最新刊期
卷 15 ， 期 5 ， 2011
- 摘要：The ability of the RossThick-LiSparseR BRDF model （Ross-Li model） to simulate the bidirectional reflectance is assessed by comparing the reflectance simulated using the Ross-Li model based on the MCD43A1 data with the observed POLDER-3 BRDF data for 9961 pixels selected from the global POLDER-3/PARASOL BRDF archive.It is found that the RossLi model is able to simulate the bidirectional reflectance of ground objects efficiently.The R 2 and root mean square error （RMSE） of simulated reflectance are 0.934 and 0.016,respectively.On average,simulated reflectance is 5.2% lower compared with the POLDER-3 data.However,the Ross-Li model underestimates the reflectance by 14% for hotspots,with R 2 equal to 0.824 and RMSE equal to 0.07.The errors in simulated reflectance for hotspots depend on land cover types.Coniferous forests have the largest underestimates of simulated reflectance for hotspots,followed by broadleaved forests,grasslands,croplands,shrubs and barren lands.The modification for the volume kernel in the Ross-Li model can noticeably improve reflectance simulation for hotspots （R 2 =0.839,RMSE=0.043）.The reflectance simulated by the Ross-Li model is relatively accurate at nadir and darkspot.The departure of simulated reflectance from the POLDER-3 observations increases with the increases in solar zenith and view zenith angles.For grasslands and croplands,the accuracy of simulated reflectance decreases with the increase in NDVI.However,for forests and shrubs,the discrepancy between reflectance simulated by the Ross-Li model and the POLDER-3 observations maximizes when NDVI approximately equals 0.5.关键词：MODIS;POLDER;hotspot reflectance;Ross-Li model;BRDF model parameters product
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发布时间：2021-06-10 - 摘要：The traditional knife-edge method has the limitation that the chosen edge must be approximately perpendicular or parallel to the sampling direction （ideal edge）,which leads to difficulties of choosing usable knife-edge.Focusing on the issue,a new model of calculating PSF based on knife-edges with any slant angles is proposed in this paper.The proposed method is not only equivalent to the traditional one with the ideal edge,but also better than the traditional method with a slant edge in the PSNR （Peak Signal to Noise Ratio）,MSE （Mean Square Error） and SNR （Signal to Noise Ratio） of the restored image by the extracted PSF.The proposed method is robust to extract PSFs from knife-edges of any slant angles for image restoration,which extends its application.The validity of the proposed method has been reasoned both theoretically and practically,and tested with simulated data andADS40 data.关键词：PSF;Levenberg-marquardt;knife-edge method;Wiener filter
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发布时间：2021-06-10 - 摘要：In order to reduce over segmentation caused by only using watershed algorithm,an efficient multi-scale approach using wavelet transform is presented for the segmentation of the pan-sharpened multi-spectral QuickBird image.The approach toward complete segmentation includes four steps,namely,multi-scale images representation,image segmentation,region merging and result projection.First,the wavelet decomposition is implemented independently for each spectral band to form a number of new images at lower resolutions according to the size of original image.Gradient images are obtained by applying phase congruency model to approximation coefficients,and gradient magnitudes of all bands are fused for each scale.The optimal scale of wavelet decomposition is selected through analysis local gradient variance varying correspond to different scales and varieties of geo-objects.Second,a multi-level marker extraction algorithm is subsequently used to locate regions that are homogeneous,by moving threshold and extended minima transform.A marker driven watershed transform is then used to get segmented image based on gradient reconstruction.Third,a multi-constraint region merging strategy considering spatial adjacency relation,areas,spectral and textural features is proposed to merge the adjacency region pairs by searching the minimum merging cost among the initial segments.Finally,the detail coefficients are updated and the inverse wavelet transform is computed to project the initial segmentation to higher scale images,and pixels at boundaries are processed to keep region contours as original scale is reached.The experimental results demonstrate that the developed method can be applied to the segmentation of high-resolution multispectral remote sensing image as well as alleviate over segmentation and get the high accuracy segmentation.关键词：wavelet transform;watershed transform;optimal scale;marker location;region merging;result projection
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发布时间：2021-06-10 - 摘要：This paper proposes a Geometric Accurate Rectification method in remote sensing image based on reference image library.Firstly,uniformly distributed feature points are obtained in reference image using FAST （Features from Accelerated Segment Test） algorithm,the original matches of feature points are found based on the geographical information.Secondly,the highprecision matches of points are searched out in the input image through translation error removing,exact matching and RANSAC （Random Sample Consensus） gross error elimination.Finally,Delaunay triangulation is constructed for image transformation and resampling.It is verified by HJ Satellite experimental images,compared with traditional method,the accuracy of proposed method has been greatly improved.关键词：remote sensing image;geometric accurate rectification;Delaunay triangulation;image matching
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发布时间：2021-06-10 - 摘要：On the basis of analyzing and comparing existing corner detection algorithms,SUSAN algorithm has been adopted and improved in this paper for corner detection and image marching for high-resolution images.Aiming at some problems existed in the traditional SUSAN algorithm such as over detection and edge sensitive for irregular texture image area,we proposed an improved algorithm.Firstly,the threshold of gray difference is calculated adaptively according to the relationship between local and global image contrast.Secondly,rectangular template is adapted to determine the possible limits of USAN region from the edge.Finally,the corners are detected based on above two steps.Experiments show that the corners location is detected more accurately with the improved algorithm,and the results are more reliable and less redundant with much higher speed in image marching.关键词：corner extraction;SUSAN;response function;image matching
