最新刊期
卷 ， 期 6 ， 2006
- 摘要：As one of the basic constraints in geographical space,spatial direction relation represents geometric distribution relations of spatial objects and is described and operated by formal models in GIS.However,the existing models are incapable of distinguishing variations between two direction relations of complex objects.This paper aims to develop a computational model with high resolution in identifying the effect of parameters such as distance and shape of spatial objects on their direction relations.First,a generic quantitative approach on direction relations was proposed on the basis of the classical computation of point/point relations,in which both geometric structures and relative distribution relations of spatial objects were utilized.To obtain a reasonable qualitative description,the conversion function was further developed to link the quantitative computation with qualitative description of spatial direction relations.Numerical examples were also provided to demonstrate how to apply the proposed model into practice.Both theoretical comparison and numerical analysis indicated that the model presented in this paper is more sensitive to the parameters such as shape,size and location of spatial objects,and thus is more accurate in distinguishing different direction relations.In particular,the resulting direction relations obtained from the model satisfy three basic cognitive characteristics,including continuity,reflectivity,and asymmetry.关键词：spatial direction relation;quantitative representation;qualitative description;computational model
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发布时间：2021-06-10 - 摘要：SARS spatio-temporal transmission and control model is established,and multi-agent technology is employed to model the SARS spatio-temporal spreading behavior.Based on the virtual geographic environment platform and applyication of Java and VRML tools,this paper designs and develops a prototype system to carry out agent-based simulation of SARS transmission and control in a virtual community.The rudimentary experimental results demonstrate that the model and simulation implemented in the paper can be used to represent the characteristics and laws of SARS transmission.关键词：virtual geographic environments;SARS;multi-agent;spatio-temporal model
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发布时间：2021-06-10 - 摘要：This paper presents a new method to simulate complex land use systems by integrating support vector machine（SVM）,cellular automata,and GIS.Recently,cellular automata（CA） have been increasingly used to dynamically simulate urban growth and land use.There are many issues that should be solved in the simulation of this type of complex systems.One major problem is how to define transition rules using training data.Linear boundaries are often used to retrieve transition rules which define the probability of state conversion.However,many geographical phenomena are very complex and transition rules should be defined using nonlinear boundaries.In this study,a CA model based on the support vector machine（SVM） is developed using Visual Basic and ArcObjects of GIS.The GIS provides both data and spatial analysis functions for constructing SVM-CA model.Training data is conveniently retrieved from remote sensing and GIS database for calibrating and testing the model.The SVM method is used to transform the data from nonlinear boundaries in the original space to linear boundaries in the Hilbert space.The nonlinear transition rules can then be defined by using the functions of SVM.The SVM-CA model can be applied to the simulation of urban development.Complex global patterns can be generated from the local interactions with the SVM-CA model.This paper demonstrates that the proposed model can overcome some of the shortcomings of the existing CA models in simulating complex urban systems by using the nonlinear transition rules.The model has been successfully applied to the simulation of urban development in Shenzhen city of the Pearl River Delta.关键词：cellular automata;support vector machine;remote sensing;land use changes
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发布时间：2021-06-10 - 摘要：This paper presents a change detection approach of remote sensing images based on fusion and general Gauss model（GGM）.This method constructs difference image by fusing the results of subtraction operation and division operation,then,processes difference image by gray morphology,again,estimates the probability density of change pixels and no-change pixels by GGM,finally,calculates the optimal threshold by the improved KI approach and extracts the changed regions.Experiments show that the method of fusion and GGM is solid and efficacious,which has preferable application value.关键词：change detection;gray morphology;GGM;KI approach
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发布时间：2021-06-10 - 摘要：The differences among traditional GIS data models result in difficulty of spatial data integrating and sharing.Commercial GIS vendors and third parties suggested the data conversion solutions.These methods cannot solve the problem perfectly.Geography Markup Language（GML） established by OGC provides standard and framework for spatial data modeling,integrating and sharing.GML has become the defacto international standard for spatial data encoding,transmitting,storing and distributing;more and more spatial data has been stored in GML format.The issue of how to manage the spatial data in GML format efficiently has become the hot one in GIS research.Combining XML database technology and traditional spatial database technology,this paper conducts a deep research on querying and indexing GML data.The spatial extensions to XQuery are suggested.Consequently one GML query language based on XQuery is developed,and native query over GML data is realized.By integrating XML document encoding techniques and traditional spatial index methods,one unified indexing model based on spatial index for GML data is suggested.Taking R-Tree as an example,the performance of the unified indexing model is tested and analyzed through a set of experiments. Experimental results show that the unified indexing model is feasible and efficient.关键词：GML;GML query;GML index;Spatial index
