最新刊期
卷 ， 期 4 ， 1999
- 摘要：The strategy ofthe Digital Earth While it could be athoughtforglobalstrategy,itcould also bea sword of Damocles,foritnotonlyinvolves knowl edge property ,international collaboration ,data sharing and so on ,itservesinternationaltrade,economic development, remote education as well.Additionally ,it hasinfluence on nationalsecurity,governmentalrights and ethnic dignity. （2） The basic policy of China For developing countries,the Digital Earth Strategyis more like a challengethan an opportunity. While China in sistsits opening policy ,italso needsto enhanceits ability to compete in a global context,formingits own independent andintegrativeframeworkin data acquisition ,updating,storing ,circulation and mining .There exitneedsto distinguish the domestic needs from international exchange,and national informationalization from countermeasures to the Digital Earthstrategy.Theseshould be no mixtureofconceptsandidenticalactions.Chinathrowsspecialattention onthe Digital Earth strategy forthe world peace and Regionalsustainable. （3） The starting pointin science and technology Since countries are notstarting atthesome place,China mustrely on its advantage and avoid itsinferior positionin developing science and technology to take the master point.In the Agenda 21st, Chinese government introduced more than 40 projectsinvolvinginformation systems;and Chinesescientistsalsoforesaw the digitaltrendin geo science andits prospectsin servingthe society,therefore have been taken partin much cooperation in globalresearches context. In 21st century ,the Digital Earth strategy should not bethe arms of hegemony,instead itshouldimprovethe pros perity of human society in following areas;（1）specialization ofsmallsatellite;（2） database update through satellite in formation and data sharing;（3） contentofchlorophylland assessmentofprimary productivity ;（4） thermalfield ofearth surface and monitoring on radio temperature;（5） spectral difference of geo chemicallandscape.Itcan help solve some environmentalproblems brought by the global change,and help reallocate resources in achieving sustainable develop ment.关键词：Digital Earth;Policy of China;Starting point.
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发布时间：2021-06-10 - 摘要：Since the Digital Earth been advanced by Al Gore—the vice presidentof USAon Jan.31 1998 ,the scien tists,entrepreneurs and politicians of many countries have responsed activelytoit ,they allproposed a digitalearth from their own pointofview ,butallofthem didn’tgive a system and overallvision .Based onthe developmentofgeographic information processing and information technology and the requirement of information society, a system and relatively overall description ofdigitalearth is given inthis paper,the research contents,keytechnologies and application prospect are covered .In this way ,a relatively objective description of digitalearth is given .关键词：Digital Earth;Spatialinformationinfrastructure;Architecture;Keytechniques;Research contents
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发布时间：2021-06-10 - 摘要：Based on the quantitative analysis ofthe major errorsources for NOAAAVHRRdata ,this paper presents a new navigation method .In this method ,correction oftime driftonboard and adjustmentofthe ephemeris datais carried out atthe criteria ofconstraint Least Mean Square Error;andthe spacecraftattitude deviationsis also estimated and cor rected .This navigation methodiscomprehensively considered with othercriticalelementsoflocation ,such asorbitcalcu lation ofsatellite,determination ofthe positioninformation ofeach pixel,and preciseimageregistration betweenreference image andslaveimage.By using high resolution 1 :1 ,000 ,000 digital map dataand LANDSATTMdatatoidentify GCPs （Ground Control Points） ,the geolocation accuracy ofselected GCPs can be improved . With these accurate GCPs,the geolocation accuracy of navigation for NOAAAVHRRdata can be improved to 1km in the whole image,and lessthan 1km at nadir.关键词：Polar orbit meteorologicalsatellite;Location;Navigation
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发布时间：2021-06-10 - 摘要：Up to now ,the correction ofatmospheric effect has not been properly solved .Itis an exigenttask to find a method for diffusive radiation correction because of continualimprovementofsensor’s pixelsize and the continualemer gence ofvariousslantview satellitebornesensors.Inthis paper,we havegotthe pointspreadfunction （PSF） ofdifferent pixelsizefor differentatmospheric condition by MonteCarlo method .The results show : （1） The effects ofatmospheric condition on the PSFand central pixel’s contributive percentage can’t be ignored . （2） The single scattering modelresultsin exaggerating contributive percentage ofbackground pixel,the maximum of its absolute erroris about7 % and its relative erroris about 40 % . （3） In the situation ofslantview ,the maximum contribution comesfrom pixels with the same azimuth angle ofsen sorandthe minimum contribution comesfrom pixels withthe oppositeside ofsensor’sazimuth angle.Thecontributionsof pixels between them are decided by zenith angle ofsensor and aerosolsize spectrum ,it has nothingto do with radiative wavelength and ground visible distance .关键词：Atmospheric pointspread function;Montecarlo method