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发布时间：2021-06-10 - 摘要：Influenced by the different spectrum with same object and the same spectrum with different object,when classifying remote sensing images,there will be a limitation on the improvement of the classification accuracy if merely relies on spectral signatures.However,this influence could be impaired by the characteristics of local spatial statistics,which are capable of describing and analyzing the spatial autocorrelation.In this paper,the effects which different Local Spatial Statistics indices （Moran’s I,Getis-Ord G i,Geary’s C）,neighborhood rule,and lags have on the classification accuracy of the high resolution remote sensing image:SPOT 5 are discussed.Firstly,band 1 is analyzed regarding to local spatial statistics,and the results are added to original spectral bands as textural ones;Secondly,supervised classification is carried out with both spectral band and textural band;Finally,test samples are selected to assess the classification accuracy and different accuracies on different conditions are juxtaposed with each other to figure out the relations and disciplines between the classification accuracy and the parameters.Results indicate that G i statistics should be the optimum choice to raise the overall classification accuracy,with an increase from 87.74% to 95.12%.关键词：local spatial statistics;neighborhood rule;lag;direction of spatial distribution
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发布时间：2021-06-10 - 摘要：For acquiring the hierarchical spatial knowledge to be applied in cognitive route directions,a method of extracting hierarchical landmarks from urban POI data according to their significances is proposed.After analyzing the factors influencing the significances of POI objects from public cognition,spatial distribution and individual characteristics,a significance measure model composed of three vectors which are public cognition degree,urban centrality degree and characteristic attribute value is constructed.Then,the processes of computing the vector values of POI objects are discussed by the methods of questionnaire survey,multi-density spatial clustering and data normalization respectively.An experiment is carried out to compute the significances of the POIs selected from the area of Wuchang region of Wuhan city,and the POIs with different significances are treated as landmarks in different levels at last.In this experiment,several levels of landmarks are extracted,and being used as seeds to compute weighted Voronoi diagrams in every level,to reflect the influence area of every landmark and associate the landmarks in the same level and between the sequential levels.关键词：Navigation;spatial knowledge;landmark;POI;hierarchy
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发布时间：2021-06-10 - 摘要：The rapid development of multimedia and Internet technology enables real-time remote sensing image and video transmission.In recent years,multiple description coding has attracted considerable attention as an optional solution to remote sensing image degradation problem caused by unreliable channel’s transmission.Combining multiple description coding with quality scalable coding mechanism,this paper proposes a layered multiple description scalable remote sensing image coding algorithm based on discrete cosine transform （DCT）.The algorithm first divides DCT coefficients into a base layer and an enhancement layer by quantization.The enhancement layer is then subsample to form multiple descriptions,while the base layer is encoded into every description as a redundancy.Since base layer contains significant information of original remote sensing image,the above strategy ensures that each description obtains as much base layer information as possible when decoding.Moreover,the base layer in each description is coded independently in an embedded manner.This can facilitate an effective protection against channel transmission errors so as to improve robustness of coded bitstream.The layered structure realizes low computational complexity,easy redundancy control,and embedded bitstream.Experimental results validate the effectiveness of the proposed algorithm.关键词：remote sensing image;multiple description coding;DCT transform;scalable coding;embedded coding
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发布时间：2021-06-10 - 摘要：Atmospheric aerosol is the primary uncertainty of earth observation precision for quantitative analysis.With the development of quantitative remote sensing,there is a higher precision requirement of aerosol optical depth.Aerosol optical depth is a key parameter in atmospheric correction study of radiation transfer model.It is difficult to obtain AOD date relevant to earth observation images.However,as an indirect parameter of aerosol optical properties,horizontal visibility can be obtained from widely distributed weather stations.AOD data transformed from visibility are useful in the atmospheric correction of radiation transfer model.In this paper,Peterson model is optimized by fitting the changes of aerosol scale height based on the measured data of visibility and aerosol optical depth.RMSE of the optimized model is 0.254.The result shows that the optimized model has a higher precision.关键词：AOD;visibility;transformation model;radiative transfer
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发布时间：2021-06-10 - 摘要：According to the problems of large memory consumption and low computation speed in SIFT （Scale Invariant Feature Transform） algorithm,this paper adopts the strategy of pyramid and partitioning to register original images coarsely and matches partitioned images to realize accurate registration.During the process of matching,the number of Gaussian image octave is restrained according to image resolution and the feature points are filtered.Meanwhile,the matching process is paralleled to improve the efficiency.Experiments show that on the premise that registration accuracy is stable,the proposed algorithm solves the problem of high requirement of memory and the efficiency is improved significantly,which is applicable for registering remote sensing images of large areas.关键词：SIFT;scale invariant feature transform;point feature;parallel;Image registration;image matching