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发布时间：2021-06-10 - 摘要：This paper discusses the spectrum function of InSAR baseline decorrelation coefficient,and analyzes the effect of weighting function to InSAR baseline decorrelation coefficient in the procedure of range compression.And the equivalent bandwidth of interferogram spectrum in range direction is defined.Based on the estimated value of the equivalent bandwidth of interferogram spectrum in range direction,the relation between the equivalent bandwidth of interferogram spectrum in range direction and InSAR baseline decorrelation coefficient can be deduced.So the effect of fixed bandwidth filtering upon the coherence of the InSAR images could be quantitatively analyzed.At last of this paper, the experimental results using X-SAR data illustrate the validity of the analysis.关键词：interferometric synthetic aperture radar;Filter;coherence
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发布时间：2021-06-10 - 摘要：It is feasible to retrieve LAI over large area from remote sensing data with physical models;however,it is quite difficult to get accurate LAI and thus limit the remote sensing application without enough prior knowledge due to the underdetermined parameters in the physical inversion models.A spectrum database system of typical objects in China（SpecLib） has been set up recently,which may provide a priori knowledge of typical land cover for LAI inversion.MODIS data is used to retrieve LAI after atmosphere correction,geometrical correction and cloud identification.The SAIL（Scattering by Arbitrarily Inclined Layers） model is applied for the inversion of LAI for MODIS data.The vegetation coverage of the mixed pixels of the MODIS data are calculated based on the TM data sets.The LAIs of pure pixels（computed from the retrieved LAIs and vegetation coverage） are compared with the field measurement data in Luancheng,Heibei Province,China.Meanwhile,the LAIs of pure pixels are also compared with the MODIS LAI data products.The inversion results show that the!SpecLib effectively improved the accuracy of leaf area index inversion.关键词：SpecLib;moderate resolution imaging spectrometer（MODIS）;leaf area index;inversion
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发布时间：2021-06-10 - 摘要：Goldstein’s branch-cut algorithm is now the most classical one of the known phase unwrapping algorithms.It connects residues with branch-cut lines to neutralize their charges so that the integral path（can’t） stride over the branches in the process of phase unwrapping,thus avoiding pervasion of error.However,due to improper connections,this always brings about excessive branch-cut lines,and even many lines form a closed ’dead area’ that can not be unwrapped,especially when many residues exist.This paper presents a removal redundancy algorithm in phase unwrapping based on minimum spanning tree theory,and its implementation is described in detail.It can accurately remove the redundancies of the branch-cut tree and ensure the effectiveness of phase unwrapping.关键词：interferometric SAR;Phase unwrapping;minimum spanning tree;branch-cut;redundancy
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发布时间：2021-06-10 - 摘要：Automatic registration of remotely-sensed imagery is a classical problem,and has not been well solved till now.In this paper,SIFT（Scale Invariant Feature Transform） feature,which has shown great success in computer vision,is introduced into image registration in remote sensing.In addition,we also proposed a feature matching approach based on the specific characteristic of the remote sensing imagery.Numerous experiments have been conducted for both aerial and satellite imageries under various conditions such as geometric distortion,illumination variation and different resolution.The results showed that our matching approach performs well,and is stable,reliable and efficient.关键词：remotely-sensed imagery;automatic registration;SIFT（Scale Invariant Feature Transform）;image registration
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发布时间：2021-06-10 - 摘要：Similarity measure is usually used to study the similar degree between multisource data,which is the basis of pattern recognition on spatial data.In this paper two kinds of similarity measures are experimentally investigated through some remote sensing image retrievals,they are feature vector based measures and probabilistic measures,accordingly two groups experiments are designed to compare the measures for application to remote sensing image retrieval.From the experiment results we find that in the first group two measures seldom used in the literature perform well,they are χ2 statistical distance measure and cosine of the angle measure.And in the second group experiments,for computing the similarity degree of two images with their histograms obeying mixture Gaussian distributions,we present a method on the basis of class separability measures according to the K-nearest neighbor rule.The experiment results show that the method has good performance.We believe that the results described in this paper will be of significance in applications to multisource data analysis.关键词：remote sensing image;similarity measure;feature vector;class separability measure;(K-nearest) neighbor rule;histogram