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发布时间：2021-06-10 - 摘要：Inthe research ofremote sensing mechanism ,the Canopy Reflectance （CR） models established the relation between the bidirectionalreflectancefeature and canopystructure.This makesthe possibilitytoretrievethe canopystruc ture parametersfrom multiangularremote sensing data by CRmodel.In our Geometric Optical BRDFmodeling study for forestcanopy,we noticethatthereflectancesignature ofsunlitcrownisnotuniform ,asub modelfor modelingitsfeature is needed to evaluatethe contribution ofthis componentto the BRDFofsurface . In this approach,to model the effect of canopy structure on the radiation transmittance and reflectance within canopy ,Li’s path scattering modelfor homogeneouslayersis developed to calculate thetransmittancein differentlayers within crown .In the positions wherethefoliage volume density arelower,such as nearthe surface ofcrown ,the contri bution ofincidentradiationis modeled bythe openness distribution withintree crown ,based on our directionalgap proba bility model. Field measurements were madein the apple orchard ,North of Beijing .3 ×3 trees wastaken as a sample set.The geometric size andfoliage area volume density（FAVD） distribution oftree crowns were measured using our Tree Comput ed Tomography indirect measuring System （TCTS） .The solarradiation ,diffused skylight,hemisphericalradiation atthe given test points within and below the crowns were measured by LI CORquantum sensor （LI 190SA,400 —700 nm） . The measured incidentradiation wastaken asinput ofthe modelto calculate the radiative transmission within and below crowns,the canopy architecture was described by FAVDdistribution and LAD.The measured radiation at points was used to validate the calculated one .The model, measurements and validation results are presented in this paper, which show thatthe modeledradiativetransmissionfitthe measurementdatavery well.The simplified modelis hopefulto supportthe CRmodelinversion study .关键词：Radiativetransmission;Canopy architecture;Openness
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发布时间：2021-06-10 - 摘要：Inthis paper we report a new application of digital photogrammetry.Itreflects ourrecentattempttoward the developmentofthe field of photo ecometrics. We illustrate the potential of digital photogrammetry in the monitoring of changes ofoak woodland of California using 1∶12 ,000 scanned aerial photographs.The photographs were taken in 1970 and 1995 .Stereopairsin 1970 and 1995 have been usedto derive digitalsurface models（DSM） thatcontain 3Dmorpho logicalcoordinates of everylandscape componentincluding oak wood ,grassland and buildings.The DSMs allow us not only to studychanges ofcanopy closure butalsoto measuretree heightsand heightchange duringthe25 yearperiod .The potentialof DSMopens many opportunities for improving the accuracy of change detection and species recognition than solely usingtraditional multispectral analysis.关键词：Digitalsurface model;Forestchange detection;Digitalphotogrammetry;Photo ecometrics
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发布时间：2021-06-10 - 摘要：The reflectance retrievalofremote sensing data can be classified intothree kinds.The first one use radiative transfer model.The second oneis base upon imageitselfto getrelative reflectance .Thethird methodisto getempirical relationship between image DNvalues and reflectance ofthe objects by using thereflectance and radiation ofthe known objects.This paperfirstanalysesthese methods,andthentransform the data ofairborneimagingspectrometer PHItore flectance using the empiricalline method .The accuracy oftheresultis also presented .关键词：Reflectance retrieval;Empiricalline;calibration
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发布时间：2021-06-10 - 摘要：Itis provedthatsome effectshave come outforrockinformation separationfrom remotesensing data usingthe principalcomponentanalysis.New information,relatively weak ,isrevealed bytwocomponentscatterplotclassification , butit does notoccurin the centerarea ofthe aggregation .These phenomenaindicate thatthere are some other relative weak featuresin multiband remote sensing raw data ,beside main features presented by the principal componentanaly sis.The principalcomponentanalysisis onlyone resultoflineartransformation .In orderto derive more potentialinforma tion from multiband raw data ofremote sensing,the stepwise orthogonaltransformation software is developed to extract potentialinformation ofrocktypes. Meanwhile ,the maskingtechniqueis usedto getrid oftheinterference of water body and dry riverfrom theraw data.Goodresultsare achieved andthe methodisalso usedin other placesofthe Huabeiplat form rim .关键词：Rock Information;Maskingtechnique;Stepwise orthogonalrotate algorithm
