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Integrative inversion of land surface component temperature

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Science China Earth Sciences 2005年第11期48卷 2011-2019页

作者： FAN Wenjie1 & XU Xiru1,2.1. Institute of remote {2. and geographical information System, peking university, beijing 100871, China 2. Center of remote {2. and GIS of beijing Normal university, beijing 100875, China 1. Institute of remote {2. and geographical information System Peking University 100871 Beijing China 2. Center of remote sensing and GIS of {2. Normal university 100875 Beijing China

In this paper, the row winter wheat was selected as the example to study the com-ponent temperature inversion method of land surface target in detail. The result showed that the structural pattern of row crop can affect the inversion precision of component temperature evi-dently. Choosing appropriate structural pattern of row crop can improve the inversion precision significantly. The iterative method combining inverse matrix was a stable method that was fit for inversing component temperature of land surface target. The result of simulation and field ex-periment showed that the integrative method could remarkably improve the inversion accuracy of the lighted soil surface temperature and the top layer canopy temperature, and enhance inver-sion stability of components temperature. Just two parameters were sufficient for accurate at-mospheric correction of multi-angle and multi-spectral thermal infrared data: atmospheric trans-mittance and the atmospheric upwelling radiance. If the atmospheric parameters and component temperature can be inversed synchronously, the really and truly accurate atmospheric correction can be achieved. The validation using ATSRII data showed that the method was useful.

关键词： components temperature, inverse pattern, atmospheric correction

A semantic geographical knowledge wiki system mashed up with Google Maps

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Science China(Technological Sciences) 2010年第S1期53卷 52-60页

作者： GAO Yong,GAO Song,LI RunQiang & LIU YuInstitute of remote {2. and geographical information systems,peking university,beijing 100871,China 1. Institute of remote {2. and geographical information systems Peking University Beijing 100871 China

A wiki system is a typical Web 2.0 application that provides a bi-directional platform for users to collaborate and share much useful information ***,computers cannot well understand the wiki pages in plain *** user-generated geographical content via wiki {2. cannot be manipulated properly and efficiently unless the geographical semantics is explicitly *** this paper,a geographical semantic wiki system,Geo-Wiki,is introduced to solve this ***-Wiki is a semantic geographical knowledge-sharing web system based on geographical ontologies so that computers can parse and storage the multi-source geographical ***,Geo-Wiki mashed up with map services enriches the representation and helps users to find spatial distribution patterns,and thus can serve geospatial decision-making by customizing the Google Maps APIs.

关键词： geo-ontology semantic wiki mashup Google Maps

Probabilistic composition of cone-based cardinal direction relations

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Science China(Technological Sciences) 2008年第S1期51卷 81-90页

作者： LIU Yu1,TIAN Yuan1 & WENG JingNong2.1 Institute of remote {2. and geographical information systems,peking university,beijing 100871,China 2.College of Software,Beihang university,beijing 100083,China peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China Beihang Univ Coll Software Beijing 100083 Peoples R China

Composition tables play a significant role in qualitative spatial reasoning (QSR). At present,a couple of composition tables focusing on various spatial relations have been developed in a qualitative approach. However,the spatial reasoning proc-esses are usually not purely qualitative in everyday life,where probability is one important issue that should be considered. In this paper,the probabilistic compo-sitions of cone-based cardinal direction relations (CDR) are discussed and esti-mated by making some assumptions. Consequently,the form of composition result turns to be {(R1,P1),(R2.P2.,…,(Rn,Pn)},where Pi is the probability associated with relation Ri. Employing the area integral method,the probabilities in each composi-tion case can be computed with the assumption that the target object is uniformly distributed in the corresponding cone regions.

关键词： spatial reasoning cardinal direction relations probabilistic composition

Automatic generalization of metro maps based on dynamic segmentation

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Science China(Technological Sciences) 2010年第S1期53卷 158-165页

作者： DONG WeiHua 1,TIAN Yuan 2.& ZHANG Yi 2.1 Institute of Geography and remote {2.,beijing Normal university,beijing 100875,China 2.Institute of remote {2. and Geographic information System,peking university,beijing 100871,China 1. Institute of Geography and remote {2. Beijing Normal University Beijing 100875 China 2. Institute of remote {2. and Geographic information System Peking University Beijing 100871 China

A metro map is usually optimized for the readability of connections and transportation networks *** order to assure good readability and meet aesthetic considerations,a set of principles for good metro map layout are *** to these principles,a new methodology based on dynamic segmentation is presented to produce the metro maps ***,routes are constructed according to the line attribute similarity and geometry *** a set of cartographic generalization methods about the shape,angle,length,and topology are presented for these *** method is validated by beijing metro plan *** the experiment results,it can be concluded that this new method is more effective than the static segmentation method to produce metro maps with better readability for route plans.

关键词： metro maps generalization dynamic segmentation visualization

The accuracy assessment in areal interpolation:An empirical investigation

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Science China(Technological Sciences) 2008年第S1期51卷 62-71页

作者： LIU XiaoHang1 & LIU Yu2.1 Department of Geography & Human Environmental Studies,San Francisco State university,San Fran-cisco,CA 94132.USA 2.Institute of {2. sensing and geographical information systems,peking university,beijing 100871,China Department of Geography & Human Environmental Studies San Francisco State University San Francisco CA 94132 USA Institute of remote {2. and geographical information systems Peking University Beijing 100871 China

Areal interpolation is the process of transferring data from source zones to target zones. While method development remains a top research priority in areal interpo-lation,the accuracy assessment aspect also begs for attention. This paper reports an empirical experience on probing an areal interpolation method to highlight the power and potential pitfalls in accuracy assessment. A kriging-based interpolation algorithm is evaluated by several approaches. It is found that accuracy assessment is a powerful tool to understand an interpolation method,e.g. the utility of ancillary data and semi-variogram modeling in kriging in our case study. However,different assessment methods and spatial units on which assessment is conducted can lead to rather different results. The typical practice to assess accuracy at the source zone level may overestimate interpolation accuracy. Assessment at the target zone level is suggested as a supplement.

