最新刊期
卷 15 ， 期 1 ， 2011
- 摘要：We analize the reason of periodic bright and shadow stripe noise generated in burst mode SAR,when the full aperture imaging algorithm is used.A simple but efficient one-dimensional frequency domain filtering method is proposed along with the flow chart of improved Range Doppler imaging algorithm including this operation.We discuss the nonperiodic abnormal stripe noise due to the spaceborne SAR system itself,and present an area filtering method in two-dimensional frequency domain.The validities of the algorithms in the paper are proved by processing actual spaceborne SAR data.关键词：Range Doppler algorithm;stripe noise;frequency domain filtering;burst mode
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发布时间：2021-06-10 - 摘要：A kernel-based signature space orthogonal projection（KSSP） technique is proposed for nonlinear subpixel target detection in hyperspectral imagery.As a nonlinear version of the signature space orthogonal projection（SSP）,the SSP is adopted in a high-dimension feature space after the pixels of input space are mapped into the feature space via nonlinear mapping.The kernel trick allows the KSSP ignor the actual nonlinear mapping.Experimental results of simulated and real data prove that the proposed KSSP approach outperforms the SSP method in target detection,and improves the robustness to noise.关键词：signature space orthogonal projection;kernel function;subpixel target detection;kernel signature space orthogonal projection
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发布时间：2021-06-10 - 摘要：The paper develops an automatic lake delineation algorithm based on"global-local"iterative scheme.The author uses NDWI（Normalized Difference Water Index） as the water identification index for the threshold segmentation process,and the slope maps and the shaded relief maps are applied in the algorithm to differentiate the shadow features from water features. Based on these methods,an automatic lakes delineation scheme is proposed to map the glacial lakes with Landsat Imagery in Himalayas mountains area.The results show that the proposed algorithm has good performance on lake mapping over the mountain areas,and lakes can be extracted automatically,accurately and efficiently,while most of melting glaciers and hill shadow features are eliminated from the segmentation processing.关键词：glacial lakes;information extraction;remote sensing;LAutomation
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发布时间：2021-06-10 - 摘要：To combine the high spatial resolution of Landsat and high temporal resolution of MODIS data,We selected an 18 km×18 km study area in upper reaches of Guanting reservoir.A new method—Spatial and Temporal Adaptive vegetation index Fusion Model（STAVFM） for blending NDVI of different spatial and temporal resolutions to produce high temporal-spatial resolution NDVI dataset has been developed based on STARFM（Spatial and Temporal Adaptive Reflectance Fusion Model）. STAVFM defined a time window according to the temporal variation of vegetation,put the vegetation phenophase into consideration and improve the temporal weighting algorithm.The result shows that the new method can combine the temporal information of MODIS NDVI and spatial difference information of ETM NDVI and can predict the missed ETM NDVI with a high accuracy（the correlation coefficients of three pairs of observed and predicted ETM NDVI are 0.82,0.90 and 0.91）.A high temporal and high spatial resolution NDVI dataset is constructed,which maintains the temporal trend of high temporal resolution data and the detailed spatial difference information of high spatial resolution data.
