数字地球英文.docx
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数字地球英文.docx
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数字地球英文
TheDigitalEarth:
Understandingourplanetinthe21stCentury
Anewwaveoftechnologicalinnovationisallowingustocapture,store,processanddisplayanunprecedentedamountofinformationaboutourplanetandawidevarietyofenvironmentalandculturalphenomena.Muchofthisinformationwillbe"georeferenced"-thatis,itwillrefertosomespecificplaceontheEarth’ssurface.
Thehardpartoftakingadvantageofthisfloodofgeospatialinformationwillbemakingsenseofit.-turningrawdataintounderstandableinformation.Today,weoftenfindthatwehavemoreinformationthanweknowwhattodowith.TheLandsatprogram,designedtohelpusunderstandtheglobalenvironment,isagoodexample.TheLandsatsatelliteiscapableoftakingacompletephotographoftheentireplaneteverytwoweeks,andit’sbeencollectingdataformorethan20years.Inspiteofthegreatneedforthatinformation,thevastmajorityofthoseimageshaveneverfiredasingleneuroninasinglehumanbrain.Instead,theyarestoredinelectronicsilosofdata.WeusedtohaveanagriculturalpolicywherewestoredgraininMidwesternsilosandletitrotwhilemillionsofpeoplestarvedtodeath.Nowwehaveaninsatiablehungerforknowledge.Yetagreatdealofdataremainsunused.
Partoftheproblemhastodowiththewayinformationisdisplayed.Someoneoncesaidthatifwetriedtodescribethehumanbrainincomputerterms,itlooksasifwehavealowbitrate,butveryhighresolution.Forexample,researchershavelongknownthatwehavetroublerememberingmorethansevenpiecesofdatainourshort-termmemory.That’salowbitrate.Ontheotherhand,wecanabsorbbillionsofbitsofinformationinstantlyiftheyarearrayedinarecognizablepatternwithinwhicheachbitgainsmeaninginrelationtoalltheothers—ahumanface,oragalaxyofstars.
Thetoolswehavemostcommonlyusedtointeractwithdata,suchasthe"desktopmetaphor"employedbytheMacintoshandWindowsoperatingsystems,arenotreallysuitedtothisnewchallenge.Ibelieveweneeda"DigitalEarth".Amulti-resolution,three-dimensionalrepresentationoftheplanet,intowhichwecanembedvastquantitiesofgeo-referenceddata.
Imagine,forexample,ayoungchildgoingtoaDigitalEarthexhibitatalocalmuseum.Afterdonningahead-mounteddisplay,sheseesEarthasitappearsfromspace.Usingadataglove,shezoomsin,usinghigherandhigherlevelsofresolution,toseecontinents,thenregions,countries,cities,andfinallyindividualhouses,trees,andothernaturalandman-madeobjects.Havingfoundanareaoftheplanetsheisinterestedinexploring,shetakestheequivalentofa"magiccarpetride"througha3-Dvisualizationoftheterrain.Ofcourse,terrainisonlyoneofthemanykindsofdatawithwhichshecaninteract.Usingthesystems’voicerecognitioncapabilities,sheisabletorequestinformationonlandcover,distributionofplantandanimalspecies,real-timeweather,roads,politicalboundaries,andpopulation.ShecanalsovisualizetheenvironmentalinformationthatsheandotherstudentsallovertheworldhavecollectedaspartoftheGLOBEproject.Thisinformationcanbeseamlesslyfusedwiththedigitalmaporterraindata.Shecangetmoreinformationonmanyoftheobjectssheseesbyusingherdataglovetoclickonahyperlink.Toprepareforherfamily’svacationtoYellowstoneNationalPark,forexample,sheplanstheperfecthiketothegeysers,bison,andbighornsheepthatshehasjustreadabout.Infact,shecanfollowthetrailvisuallyfromstarttofinishbeforesheeverleavesthemuseuminherhometown.
Sheisnotlimitedtomovingthroughspace,butcanalsotravelthroughtime.Aftertakingavirtualfield-triptoParistovisittheLouvre,shemovesbackwardintimetolearnaboutFrenchhistory,perusingdigitizedmapsoverlaidonthesurfaceoftheDigitalEarth,newsreelfootage,oralhistory,newspapersandotherprimarysources.Shesendssomeofthisinformationtoherpersonale-mailaddresstostudylater.Thetime-line,whichstretchesoffinthedistance,canbesetfordays,years,centuries,orevengeologicalepochs,forthoseoccasionswhenshewantstolearnmoreaboutdinosaurs.
Obviously,nooneorganizationingovernment,industryoracademiacouldundertakesuchaproject.LiketheWorldWideWeb,itwouldrequirethegrassrootseffortsofhundredsofthousandsofindividuals,companies,universityresearchers,andgovernmentorganizations.AlthoughsomeofthedatafortheDigitalEarthwouldbeinthepublicdomain,itmightalsobecomeadigitalmarketplaceforcompaniessellingavastarrayofcommercialimageryandvalue-addedinformationservices.Itcouldalsobecomea"collaboratory"--alaboratorywithoutwalls—forresearchscientistsseekingtounderstandthecomplexinteractionbetweenhumanityandourenvironment.
