最新刊期
卷 ， 期 2 ， 2006
- 摘要：In this study,a recent crane based thermal camera system developed by INRA-Avignon of France is presented,and then four measuring methods for hemispherical directional brightness temperature（DBT） observations are introduced.These methods are based on different measurement principles:（1） view the same surface from different angle by moving the crane and platform to assure the sensor always toward the target;（（2） view） different part of the field to collect DBT of different angles by means of rotating the camera to different directions instead of moving the camera;（3） view different part of the field by moving the camera along the row direction;and（4） scan the field with a high imaging frequency while the camera moves along the crane bar vertical to the row direction.During the comparison of these methods,special emphasis is on the analysis of temporal and spatial variations of maize canopy brightness temperature distribution,from which the main errors of these methods are analyzed.The study also presents common shortcomings and limitation of the field observations with this system.At last,recommendations for optimal field measurement of hemispherical DBT with the system are given from an application-oriented viewpoint.关键词：maize canopy;directional brightness temperature（DBT）;field measurement;thermal camera mounted on crane platform
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发布时间：2021-06-10 - 摘要：Generally,there are two contents of detecting shadow areas and eliminating shadows in removing shadows of remote sensing images.In this study,the conclusion was drawn from the forming mechanism of remote sensing images and the reflection spectral characteristic of surface objects,which are the datum of green band having very high correlation with that of blue band,and the shadows of green band being obviously stronger than that of blue band.The reduced（divided） image derived from green band subtracted from（divided by） blue band,can be used to detect shadows with threshold value,due to the more differences between shadow areas and non-shadow areas in it.This method of detecting shadows is related to variational reflectance of the same object.In addition,the precision of detecting shadows with Histogram threshold value in near-infrared band is higher than the other’s.This method of detecting shadows is related to the reflectance of surface objects.Multispectral detecting shadow is the combination of the two methods.Shadow is sheltered by the objects higher than the ground from direct irradiance,the lost information is direct irradiance mainly,which is compensated,then the shadows could be removed.In this paper,a theoretical model,which was based on the radiation transfer theory to calculate the proportions of direct irradiance,diffuse irradiance and environment irradiance,was put forward to remove shadows through compensating direct irradiance.Finally,the method and the model were validated using the IKONOS images,and the results were turned up trumps.关键词：remote sensing;shadow detection;shadow removal;Model;IKONOS
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发布时间：2021-06-10 - 摘要：System integration has been proposed as one of the characteristics which distinguish GIS from other information systems,but there are no appropriate methods to integrate with GIS and geography-model to perform flexible retrieval,development,and reuse mechanism.This paper makes an analysis on the modelbase system and the methodology of integration with GIS and geographic models,and proposes a service-oriented framework of distributed geography model integration.The goal of our research is to design a software framework,which can support distributed model construction,management and integration,with a concept of service and share.At first,we describe the model definition framework which defines model functions and data interfaces on the basis of the ideology of the document object model（DOM）,with more details of the flexible data definition mechanisms which can support dynamic data interchange and definition with XML. The framework can assist modeler to construct models for particular application domains and make the model features understood by GIS-developers more easily.Next,we describe the software structure with two components,the model server and the client,which are both based on the COM/DCOM technology: the model server,supporting RPC access,expands the function of traditional model base,provides the run-time supports and the integration environment into all kind of model programs,will facilitate the incorporation of legacy simulation models into the environment;the client component,composed of a set of COM components with DOM,provides the uniform pattern for integrating models and GIS application with the object-oriented application programming interface.Thus,this framework provides a basis for distributed model construction and sharing not only on the combination of GIS and model program,but also on other SDSS projects.关键词：geography model;model integration;distributed system;service framework;GIS
