ADirectManipulationUserInterfaceforQuerying GeographicDatabases

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1 ADirectManipulationUserInterfaceforQuerying GeographicDatabases DCC-IMECC-UNICAMP-CP CampinasSPBrazil JulianoLopesdeOliveira ClaudiaBauzerMedeiros browsingandqueryinggeographicdata.thisinterfaceprovidesuserswithahigh facilities. asinglegeoreferencedentity,therebyaddinganewdegreeofexibilitytoquerying levelobjectorientedconceptualviewoftheunderlyingdatabase,independentofthe database'snativedatamodel.itletsusersmanipulatedierentrepresentationsof Thispaperpresentsanarchitectureforadirectmanipulationuserinterfacefor Abstract enaassociatedwiththeirphysicallocation(coordinates)andspatialrelationships[car89]. 1Introduction GeographicInformationSystems{gis{aresystemsthatperformdatamanagementandre- aspectsofgeoreferenceddata. Examplesofgis~applicationsareurbanplanning,thematicandstatisticmappingfornatural resourcemanagementandpublicutilitymanagement[aro89]. oncombininga(usually)relationaldbmswithspecialhandlerswhichmanipulatespecic trievaloperationsforgeoreferenceddata.thistermreferstodataaboutgeographicphenom- [VE93]: aspatialdata{traditional,descriptivealphanumericattributes,handledbyconventionaldbms; properties. Oncestoredintoagis,georeferenceddatacanbeclassiedintotwomaincategories Datahandledbygisareoftenstoredingeographicdatabasesystems,whicharebased spatialdata{attributesthatdescribethegeometryandlocationofgeographicphenomena.spatialdatahasgeometrical(e.g.,size)andtopological(e.g.,connectivity) 1

2 cartographicform.gisusersmustthereforebeabletodenethepresentation(i.e.,display characteristics)oftheanswertoqueries.normally,thisissupportedinagisbyprocessing thequeryinthreesteps: 1.Thequeryprocessingmanagerretrievesfromthedatabasethedatathattheuserhas Geographicapplicationsrelyheavilyonsophisticatedgraphicaldisplays,usuallyinsome 2.(optional)Theretrieveddataiscombinedthroughdataanalysisfunctionstoobtain spatialprocessingalgorithms(e.g.,fromcomputationalgeometry); selectedinthequery.thisinitialstepcombinestraditionalretrievalwithspecic ingdata(correspondingtothedatabaseschema)andavailabledataranges.presentation specicationoftenrequireslearningadditionalconcepts. 3.Theretrieved(orderived)dataaredisplayedaccordingtotheuser'spresentationspecications(symbols,texture,color). derivedinformationandcorrelationsamongthedata; Throughoutthisprocess,usersareexpectedtoknowtheorganizationoftheunderly- dierentlevels: degreeofexibilitytothedatabasequeryinterface.itconsistsofanarchitecturethatoers totheuseranobject-orienteddirectmanipulationinterfacethatallowsaccessingdataintwo Meta-datalevel:ithelpsusersnavigatethroughtheschemaofthegeographicdatabase, Thispaperpresentsasolutiontothebrowsingandretrievalissue,byaddinganew Datalevel:theuserdenestextualandvisualquerypredicates,throughsimultaneous selectingthetypesofdataforsubsequentquerying;and useoftwointeractionparadigms: {textual(traditional);and {visual-inthissecondinteractionmode,theusercanatthesametimedetermine thedevelopmentofgisapplicationsfromadatabasepointofview,pointingoutproblems iestool[oa93a]. Thisarchitecturehasalreadybeenimplemented,fortraditionaldatabases,inthegood- Theremainderofthispaperisorganizedasfollows.Section2discussessomeissuesin bothconventionalandspatialdata. thevaluerangesforaspatialattributes,aswellasthedisplaycharacteristicsof intheeldofvisualizationandqueryinterfaces.section3presentsthearchitectureofthe proposedinterface.section4describesaworkingsessionusingthisarchitecture.finally, section5presentsconclusionsanddirectionsforfuturework. 2