TechnologiesneededforaDigitalEarth
Althoughthisscenariomayseemlikesciencefiction,mostofthetechnologiesandcapabilitiesthatwouldberequiredtobuildaDigitalEarthareeitherhereorunderdevelopment.Ofcourse,thecapabilitiesofaDigitalEarthwillcontinuetoevolveovertime.Whatwewillbeabletodoin2005willlookprimitivecomparedtotheDigitalEarthoftheyear2020.Belowarejustafewofthetechnologiesthatareneeded:
ComputationalScience:
Untiltheadventofcomputers,bothexperimentalandtheoreticalwaysofcreatingknowledgehavebeenlimited.Manyofthephenomenathatexperimentalscientistswouldliketostudyaretoohardtoobserve-theymaybetoosmallortoolarge,toofastortooslow,occurringinabillionthofasecondoroverabillionyears.Puretheory,ontheotherhand,cannotpredicttheoutcomesofcomplexnaturalphenomenalikethunderstormsorairflowsoverairplanes.Butwithhigh-speedcomputersasanewtool,wecansimulatephenomenathatareimpossibletoobserve,andsimultaneouslybetterunderstanddatafromobservations.Inthisway,computationalscienceallowsustoovercomethelimitationsofbothexperimentalandtheoreticalscience.Modelingandsimulationwillgiveusnewinsightsintothedatathatwearecollectingaboutourplanet.
MassStorage:
TheDigitalEarthwillrequirestoringquadrillionsofbytesofinformation.Laterthisyear,NASAsMissiontoPlanetEarthprogramwillgenerateaterrabyteofinformationeachday.Fortunately,wearecontinuingtomakedramaticimprovementsinthisarea.
SatelliteImagery:
TheAdministrationhaslicensedcommercialsatellitessystemsthatwillprovide1-meterresolutionimagerybeginninginearly1998.Thisprovidesalevelofaccuracysufficientfordetailedmaps,andthatwaspreviouslyonlyavailableusingaerialphotography.Thistechnology,originallydevelopedintheU.S.intelligencecommunity,isincrediblyaccurate.Asonecompanyputit,"It’slikehavingacameracapableoflookingfromLondontoParisandknowingwhereeachobjectinthepictureistowithinthewidthofacarheadlight."
Broadbandnetworks:
Thedataneededforadigitalglobewillbemaintainedbythousandsofdifferentorganizations,notinonemonolithicdatabase.ThatmeansthattheserversthatareparticipatingintheDigitalEarthwillneedtobeconnectedbyhigh-speednetworks.DrivenbytheexplosivegrowthofInternettraffic,telecommunicationscarriersarealreadyexperimentingwith10gigabit/secondnetworks,andterrabitnetworkingtechnologyisoneofthetechnicalgoalsoftheNextGenerationInternetinitiative.Thebadnewsisthatitwilltakeawhilebeforemostofushavethiskindofbandwidthtoourhome,whichiswhyitwillbenecessarytohaveDigitalEarthaccesspointsinpublicplaceslikechildren’smuseumsandsciencemuseums.
Interoperability:
TheInternetandtheWorldWideWebhavesucceededbecauseoftheemergenceofafew,simple,widelyagreeduponprotocols,suchastheInternetprotocol.TheDigitalEarthwillalsoneedsomelevelofinteroperability,sothatgeographicalinformationgeneratedbyonekindofapplicationsoftwarecanbereadbyanother.TheGISindustryisseekingtoaddressmanyoftheseissuesthroughtheOpenGISConsortium.
Metadata:
Metadatais"dataaboutdata."Forimageryorothergeoreferencedinformationtobehelpful,itmightbenecessarytoknowitsname,location,authororsource,date,dataformat,resolution,etc.TheFederalGeographicDataCommitteeisworkingwithindustryandstateandlocalgovernmenttodevelopvoluntarystandardsformetadata.
Ofcourse,furthertechnologicalprogressisneededtorealizethefullpotentialoftheDigitalEarth,especiallyinareassuchasautomaticinterpretationofimagery,thefusionofdatafrommultiplesources,andintelligentagentsthatcouldfindandlinkinformationontheWebaboutaparticularspotontheplanet.Butenoughofthepiecesareinplacerightnowtowarrantproceedingwiththisexcitinginitiative.
PotentialApplications
Theapplicationsthatwillbepossiblewithbroad,easytouseaccesstoglobalgeospatialinformationwillbelimitedonlybyourimagination.Wecangetasenseofthepossibilitiesbylookingattoday’sapplicationsofGISandsensordata,someofwhichhavebeendrivenbyindustry,othersbyleading-edgepublicsectorusers:
Conductingvirtualdiplomacy:
TosupporttheBosniapeacenegotiations,thePentagondevelopedavirtual-realitylandscapethatallowedthenegotiatorstotakeasimulatedaerialtouroftheproposedborders.Atonepointinthenegotiations,theSerbianPresidentagreedtoawidercorridorbetweenSarajevoandtheMuslimenclaveofGorazde,afterhesawthatmountainsmadeanarrowcorridorimpractical.
Fightingcrime:
TheCityof
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