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发布时间：2021-06-10 - 摘要：Chlorophyll concentration is an important index for evaluating water quality.To make the inversion of remote sensing more accurate and more reality,it is significant to build analytic model for simulating water（R（0-）,） and by the analytic model to inverse chlorophyll concentration.18 points in Taihu lake were chosen,and at those points,the spectra of the water and water chlorophyll concentration were measured at the same time in June,2004.The simulation model of R（0-） was built using Gordon model,and the chlorophyll concentration was inversed using optimization method.The correlation of measured and inversed R（0-） is 0.99.When the chlorophyll concentration is higher than 30mg/m3,the relative error of inversed value is less than 20%.Then,the chlorophyll concentration is inversed by this model for seven measured samples in July,2004.The correlation of measured and inversed R（0-） is 0.94.And the relative error of the majority points is less than 60%.关键词：analytic model;water;Chlorophyll concentration;R（0-）
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发布时间：2021-06-10 - 摘要：There are always some uneven aerosol or thin cloud effects in the remote sensing image of large-scale inland water.These uneven effects bring great difficulty to atmospheric radiant correction of remote sensing images in such regions.Furthermore,because the water is the object with low reflectivity,these uneven effects bring large errors to the water information inversion by remote sensing technology.For some reasons,it is some times impossible for us to use traditional atmospheric radiant correction algorithms（such as MODTRAN or 6S software） to reduce such effects.With some remote sensing images and ground collecting data in Taihu Lake in China,an important inland water research place of Chinese remote sensing scholars,the authors use a new method to resolve this problem.This method considers the optical characteristics of water-atmosphere environment carefully,assumes each pixel’s spectrum is the mixed result of water,pollutant and aerosol or thin cloud,for the optical property of Taihu（Lake’s） remote sensing images is determined by water,pollutant and aerosol or thin cloud.Based on Mixed Pixel Model,this method reduces the effects of aerosol and thin cloud effectively.After the process of this method,we can get more veracious water quality information from remote sensing images.In（author’s） test,to the same remote sensing inversion model,this method can increase 5 percent precision.关键词：cloud-moving;mixed pixel;remote sensing
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发布时间：2021-06-10 - 摘要：According to weather sampling data from static GMS-5 images,the projections of IR1,IR2,VS WV in high-dimension feature spaces such as gray degree,grade degree and veins can be clustered.In this way,we can get to know the subject area of each weather sample in the feature spaces,so that we can get the weather classification of each nephogram.In view of the disadvantages of the conventional clustering algorithm,we develop an idea to combine FCM,GA with FSC mutually.In this way,we can not only overcome the local/the global optimum of GA/FCM algorithm,but also confirm the number of clustering centers objectively.Especially to estimate the classifications of the overlapped samples in high-dimensional feature spaces,we can calculate the distance between these samples and the clustering centers to determine their classifications.The type of the pixels in original cloud images can be found out which group in high-dimensional feature spaces the pixels belong to.So that we can make sure its weather area to accomplish the automatic classifications of the weather area.A lot of experimental test to our method has shown good classification effect and the estimated outcome basically conforms to the weather fact.关键词：satellite image;weather classification;genetic algorithm;FCM;subtractive algorithm
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发布时间：2021-06-10 - 摘要：Different vegetation species have different biological quality and produce different ecological functions and greenery effect.Considering the "Vegetation Quality" is difficult to be obtained,the biological quality and ecological effect of urban greenery can be indirectly reflected using urban green-land area and vegetation species.Based on the comparison of the traditional statistic parameter and non-parameter classification methods and the analysis of kernel-function of SVM,SVM decision-making tree model for urban vegetation classification is designed in this paper using the high resolution imagery data of IKONOS.The classification results are compared to other traditional methods and have an average vegetation classification accuracy of about 83.5% and green-land area accuracy nearly 95%.关键词：urban vegetation species;high resolution imagery;SVM decision-making tree;remote sensing classification model
