最新刊期
卷 ， 期 1 ， 2006
- 摘要：Under the constant advancement of remote sensing technology,more and more high spatial and spectral resolution and high time frequency data are becoming available.The spatial resolution of satellite data is approaching 0.6m while for aerial imagery it is better than 0.1m.The spectral resolution of data can be as high as 3—4nm.These developments not only greatly increased our capability and accuracy in information extraction and monitoring but also opened new application opportunities.Existing research activities have focused on how to increase the utilization efficiency of high resolution data,particularly for high spatial resolution data in a wide range of applications such as urban environment,precision agriculture,transportation and road infrastructure,forest inventory,artificial targets recognition and disaster risk assessment.However,the overall level of automation is still low.In this paper,we introduce some of the bottleneck problems and research questions related to information extraction from high spatial resolution imagery,and high spectral resolution and polar imagery,data fusion,and high spatial resolution image change detection.We suggest that an image base and a corresponding relevant knowledge base be built to improve data sharing and to facilitate investigations in this field.关键词：high resolution remote sensing;information extraction;data fusion;change detection
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发布时间：2021-06-10 - 摘要：A hybrid inversion scheme for estimating surface variables of vegetation is proposed under Bayesian Network（BNet） theory,and then is used to estimate chlorophyll content of winter wheat leaves（Cab） and Leaf Area Index（LAI） of canopy.A coupled physical model named PROSPECT+SAIL was chosen to generate simulation data set,which means that the SAIL model uses the leaf reflectance and transmittance derived from PROSPECT model to simulate canopy directional reflectance.Results derived from simulation data and SHUNYI Experiment in 2001 data show that both LAI and Cab can be estimated with an appreciated accuracy under the proposed scheme,except that there are about 10% of total points falling into failure inversion.Then an uncertain data handling method,which considers the measured data as the random variables obeying Gaussian distribution,is employed to solve the failure problem.As a result the failure points are removed successfully though the RMSE of estimated the two variables is larger slightly.The presented hybrid inversion scheme is a knowledge-based inferring mechanism in principle,so the updated information content in the inversion process is quantitatively calculated thanks to the concept of entropy introduced from thermodynamics.Contrasting to the conditional entropy,the posteriori entropy calculated according to our proposed probability revision algorithm is not a descending parameter.This property can give some indications in estimating the information content parameters and the currently used data,that is to say,if the data are consistent with the previously derived information of estimated parameters,then there is descending entropy,otherwise,it is ascending.In the last section of this paper,some discussions are presented about the problem on how to estimate and control the information stream,especially when the inversed physical model is nonlinear.关键词：spectra library;hybrid inversion;bayesian network;information entropy
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发布时间：2021-06-10 - 摘要：A modeling study on the variations of directional brightness temperature（DBT） for row-structure crops was carried out with the help of the images captured by a large aperture thermal infrared camera over a maize canopy.The model assumes that the DBT is a function of component brightness temperatures and their directional fractions.Component fractions in the scene of view depend on sun-view geometry and the distributions of gaps within and between plant rows.To describe canopy geometrical features,a system of porous hedgerows with rectangle cross-section has been used;the directional variations of gap fraction are described by Kuusk function.The model demonstrates directional variations of DBT as a function of sun-viewing geometry and canopy geometrical structure as well as component brightness temperatures.In the simulation of DBT over a middle dense canopy near the noontime,the results reveal an evident row-direction-oriented hot stripe in DBT polar map,where appeared the hot spot along the sun direction.Further validation analysis has also been conducted which demonstrates modeled DBT agreeing closely with field observations.关键词：DBT;GORT model;crop canopy;row-structure