3 ations. manipulationofobjectsin2dand3dspace;andstructuresforsupportinggeometricoper- 2GISapplicationsanddatabases algorithmsintwoelds:spatialdatastructures(e.g.,quadtrees)whichallowtheecient Thedatabasecommunityhascontributedtogisresearchbydevelopingdatastructuresand aspointedoutby[ve93],thattheinteractionaspecthasbeenconsideredinthedesignof theuser'srequestsintoappropriatedatabaseoperations)andoptimization(byindexingdata withspatialstructures,andusingcomputationalgeometryalgorithms).itisonlyrecently, gisinterfaces. Ingeographicqueryprocessing,theemphasishasbeenoncomputation(i.e.,translating space{cells{inamatrix).eachcellcontainsonethematicvalue.cellsmayhavedierent intheroad).databaseentitiescorrespondtotheserecognizableobjects. (e.g.,agivenroad).inthismodel,twoobjectscanoccupythesameplace(e.g.,aturnpike world:theeldmodelandtheobjectmodel[fg90,goo91].theobjectviewtreatstheworld asasurfacelitteredwithrecognizableobjects,whichexistindependentofanydenition Fielddataisprocessedintesseralformat(spatialobjectsdescribedaspolygonalunitsof Users'modellingofgeoreferencedentitiesisassociatedwithdierentperceptionsofthe shapes;squarecellsarecalledpixels.therasterformat(whichisoftenusedasthegeneric namefortesseraldata)isjustonespecialtypeoftesselationwithrectangulargridformat. ofcoordinatepairs.thistypeofformatisusuallymoreadequateforrepresentingmanmadeartifacts(e.g.,bridges),whereastheeldmodelisadoptedmostlyinenvironmental applications[cou92].onechallenge,fortheinterfacedesigner,istoaccommodateboth Thisoftenrequiresthatdierentrepresentationsbestored(e.g,varyingaccordingtotime Objectdataisstoredaspoints,linesandpolygons(thevectorformatmodel),usinglists typesofmodelinqueryprocessingmechanisms. orscale),incurringtherebyintoproblemssuchasestablishinglinksandconsistencyamong distinctrepresentationsofagivenregion.queriesingeographicdatabasesmustthuscombine andintegratebothspatialandaspatialdata,aswellasconsiderthedierentrepresentations foragivengeoreferencedentity. Geographicrealityisperceivedaccordingtotheuserneedsandtheapplicationdomain. interactivemanipulationofgeographicelements textualquerylanguages;and gisinterfacesusuallysupporttwotypesofinteractionmechanisms[mp94]: arepointedoutin[ege92].othertextualquerymechanismsusuallyrelyonextending assql(e.g.,[gut88,goh89,pz91,ooi90,lor91]).thedisadvantagesofthisapproach objectorientedquerylanguageswithspatialprocessingmethods(e.g.,[sv92]).somerecent resultsexploittheuseofnaturallanguageinqueries,forrestrictedapplicationdomains(e.g., [Wan94]). Mosttextualquerylanguagesarebasedonextensionsofrelationalquerylanguagessuch 3