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发布时间：2021-06-10 - 摘要：In general,two or more images merging of multi-sensors is to merge a variety of image information of different sensors or different wave band,and then gain the determinant image of the target status and signature.In the process of image merging,a lot of information is complementary,but a great deal of information may still be redundant,we can reduce the redundancy degree and enhance the reliability of images through the merging of redundant information.On the basis of traditional method of image single-step merging,the paper puts forward a stepped strategy for image merging based on Genetic Algorithms,it is fit for the situations that the redundancy degree,complementary degree and the order of merging of images are all unknown.The algorithm uses fuzzy logic and Genetic Algorithms to make sure the redundancy degree and complementary degree among images,and determine the approximate optimal image merging strategy.At last we compare the visual effect and mathematic statistics of stepped merging with single-step merging and source image through experiments.关键词：GA;image merging;stepped strategy;fuzzy logic;invariable moment of histogram
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发布时间：2021-06-10 - 摘要：Discrete Wavelet Transform（DWT） was widely used in the application of Remote sensing image compression,noise reduction and image fusion recently.Principal Component Analysis（PCA） and DWT are performed separately with airborne hyperspectral data before a classification and regression tree are applied.The classification results of DWT are compared with PCA and with different mother wavelet DWT themselves.The results indicate that,when the number of the training samples is equal,the classification accuracy of DWT is higher than PCA,among them Haar wavelet performs best.The demanding number of samples of classification after DWT is less than PCA,but when the samples are enough,the compression ratio of PCA is higher than DWT.However,when DWT compression is performed,the most of the spectral information is preserved while PCA keeping the variance of the image only.关键词：DWT;decision tree classification;PCA;hyperspectral remote sensing
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发布时间：2021-06-10 - 摘要：With the MODIS as a reference sensor,the radiometric cross-calibration was performed for（CBERS-02） WFI and the calibration coefficients and the offsets were obtained.The offsets for both channels were very large,about 42 and 21 respectively.For validation,the calibration results were applied to another region of WFI image to get the apparent reflectance,which was compared to the one from MODIS image.The differences for both two corresponding channels were 3.6% and-3.6%,which demonstrated that the calibration results we got should satisfy the quantitative application.Five experimental regions from WFI images were selected to calculate their vegetation index both before and after radiometric calibration and the comparison showed that the degree of fitting using the quadratic polynomial function could reach 99% after the offsets were subtracted from the original DNs.The comparison between the NDVI and RVI from WFI and those derived from MODIS illustrated clearly that the VI derived from the WFI with calibration coefficients were much closer to those of MODIS and the variation of the RVI between two sensors was smaller than that of the NDVI.关键词：CBERS-02;WFI;radiometric cross-calibration;NDVI;RVI
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发布时间：2021-06-10 - 摘要：Based on bistatic,squint and spatial baseline characteristics of spaceborne parasitical interferometric synthetic aperture radar（InSAR）,models of absolute and relative digital elevation model（DEM） errors are set up.The influence of baseline decorrelation imposing on interferometric phase error is analyzed in detail,which is an important influence of DEM error.The absolute and relative DEM performance of interferometric Cartwheel and Pendulum are simulated.The relation of absolute and relative DEM accuracy with baseline vector are simulated too.Two classical approximate geometries including side-glance and identical range-elevation plane geometries are analyzed.The absolute and relative DEM accuracy of them are compared with those of actual geometry.The simulation results show that baseline decorrelation must be considered in DEM accuracy analysis of spaceborne parasitical InSAR,relative DEM accuracy value is prior to absolute DEM accuracy value,the classical approximate geometry bring great errors which cannot be neglected.关键词：interferometric synthetic aperture radar;formation flying;distributed satellite;DEM accuracy
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发布时间：2021-06-10 - 摘要：The spatial and spectral information in remote sensing data should be exploited to improve classification precision.Unfortunately,the spatial information is neglected in most traditional remote sensing classification methods.Considering two stages probability method of maximum likelihood classification（MLC）,this article proposed a new method of exploiting spatial information to improve classification rules by adjusting the prior probability according to the local spatial information.The local or global spatial features of typical ground targets were analyzed,and there were four principles proposed to decide the prior probability,including spatial geometrical features,local spatial autocorrelation law,contextual knowledge,and landscape parameters.An algorithm was designed to exploit the spatial features and prior knowledge to adjust the prior probability of MLC.The experimental classification was carried out,the classification error matrices and its precision results showed that the floating prior probability MLC method proposed in this article could integrate ground targets’ spatial knowledge with spectral information,and overcome the flaws of traditional pixel-based classification methods,such as minimum distance,MLC,and that the classification precision was improved greatly.关键词：maximum likelihood classification;prior probability;spatial autocorrelation;spatial feature;spectrum