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发布时间：2021-06-10 - 摘要：The computation of exterior orientation elements using the navigation outputs of INS/DGPS system is addressed,then the direct and indirect geometric rectification of airborne linear array CCD imagery based on the line orientation data is introduced.The emphasis is put on the positioning and resampling problems in the direct rectification and the determination of the best scan line in the indirect rectification.Test results using PHI hyperspectral image prove that the rectification algorithm developed in this paper can reach the absolute positioning accuracy of better than 1.5 meters and the relative accuracy of 0.7 meters.关键词：INS/DGPS;linear array CCD;geometric rectification;exterior orientation;scan line
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发布时间：2021-06-10 - 摘要：In order to preserve the textural feature affected by multiplicative speckle especially in high resolution synthetic aperture radar（SAR） images,this paper proposes a despeckling method based on the Gauss-Markov model to suppress the speckle in SAR images.By introducing bayesian analysis framework,restoration model of degradation image of markov random field is built,and then the problem of image restoration is transformed into the problem of solving a maximum a posterior（MAP）,random field model parameters can be also estimated directly from noise image,thus speckle is effectively reduced.In this paper,on the basis of discussing the main idea of the restoration model based despeckling（RMBD） algorithm in detail,other commonly used denoising methods are compared with the proposed method,experiments show that the model-based despeckling algorithm achieves better performance not only at speckle reduction but also at preservation of structural detail information than other commonly used speckle filters.关键词：SAR;gauss-markov random field;speckle
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发布时间：2021-06-10 - 摘要：Monitoring the soil moisture variety in large-scale is very important to establishing the global water-cycle model,and to forecasting the weather and the floods.The spaceborne microwave radiometer is an efficient way to monitor the soil moisture variety in large-scale.When the radiometer observes the earth from the space,the absorbing and the scattering affection in the vegetation layer will attenuate the up-forward radiance from the soil,and this affection must be counted and reduced during the process of soil moisture retrieval.Much ancillary data are needed for computing the attenuating effects of the vegetation layer in the soil moisture retrieval model before,and the ancillary data are often unavailable.This paper proves that the Microwave Polarization Difference Index（MPDI） can be used to indicate the vegetation coverage conditions with the AMSR-E L2A brightness temperature data product.In this paper,we select the north-east and east part of China as the experiment area and the AMSR-E L2A brightness temperature and MODIS data as the sample data,and get the negative exponent relationship between MPDI and NDVI.Based on the relationship function and the knowledge about NDVI,MPDI has three threshold values that stand for High,Medium and Low vegetation coverage level.The threshold values can be used in the process of the soil moisture retrieval to judge the vegetation coverage level at the observed point and work out vegetation opacity.关键词：Microwave radiometer;AMSR-E;soil moisture;vegetation opacity;MPDI;NDVI
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发布时间：2021-06-10 - 摘要：Accuracy assessment is an indispensable step in the process of classification of remotely sensed data.The common method is carried out through confusion matrix established on reference data,which has three deficiencies: the heavy workload,inability to guarantee the complete correctness of reference data,the cost of reduction error resulting in the increase of workload.In remotely sensed imagery,the feature vector belonging to one category obeys the normal distribution.Based on this hypothesis and statistic theory,a new method is proposed established on category distribution.The reference data is unnecessary for proposed method.For the supervised classification,the workload is extremely little.The key to the proposed method is that the category population can pass the hypothesis test of a certain distribution,in this case,producer’s accuracy can be figured out easily.Given the number of the category population,the user’s accuracy can be figured out too,and then the overall accuracy can be estimated by user’s accuracy and area proportions of all categories after classification.Finally,the proposed method in this paper was applied to image classification for Zhengzhou city as an example.The result shows: if the distribution of category population can be given,producer’s accuracy obtained by common method and proposed method completely conforms in the perspective of statistics.关键词：accuracy assessment;remote sensing classification;hypothesis testing