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发布时间：2021-06-10 - 摘要：As any physically-based BRDF models were established on some assumptions,there always exist some differences between the simulated data and the measured data.When using the model to invert the ground parameters,the accuracy will be decreased if we use all measured data without distinguishing them.A merit function is usually used as the fitness of the modeled value and that of measured.The least-squares（LS） criterion,traditionally selected as the merit function,lacks the robustness when there are some stochastic errors in the measured data,though it can deal with the normal distribution errors.The least median of squares（LMS） method has the potential to find the abnormal data which belong to the stochastic errors.So we can improve the accuracy of the inversion through kicking away the abnormal data relative to the model with LMS.Using LMS and LS as the merit function separately,in this paper we take the multi-stage inversion of the SAIL model as an example to inverse the ground parameter.It has demonstrated that,toward the measured data which have some errors or can’t be simulated by the model,this approach is robust to estimate the parameters.关键词：BRDF model;multi-stage inversion;robust estimation
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发布时间：2021-06-10 - 摘要：This study was conducted to establish correlations between reflectance spectra and water quality indexes of the Huangpujiang River of Shanghai, sampled in August and November of 2002.31 typical stations were selected to measure the spectral reflectance and 9 water quality parameters were analyzed for every measured stations,including Total Phosphorous（TP）,Total Nitrogen（TN）,Chemical Demand Oxygen with potassium permanganate(CODMn) and with chromate (CODCr),Dissolved Oxygen（DO）,Biological Demand Oxygen（BOD5）,Suspended Sediments and Turbidity.With significant correlation between the nine water quality indexes,TN and suspended sediment concentration were selected,then the paper mainly analyzed the correlations between the two water quality indexes and the normalized reflectance,its logarithm,derivative spectrum,and the ratio of spectral reflectance at different bands.The characterized bands were analyzed for the two water quality parameters with single band normalized spectral reflectance and the first derivative reflectance,and the linear models were built between the water quality parameters and the spectral reflectance ratios of different band,all these models had the good correlation coefficient of more than 0.75 between the two parameters and the spectra reflectance.关键词：spectral reflectance;Huangpujiang River;water quality index
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发布时间：2021-06-10 - 摘要：Impacts of coal exploitation on grassland are grassland destruction and desertification.In this paper,the desertified grassland in Huolinhe open-cast coalmine was extracted from remote sensing imagey by using decision tree and back-propagation（BP） neural network,and the desertification during the past 16 years in the study area was analyzed.The results indicate that ① from 1987 to 2003,there is a strong to weak,then weak to strong evolution process for the total grassland desertification,which can be attributed to climate change and human activities,especially to the influence of climate change;② there is a evolution similar rocess from strong to weak,then from weak to strong for the area of medium desertification and slight desertification,which can be mainly ascribed to the climate changes,then to the over-grazing,uprooting of the medicinal materials,and over-reclamation;③ due to the coal exploitation,the severe desertification is always in shape of " ▲" around the mining land,and developed to the east quickly with the help of monsoon;④ the area of severe grassland desertification is on the increase during the past 16 years,and there is much correlation between the mining land and severe grassland desertification area,so the mining land area can be served as an important indicator for coalfield eco-environment assessment and prediction.关键词：mining exploitation;grassland desertification;remote sensing;Huolinhe open-cast coalmine
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发布时间：2021-06-10 - 摘要：The threshold of NDVI classification is one of the most popular methods in the classification of remote sensing image.However,based on spectrum characteristics of objects,it cannot correctly identify objects with the same spectrum characteristics and therefore cannot reach the required accuracy.In this paper,we take an area of the upper part of Xitiaoxi River in Anji County as an example and discuss the method of combining texture of high-resolution images with spectrum to improve the accuracy of extracted information of SPOT5 image.Firstly,principal components are extracted from SPOT5 image,and high-resolution texture information is acquired by means of the algorithms of signal decomposition and reconstruction of（Mallet’s） Wavelet.Subsequently textures of the SPOT5 image are analyzed using Gray Level Co-occurrence Matrices and selected statistic index.Then the threshold is selected and an optimal threshold is obtained according to contrast and entropy.Objects with same spectrums,such as residence and water body,are identified using image segmentation in virtue of the optimal threshold.Finally,the final result is compared with the classification results based on single spectrum or texture.The result shows that objects with same spectrum are well identified by using texture analysis in image classification,and higher accuracy is obtained than using single spectrum or texture analysis.关键词：principal components analysis;Texture analysis;wavelet transformation;gray level co-occurrence matrices;thresholding
