最新刊期
卷 14 ， 期 4 ， 2010
- 摘要：The application effect of the hyperspectral imaging system heavily relies on the signal to noise ratio.According to design features of hyperspectral imaging system and source of various noises,various noise models are established like time-domain noise,spatial-domain noise,spatial interference,spectrum superposition and so on and the influence and restriction of various noises on hyperspectral imaging system are analyzed in detail on this basis.The conclusion of this paper plays an important role in promoting the practicability of the hyperspectral imaging system in China.关键词：hyperspectral;radiation sensitivity;noise model
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发布时间：2021-06-10 - 摘要：This paper constructs a realistic three-dimensional scene of maize,and develops a coherent scattering model to simulate the polarimetric Synthetic Aperture Radar（SAR）data by analyzing the structure characteristics of maize,especially considering the relative spatial position and orientation of maize leaves.The multi-angle,multi-polarization backscattering coefficients dataset acquired from the scatterometer are compared with that calculated from the simulated polarimetric SAR data,showing that the amplitude information simulated by the model is valid.The HH-VV,HH-HV,and VH-VV phase difference of the simulated data are analyzed,showing that the simulated phase information is valid.Besides,Polarization response method and Cloude H-α classification method are applied to validate the simulated PolSAR data from the viewpoint of scattering types.关键词：PolSAR simulation;coherent scattering model;maize
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发布时间：2021-06-10 - 摘要：Atmospheric upward and downward radiations in visible and near-infrared bands are the key input parameters for radiative transfer modeling,imaging simulation and atmospheric correction.This study presents the numeral models and computing methods of the atmospheric parameters which are related to the two parameters according to four-stream radiative transfer theory.Focusing on the six bands of Landsat 5 TM,the parametric models among atmospheric parameters,water vapor content,visibility distance and solar incidence zenith angle were designed,based on which the sensitivity of each parameter is analyzed.The results showed that the parametric models have higher precision.Meanwhile,the atmospheric upward and downward diffuse radiation of each band for TM remote sensing was calculated and the changes under the coverage of vegetation and bare soil were analyzed.关键词：atmospheric upward and downward radiation;Radiation transfer;atmospheric correction;parametric model
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发布时间：2021-06-10 - 摘要：Ship detection is one of the important areas in remote sensing applications.However,many ship detection approaches often face a difficult dilemma between low detection rate and high false rate,because of the un-matching between object and its features caused by the complicated characteristics of remote sensing images.Therefore,this paper proposes a novel detection algorithm based on Probabilistic Latent Semantic Analysis（PLSA）.It firstly describes the object in terms of the probability combination of latent aspects generated by PLSA,then discriminates the latent aspects model of object by statistics recognition method to obtain the final detection result.The generated latent aspects model represents the joint probability of objects and their features,and gives an explanation for the above un-matching problem by the probability distribution of latent aspects.The performance of the proposed algorithm is demonstrated through the ship detection in various optical remote sensing images,and substantiated using quantitative criteria.关键词：ship detection;optical remote sensing images;probabilistic latent semantic analysis;tempered expectation maximization;local-binary-pattern operator
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发布时间：2021-06-10 - 摘要：This paper studies the dual stripmap imaging program of the airborne SAR which carries a circular scanning antenna system that has the ability to map both sides of the radar’s flight path.This imaging mode is developed from the circular-scanning mode,which effectively improves the image size and the imaging efficiency.The basic imaging procedure is firstly analyzed,then the implementation as well as the rules of choosing the system parameters to fulfill the image resolution and the seamless mosaicing requirements are presented,while considering the actual motion conditions of the radar platform.The point-target simulation and live data processing results of one real system are given to show the validity of the proposed imaging methodology.关键词：synthetic aperture radar（SAR）;dual stripmap mode;imaging algorithm;parameter design
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发布时间：2021-06-10 - 摘要：Spatial clustering is an important tool for spatial data mining and spatial analysis.It can be used to discover the spatial association rules and spatial outliers in spatial datasets.Currently most spatial clustering algorithms cannot obtain satisfied clustering results in the case that the spatial entities distribute in different densities,and therefore more input parameters are required.To overcome these limitations,a novel data field for spatial clustering,called aggregation field,is first of all developed in this paper.Then a novel concept of aggregation force is utilized to measure the degree of aggregation among the entities.Further,a field-theory based spatial clustering algorithm（FTSC in abbreviation） is proposed.This algorithm does not involve the setting of input parameters,and a series of iterative strategies are implemented to obtain different clusters according to various spatial distributions.Indeed,the FTSC algorithm can adapt to the change of local densities among spatial entities.Finally,two experiments are designed to illustrate the advantages of the FTSC algorithm.The practical experiment indicates that FTSC algorithm can effectively discover local aggregation patterns.The comparative experiment is made to further demonstrate the FTSC algorithm superior than classic DBSCAN algorithm.The results of the two experiments show that the FTSC algorithm is very robust and suitable to discover the clusters with different shapes.关键词：spatial clustering;aggregation force;field theory;spatial data mining