4 ofagivengeoreferenceddataset,aswellasdeningtheamountofobjectsthataretobe displayedforagivenwindowsize(e.g.,[akk94]).mostcommercialsystemsallowpredenitionofthepresentationcharacteristicsofstoredelementsbyclickingonmenuswhichallow Somegisqueryingmechanismsallowspecifyingtheoutputvisualcharacteristicsaspart ofatextualquery(see[ege94]).othermechanismsallowdeterminingmultiplepresentations associatingeachdatatypewithitsvisualizationfeatures(color,texture). (e.g.,[ccm92,vms+93]).forsomeapplicationdomains,queriesmaybespeciedasdirectedgraphswithpredicates(e.g.,[men93]),hypertextfacilities(e.g.,[lr93])orcombining formsandicons[wcy89].theproblemsinvisualqueriesconsistmainlyinprovidingthe querytranslationmechanismwithenoughinformationtodisambiguatetheusers'requests, necessarilytakeatleastthefollowingaspectsintoconsideration: sincesomeoftheiconicoperatorsaresemanticallyoverloaded(e.g.,[cm91,bm92]). Integrationbetweentheinterfaceandtheunderlyingdatabase Thedesignofinterfacesforgeographicdatabases,and,morespecically,gis,mustthus shipsamongdatafromthisvisualoutput(e.g.,bydierencesincolor,orfromrelativedis- tances{[spo93,kk94]).however,theselanguagesarenotdirectlyapplicabletogeographic Visualquerylanguagesfordatabasesystemsallowtheusertoassociateweightstovalues inthedatabase,whicharedisplayedinsomegraphicalform.userscaninferrelation- userspecifypredicatesbycombiningapredenedsetofspatialoperatorsavailableiconically databases.veryfewproposalsexistforvisuallanguagesforgis.theserelyonlettingthe Representationofspatialconcepts gisusersareusuallyexpertsinagivenapplicationdomain,butknownothingabout theunderlyingdatamanagementsystem.usersmustnotbeforcedtolearnmorethan Querytypes onequerylanguage,norhavetoknowtheunderlyingdatabaseschema. Aninterfacemustsupportmultiplerepresentationsofagivengeoreferencedentity, (whathaschangedinanareathroughtime,andhow),alternativeevaluation,routing. dependingontheusers'needs[rig95]. Basictypesofqueriesinvestigatecontents(describingcontentsofaregion),location (determininglocationofelementssatisfyingagivensetofpredicates),time/trends theaboveissues,therebyaddinganewdegreeofexibilitytogeographicdatabases. ographicdatabases,whichcombinesbothtextualandvisualcharacteristics.itcontemplates Thenextsectiondescribesourarchitectureforabrowsingandqueryinginterfaceforge- Aninterfacemustthusbeabletoprovideuserswithenoughtoolstoaccessdatainall theseways. 4

5 ticulartoagis:strongintegrationandweakintegration[voi94].intheformer,theuser 3SystemArchitecture Therearetwobasicapproachestointegrateauserinterfacesystemtoadbms,andinparever,itpresentsthedisadvantageofdemandingthedenitionofcommunicationanddata conversionprotocolsbetweentheuserinterfacesystemandthegeographicalsystem. interfaceispartofthegeographicalsystem,sharingitsdatamodelandtakingadvantage oftheknowledgeabouttheinternaldatastructures.asaconsequencethereisgreatdif- consideredanexternalmodule,andisthereforeadaptabletomorethanonesystem.how- interfacetodierentgis.inthesecondapproach,weakintegration,theuserinterfaceis cultyinusingdatafromdierentsources,anditisnotpossibletoadaptthesameuser systemsthatpursuethiskindofarchitecture(e.g.,[aya+92,vvo92,gr93,pmp93,vs94]). vantagesoutnumberitsshortcomings.first,thereisaworld-widetrendtowardsthedevelop- mentofopensystems,whichcanbeintegratedwithotherproducts,andgisareamongthe tionalityofeachcomponent(userinterfaceandgeographicaldatamanagement).further- more,thisphilosophyallowsimportingspecializedpackages,suchasgraphicallibraries,into Thearchitecturepresentedhereisbasedontheweakintegrationapproach,sinceitsad- Second,thiskindofintegrationprovidesindependenceandimprovesspecializationoffunc- theuserinterface.lastbutnotleast,thisintegrationapproachallowstheprogressiveinclusionofnewservicesandfunctionsinthegis. andtheobjectviewsofthegeographicalworld.itconsistsoffourlevelsofabstraction:the realworldlevel(therealgeographicalphenomena);theconceptuallevel(anabstractviewof therepresentationlevel(whereoperationsarespecializedtoeachparticularrepresentationof thesephenomena,inwhichoperationsareindependentfromtherepresentationofthedata); Intheweakintegrationapproach,theuserinterfacecanbecoupledtodierentgis.This chosetheobject-orientedgismodelof[cfs+94].thisdatamodelsupportsboththeeld approachneedsthereforearichdatamodeltorepresentconceptsusedindierentgis.we phenomenonmaybeperceiveddierentlyaccordingtoapplicationneeds.bysupporting view).eachsuchclasshasitsownhigh-leveloperationsandparticularrepresentations. thismodel,theinterfacearchitectureestablishesaframeworkfortwoimportantend-users Themodelsupportsthemultiplerepresentationparadigm,inwhichagivengeoreferenced storageandretrievalofdata,forinstance,spatialindexesandaccessmethods).georeferencedentitiesareconceptuallyclassiedintogeo-objects(objectview)andgeo-elds(eld ageographicalentity);andthephysicallevel(whichdealswithissuesthatprovideecient requirements:userscanmanipulatemultiplerepresentationsattheinterfacelevel;andusers candenedistinctpresentations(displaycharacteristics)foreachrepresentation. Theuserdialogmodulemanagestheuserinteractionwiththeinterfacesystem.Itis Thearchitectureoftheinterface,presentedingure1,hasthreemaincomponents: model(andvice-versa).thesetasksareperformed,respectively,bythepresentation thetranslationofuser'srequestsintooperationsoftheunderlyinggeographicdatabase responsiblefortwomaintasks:thecreationandmanagementofpresentations,and 5

