Home Tekniikka Tietojen järjestäminen

Tietojen järjestäminen



Hierarchicaldataorganization

People’sperceptionoftherealworldisoftenlimitedtoasmallareaoracertainindividualobject.TheserealworldobjectsarecalledAnentityisanobjectivelyexistingobjectwithcertaincharacteristics.Atypeofentitywithcertaincommoncharacteristicscanbecalledanentitygroup;inaddition,therearemanygeographicalphenomenaonthesurface,whichcanbedescribedbyfields,forexample,Terrainelevation,airtemperature,soilmoisture,etc.;accordingtothedatatypeofthedependentvariable,thefieldcanbedividedintotwotypes:continuousfieldanddiscretefield.Infact,anygeographicalphenomenoncanbeexpressedthroughthefield.However,inmanycases,amethodcanprovideabetterbasisforeffectivecalculations,anditmayalsobeabettermodelforpeople'spsychologicalexpressionofgeographicphenomena.Forexample,thestateorprovinceofacountryisusuallyexpressedinGISasagroupofareaobjectsoragroupoflineobjectsformingitsboundary;ofcourse,itcanalsobeexpressedasadiscrete2-dimensionalfield.Entityandfieldcananswerdifferentquestions(whereandwhat)respectively.Ofcourse,theprocessofansweringquestionsmustbebasedontime(when).ThiswayofcognitionresultsinahierarchicaldataorganizationmethodinGIS,thatis,thestructureofgeographicentitiesintomathematicalpoints,lines,areas,andgridcells(grid).

Thehierarchicalclassificationtheoryisoneofthebasictheoriesforpeopletoperceivetherealworld."Layer"isanimportantbasicconceptinGIS,and"Layer"isoneofthemostbasicandimportantmethodsofGISdataorganization,asshownintheupperdiagraminFigure1.Hierarchyinthevectormodelisaccompaniedbyclassification(mainlyreferstotheclassificationofabstractgeometricelements,suchaspoint,line,surface,andbody,etc.).Therastermodelismainlyhierarchical,andeachlayerofdataafterlayeringhasCorrespondingattributesandspaceandotherinformation,thelogicalorganizationmodelisshowninthefigurebelow.

GISdataisorganizedbyseveralspatialdatalayersandtheirrelatedattributedata.Aspatialdatalayerisstoredintheformofseveralspatialcoordinatesorrasterpixels.Thislogicalorganizationmodelcanbesummarizedascoordinatepair-spatialobject-layer-map.Aspatialobjectanditsattributeinformationbelongtothemostbasiclevelinthismodel,andthemapisthehighestlevelofthismodel.Theinformationinthegeographicdatalogicalorganizationmodelcanbeclassifiedasfollows:

(1)AtlasTämä on maantieteellisen tietoorganisaation huipputason tiedot,joka hallitseekokoa lasiajaprosessoi eri karttoja, mukaan lukienseuraavat tiedot:karttapreference(taulukonnimi,maplayernumber jne.),kartan koordinaatit(koordinaattijärjestelmä,rekisteröintitiedotmaacddescripts,etc. .)ja muita tietoja.

(2)LayersetTämä on kerrosjoukko, joka koostuu useista tilakerroksista, jotka voivat täyttää tietyt sovellusvaatimukset, mukaan lukien kerrosviittaukset (tasotunniste, kerroksen taulukon nimi), tasotilaindeksi (koko, tarra, taulukon nimi), kerroksen näyttö, kerroskoordinaattialue (maksimi- ja vähimmäistiedot) ja vähimmäismäärä.

(3)LayerTämä on kokoelma saman tyypin useita tilaobjekteja, joilla on tietyt samat tai samankaltaiset ominaisuudet, mukaan lukien tilaobjektin tunniste (tunniste, nimi) ja kuvaus (nimi, ominaisuuden attribuutti, tyyppi), tilaobjektien geometrinen esitys (binary OBge).

TheaboveisthedataorganizationmethodofGISverticallayering.Thislayereddataorganizationismap-oriented.Inthedatabase,thelibrary—mapsheet—layer—geographicalobject—geometricobjectisgenerallyused.Dataorganizationstrategy.Horizontally,GISdataisorganizedbyframingordividinggrids(tiles),andthentheyarespatiallyindexed.Thiskindofdataorganizationisrealizedinthecomputerthroughtheseparationofgraphichierarchicalfilemanagementandattributedatarelationaldatabase(RDBMS)management.Therearetwoways:oneistoembedRDBMSintotheGISsystemInternal;theotheristouseanextendedRDBMStomanageattributedatainadditiontotheinternalRDBMS.TheconnectionbetweenspatialdataandattributedataiscompletedbythekeyID.

