyinareaswhereaccesstogeographicinformationisregardedasanissueofnationalsecurity.

ItisalreadyclearinmanyfieldsthatsuchinformalsourcesasblogsandVGIcanactasveryusefulsourcesofmilitaryandcommercialintelligence.ThetoolsalreadyexisttoscanWebtextsearchingforreferencestogeographicplaces,andtogeocodetheresults.ThusthemostimportantvalueofVGImaylieinwhatitcantellaboutlocalactivitiesinvariousgeographiclocationsthatgounnoticedbytheworldsmedia,andaboutlifeatalocallevel.ItisinthatareathatVGImayofferthemostinteresting,lasting,andcompellingvaluetogeographers.

REFERENCES

Brown,M.C.,2006.HackingGoogleMapsandGoogleEarth.NewYork:Wiley.Butler,D.,2006.Virtualglobes:thewebwideworld.Nature439:776778.Estes,J.E.andW.Mooneyhan,1994.Of mapsandmyths.PhotogrammetricEngineering

andRemoteSensing60:517524.FernndezArmesto,F.,2006. Amerigo:TheManWhoGaveHisNametoAmerica.

London:WeidenfeldandNicolson.Goodchild,M.F.,P.Fu,andP.Rich,2007.Sharinggeographicinformation:an

assessmentoftheGeospatialOneStop. AnnalsoftheAssociationofAmericanGeographers97(2):249265.

Johnson,S.,2006. TheGhostMap:TheStoryofLondonsMostTerrifyingEpidemic,andHowItChangedScience,Cities,andtheModernWorld.NewYork:Riverhead.

Monmonier,M.,2006.FromSquawTittoWhorehouseMeadow.Chicago:UniversityofChicagoPress.

NationalResearchCouncil,1993.TowardaCoordinatedSpatialDataInfrastructurefortheNation.Washington,DC:NationalAcademiesPress.

NationalResearchCouncil,2007.SuccessfulResponseStartswithaMap:ImprovingGeospatialSupportforDisasterManagement.Washington,DC:NationalAcademiesPress.