6 USER Graphic Package Interaction Manager User Dialog Module Display Manager Figure1:ArchitectureoftheUserInterfaceSystem Data Model Module Conceptual Representation Manager Manager External Driver GIS ofwidgets(controlarea).eachrepresentationofthedatacanbevisualizedthrough managerandbytheinteractionmanager.thebindingwiththegraphictoolkitis anotherimportanttaskwithintheuserdialogmodule. Thistaskinvolvesgraphicaldisplayoperations(displayarea)anddynamicconstruction Schema Data Operation dierentpresentations(e.g.,graphical,diagramsortabular). Thedenitionandmanagementofpresentationsarehandled,inthescreen,through twoareas:acontrolareaforquerydenitionandadisplayareaforresultvisualization. Manager Manager Manager Thedatamodelmoduleisresponsibleforprovidingtotheuseraviewoftheunderlying high-levelconceptualoperationsongeoreferenceddata,managedbythedatamodel Thesecondmaintaskisthetranslationofdirectmanipulationactionsoftheuserinto ties.therepresentationmanagerrecordsthedierentrepresentationsassociatedwith module. managerisresponsiblefortheobject-orientedschemathatdescribesgeographicalenti- databasewhichiscompatiblewiththeadopteddatamodel[cfs+94].theconceptual 6