Ominaisuuksiin perustuva tietoorganisaatio

Hierarkiseen tietoorganisaatioon perustuvassa maantieteellisten ilmiöiden kuvauksessa on seuraavat puutteet:

(1)Real-worldspatialgeometrytargetsAbstractionignorestheessentialcharacteristicsofgeographicphenomenaandtheirinternalconnections,andartificiallydividestherealworld,whichresultsinthesimplificationofGISinformationandreducesthecapacityofGISinformation.

(2)PayattentiontothedescriptionofspatiallocationsThevectororrasterdataorganizationmodelofthecompanylosestherichanalysiscapabilitiesprovidedbythestructuredentitiesbasedontheclassificationattributesandinterrelationships;

(3)TheoverlapmethodTherealworldisdividedintoaseriesoflayerswithstrictboundaries,buttheseboundariescannotfullyreflecttheobjectivereality,whichcausesmanyhumanerrors;inaddition,thismethodcannotprovidethespatialanalysiscapabilitiesofmanybasicobjects.

Actually,inthehierarchicaldataorganization,point,line,surface,andgridunitsdonotexist.Inreality,roadsarenotmathematicallines,andcitiesarenotmathematicalpoints.Thisabstractionisnotadescriptionorexpressionofrealgeographicspace.Theperceptualworldaroundusisasetofmaterialentitieswithhighlycorrelatedstructures,thatis,theseentitieshaveasetofcommonattributesthatallowpeopletoclassifyonthebasisofsimilarity.Therecognitionofthecommonalityofgeographicentityattributesandrelationshipsisthestartingpointofpeople'scognition(Usery1993).Itcanbeseenthatpeople'sfirstknowledgeoftheobjectiveworldisbasedongeographicfeatures,andthiswayofcognitioncreatesamethodofdataorganizationbasedongeographicfeatures.ISO/TC211andOGCrespectivelydefinegeographicfeatures:

(1)AccordingtothedefinitionofISO/TC211,featureshavetwolevels:featuretypesandfeatureinstances.Featuretypesaregeographicphenomenawithcommonattributes.Afeatureinstanceisaspecificgeographicphenomenonofafeaturetype;eachfeatureinstancehasauniqueidentifier,whichisencapsulatedwithattributes,functionsandrelationships,andcancomprehensivelydescribethecharacteristicsoftheoccurrenceanddevelopmentofthefeaturetype.Symbols,aseriesofcharacteristicstatesoreventscanbeorganicallylinkedandorganizedtogether,andcanbepositionedinthespace-timecoordinatesystem,whichisconducivetothemanagementandqueryofspace-timedata;

(2)DefinitionofOGC,Featureisthebasicunitofgeospatialinformation;Inaddition,USGISintheUnitedStatesalsogivesitsowndefinitionoffeature:Featureisanentityortarget(digital/orgraphic)expressionoftheobjectiveworld.Itcanbeseenthatafeatureisadescriptionorexpressionofarealgeographicalphenomenon.Thisgeographicalphenomenoncanbearealgeographicalentity,suchasariverorlake,oritcanbeaclassificationresult,suchasdifferenttypesofland,orItisameasurementresultofacertainphenomenon,suchashightemperaturearea,highrainarea,etc.Therefore,ageographicfeatureisageographicentitythatexistsobjectivelyontheearthandhasdescriptiveinformation,andthisgeographicentitycanbedefinedbyitsidentificationanddescriptionofitsattributesandrelationships.

Thebasisoffeature-basedGISdataorganizationisfeatureclassification.Itdirectlyaffectstheeffectivenessofgeographicdataorganization,management,queryandanalysis;itaffectsthecompletenessofgeographicdatamodelsemanticsanddatasharing.Therefore,feature-basedGIScanbeconstructedusingobject-orientedtechnology.Itsdataorganizationframeworkneedstousetherelevantconceptsofcognitiveclassificationtheoryandtherelevantmethodsofcartography.Thismethodofdataorganizationrequiresacorrectandappropriategeographicclassificationsystem.Whilefollowingthegeneraltaxonomyprinciples,thesystemmustalsoconsidertheneedsofGIStechnology(suchasobject-orientedtechnology).Itrequiresthattheclassificationsystembeincorporatedintoanon-spatialattributeInthedeterminedspacesystem.