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发布时间：2021-06-10 - 摘要：Improve HJ-1B B08 on-board absolutely radiometric calibration precision by virtue of a constructed lookup table （LUT） method that fit for HJ-1B B08 characteristic to calculate its effective bandwidth.LUT method is based on HJ-1B on-board radiometric calibration theory,pre-launched experiment datum and Planck formula.As a result,HJ-1B B08 effective bandwidths are 2.01μm,1.940μm and 2.394μm corresponding to LUT method,FWHM method and moments method（MM）. LUT method has low association to blackbody temperature,and the relative difference is 0.3%between normal temperature and high temperature state.FWHM method and MM method are either higher or lower,and the calibrated top of atmospheric（TOA） radiance is either lower or higher,so they are not fit for HJ-1B B08 characteristic.LUT method gives a result that very close to field experiment,and the absolutely error is 0.04 W·m-2·sr-1·μm-1 corresponding to approximately 0.4 K TOA radiant temperature error,so it can be better when used to HJ-1B B08 on-board absolutely radiometric calibration.关键词：remote sensing;thermal infrared;HJ-1;calibration;effective bandwidth
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发布时间：2021-06-10 - 摘要：The traditional Fourier Descriptors（FDs） are normalized in this paper to make it independent of translation, rotation and scale changes.Four typical objects i.e.building,paddy,road and river are selected and their boundaries are expressed as sequences of complex numbers.FDs are obtained through one-dimensional Fourier transform.The characteristics of the frequency spectrum,contribution rate and the shape reconstruction are analyzed.The results show that the different frequency ranges have different contribution rates;the Direct Component（DC） reaches a proportion of more than 70%;the Low Frequency（LF） and High Frequency（HF） totally reach 7%-24%while the Medium Frequency（MF） merely 2%-4%.The LF components（descriptors 1—5） make a commendable reconstruction of objects’ shape and these descriptors are applied to the object-oriented classification.The overall classification accuracy is 98.48%with a Kappa coefficient 0.9714.关键词：shape feature;Fourier Descriptors;high-resolution;remotely sensed imagery
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发布时间：2021-06-10 - 摘要：The image classification is a key step for remote sensing data transforming into practical information and knowledge,which has always been the core problem in the remote sensing field.The limitations in traditional spectral classification method otherwise promotes the theory development on the spatial-spectral coupled information cognition of remote sensing,which focuses more on the spatial relationship.However,the current classification revision methods have configured the spatial forms and relationship while,going further,but there still exist some deficiencies in spatial distribution theorem about quantitative description,objects’ actual distribution,and so on.Thus,the paper proposes a spatial-adjacency-supported classification revision method inclusive of reference object extraction,target object pixels searching and reference adjacent objects distinguishing which detailed steps are:（1） marking the objects out and getting their distribution rangepicking up the other objects in the range,（2） selecting them as the target object,picking out the unavailable target object in the range and selecting them as a certain objectwhich also provides a convenient and effective way for stepwise and accurate extraction of other objects subsequently.We also carried out an experiment on offshore area classification revision,and the result proved to be more accurate and reasonable.关键词：remote sensing classification;spatial-spectral coupled information;spatial adjacency;classification revision
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发布时间：2021-06-10 - 摘要：Based on the theory of the relief effects on passive microwave radiation,we think that it is necessary to do the experiments in the field by observing the different topographic landscapes we design and compare the data we observe with the simulations of relief effects modeled by AIEM.The result shows there are 10-15 K bias of brightness temperatures affected by the tilted angles between flat terrain and mountainous terrain.When the frequencies are less than 10 GHZ,the relief effects of terrain elevation becomes weakening.Therefore,we certified that microwave polarization paths and directions have obviously changed due to the surface geometrical property,such as shape and the orientation of hills.关键词：relief effects;passive microwave radiation;experiment;AIEM