7 Theexternaldriverconvertsdatafromtheformatusedinthegistotheinternal eachconceptualentity.themaintaskofthedatamodelmoduleistosupporta highlevelconceptualviewofdata.itthereforesupportsbrowsingonconceptsrather thanonrepresentations,allowingtheusertoseemultiplerepresentationsofthesame data.anotherimportanttaskofthismoduleistoconvertconceptualoperationsinto representationdependentoperations,whicharesenttotheexternaldriver. datamodeloftheinterfaceandvice-versa.thisisachievedbymeansofacommunicationprotocolthatisbasedonprimitiveoperationsthatallowretrievingfromthe gisdatabaseschemas,classdescriptionsanddatavalues.theapproachusedinthe denitionofthismoduleisthesameweusedtointegrateauserinterfacetodierentobject-orienteddatabasesystems[oa93b].theinterfacesendsqueriestothegis abletodealwithmanyunderlyinggis,dependingonaddingnewexternaldrivermodules. Althoughgure1showsonlyoneexternaldriverandonegis,thearchitectureisperfectly geographicdbms. usingtheprimitiveoperations(get-schema,get-class,andget-value),andtheexternaldriverimplementstheseoperationsaccordingtothesyntaxoftheunderlying dialogmoduleusesthegoodiesopensystem[oa93a],agenericoodbmsbrowser. thedatamodel.toprovidefacilitiesfornavigatinginbothobjectandschemalevel,theuser builtfromtheunderlyinggisschemasaccordingtothedenitionoftheconceptuallevelof graphicalspace.eachconceptualviewcorrespondstoanobject-orienteddatabaseschema Thearchitectureoftheinterfacesystemsupportsdistinctconceptualviewsofthegeo- 4AQueryInterfaceforObjectsandFields Theprevioussectionshowedanarchitectureforaweaklycoupledgisuserinterface.The architecturehasthreemaincomponentswhichhandle,respectively,thecommunicationwith user.thissectionpresentshowtheinterfaceguidestheuserthroughbrowsingandquerying uleisresponsiblefortranslatinguseractionsintooperationsongeoreferenceddataandfor levelsofthefour-levelobject-orienteddatamodelof[cfs+94].finallytheuserdialogmodternaldrivermoduleisanextensionofourpreviousworkintheintegrationofuserinterfaces inoodbms[oa93b].thedatamodelmodulereliesontheconceptualandrepresentation convertingthedataprovidedthroughthedatamodelmoduleintowindowspresentedtothe thegeographicdatabase,theinterfacedatamodelandtheinteractionwiththeuser.theex- Oneimportantproblemingisinterfacesishowtosupportuserquerieswithoutrequiring specializedknowledgeoftheunderlyingdatabase.thisissolvedinthepresentinterface georeferenceddata. 4.1WorkingSession{GuidingtheUserthroughDataSelection byhelpingtheuserthroughasequenceofstepsthatwillconstructthequery.oncethe 7

8 dataisretrievedanddisplayed,theusercaninteractwithitthroughdirectmanipulation intoschemadenitionofthequeryandquerypredicatespecication.dataisthusretrieved mechanisms[shn83]. intoapre-establishedqueryschemasimilartoaviewmechanism[mm91].theschema bothforenvironmentalcontrolandutilitymanagementapplications.thestepsaredivided denitionstepsare: 1.schemanavigationandclassselection; Thestepsthatareprovidedarebasedonourexperienceofworkingwithdierentgis, underlyinggeographicdatabaseandretrievestheavailableschemasusingtheprimitiveoperationget-schema.ingeneral,adatabasecontainsdatafromaparticularprojector application,andreferstothesamegeographicalregion.usingthesedatatheconceptual 3.denitionofrepresentationsforeachselectedentity; 4.determinationofvisualaspect. 2.choiceofclassentities; managermountstheschemasintheinterfaceconceptualmodel(geo-schemas). arerelevanttotheuser'sneeds.astheelementsareselected,theyareaddedtothecontrol Whentheuserstartsasession,theexternaldriverestablishesaconnectionwiththe entitiesisatrivialprocessofselectingoptionsinamenu.thesamegeoreferencedentity areaoftheinterface.theselectionofrepresentationandvisualizationcharacteristicsfor canselectthedesiredrepresentationfortheentity.theinterfacesystemalsoallowstheuser mayhavemorethanonerepresentation.ageo-eld,forexample,mayberepresentedbya satelliteimageorbyasetofcoordinatevaluepairs.thus,afterchoosinganentity,theuser Theusercanbrowsethroughdierentgeo-schemastoselecttheelements(classes)that toeachrepresentation.forinstance,ageo-eldthatisrepresentedbypairs(coordinate, toselectthelookoftheentityinthedisplay,i.e,itassociatesdierentkindsofpresentations asamap(e.g.,a2dsurface). schema.theslidershowsthreevalues:theminimumandmaximumvaluesthatthegeo- value)maybepresentedinatabularform,asagraph(histogram,pie-chart,andothers)or representedbyapushbuttonlabeledwiththenameofthegeo-objectintheconceptual objectattributes.oncetheschemaisdened,theuserformulatesaquerybyselecting eldmayassume,andacurrentvalueselectedbydirectmanipulation.geo-objectsare schema.clickingthebuttoncausesthedisplayofanauxiliarywindowcontainingthegeo- rangesforgeo-elds,valuesforattributesofgeo-elds,andtypingalphanumericalpredicates. Geo-eldsarerepresentedbyasliderlabeledwiththenameoftheclassintheconceptual Thesepredicatescancombinecomparisonoperators,logicalconnectorsandspatialfunctions implementedintheunderlyinggis. 8