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发布时间：2021-06-10 - 摘要：Based on the MLE（Maximum Likelihood Estimation） algorithm for SeaWinds scatterometer wind retrieval and according to the general distribution characteristics of its objective function,a fast wind vector search algorithm is described and realized in this paper.Using some SeaWinds L2A data,the fast algorithm is validated and compared with the ordinary one.The results indicate that the fast algorithm is more efficient than the ordinary one without reducing the retrieval accuracy.关键词：scatterometer;wind retrieval;objective function;search strategy
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发布时间：2021-06-10 - 摘要：The study aims to search for the hyperspectral remote sensing bands most sensitive to chlorophyll-a concentration.Through repeated measurements in Taihu Lake,a large quantity of hyperspectral reflectance data and water quality data of the Lake were obtained from June to August of 2004.Those data acquired in unfavorable or abnormal monitoring conditions were removed from the dataset.The remaining ones were analyzed to calculate water-leaving radiance and reflectance of water in Taihu Lake.Chlorophyll-a concentration was then regressed against the reflectance data to identify the most sensitive hyperspectral bands.The established regression model was then used to estimate chlorophyll-a concentration in the Lake.Finally,accuracy of the model was assessed using other independent data.The result generated with the given monitoring method indicates that there are two reflectance peaks at 719nm & 725nm.Of them,the one at 719nm is more enhanced and stable.Through comparative analysis it is found that hyperspectral reflectance at these two peaks can improve the accuracy of estimating chlorophyll-a.Moreover,the accuracy of estimation is the highest using the ratio R719/R670 as the independent variable in the linear model.关键词：hyperspectral remote sensing;taihu lake;chlorophyll-a;estimation model
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发布时间：2021-06-10 - 摘要：With the development of imaging spectrometer technology,the ground objects’ consecutive information from it makes it possible to identify different vegetation types,though some relevant research was carried out in the past few years,most are about forestry,yet few about crops.Further,there exist strong correlation between bands of imaging spectrometer,so how to reduce as much as possible the redundant information and reserve useful information appear much more important.This paper first did feature selection based on genetic algorithm（GA） and wheat biophysical characteristics.In feature selection using GA,for the training samples,when combined bands reach 4,the JM distance of optimal combination reach much high level,when bands go on increasing,the average JM distance increases slowly until when bands reach 8,the distance does not increase further,so the optimal bands combination can be obtained.In feature selection using wheat biophysical characteristics,we found that there appear strong correlative bands for wheat protein and dry gluten with spectra,so the sensitive bands can be obtained.Combining these two feature selection steps,the ultimate optimal bands combination was given.After feature selection,we use the selected bands and classifier Fuzzy-Artmap to classify the imaging spectrometer data.It showed that for 4 wheat types,they can be identified clearly,the average classification accuracy is above 90%.关键词：imaging spectrometer;feature selection;type identification
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发布时间：2021-06-10 - 摘要：In order to establish the forest canopy density and stock volume estimation equation based on remote sensing and GIS in the monitoring area,it’s needed to sample certain amounts of representative sample plots.How to rationally select certain amounts of representative sample plots belongs to the problem of multi-objective optimization.It’s hard to do in practical work because of the heavy calculation workload from the selecting by certain optimizing standards with all the combination method according to the known amounts of sample plots in monitoring area.Therefore,to classify the sample plots firstly and then select certain representative ones is needed.Because of the manifold of statistic measuring distance between sample plots and concrete clustering method,different categorized results appeared in the same monitoring area result in different statistic and clustering methods.Designing different factors of remote sensing and GIS that influencing the estimation of canopy density and stock volume, there will be a large difference in classifying results.To a specific monitoring area,the influencing law of different factors to classifying is studied systematically by means of computer simulation.Meanwhile how to choose the statistic measuring distance between sample plots and clustering methods in practical work is also studied in this paper.The results can be useful to real work.关键词：cluster analysis;resemble extent statistical;Correlation coefficient