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发布时间：2021-06-10 - 摘要：The forest ecosystem is the important component in the terrestrial ecosystem and plays an important role in global change study.Aboveground biomass（AGB） of forest ecosystem is an important factor in global carbon cycle studies.This paper uses the ETM+ image in combination with the field measurement data to estimate the aboveground biomass.After getting the various vegetation indexes,we get the LAI（Leaf Area Index）,and then build the correlation between the LAI and field biomass data to get the initial biomass map.In addition, a shortwave infrared based vegetation index（SWVI） was calculated to get the forest age spatial distribution map,then,by incorporating the stand age and forest category information into the new regression model to get the final biomass map.We found that the AGB estimation for overall was related to the LAI and SR（Simple Ratio）（R2=0.895）,and for Chinese fir has a good correlation with the LAI and NDVI（R2=0.93）.The LAI and AGE are good predictors for the aboveground biomass of Conifer（R2=0.937）;for the Broadleaf and Masson pine mix forest,the age is correlated to the AGB（R2=0.792）;for the Broadleaf and Chinese Fir mix forest,the AGB was strongly related to the LAI and SR（R2=0.931）.The result shows that combining the stand age and forest categories information into the AGB estimation is a better way to improve the accuracy of aboveground biomass estimation with the optical remote sensing,the high-resolution forest stand age and aboveground biomass spatial distribution map can provide basic and effective information for the forest sustainable development and management.关键词：stand age;aboveground biomass;remote sensing;vegetation index
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发布时间：2021-06-10 - 摘要：An experiment was conducted successfully to retrieve the leaf temperature of grass canopy by applying LSF conceptual model on data obtained on August 6,1999 from AVHRR and synchronized ground observations with the known soil surface temperatures beforehand.The difference between the retrieved leaf temperatures from these two different data sources is less than 0.2k,which means that the grass canopy leaf temperature can be retrieved satisfactorily through LSF conceptual model combined with satellite data.Further analysis on the retrieved leaf temperatures under different leaf and soil emissivity conditions reveals that the estimated accuracy of component emissivity shows little impact on the retrieved results,whereas the estimated accuracy of the precipitable vapor in the whole layer of the air column could affect the retrieved leaf temperatures significantly.The precipitable water vapour estimated based on the sounding data and dew-point temperature can lead to an error up to 1.1k in the retrieved leaf temperatures.When there exists sufficient vapour in the air,the variance of leaf temperature is only 1.22k in spite of the quite intensive solar radiation during 11.00—17.00 on fine days.In contrast,the variance of soil surface temperature can be 9.5k and the variance of air temperature at the height of 1.5m is 6.0k,therefore the variance of leaf temperature is much less than that of the soil surface temperature and air temperature.The experimental results also show that in the southeastern Tibetan plateau,the land surface temperature can be retrieved with quite high accuracy by Becker and Li’s split window algorithm.关键词：LSF conceptual model;leaf temperature of grass canopy;Becker and Li’s split window algorithm
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发布时间：2021-06-10 - 摘要：CDOM is one of the three-components of ocean color.The research of CDOM has been made for several decades,this article reviews the development history of CDOMS definition and the investigation of sources.Absorption coefficient and S are two important parameters.Two models for absorption by CDOM are the Exponential model（250—650nm） and Gaussian model（190—250nm）.Gaussian model offers a deeper understanding of chemical interaction affecting CDOM molecular structure while Exponential model is acceptable for optical modeling and remote sensing applications.There are three methods to calculate S parameter,and non-linear regression with background parameter is the one.That provides the best fit and makes the average of S with 13% improvement and the standard deviation with 72% reduction.Furthermore there is a strong linear relation between the absorption coefficient and the fluorescence.Absorption coefficient is not only the optical properties of CDOM but the base of remote sensing.This article summarizes several kinds of retrieval equations such as those for SeaWiFS,MERIS,MODIS and GLI color sensors.The retrievals of color sensors have different characteristics and difficulties,so the remote sensing of CDOM is expected to be more exact in the future.关键词：CDOM;absorption coefficient;S;remote sensing model
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发布时间：2021-06-10
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