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发布时间：2021-06-10 - 摘要：Spaceborne scatterometertechnologyis meaningfulforobservation ofthe globalocean windfield.The Process ing and analysis method were studiedforthe European Remote Sensing Satellite （ERS） wind scatterometerdata （WNF） . The Global ocean wind fields were averagedin March,June and December 1997 respectively.They were compared with those ofJune 1996 and October 1995 .The wind field abnormal was observed in the equatorial Western Pacific ,which wasrelatedto El Nino 1997 .The evolution characteristicsofocean wind abnormal（speed and direction） relatedto El Ni no 1997 wasanalysed using ERSWNFdata.Itisshownthatspaceborne scatterometer playsanimportantroleinthe mon itoring of gloabalchanges.关键词：scatterometer;ERS;Global ocean wind field;Globalchange;El Nino
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发布时间：2021-06-10 - 摘要：This paper presents a detailed analysis and comparison of14 modelfunctions,published in the open litera ture,forretrievingseasurface wind speedfrom satellite altimeters.Theaccuracyofthese modelfunctionsarefoundto be within 1 .5 —2 .5m/sin general. Moreover,the modelfunctions appearto converge around 7m/s,correspondingto the peak ofthe wind speed probability density function .An “intermediate”modelfunctionissubsequently proposed and ap plied to derive sea surface wind speedfrom TOPEXaltimeter data,yieldinginterestingresults.The characteristicsof al timeterderived globalsea surface wind speed are described and potential approachesforimprovingthe accuracy of wind speed modelfunctions are discussed .Theimportance of abnormal atmospheric process,such asrain effect,on altimeter wind speed retrievalis also stressed .关键词：satellite altimeter;Sea surface wind speed;Modelfunction;Retrieval
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发布时间：2021-06-10 - 摘要：The matching errorof GPSpositioning results and GISdigital mapsin vehicle guidance and monitoring appli cationsare analyzedinthispaper.Accordingtothe errorsources andthe procedure ofdata processing ,the matchingerror is divided intofive parts.Itisdetailedinthis paperthe possible errorextents ofthe coarseerror,conventionalerror,and theincorrectcoordinatetransformation and projection methods.The errorprocessing methods are discussed concerningthe stepsrespectively.Furthermore,a map matching methodis putforwardtoimprovethe matching results,andthe effectis discussed .The presented methods minimize the matching error of GPSpositioning and GISdigital mapsin vehicle guid ance and monitoring with the basic hardware platforms available .关键词：Vehicle Guidance and Monitoring;GPS;Digital Map;Matching Error
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发布时间：2021-06-10 - 摘要：Withthe advance ofthesociety and economy ,land is decreasing rapidly.Governmentneedsexactand quan titative data aboutlanduse statusto make reasonable decisions. However,traditional methods concerning dynamic moni toring oflanduse havelow efficiency and poor precision .Therefore ,a better method tosolvethis problem isneeded .The developmentof Space Science gives us a chance. Remote Sensing can forwardly find the changed regions,Global Posi tioning System can determinethe accuratelocations oftheregions,and GeographicalInformation System can manage vari ous data asa platform .GPScan notonlyserve asan auxiliary positioning meansafterhavingfoundthetargetregionsfrom remote sensing data,butalso actas an independent data acquisition method .This paperfirstlyintroduces several basic GPSpositioning methods and their precision,and then ,discusses the requirements of dynamic monitoring oflanduse at countylevel,which decidesthe modelselection of GPSreceiverand working pattern of GPS’outdoorsurveying .Combin ing a key projectof“the Ninth Five year Plan”,the authors describefive kindsof GPSacquiring data methods with com prehensive consideration of GIS’functions.The disadvantageoussurveyingconditions willleadthecreation of“2Dabnor mal data”,which can notreflectthetrue world. Deletingthe “2Dabnormal data”from original data set can provide an alternative with good authenticity.Deletingthe “2Dabnormal data”meansthe loss of acquired data.But under certain conditions ,thisloss will notaffectthe computation results’precision and reality.The data acquired by GPSreceiversis based on WGS 84 ,but our basic databaseis on Beijing 54 .Rationalresolventis “true 54”theoretically.Here,“pseu do 54”thoughtis proposed and proved feasible in Jiaoqu County ,Baotou City by a large number oftests.The conclu sions could effectivelyimprovethe efficiency ofindoorand outdoor work,and improve data precision .关键词：Globalpositioning system;Landuse;dynamic monitoring
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发布时间：2021-06-10
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