9 noviceuserstousethequeryingfacilities;toimprovetheprocessofselectionandexploration fromanspecicgis;toprovidepowerfultoolsforexpertusers;toreducethetimeneededfor 4.2RequirementsandDesign Thecharacteristicsofauserinterfacesystemforgisimposeseveralchallengestotheinterface developer.themainrequirementsfortheinterfacepresentedherewere:tobeindependent ofdata;toprovideaconceptualviewofthegeographicalspaceintermsofobjectsand model.theotherrequirementswereprovidedbysupportingastepwisequerydenitionand representationfacilitieswereensuredbybasingthearchitectureontheappropriatedata aparticulargiswasensuredbytheweakintegrationapproach.theconceptualviewand representationsofthesamegeographicentity,andmultiplevisualizationsofasingledata representation. elds;tosupportnotonlydatalevelbutalsoschemalevelnavigation;toallowmultiple bythecharacteristicsofthedisplaymanager. ofthedynamicqueryparadigm[aws92].thisparadigmiswellsuitedfordatasetswith Inordertomeettheusabilityrequirements,theuserdialogmoduleimplementsavariation Someoftherequirementsweremetbythearchitecturespecication.Independencefrom multiplesearchkeys,andisbasedonthegraphicalrepresentationofbothqueriesandresults, thedynamicqueryparadigmhasgainedinterest,becauseitisnowpossibletoprovide thenecessary(almost)real-timeanswersforcomplexqueries.interfacesystemsusingthis paradigmarebeginningtoappearintheliterature[kk94,akk94].withdynamicqueries, theinterfacesystemisusuallyveryeasytouse,evenfornoviceusers;atthesametime, feedbackforthiskindofinteraction.withtherecentadvancesinsoftwareandhardware, ontheuseofdirectmanipulationofgraphicalobjects(widgets)andontheimmediate theparadigmcanprovidepowerfultoolsforexpertusers.butthemostdesiredfeatureof dynamicqueriesisthatitencouragesuserstoexplorethepotentialofinformationsinthe database. 4.3Usingtheinterface:atypicalexample acivildefenseapplicationwheretheuserisinterestedinidentifyingriskareasfornatural Thefeaturesoftheinterfacecanbebetterunderstoodbymeansofanexample.Consider distributionofcitiesasregardsforestsanddeclivities.theuseridentiesthatthereisa catastrophes,fortheregionstoredinthedatabase.consideraqueryconcerningspatial potentialreriskforallcitiesthatareclosetoconiferousforestsinhighdeclivityareas,and wantstovisualizethesedata. informationavailableintheunderlyinggis,inaveryabstractlevel.theuserndstheentity selectedforquerying.inresponsetothisselection,theinterfacesystemindicatestheonly Vegetation,whichistherootofaclasshierarchycontainingsubclassConiferous,whichis representationavailableinthedatabasefortheentity,andoerstheuserthepresentation relatedtothedenedproblem.duringthisprocesstheusergainsknowledgeaboutallthe optionsthatareallowedforthiskindofdatarepresentation.theuserselectsthedefault Firsttheuserbrowsesthroughtheobject-orientedschemas,lookingforclassesthatare 9