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发布时间：2021-06-10 - 摘要：Based on the clutter statistical characteristics of SAR image,this paper takes advantage of the generalized Gamma model to fit the filtered and co-registered SAR images,in order to gain the characteristics information,such as radiation value,local texture,etc.Then,the degree of evolution between the statistical characteristics of multi temporal SAR image is measured by the definition of Kullback-Leibler Divergence in information theory.Afterwards,a combination of KS and KL test has been applied into the evaluation of fitting function for the difference map captured in the former step,which help select the best fitting function automatically for the model-based KI threshold segmentation.Experiment was carried on the multi temporal SAR images for Southern Part of Tianjin,acquired by Radarsat-1/2,as well as Shunyi District of Beijing,acquired by Envisat-ASAR.Such results confirmed the method proposed in this paper not only avoid large number of false alarms generated from the changes of surface corrugation,but also effectively detected the regions ignored by traditional methods,which have no variance in mean value,but differ in texture.关键词：generalized Gamma;Kullback-Leibler Divergence;KI;SAR;change detection
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发布时间：2021-06-10 - 摘要：This paper uses Savitzky-Golay filter method to reconstruct MODIS 16d NDVI time-series product of Ruoergai plateau wetland from 2000 to 2009,and the results are compared with other two methods— Mean Value Iteration filter and Fourier method.As a result,reconstructing method based on Savitzky-Golay filter has got a better result in both image visual effects and NDVI temporal profiles.High-quality long time-series NDVI which is reconstructed based on this method offers a good foundation for the monitoring of ecosystem of Ruoergai wetland.关键词：Savitzky-Golay filter;NDVI;time-serie;MODIS
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发布时间：2021-06-10 - 摘要：High accuracy surface modelling（HASM） constructed based on the fundamental theorem of surface is more accurate than the classical methods,but the computational speed of HASM is proportional to the third power of the total number of grid cells in the computational domain.In order to decrease the computational cost and improve the accuracy of HASM,this paper employed a modified Gauss-Seidel（MGS） to solve HASM.The fact that MGS is more accurate and faster than GS is proved in terms of theorem.Gauss synthetic surface was employed to comparatively analyze the simulation errors and the computing time of MGS and GS.The numerical tests showed that under the same simulation accuracy,MGS is faster than GS,and the time difference between MGS and GS is approximately proportional to the second power of the total number of grid cells.Under the same outer or inner iterative cycles,MGS is more accurate than GS.The computing time of MGS is proportional to the first power of the total number of grid cells.Compared with the direct methods for solving HASM,MGS greatly shortens the computing time of HASM.SRTM3（36°—37°N,107°—108°E） of Dongzhi tableland located in Gansu province was employed as a real word example to validate the accuracy of HASM based on MGS.In the example,about 50% of SRTM3 was used as validation points,the others for DEM simulation.The results indicated that RMSE of HASM based on MGS is about 2.4,1.8,1.3,2.7 times less than those of KRIGING,IDW,TIN and NEAREST.关键词：GS iteration;surface simulation;accuracy;test analysis;interpolation
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发布时间：2021-06-10 - 摘要：Hyperspectral remote sensing image provides not only abundant spectral information but also spatial detailed infor-mation.For making full use of the information,this paper considered the variations of the spectral feature among pixels in local neighborhood and researched on a kind of Local Neighborhood Spectral Similarity Measure Index to extract the spatial detailed information.Furthermore,the spectral feature of endmember in local neighborhood was also considered.And a kind of Local Neighborhood Independent Endmember Index was proposed.In experiments,these local neighborhood indexes demonstrated excellent performance in the real hyperspectral image.Based on these work,it can further improve the capability of hyperspectral target detection and identification by combining with spatial and spectral information.关键词：hyperspectral remote sensing;spectral similarity measure;endmember;local neighborhood index
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发布时间：2021-06-10 - 摘要：Plant nitrogen status is a key indicator for evaluating crop growth,increasing yield and improving grain quality.Non-destructive and rapid assessment of leaf nitrogen is required for improving nitrogen management in fruit tree production.The hyperspectral reflectance and corresponding total nitrogen concentration of different species of apple trees’ leaves were measured by Field-Spec PMI-MASTER PRO.The correlation among raw hyperspectral reflectance,first derivative spectra,and hyperspectral characteristic variables were analyzed.This paper makes a model for the quantitative detection of leaf ’s total nitrogen with a view to providing a theoretical foundation for nutrition diagnosis of the apple by remote technology.The results showed that the raw spectral reflectance has the maximum negative correlation coefficient at 715nm（r = ?0.817） with total nitrogen concentration and the logarithm model constructed with reflectance at this point is the better one as compared to linear model;the first derivative spectral reflectance has the maximum positive correlation coefficient at 723nm（r = 0.87） and the linear and non-linear models have the similar capacity for the nit rogen est imation;as to hyperspectral characteristic variables,they all show significant correlation with nitrogen contents except λy,SD /SDy and（SDr + SDy）/（SDr ? SDy）.Those results indicate that the variables adopt in this paper have great potential for nitrogen concentration test.By the precision evaluation of estimation models,the logarithm model constructed by the first derivative reflectance at 723 nm was proved to be the best for the estimation of apple leaves nitrogen concentration.关键词：apple;spectral parameter;leaf total nitrogen concentration;monitoring model