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发布时间：2021-06-10 - 摘要：The RS image shows a very promising perspective for urban land-cover and land-use classification,particularly with very high resolution（1—4m） satellite images,while the traditional extraction methods of the high spatial resolution image has the shortcomings of the low accuracy and classification efficiency.This paper deals with the high spatial resolution image（IKONOS） classification based on the SVM method integrating the information of spectral,texture and structure.And comparing to the results based on Maximum Likelihood and SVM method with single-source data,this shows that the high spatial resolution RS image classification based on SVM Method with multi-source data can solve the image classification fragmentation which is based on the single-source data,spectrum,and has the good generalization ability with the high dimension vector.It has more accuration than the maximum likelihood method and SVM based on the single source data,adapts to the high spatial resolution RS Image classification.关键词：high spatial resolution;SVM;the optimal hyperplane;Texture;structure
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发布时间：2021-06-10 - 摘要：Fuzzy clustering is an important method in unsupervised classification.In application of traditional fuzzy clustering algorithm to unsupervised classification of remote sensing imagery,pixels are assumed to be independent of each other and their fuzzy memberships are determined individually,so that context information,i.e.statistical dependencies among neighboring pixels,are not taken into account.Aiming at this problem,an improved fuzzy clustering algorithm considering context information is put forward by incorporating the concept of spatial fuzzy membership under MRF framework.In this way,accuracy and reliability of clustering can be improved upon traditional ones.To evaluate the quality of clustering results,a validation index considering both intra-cluster compactness and inter-cluster separation is introduced,further more it is employed to find out naturally optimal cluster numbers and promote objectivity of clustering results.Finally an experiment on real remote sensing imagery is carried out to demonstrate the effectiveness of our proposed scheme.关键词：fuzzy clustering;context information;spatial fuzzy membership;CWBS index;remote sensing imagery
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发布时间：2021-06-10 - 摘要：With the development of SAR（Synthetic Aperture Radar） remote sensing techniques,SAR images have been widely applied in a lot of fields.But because of its side-looking character,we have to rectify the images into orthoimages before we use them.Building mathematical models is an important step in SAR rectification.In this paper we first recapitulate some mathematical models used for SAR image rectificaion,including Soviet Model,Polynomial Model and G.Konecny Model.The characteristics of these models are analyzed.Then we introduce the F.Leberl Model in detail,which is based on the distant condition and the zero-Doppler condition.In airborne condition the range direction is perpendicular to the flight track so the Doppler center frequency is zero.But in spaceborne condition,the Doppler center frequency does not always equal to zero,so the zero-Doppler condition needs to be corrected.In this article we use a polynomial to substitute the value of the Doppler center.By this way we corrected the zero-Doppler condition.In the experiments we used both the original F.Leberl Model and the corrected model to validate the precision of our model.From the results we come to the conclusion that the new model is acceptable to both the airborne SAR and the spaceborne SAR,at the same time it can get higher precision than the original model in spaceborne condition.关键词：SAR;F.Leberl model;doppler center frequency;zero doppler condition;distance condition
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发布时间：2021-06-10 - 摘要：A jamming method for SAR is proposed for the problem of protecting military moving target.This method uses received radar signal,modulates various RCS and position information,produces multi deceptive moving targets.This kind of jamming can protect moving targets,provide deceptive information to the jammed SAR,avoid the shortcoming of unable to protect moving target of stable scene.This paper discusses the configuration of jammers and the effects of the estimation error of radar’s position,and lastly gives the simulation result, which testifies the effectiveness of this jamming method.关键词：MTI;synthetic aperture radar;deceptive moving target;configuration of jammers
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发布时间：2021-06-10 - 摘要：This paper introduced the algorithms of SAR image location on the basis of image processing.And the precision of location is analyzed by the simulated datum and Radarsat slant image.The result indicated that the terrain variation,orbit measurement and echo pulse delay are the main factors which influenced the location precision.To Radarsat image,the location precision can attain 600—800m.关键词：SAR;pixel location