10 Declivityclass,butthereisatightlyrelatedclass,Altitude,whichisthusselected.The presentation:acolorplanarmap. interfacesystemndsouttworepresentationsfortheselectedclassinthegis:triplesof coordinates(x,y,z)andsatelliteimages,bothofwhichcorrespondtoeldviews.the Continuingtheschemalevelbrowsing,theuserrealizesthatthereisnoschemawitha Figure2:Finalscenariowithselectionofgeo-object indicated,alldataelementsarepresented.thenalresultisdisplayedingure2,where classcity,withtherespectiverepresentationandpresentationoptions.ifnopredicatesare foreachclasscanbevisualizedthroughthelegendoptionoftheviewmenu.thesliders declivityaspect). thecontentsofthethreeclassesareoverlayedanddisplayedinonescenario.thelegend userselectstherstrepresentation,andchoosestheisolinepresentationoption(toseethe indicatethattheuserisgettingthecompleterangeofaltitudes(100to1500meters)and alltheninedierenttypesofconiferousforeststoredinthedatabase.movingthesesliders Thelastconceptinvolvedintheusertaskareurbanareas,andtheuserselectsthe discardingallothers,aswellasdeningtextualpredicatesforthem.valuesofattributes ofgivenobjectscanbevisualizedthroughselecting(clicking)theminthegraphicalareaof dowcontainingallthecityclassattributes.theuserisallowedtoselectrelevantattributes, themainwindow.figure2showstheselectionofanobject(whichishighlighted)closeto geo-object.clickingthecitybuttoncausestheinterfacesystemtopresentanauxiliarywin- allowuserstospecifytherangeofvaluesforvisualizationofsuchgeo-elds. aconiferousforest,andgure3(left)showstheobject'sattributewindow. Examiningthecontrolareaofthemainwindow,theusercaninferthattheCityclassisa Forinstance,gure3(right)showsauser-denedpredicatethatselectsfordisplaythecities Theusercanapplypredicates,asdenedinsection4.1,torestrictthedisplayedobjects. 10

11 queryisshowningure4. withmorethanonemillionhabitantswhichhavelessthanvehospitals.theresultofthe ableintheunderlyingdatabase(e.g.,distance,area).thesefunctionsareactivatedbya combinationofselectionoftheappropriategeo-classesandclickingthefunction(intheedit Dierentgeographicqueriesmaybeposedbyapplyingthecorrespondingfunctionsavail- Figure3:Visualizingandqueryingattributesofageo-object menuofthemainwindow). 5Conclusionsandfuturework databases.thisarchitecturehasthefollowingadvantagesoverothergisinterfaces: Thispaperpresentedanarchitectureofadirectmanipulationuserinterfaceforgeographic itgivestheuserahighlevelobject-orientedviewoftheunderlyingdata,whichapproachestheusertoaconceptualviewoftheworld; thereof; determinedisplaycharacteristicsatthesametimequerypredicatesareposed itdoesnotrequirethatusershavepreviousknowledgeoftheunderlyingdatabase schemaorquerylanguage; itallowsuserstoposequeriesbymixingtextualandvisualparadigms,therebyhelping itsupportsmanipulationofdierentrepresentationsofdata,anddistinctpresentations 11

12 iestool[oa93a].thisisnowbeingextendedtoaccommodatequeriesongeographic istotrytosupportupdatesthroughtheinterface,whichnecessarilywillneeddierent databases. Thisuserinterfacearchitecturewasimplemented,fortraditionaldatabases,inthegood- Otherextensionsbeingconsideredconcernthearchitecture'sdesign.Animportantissue Figure4:QueryResultsinMainWindow translationsdependingontherepresentationandpresentationchosenforagivendata.this, inturn,fallsintotheproblemofspatialintegrityconstraints,itselfanopenissue.another problembeingconsideredisthemaintenanceofthespatialfunctionsprovidedthroughthe TheworkdescribedinthispaperwaspartiallynancedbygrantsfromFAPESPandCNPq, underlyingdatabase. Acknowledgements aswellasgrantsfromcnpqprotemprojectgeotecandtheeuropeancommunityitdc projectgeotoolsnumber References [AKK94]M.Arikawa,H.Kawakita,andY.Kambayashi.DynamicMapsasComposite [Aro89]S.Arono.GeographicInformationSystems.WDLPublications,Canada,1989. ViewsofVariedGeographicDatabaseServers.InProceedingsoftheInternational ConferenceonApplicationsofDatabases,

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