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发布时间：2021-06-10 - 摘要：After the brief introduction of existing dodging methods,the piecewise mean-variance adjustment is presented for both brightness and contrast homogenization.Then,the focus of the paper is put on the experimental comparison among the results obtained by the following five algorithms:MASK dodging,interpolation dodging,homomorphic filtering dodging, retinex dodging,and piecewise mean-variance adjustment.The experiments indicate that the piecewise mean-variance adjustment can deal with non-uniform brightness and contrast in an image.MASK dodging,interpolation dodging and retinex dodging can eliminate the phenomenon of non-uniform brightness.However,homomorphic filtering dodging can only weaken the phenomenon of non-uniform brightness.The dodging performance ranks piecewise mean-variance adjustment,MASK dodging,interpolation dodging,retinex dodging,and homomorphic filtering dodging from the best to the worst,respectively.关键词：non-homogeneity;interpolation dodging;MASK dodging;homomorphic filtering dodging;retinex dodging;piecewise mean-variance adjustment
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发布时间：2021-06-10 - 摘要：The MODIS sensor has 36 spectral bands,the desired effect can not be obtained with only one destriping method. Based on compensation and elimination of equalization curve method,a new set of algorithm is proposed in this article to rapidly detect and remove stripes,through giving a definite judging parameter of the stripe.If the correcting coefficient of 10 groups sensors in A-frame and B-frame are separated by 0,and the ABS（Ci）>0.008,then there exist wide stripes.If the maximum correcting coefficient（C’i） of 10 groups sensors is greater than 0.05,then there exist single-line stripes.The wide destriping process is as follows.Take the current column as the first one;then extract the correcting coefficient from the next 100 columns of each sensor compared with the first column seperatively.The results show that the detecting model can effectively identify the single-line stripes and the wide stripes,but the multi-line stripes need visual assistant.The removal effect of the single-line and the wide stripes is better than that from NASA website,the image quality is significantly improved after the treatment,though multi-line stripes are not completely removed.关键词：MODIS;stripe detection;destriping;compensation and elimination of equalization curve
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发布时间：2021-06-10 - 摘要：As a China’s second generation of polar-orbitting meteorological satellites,FY-3A（Fen Yun means wind and cloud） was launched on May 27,2008.The microwave temperature sounder（MWTS） and microwave humidity sounder（MWHS） are first aboard the Chinese FY satellite for the purpose of retrieving atmospheric temperature and humidity profiles.There are four channels of MWTS,i.e.50.30,53.596±0.115,54.94 and 57.29 GHz, with corresponding bandwidths 180,340,400 and 330 MHz,respectively,and five channels of MWHS,i.e.dual polarized（V,H） 150,183.31±1.0,183.31±3.0 and 183.31±7.0 GHz,which are corresponding to the bandwidths 1000,500,1000 and 2000 MHz,respectively.The spatial resolutions of MWTS and MWHS at sub-point are 50/75 km and 15 km,respectively,and the fields of views are 15 and 98 lines,respectively.Both scan modes are cross-track scanning. Based on the algorithms of atmospheric absorption coefficients,i.e.the MPM（Millimeter Propagation Model） and ROS（Rosenkranz’s model）,this paper presents a novel MIX（mixed） model for calculation of atmospheric absorption coefficients in the multiple channels of MWTS and MWHS under China National Standard Atmosphere （GB 1920-80） and U.S.Standard Atmosphere,1976. Using atmospheric radiative transfer with the in situ measurements of 836 radiosonde datasets（including the altitude,pressure,atmospheric temperature and humidity） from 16 sites in China and Japan,multiple channel brightness temperature（Tb） are simulated,and compared with FY-3A MWTS/MWHS observations as good validation.The radiosonde measurements were issued by NOAA/ESRL（National Oceanic and Atmospheric Administration/Earth System Research Laboratory）.The simulations with the atmospheric absorption coefficients based on respective MPM,ROS and our MIX algorithms are also analyzed.Data validation shows good performance of the MIX model. The statistical D-matrix is firstly constructed from the MWTS/MWHS Tb data and the corresponding radiosonde measurements,and then is applied to the retrieval of atmospheric temperature and humidity profiles over the northwestern Pacific Ocean during 2008’s Phoenix typhoon.A 3D distribution of the atmospheric temperature and humidity is also presented.Comparison and data fusing of FY-3A and other satellites shall be an interesting mission for future operational service.Large coverage of MWHS can be beneficial to further study of atmospheric parameters retrievals.关键词：FY-3A MWTS/MWHS;atmospheric absorption;radiative transfer;D-matrix;atmospheric temperature and humidity profiles