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发布时间：2021-06-10 - 摘要：In communications using air-ground data link,the data that comes from various kinds of airborne image sensors is becoming huger and huger,but the bandwidth of the data link is relatively small.In order to improve image transmission efficiency in battle field condition,there is a requirement for CCD aerial camera using central projection acquired images to be transmitted with high fidelity and speed over long distance.This paper proposed an airborne automatic data reduction scheme to solve the aforementioned problem.The key of this scheme is automatic image matching and clipping.The algorithm utilizes the strong logic relativity between adjacent aero-photograph and it is based on the model of 2-D affine transform.Under the conditions of detecting no highlight moving target,the algorithm performs automatic clipping on overlapping part of two adjacent images by the use of Fourier-Mellin transform.The experimental results of automatic clipping and mosaic show that the proposed algorithm is computationally efficient and very easy to realize.It is a robust algorithm and can effectively reduce data quantity of the downside data link.All these prove that the proposed algorithm has great potential of being applied to practical use.关键词：air-ground) data link;image transmission;data reduction;automatic clipping;affine transform;Fourier-Mellin transform;highlight moving target
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发布时间：2021-06-10 - 摘要：In recent years,many methods for fusing panchromatic and simultaneously multispectral（SM） images have been developed,however,there is little work concerning the fusion of images with significantly different spectral properties and pixel spacings though existing techniques either cannot avoid distorting their spectral characteristics or introduce artifacts.As an application of the Intensity Hue Saturation（IHS） transform and the orthogonal wavelet decomposition（OWD） in order to enhance the spatial resolution of MODIS images,intensity correlation moment model（ICMM） has been proposed based on mean and the standard deviation of both the intensity component obtained by averaging three MODIS images and the approximate component of the SPOT image decomposed with an orthogonal wavelet basis to produce one new intensity component while minimizing the degree of resampling.This system uses a self-adaptive correlation response to determine that how much the corresponding wavelet coefficients contribute to the dominant features for accurately transferring visually chromatic emergent information from any number of the input images into a single fused image.Subsequently,the high spatial resolution MODIS images are achieved through reconstructing the fused OWD coefficients by using the modulated MODIS images obtained through an inverse IHS as the approximate component and the details of the SPOT image as high frequencies.By using the ICMM as fusion rule,texture and pattern details coming from the SPOT image can be modulated to MODIS images without altering their spectral properties and contrast because fusion in the correlation response domain significantly improves the reliability of the feature selection and information fusion process.This technique can be applied to improve spatial resolution for either colour composite or individual bands.By an image fusion experiment using MODIS and SPOT images of Dapeng bay area of Shenzhen,China,the visual evaluation and statistical analysis between the original MODIS images and the fused MODIS images confirm that ICMM overcomes the preservation tradeoff and can achieve better performance in terms of both preserving spectral information and improving spatial resolution of SM images.Finally,the influence of the decomposition levels on the result is also discussed.关键词：OWD;ICMM;MODIS;SPOT;image fusion
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发布时间：2021-06-10 - 摘要：Large footprint lidar has demonstrated its great potential for accurate estimation of many forest parameters,e.g.forest height,forest biomass and vertical structure of forest canopy.In addition to the canopy vegetation, many factors such as atmosphere,underlying surface,the shape of crown,et al.,influence the lidar waveform.The illuminating intensity of the laser beam across the lidar footprint is a Guassian distribution and reduces from 1.0 to e-2 from the center to the edge of the footprint.So the forest stand spatial pattern plays an important role in the lidar waveform.The contribution of each tree to the lidar waveform varies with its location in a forest stand.This paper simulated the random,uniform and clumped tree distribution patterns in a stand.Then waveforms were simulated using a three dimensional lidar waveform model.The results show that the tree distribution patterns affect the lidar waveform profiles.The area（or energy） under the waveform from vegetation（AWAV） and the height of median energy（HOME） were used to estimate the effects.Following trends have been revealed from the simulation: for AWAV and HOME,uniform>random>cluster.The difference between uniform and random is not obvious.For the clumped case,the number of clusters does not have much effect on the lidar waveform.关键词：large footprint lidar;waveform;tree pattern