关键词： areal interpolation accuracy assessment area-to-point kriging

Positioning localities from spatial assertions based on Voronoi neighboring

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Science China(Technological Sciences) 2010年第S1期53卷 143-149页

作者： GONG YongXi 1,2.3,LI GuiCai 1,LIU Yu 2.& YANG Jian 1 1 Shenzhen Key Lab of Recycling Economy,peking university Shenzhen Graduate School,Shenzhen 518055,China 2.nstitute of remote sensing and geographical information systems,peking university,beijing 100871,China 3College of Urban and Environmental Science,peking university,beijing 100871,China peking Univ Shenzhen Grad Sch Shenzhen Key Lab Recycling Econ Shenzhen 518055 Peoples R China peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China peking Univ Coll Urban & Environm Sci Beijing 100871 Peoples R China

With the rapid development of Internet,much spatial information contained in non-structured or semi-structured documents is available on the World Wide *** such documents,localities are always textually described using spatial relationships and named places,instead of numerical ***,extracting positional information from locality descriptions is an important *** this paper,we bridge two aspects of locality descriptions,namely generating locality descriptions and positioning localities,and provide a method to compute probability density according to the selection probability of a reference object to describe the position of the target *** operation on uncertainty field is used to deal with locality description involving multiple reference *** metrics are introduced to measure the results of positioning *** choose the mixed selection probability function based on Euclidean distance and Voronoi stolen-area to compute probability density ***,we use three cases to demonstrate the proposed methods.

关键词： geographic information science positioning locality Voronoi neighboring probability density function

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

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Science China Earth Sciences 2005年第9期48卷 1501-1509页

作者： CHEN Junfeng1,2. LI Xiubin2.& ZHANG Ming2.1. Institute of remote {2. & GIS, peking university, beijing 100871, China 2. Institute of geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, China 1. Institute of remote {2. & GIS Peking University 100871 Beijing China 2. Institute of geographical Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing Chin

Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1970, 1986 and 1999 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 2.%.

关键词： climate variation, land-cover changes, Suomo Basin, CHARM model, SWAT model.

A method for blind separation of components information from mixed pixel

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Progress in Natural Science:Materials International 2006年第07期16卷 760-765页

作者： FAN Wenjie and XU Xiru ( Institute of remote {2. and geographical information System, peking university, beijing 100871, China Center of remote {2. and GIS of beijing Normal university, beijing 100875, China) [a]Institute of remote {2. and geographical information System Peking University Beijing China [b]Center of remote sensing and GIS of {2. Nornal university Beijing China

In the field of remote sensing, it is important to separate the component {2. from mixed pixel. If the physical process of remote sensing can be expressed by a set of linear equations, the remote sensing {2. matrix is equal to the weight matrix multiplied by the component {2. matrix. Generally speaking, the precondition of retrieval of component {2. matrix is that the weight matrix is known. However, the blind signal separation (BSS) method can separate the matrix unconditionally, whose basic principle is that the additive {2. needing separation can be achieved from the statistical characteristics contained in a mass of samples in the remotely sensed {2. matrix. Therefore, the values of the component {2. matrix and the weight matrix can be estimated. The wave shape of components can be retrieved by BSS, but the amplitude cannot. In this paper, the plant-soil mixed pixels were chosen as the studying targets in this paper to quantitatively separate the component {2. and solve the uncertainty of BSS. Simulation and field test verify the reliability of the method. Results show that the BSS can be one of the effective methods of mixed pixel separation, and the foreground of application is very promising.

关键词： mixed pixel component information blind signal separation.

L curve for spherical triangle region quadtrees

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Science China(Technological Sciences) 2004年第3期47卷 265-280页

作者： YUAN Wen1,CHENG Chengqi1,MA Ainai1 & GUAN Xiaojing2.1.Institute of remote {2. and Geography information System,peking university,beijing 100871,China 2.Centre of State information,beijing 100045,China peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China Ctr State Informat Beijing 100045 Peoples R China

The sequence of facets and nodes has a direct influence on the efficiency of access to spherical triangle region quadtree. Based on the labeling schema by Lee, spatial curves both for facets and nodes are proposed and the main algorithms for coordinate translation, node Lsequence generation and visiting nodes are presented. In particular,constant time algorithms for generating node Lsequence are advanced by using bit manipulation operations,which can be easily implemented with hardware. In L curve the distance between three nodes of a facet is mostly limited in a range of small value, thus making fast access possible. Though codes of sibling facets are continuous, the difference between codes of some cousins may occasionally be very large and makes the distance of a few facets also very large, thus greatly increasing the mean node distance and the total traversing distance. Therefore an m cluster of nodes is proposed as a basic storage unit fo n cluster, which should store eery shared node in each,and the distance between three nodes of a facet is limited to a controllagle scope.

关键词： global grid, spherical triangle region quadtree, SQT, QTM, space-filling curve.