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Effective solutions to a global 3D visual system in networking environments

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science china Earth sciences 2005年第11期48卷 2032-2039页

作者： ZHANG Liqiang1,2. ZHANG Yan3, YANG Chongjun2. LIU Suhong1, REN Yingchao2. RUI Xiaoping2.& LIU Donglin2.1. state Key Laboratory of remote {2. sciences, School of Geography and remote {2., beijing Normal University, beijing 100875, china 2. state Key Laboratory of remote {2. sciences, Institute of remote {2. Applications, Chinese Academy of sciences, beijing 101001, china 3. Institute of Geographical sciences and Natural Resources Research, Chinese Academy of sciences, beijing 101001, china 1. state Key Laboratory of remote {2. sciences School of Geography and Remote Sensing Beijing Normal University 100875 Beijing China 2. Chinese Academy of sciences State Key Laboratory of Remote Sensing SciencesInstitute of Remote Sensing Applications 101001 Beijing China 3. Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences 101001 Beijing China

The development of Web-based global 3D visual system has made progresses. However, there exist few mature and effective ways for managing, transmitting and visualizing massive spatial data. Based on the related work, the paper illustrates the ellipsoidal quadtree technique for rapid access multi-scale and multiple level geographical data, integrates the streaming with level-of-detail rendering method for transmitting the data on the network, and im-plements large-scale terrain surface simplification using M-band wavelet transforms and mul-tiresolution triangulations. We fulfil a web-based global terrain visual system using COM com-ponents on the basis of the above techniques. The system has a good prospect in the military simulation and city plans.

关键词： massive spatial data, streaming transmission, system architecture, M-band wavelet

Polynomial analysis of canopy spectra and biochemical component content inversion

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science china Earth sciences 2005年第10期48卷 1780-1791页

作者： YAN Chunyan1, LIU Qiang1, NIU Zheng1, WANG Jihua2. HUANG Wenjiang2.& LIU Liangyun 2.1. state Key Laboratory of remote {2. science, Jointly Sponsored by the Institute of remote {2. Applications of Chinese Academy of sciences and beijing Normal University, beijing 100101, china 2. National Engineering Research Center for Information Technology in Agriculture, beijing 100089, china state Key Laboratory of remote {2. science Jointly Sponsored by the Institute of remote {2. Applications of Chinese Academy of sciences and beijing Normal University beijing china National Engineering Research Center for Information Technology in Agriculture beijing china

A polynomial expression model was developed in this paper to describe directional canopy spectra, and the decomposition of the polynomial expression was used as a tool for re-trieving biochemical component content from canopy multi-angle spectra. First, the basic formula of the polynomial expression was introduced and the physical meaning of its terms and coeffi-cients was discussed. Based on this analysis, a complete polynomial expression model and its decomposition method were given. By decomposing the canopy spectra simulated with SAILH model, it shows that the polynomial expression can not only fit well the canopy spectra, but also show the contribution of every order scattering to the whole reflectance. Taking the first scattering coefficients a10 and a01 for example, the test results show that the polynomial coefficients reflect very well the hot spot phenomenon and the effects of viewing angles, LAI and leaf inclination angle on canopy spectra. By coupling the polynomial expression with leaf model PROSPECT, a canopy biochemical component content inversion model was given. In the simulated test, the canopy multi-angle spectra were simulated by two different models, SAILH and 4-SCALE re-spectively, then the biochemical component content was retrieved by inverting the coupled polynomial expression + PROSPECT model. Results of the simulated test are promising, and when applying the algorithm to measured corn canopy multi-angle spectra, we also get relatively accurate chlorophyll content. It shows that the polynomial analysis provides a new method to get biochemical component content independent of any specific canopy model.

关键词： polynomial expression, canopy spectra, decomposition, biochemical component content, inversion.