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发布时间：2021-06-10 - 摘要：With the improvement of the spatial resolution of remote sensing image,the objective basis is provided for extracting the texture and shape features,at the same time,the traditional pixel-based classification methods are challenged severely.So it is necessary to improve existing methods or to develop new one.In this paper,according to object-oriented analysis method,firstly a serial of pre-processing procedures are performed,such as image segmentation,edge tracing and vectorization,and vectorization compression;then the shape features are extracted from the vectorization information,finally with the help of the spectral feature and shape features,the classification for two kinds of typical artificial objects is finished by using the fuzzy classifier,and the classification accuracy is evaluated by visual interpretation.The results show that the extraction of shape features enriches enormously the feature database for object identification,especially under the condition when the object of interest and background have the similar spectral reflection and the apparent different shape features,this object-oriented classification by integrating spectral and shape features can improve greatly the identification accuracy.关键词：object-oriented identification;segmentation;vectorization;shape features;object identification
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发布时间：2021-06-10 - 摘要：Coupled with physical geographical features in arid areas,multi-temporal backscattering coefficients data（wet and dry seasons） were generated by IEM model.Analyzing these simulated data,we found there is a strong correlation between difference of wet and dry seasons backscattering coefficients(σ0wet-σ0dry) and soil dielectric constant,which is in agreement with the experimental observation in the literature;and then established the relation model between σ0wet-σ0dry and dielectric constant.This paper also carried out the research about salinization that is common in arid areas,and found there is a good correlation between σ0wet-σ0dry and the large difference of imaginary part of dielectric constant.This result is helpful to retrieve soil salt content if there is a clear understanding about the relation of imaginary part and soil moisture and salt content.关键词：IEM;arid areas;soil water;soil salt
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发布时间：2021-06-10 - 摘要：The ability of detecting small look-of-sight deformation remotely and precisely makes repeat-pass SAR interferometry an effective means for detecting ice flow over polar ice sheet.INSAR measurements based on ERS-1/2 SAR images have revealed various ice motions on ice sheet in Arctic and Antarctica.The latest and advanced SAR sensor is the ASAR sensor carried on-board the ENVISAT satellite launched in early 2002.Few interferometric applications of ASAR are reported till present,even fewer on glacier motion study in Antarctica.Grove Mountain is the newly found meteorites trap in East Antarctica.The wide-spread nunataks makes the ice flow quite complex in this region,which makes the ice motion measurement challenging.In this paper,a 35-day-apart ENVISAT ASAR image pair acquired at the end of 2004 is selected for interferometry to calculate the interferogram in Grove Mountain.The resulting interferogram consists of both topography and ice flow information.For evaluation,the interferograms of the same region calculated from sequential ERS-1 and JERS-1 image pairs acquired in 1996 were introduced for analysis.As for the difference of L and C band radar in sensitivity to displacement,the fringe densities of JERS and ASAR interferogram are different while the patterns are similar.The shape and distribution of ERS and ASAR interferometric fringes are slightly different for the difference in sensitivity to displacement in near and far range of SAR imagery.The qualitative comparisons indicate that ENVISAT ASAR data is of fine quality in such application on INSAR over ice sheet.The quantitative analysis shows that the motion state of revealed two ice flow subsystems among nunataks in Grove Mountain are relatively stable.Further research will focus on the topography removal,noise reduction and quantitative analysis of the composite interferogram.关键词：ASAR;ice flow;SAR interferometry（INSAR）;glacier;Antarctica