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发布时间：2021-06-10 - 摘要：A method of road extraction for high spatial resolution multi-spectral images is presented based on the advantages and disadvantages of Snake model theory.The quaternion expression of multi-spectral image is used to solve the limitation of Snake model for multi-spectral images.The road initial profile is gotten by marked watershed segmentation in quaternion space with multi-spectral images which solve the question of how to set the initial border in the model.At the same time,how to get the approximate road hollow position is solved to realize the road contour extraction by gradient vector flow model with iterative solution.After experiments on QuickBird multi-spectral image with above method,the results indicate that the presented method is feasible for road extraction from high spatial resolution remote sensing image.Comparing with road extraction result by Snake model directly,the method presented in the paper has a better performance in extracting the main road contour information from high spatial resolution multi-spectral images.关键词：road extraction;quaternion;edge detection;watershed transform;GVF Snake
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发布时间：2021-06-10 - 摘要：By a careful analysis on the requirements of the national disaster emergency management,the international data sharing and application cases,and the national disaster management experiences,this paper proposed a new concept for constructing an Emergency Disaster Spatial Information Cooperative Service Mechanism （EDSICSM）.Based on their respective functions,a tri-dimensional platform consisting of Command Center （CC）,Data Center （DC） and Information Center （IC） is formed,and according to the actual work of the national disaster management,the operation relationship and operation procedures for the service mechanism are established,and two kinds of operation modes are proposed:normal mode and emergency mode.Meanwhile,some necessary auxiliary security mechanisms have also been discussed.By now,the mechanism has already been partly applied in the national disaster management department,and the social and economic benefits of the mechanism have also been proved.关键词：nature disaster;spatial information services;data sharing;coordination scheduling;cooperative mechanism
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发布时间：2021-06-10 - 摘要：Monitoring water pollution using remote-sensing techniques has the advantage of large scale coverage and real-time processing.The rivers with prominent gradient of water quality in South China were selected as a case study,and the polarimetric SAR （POLSAR） data obtained by C-band spaceborne POLSAR system RADARSAT-2 was utilized to investigate the potential of monitoring the river pollution based on POLSAR data as the primary exploration.We firstly introduced the polarimetry of electromagnetic wave and the principle of POLSAR.Then based on a simultaneous measurement with POLSAR scanning,we extracted the river region and compared the pollution status with POLSAR data.By analyzing the measured water quality index of 18 samples in 10 measuring spots,we found that the T22 element in the polarimetric coherence matrix is highly correlated to some water quality indexes,such as the 5-day biochemical oxygen demand （BOD 5）,therefore it can reflect the pollution in river.Using least square estimation on the measured data,we obtained the retrieval model for BOD 5 from coherence matrix,with the correlation coefficient of 0.82.Finally from the analysis of the random surface scattering model and the Fresnel Coefficient,we investigated the underlying reason for the relevance between T22 element and the physical property of water.It is indicated from the preliminary theoretical analysis and experimental result that T22 element is capable of reflecting the water pollution status.关键词：polarimetric SAR;water pollution monitoring;coherence matrix;5-day biochemical oxygen demand
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发布时间：2021-06-10 - 摘要：The wind speed,wind direction and wind stress over the ocean with respect to altitude are derived based on empirical relations.Taking into account the height of rain formation and assuming that wind speed at 10 m is 10 m/s,wind induced spatial drift for a unit mass of rain cell is estimated to range from 3—100 km,which is considered as the error of mislocation in satellite precipitation measurement.This source of error is analyzed and corrected using 10 sets of rain data from TRMM satellite.Comparison with simultaneous GPCP data shows an overall improvement of 12% in their consistency,suggesting that the proposed correction scheme is both feasible and effective.关键词：remote sensing;wind field;rainfall;drifting;TRMM;correction
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发布时间：2021-06-10 - 摘要：Light Detection and Ranging （LiDAR） is one of the most promising technologies in forestry,which shows potential for timely and accurate measurements of forest biophysical properties over time.This study explores several regression models relating variables derived from airborne laser scanner for the estimation of various forest metrics,and discusses the results of prediction concluding accuracy.These prediction models use 78 plots with radius of 7.5 m or 15 m in Kunming,Yunnan province,China.Two series of variables are provided from the airborne laser scanner data,one is canopy height and to the other canopy density.These variables are used as independent variables in the regressions.The stepwise regression analysis has been used to select various independent variables.The results show high correlation between forest metrics and variables derived from airborne laser scanner.For the three different forest types （coniferous,broad-leaf and mixed）,all the prediction of mean heights are accurate.However,for the predictions of above ground biomass,the result of coniferous is better than broad-leaf,while there is no significant correlation between the biomass of mixed and the laser variables.Finally,the results of regression and factors affect the accuracy of prediction are discussed.The accuracy of prediction may be relate to the forest type,sampling time and density of laser scanning and position errors.关键词：airborne laser;scannersub-tropical forest;mean height;above ground biomass
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发布时间：2021-06-10
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