Water target based cross-calibration of CBERS-02.CCD camera with MODIS data

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science china(Technological sciences) 2005年第S2期48卷 61-71页

作者： TANG Junwu1,2. GU Xingfa2. NIU Shengli1, MA Chaofei1 & MIN Xiangjun3 1. National Satellite Ocean Application Service (NSOAS), beijing 100081, china 2. {2. Key Laboratory of remote sensing science, beijing 100010, china 3. china Center for Resource Satellite Data and Applications (CRESDA), beijing 100083, china 1. National Satellite Ocean Application Service (NSOAS) 100081 Beijing China 2. state Key Laboratory of remote {2. science 100010 Beijing China 3. china Center for Resource Satellite Data and Applications (CRESDA) 100083 Beijing China

In order to make quantitative watercolor sensing with china-Brazil Earth Resources Satellite (CBERS-02. CCD camera, the MODIS data with higher accuracy is used to cross-calibrate the CCD camera over water targets. In homogeneous clear water area, two pairs of images obtained over the same area on the same day by the two sensors are selected. The top-of-atmosphere (TOA) radiances of the multispectral bands of CCD are calculated with the water and aerosol parameters from MODIS based on a water-atmosphere radiative transfer algorithm. The stripes in CCD image that caused by unequal response of the CCD array detectors are firstly removed before making the cross-calibration. The same part of CCD detectors is selected for the calibrations in the two images to eliminate the residual error of destriping and uniformity correction for the focus plane irradiance. It is shown that the calibration results from two different images are consistent. The error of this method is about 5%.

关键词： CBERS-02 CCD MODIS radiometric calibration cross-calibration. DOI: 10.1360/05ze1006

The primary results of quantitative ocean color retrieval in china coastal area with CBERS CCD data

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science china(Technological sciences) 2005年第S2期48卷 161-176页

作者： TANG Junwu1,2. MA Chaofei1, NIU Shengli1, WANG Xiaomei1, SONG Qingjun1 & DING Jing1 1. National Satellite Ocean Application Service, beijing 100081, china 2. {2. Key Laboratory of remote sensing science, beijing 100010, china 1. National statellite Ocean Application Service 100081 Beijing China2. State Key Laboratory of Remote Sensing Science 100010 Beijing China

Using the techniques of quantitative ocean color sensing, the in-water ocean color algorithms for sediment and chlorophyll-a retrieval are established for CBERS-02.CCD broad spectral bands based on in situ data. The remote sensing reflectance of water is derived from CCD radiance data by a clear water atmospheric correction algorithm. Then, the sediment and chlorophyll-a concentrations are retrieved from CCD image. The sediment retrieval is quite satisfactory, but the chlorophyll-a retrieval is not so good because of the broadband width and low signal-to-noise ratio of the CCD camera.

关键词： CBERS-02 CCD ocean color sensing atmospheric correction retrieval of water constituents.

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 sensing & GIS, Peking University, {2. 100871, china 2. Institute of Geographical sciences and Natural Resources Research, Chinese Academy of sciences, {2. 100101, china 1. Institute of remote sensing & 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.

Study on NDVI-T_s space by combining LAI and evapotranspiration

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science china Earth sciences 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2.3, WANG Pengxin4, YANG Hua1,2.3, LIU Shaomin1,2.3 & WANG Jindi1,2.3 1. Research Center for remote sensing and GIS, School of Geography, {2. Normal University, {2. 100875, china 2. state Key Laboratory of remote sensing science, {2. 100875, china 3. {2. Key Laboratory for remote sensing of Environment and Digital Cities, {2. 100875, china 4. Department of Information Management, College of Information and Electronic Engineering, china Agricultural University, {2. 100083, china 1. Research Center for remote sensing and GIS School of Geography Beijing Normal University Beijing 100875 China 2. state Key Laboratory of remote {2. science Beijing 100875 China 3. beijing Key Laboratory for remote {2. of Environment and Digital Cities Beijing 100875 China 4. Department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing 100083 China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

Study of thin cloud removal method for CBERS-02.image

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science china(Technological sciences) 2005年第S2期48卷 91-99页

作者： MA Jianwen1, GU Xingfa1, FENG Chun2.& GUO Jianning2.1. Institute of remote sensing Application, Chinese Academy of {2.s, beijing 100101, china 2. china Center for Resource Satellite Data and Applications, beijing 100073, china 1. Institute of remote sensing Application Chinese Academy of Sciences 100101 Beijing China 2. china Center for Resource Satellite Data and Applications 100073 Beijing China