Comparativeanalysisofthetwomethods

Thehierarchicaldataorganizationandthefeature-baseddataorganizationareatthesamelevelofabstraction.Botharebasedontheentitymodelandthefieldmodel,butFeature-baseddataorganizationusesobject-orientedtechnicalmethodstoorganizedataonthebasisofobject-orienteddatamodels,whilehierarchicaldataorganizationmainlyuseshierarchiesonthebasisofvectordatamodels,rasterdatamodels,andrelationaldatamodels.Themethodtoorganizedata;althoughwiththecontinuousdevelopmentandimprovementoftechnicalmeans,thelayereddataorganizationmethodhasalsoinfiltratedtheobject-orientedtechnology,butthisdoesnotconstituteatrueobject-orienteddatamodel.Itcanbeseenthatthereisafundamentaldifferencebetweenthetwo.

AsshowninFigure2,thesamegeographicphenomenonusesahierarchicaldataorganizationmethodtobedividedintoatleast3layers(points,lines,andareas),whileusingadataorganizationmethodbasedongeographicfeaturesonlyrequires1layer.,Andthespatialrelationshipbetweenthemisobvious.However,whetheritishierarchicalorfeature-baseddataorganization,itisinseparablefromtheanswerstothreebasiccognitivequestions,namelywhere,whatandwhen.

Spatialdataorganization

Intermsofdatamanagement,GISwillstorespatialdataandattributedatainthegeometricsenseseparately,andusefilesanddatabasemanagementrespectively.ThefuturedevelopmenttrendisapplicationObject-orientedmathematicalmodelandspatialdatawarehousetechnologythatusesadatabasetomanagemassiveamountsofdatainarealsense.

Yllä olevia periaatteita noudattaen suurikokoinen GIS-tietoorganisaatio, joka täyttää "digitaalisen maan" vaatimukset, on seuraava:

(1)Vektoritiedot: tallennetaan erikseen karttakehyksen ja mittakaavan mukaan.

(2)Rasterdata:regulargriddatawithacertaingridspacing(suchasDEM,imagedata,etc.),anditsdataorganizationisdifferentfromvectordata.Duetotheinfluenceofmapprojection,whenthedataisstoredingeographiccoordinates(latitudeandlongitude),thenumberofgridscontainedineachstandardframingmapisthesame,andthedataformsastandardrectangle;andwhenthedataisstoredinrectangularcoordinates(x,y)Whenstoring,thequantitycontainedineachstandardframingmapformsatrapezoid(approximately).Inordertosolvetheproblemofdataconnection,generallythecircumscribedrectangleofthefigureprofileisusedastheboundarytoformastandardrectangle,andthedataoutsidethefigureprofileFillitwithadjacentmapframedata,asshowninFigure3.

Duetotheunequalsizeoftheoriginaldata,dataconnectionproblemsareoftenencounteredduringdataroaming.Therearemanywaystosolvethisproblem.Amorefeasiblemethodistore-splicethedataandcutdatablocksofuniformshapeandsize.Inthisway,indataroaming,thesplicingofadjacentdatablocksisextremelysimple,whichavoidsdataredundancy.Iimprovedtheefficiencyofthesystem.Thedatacuttingrulesare:

①Aseta kaikki tiedot"digitaalisen maan" paikkakoordinaattikehyksen alle.

②Asiakaavasta ja ruudukkovälistä riippumatta jokaisen tietotiedoston (tietolohkon) koko on yhtenäinen.

③Määritä mittakaavan ja käyttöresoluutio(ruudukkoväli)käsite tietoskaalana.

④Establishfiledescriptioninformation,andrecordtheresolution,projectionzonenumber,filelocationandotherrelatedinformationofeachfileforeasysystemcall.

(3)IntegrationofvectordataandrasterdataDuetothedifferentdatastructure,dataorganizationanddisplaymethodsofvectorandraster,theintegrationofvectordataandrasterdatarequiresthefollowingprocess:

①Datamatchinganddisplay:includingunifiedprojection,scalematchingandcoordinatematching.

②Theconversionofvectordataandrasterdata:Thisconversionincludestheconversionofpoints,lines,andareas.Theconversionfromvectordatatorasterdataisrelativelysimple.Inpracticalapplications,thisconversionisoftenused.

This article is from the network, does not represent the position of this station. Please indicate the origin of reprint
TOP