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发布时间：2021-06-10 - 摘要：A new scheme was proposed in this study to account for such a handicap,which is based on the statistics of object area fraction that is somewhat insensitive to the orbit truncation.In order to get a measurement that could be accurately received,continuous circle object was consulted.Accordingly the equivalent radius was finally defined by using a minimum deviation principle to indicate the object scale.Since the equivalent radius is an indirect indicator of object spatial scale,it could be used as a secondary strategy to modify the results from counting method,by which the underestimate would be restrained to some extent.关键词：precipitating clouds;spatial scale;object area fraction;equivalent radius
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发布时间：2021-06-10 - 摘要：With the significantly improved data availability in remote sensing technology,mid-resolution images have become the primary data source for crop sown area estimation in large scale.However,it is still difficult to solve the problems of spectrum heterogeneity in one field and spectra similarity between fields,especially in transitional region by using mid-resolution images.In order to maximally avoid above motioned problems and accurately measure the sown area of winter wheat,this paper developed per-field classification method and tested the method in an urban agriculture region with complex planting structure through several steps:first,digitalizing field boundary from QuickBird image;second,extracting characteristic index including spectrum and texture information as well as vegetation index for each field from the multi-temporal TM images;third,operating support vector machine（SVM） and maximum likelihood classification（MLC） with different field characteristic index;finally,estimating the accuracy of our method.Results show that the per-field classification method has a higher accuracy than per-pixel classification both in amount（estimated sown area of winter wheat divide by reference sown area of winter wheat,Kr） and position（equal to product accuracy,Kp）.Although both SVM and MLC could get very high amount and position accuracy（97% and 90% respectively）,the estimations of SVM are more stable.The errors of per-field classification mainly happened at the fragmentized parcels.Additionally,characteristic information could enhance the performance of per-field classification.Our method also has an outstanding advantage that no optimum period requires on satellite imagery which could enhance practicability and operationality of our method.关键词：per-field classification;winter wheat;sown area;support vector machine;maximum likelihood
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发布时间：2021-06-10 - 摘要：Forest height extraction with polarimetric SAR interferometry（POLInSAR） is a hot research field of imaging SAR remote sensing.Several available forest height inversion methods using POLInSAR data were validated and compared with repeat pass E-SAR datasets and the corresponding ground measured forest stand height through the analysis of the Random Volume over Ground（RVoG） scattering model.After analyzing the experiment results in the view of physical mechanisms,we developed an integrated inversion method combining interferometric coherence optimization and compensation of non-volumetric scattering decorrelation.Validation result shows that the general performance of the developed forest height inversion method is superior to the others.关键词：POLInSAR;polarimetric interferometric coherence optimization;RVoG;forest height;non-volumetric scattering decorrelation
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发布时间：2021-06-10 - 摘要：The differences between the geographic environment and the geo-spatial concept of current geo-information technologies,and the characteristics and development processes of spatial cognition of maps and geographic information systems are analyzed.The concept of virtual geographic environment cognition is proposed.The objectives of virtual geographic environment cognition include the cognition of the real world phenomena of surface features,geographic processes,human behavior and their relationships.This paper studies virtual geographical environment cognition from two aspects:acknowledgement and understanding of the geographic space,geographic processes and human behaviors;and then the representation of the real geographic environment in the virtual geographic environment,as well as obtaining and sharing geographical knowledge based on virtual geographic environments to gain insight to the real geographic environment.Representation of virtual geographic environments involves three levels.Research on cognition of virtual geographic environments needs to develop geo-spatial cognition theories and methods of geographic entities and phenomena,as well as cognition and modeling of geographic dynamic processes and the perception of human behaviors.Geographic processes representation and human behavior simulation are focused upon and relevant preliminary study ideas and contents are presented.关键词：geo-spatial cognition;virtual geographic environment cognition;geographic process representation;human behavior modeling
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发布时间：2021-06-10
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