The china Brazil Earth Resources Satellite (CBERS) ended the dependence on foreign satellites. Along with the series of CBERS and the enhancement of satellite applications, it is necessary to search correlative data processing methods. Because cloud appears in the atmosphere, an image with clear sky conditions is often hard to obtain. How to remove cloud is an important sector of increasing image quality. An improved homomorphism filtering method is adopted to remove thin cloud qualitatively at first, and all bands are selected to classify pixels. Based on the fact that visible band images contain more aerosol effects than infrared bands, visible bands are used to determine clear or hazy regions and the reflectances of different surface classes in clear regions are calculated. At last the mean reflectance of the same classes in clear and hazy regions is matched to remove cloud. The image visual effect is improved; meanwhile, the ground reflectance is retrieved to meet the needs of remote {2. quantification.

关键词： CBERS-02 cloud removal surface reflectance mean reflectance matching.

A suspended sediment satellite sensing algorithm based on gradient transiting from water-leaving to satellite-detected reflectance spectrum

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Chinese science Bulletin 2000年第10期45卷 925-931页

作者： LI Yan & LI Jing1. Second Institute of Oceanography, state Oceanic Administration, Hangzhou 310012. china 2. Institute of {2. sensing Technology and Application, Peking University, beijing 100871, china Second Institute of Oceanography State Oceanic Administration Hangzhou China Institute of remote sensing Technology and Application Peking University Beijing China

In order to remove the fluctuating atmospheric effects from the Case 2.water, an algorithm for retrieval of suspended sediment concentration from NOAA weather satellite imagery was developed under a new approach. This model is based on the linear response from water-leaving to satellite-detected reflectance spectra, simply reflected by the gradient for correlation curve between reflectance of the advanced very high resolution radiometer (AVHRR) channels 1 (R1, 580-680 nm) and 2.(R2. 72.-1 100 nm). Proportional factor for this gradient transiting, mathematically represented as (td2.td1) (toz2.toz1), depends on a ratio of atmospheric transmittance for such two channels, including ozone and diffuse transmittance. As a simple but efficient algorithm of gradient, the algorithm of αR1-R2.is selected to retrieve gradient a and then sea surface suspendend sediment concentration.

关键词： marine remote sensing suspended sediment atmospheric effect removal gradient transit AVHRR.

Multiple time scale evaluation of the energy balance during the maize growing season,and a new reason for energy imbalance

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science china Earth sciences 2009年第1期52卷 108-117页

作者： GUO JianXia1,2.BIAN LinGen3 & DAI YongJiu2.1 Meteorological Observation Center of china Meteorological Administration,beijing 100081,{2. 2.state Key Laboratory of remote sensing science,School of Geography and remote sensing science,beijing Normal University,beijing 100875,{2. 3 Chinese Academy of Meteorological sciences,beijing 100081,{2. Meteorological Observation Center of china Meteorological Administration Beijing 100081 China state Key Laboratory of remote {2. science School of Geography and Remote Sensing Science Beijing Normal University Beijing 100875 China

Energy imbalance is a common problem associated with the measurement of surface energy using the eddy covariance *** the evaluation of the energy balance,people usually pay more attention to the statistical result that the effective energy(the sum of sensible and latent heat) is systematically lower than the available energy(the difference of net radiation and ground heat flux).However,little attention has been paid to the existence of the reversed situation when the effective energy is larger than the available energy or their contribution to the overall energy closure *** this paper,based on the analysis of the energy balance on multiple time scales across the maize growth season,we conclude that the non-synchronization of energy components is the main reason for the existence of the reversed *** shifting the phase of the effective energy components half an hour ahead,the rates of energy closure over all time scales are improved and dramatically reduce the number of the half-hourly samples when the energy ratio exceeds 1 or is below *** to the characteristics of the energy distribution and transformation over multiple time scales,latent heat is always the main type of energy cost,and the residual of the energy balance increases with the growth of the maize plant surpassing the sensible heat for seventy *** is suggested that the heat storage and photosynthetic energy play an important role in the energy balance during the growing period of maize.

关键词： maize energy balance multiple time scale energy hysteresis