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发布时间：2021-06-10 - 摘要：Texture plays an important role in the composition of natural images and its analysis and classification are essential in a variety of image processing application.The method of texture analysis chosen for feature extraction is clearly critical to the success of the texture classification.Markov random fields（MRF） are a popular statistical model for textures.They capture local characteristics of an image by assuming a local conditional probability distribution.Many models used for gray level images have been proposed,but they cannot perform well in multispectral textured images.In this paper,a universal MRF model for multispectral textured images is developed,which take into account not only the spatial interaction within each of the multispectral bands,but also the interaction between different bands.As we all know,A MRF-based approach employs MRF model parameters as texture features to discriminate different textures.Because of the interaction between different bands,the universal MRF model is very complex,and estimating the corresponding parameters is very difficult.Therefore,in order to compute the universal MRF is parameters efficiently,a simplified equation using the maximum pseudo-likelihood method is built.After texture feature extraction,a supervised classification is applied to the original spectral bands combined with textural images.In this supervised classification system,the feature values are used by a Bayes classifier to make an initial probabilistic labeling.The spatial constraints are then enforced through the use of the Peleg’s Probabilistic relaxation algorithm.Necessary experiments are performed on samples of FG Forrest and QuickBird imagery,and the results indicate that the proposed algorithm provides better classification accuracy than other conventional approaches.关键词：MRF;texture features;multispectral image;classification
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发布时间：2021-06-10 - 摘要：The amount of chlorophyll fluorescence emitted by a leaf or canopy under natural sunlight is difficult to quantify because the signal is obscured by the reflected light.Firstly,the principle and method of separating the fluorescence emissive signal from canopy radiance spectrum based on Fraunhofer line was introduced.Secondly,the Solar Fraunhofer line was linked to the molecular oxygen absorption by the terrestrial atmosphere at 688nm and 760nm.The two Fraunhofer lines at 688nm and 760nm are obvious in the radiance spectra by ASD FieldSpec Pro NIR spectrometer,which largely overlap the chlorophyll fluorescence emission spectrum of leaves.Therefore,the two Fraunhofer lines at 688nm and 760nm could be selected to detect the emissive fluorescence.Thirdly,the statistical correlative coefficients（R2） between PAR and emissive fluorescence of winter wheat and Parthenocissus tricuspidata at 688nm and 760nm reach 0.9.The emissive fluorescence of winter wheat at 688nm equals to that at 760nm,the emissive fluorescence of Parthenocissus tricuspidata at 688nm is 3 times larger than that at 760nm.Compared with canopy reflectance spectrum,fluorescence spectrum is more sensitive to species and plant stress conditions.Finally,the emissive fluorescence at 688nm and 760nm was related to Fv/Fm by a OS1-FL modulated chlorophyll fluorometer,the correlative coefficients are highly significant at 0.999 confident level,which means that the emissive fluorescence calculated from the two Fraunhofer lines at 688nm and 760nm could replace the modulated chlorophyll fluorometer method and be applied to airborne remote sensing.
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发布时间：2021-06-10 - 摘要：With the developing of the computing technology,the technology used in the development of the real time SAR processor is mature.Not only the larger and larger data needs processed,but also the better and better image quality is demanded.The auto-focus algorithm must be used in the real-time SAR processor to improve the SAR image quality and adjust the parameters in the image reconstruction.However due to the special architecture and the real time demand of the real-time processor,the computing load cannot be a random quantity and too large.So that it is not all algorithm fit for real-time processor.In this article,the Map Drift Algorithm（MDA） is used for SAR auto-focus processing.The theory and method of the Map Drift Algorithm are introduced,and its application in real-time SAR processor is discussed.A linear relationship between the secondary phase error in the spectrum of the SAR signal and the position of correlation peak can be confirmed.The iteration times of MDA and also the computing quantity can be reduced effectively using this relationship.An interpolation was introduces to calculate the position of correlation peak in our paper,therefore the errors brought by discrete processing is greatly improved.It also make the estimation of the Doppler parameters more precise.The computing quantity and the image quality of our algorithm are shown as a test result with the Radarsat’s data.
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发布时间：2021-06-10
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