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发布时间：2021-06-10 - 摘要：Land cover change is an important scientific issue for the land evaluation and eco-environmental change forecasting.It is the necessary means to study the eco-environmental changes in coal fire zone by acquiring high precise land cover map through accurate classification approaches.In this paper,Maximum likelihood classification（MLC）,Spectral Angle Mapping（SAM）,object-oriented classification（OOC） and the multi-level classification based on compound subregion（MCBCS） approaches are used to classify land cover in the Wuda coal fire area.The results show that the multi-level classification based on compound subregion method leads to the highest accuracy up to 92.97%and the Kappa Coefficient is 0.9155.This method segments the study area based on the thermal characteristic,thermal anomalies,landscape and the disturbing to ecosystems.It reduces the confusion among different landcover types,emphasizes the zonal and regularity of land cover of the coal fire area in Gobi,and increases the separability of land cover.The multi-level classification based on compound subregion increases the whole accuracy by the accuracy improvement of single land cover.关键词：image classification approach;land cover;object oriented classification;multi-layer classification;coal fire
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发布时间：2021-06-10 - 摘要：The paper proposes a novel algorithm of SAR sea ice image incidence angle bias field correction using multi-exponential model.In the algorithm,the image mean values along SAR azimuth direction are firstly calculated.Then an one-dimensional correction field is modeled by a multi-exponential model.Whereafter,the one-dimensional correction field is calculated by applying entropy minimization method.After that the original image is corrected by the two-dimensional correction field derived from the one-dimensional correction field.The experiment result indicates that the proposed algorithm is effective in correcting SAR sea ice image’s incidence angle bias field.Besides,the proposed algorithm has better correction result than Karvonen’s method without the incidence angle information of the pixels.关键词：multi-exponential model;entropy minimization;incidence angle bias field correction;SAR;sea ice
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发布时间：2021-06-10 - 摘要：A fractal feature may be analyzed spectrally and spatially due to the"combination of spectrum and image"character inhered in hyperspectral images.The blanket method used for computing fractal dimension of surface is transferred to calculating fractal dimension of curves of Hyperion image.Up and down fractal signature for each scale is calculated based on the hyperspectral curve of each pixel.The fractal signature and their corresponding scale are analyzed.The result shows that fractal signature changes obviously at some special scales for different targets.As for the Hyperion data,the down fractal signature is more salient for effectively discriminating targets.A brief discussion about the relation of fractal feature scale with up and down fractal signature,initial calculating scale and number of samples is presented at the end of this paper.关键词：hyperspectral;fractal signature;feature extraction
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发布时间：2021-06-10 - 摘要：The coastal wetlands along the Bohai rim are undergoing rapid change.It is significant for regional planning to aware of these spatial and temporal changes.Multi-years of Landsat TM data and some other remote sensing data are used to conduct Human-Computer interaction visual interpretation of wetlands.Assisted by the collection of field samples,the distribution and classification of wetlands along the Bohai Sea in 2000,2005 and 2008 are extracted.The change rate model of single type and the regional dynamic degree model are constructed under GIS to reconstruct spatial and temporal pattern and dynamic pattern of the wetlands.The dynamic transfer matrix is constructed to reflect the dynamics reasons.The results show that:the brine pan and reservoirs/aquiculture,which are all manmade wetlands,have the biggest area amount and the biggest growth rate,with annual growth 205.52 km2 and 146.10 km2,respectively.The reduction of bottomland and tideland are more obvious than the other types.The Yellow River basin has the most significant wetland change,which is twice bigger than that of Liao River basin and Hai River basin,and still growing larger.The dynamic degree of the Hai River basin has shown the reducing trends.The wetland change driven by human activities is more obvious than the natural drive.The main wetland types transfering are caused by human activities such as the reclamation,tideland or bottomland for aquiculture,constructed land or brine pan.关键词：Bohai Rim;change of wetlands;monitor by remote sensing;spatiotemporal analysis
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发布时间：2021-06-10
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