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发布时间：2021-06-10 - 摘要：This paper focused on retrieving soil water content of bare and winter wheat planted field from ENVISAT ASAR image.The relationship between bare soil’s back scattering coefficient and soil water content or land surface roughness was analyzed,and the relationship between winter wheat field’s backscattering coefficient and soil water content or wheat coverage was also analyzed.The result have shown:（1） because bare soil’s backscattering was greatly affected by land surface roughness and soil texture,the positive correlation existed between bare soil’s backscattering and soil water content was not significant,therefore their effects must be considered in the retrieval of soil water content.（2） The difference of sensitivity of two（polarization’s） backscattering to soil water content and wheat coverage was obvious.The difference of the horizontal polarization backscattering coefficients of winter wheat and bare soil was great.Therefore,the horizontal polarization backscattering coefficient was significantly correlated to wheat coverage and soil water content.The vertical polarization backscattering coefficient of winter wheat planted field was sensitive to soil water content.Therefore,the vertical polarization backscattering coefficients was significantly correlated to soil water content,but not significantly to wheat coverage.Combining two polarization backscattering coefficients of winter wheat field,the models between backscattering coefficients and soil water content or wheat coverage were built,and winter wheat coverage and soil water content under wheat canopy were obtained from ASAR image.As expected,the retrieved soil water content and wheat coverage are consistent with those of field measurements.关键词：SAR;Backscattering coefficient;soil water content;wheat coverage;Retrieve
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发布时间：2021-06-10 - 摘要：2L-IHP algorithm for man-made target detection is discussed briefly first.In order to apply it widely,it is modified to circumvent the constraint of the data.For polarimetric SAR images,PWF is used to generate an image for target detection.According to ADTS dataset,these algorithms are analyzed and evaluated respectively.C-、L- and P-band AIRSAR data are also processed,and we derive some conclusions.Considering the penetrating ability of the microwave,C- and L-band SAR data obtain the best detecting accuracy among the three bands.HH polarization performs better than VV and HV polarization for man-made target detection.Moreover,because more information is contained in polarimetric SAR data,they should get better detecting results theoretically.It is concluded from the experiments that polarimetric SAR data have advantages over single channel SAR data when they are applied for man-made target detection,which is consistent to the theoretical analysis.But all these conclusions need further validation.关键词：2L-IHP;target detection;SAR Images
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发布时间：2021-06-10 - 摘要：This paper presents the expressions for imaginary part of dielectric constant of moisture salt soil at low and high frequencies respectively,which is functions of（1） soil water content and（2） soil salt content.This paper carried out a series of relevant studies,including: the relation of imaginary part of dielectric constant ε″ and soil bulk conductivity σa;relation of soil bulk conductivity σa and conductivity of soil solution σw;relation of conductivity of soil solution σw and soil solution concentration SMv;and relation of soil solution concentration SM<sub>v and soil salt content S have been established gradually(ε″～σa～σw～SMv～S).Based on these relations,the relation of ε″ and S,Mv had been established, which is the dielectric imaginary part model for wet and salty soil.Dielectric constants of 150 samples from five soil types had been measured with microwave net analyzer at the 396 frequencies ranging from 0.2GHz to 20GHz with the interval of 0.05GHz.These measured data were applied to calibrate the dielectric imaginary part model and then achieved the calibrated model at different frequencies.In addition,other 41 soil samples from Jilantai had been measured to test the dielectric model;as a result,the calculated value from model and the measured value had a strong correlation.Finally,the paper made the conclusions:（1） effect of salt content will decrease with the increasing frequency;（2） soil type has little influence on imaginary part of dielectric constant.关键词：imaginary part of dielectric constant;wet and salty soil
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发布时间：2021-06-10
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