最新刊期
卷 13 ， 期 1 ， 2009
- 摘要：In this paper,I propose a personal view on the general contents of remote sensing science and technology,which includes sensor research and manufacturing,remotely sensed data acquisition,data processing,information extraction and remote sensing applications.Serving as the basis for all these components is radiative transfer process modeling and inversion.Also of importance is the effective visualization of remotely sensed data and their efficient distribution to end users.In all these areas,there are critical research questions.In particular,I consider 4 fundamental areas for improved application of remote sensing.These include the scale and angular issues in remote sensing,removal of topographic effects on the radiance and geometry of remotely sensed imagery and the related question of multisource and multitemporal data registration,integrating knowledge and remotely sensed data into effective information extraction,and four dimensional data assimilation techniques.Strategies of information extraction can be broadly divided into manual visual analysis and computer-based analysis.The computer based information analysis include radiative transfer model inversion,image classification,regression analysis,three dimensional information extraction,shape analysis and change detection.Successful information extraction is the key to the success of remote sensing.There are many important issues that need to be solved including how to make better use of the spatial and temporal data present in remotely sensed data in information extraction.How to effectively combine the strength of both computer analysis and human interpretation? Finally,4D data assimilation is the new direction that allows for the integration of instantaneous observation with process-based climate,hydrological and ecological models.Further work along this direction will enhance the contribution of remote sensing in global change studies.In return,the quality of remotely sensed parameters can be improved.
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发布时间：2021-06-10 - 摘要：将人不可及的观测统称为遥感,使地面传感器成为遥感的一部分。提出遥感科学与技术的基本内容,包括传感器研制、遥感数据获取、数据处理、信息提取和应用5个部分。其理论基础是辐射传输过程模拟与反演,贯穿于各个组成部分。数据的可视化及传输发布存在于从数据获取到应用的各个环节。遥感科学与技术正处于快速发展时期,各个方面都有前沿问题。辐射传输理论中的尺度和多角度问题,地形对辐射和图像几何影响及相应的多源多时相数据的匹配问题,遥感信息提取中自动化和目视解译的结合以及信息提取新策略问题,遥感与基于过程模拟的气候—水文—生态模式相结合的四维数据同化技术等是当前遥感科学与技术发展中的重要学科前沿。四维数据同化技术是突破遥感瞬时信息获取、实现图像与机理模型有机结合、改善自身数据产品质量和促进地学大范围模拟准确性的重要发展方向,能增强遥感对全球变化科学的贡献。关键词：遥感新定义;地面传感器;几何/辐射校正;信息提取;数据同化
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发布时间：2021-06-10 - 摘要：A three-layer scatter model is developed for the retrieval of moisture profile of the terrain subsurface under SAR observation at UHF/VHF bands.Based on different penetration depths at UHF and VHF channels,scattering observations at these two bands are alternatively used to iterate the retrieved moisture of the layered media,and finally reach the convergence of the moisture profile of the layered subsurface media.关键词：soil moisture;UHF/VHF SAR;subsurface
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发布时间：2021-06-10 - 摘要：Image segmentation is the basic of extracting and recognizing interesting region,and it is also the key step of image analysis.Region-based JSEG algorithm is a new image segmentation algorithm considers not only color information but also spatial information,and also has a good effect in region segmentation for ordinary images and video images.In this paper,JSEG algorithm is introduced to segment remote sensing images,and is also improved to be applicable to segment multi-spectral remote sensing images and VHR remote sensing images which contain complicated texture characters.Experiments demonstrate that it can solve fuzzy region boundary problem effectively which is caused by complicated land object information.关键词：region segmentation;multi-spectral remote sensing image;JSEG algorithm
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发布时间：2021-06-10 - 摘要：Small footprint airborne LIDAR systems now possesses the capability to sample the whole returned waveform rather than to extract discrete 3D coordinate values（discrete point cloud）,thanks to the improvement of data storage hardware and data processing speed.One merit to analyze waveform data is that the end-user can extract point cloud by him/herself from the raw waveform data in the post processing,instead of being provided by the LIDAR system.The first step to analyze waveform data is to decompose the waveform into individual components.Conventional methods for waveform decomposition are usually polynomial fitting by non-linear least square algorithm,or simply thresholding with the threshold value provided by system vendor.Literature has pointed out that it is impossible to get higher accurate decomposition results by such conventional methods.The paper modifies the Expectation Maximum（EM）algorithm in the context of laser scanning waveform decomposition.Experiments with data from both airborne and space borne LIDAR systems show the high reliability and accuracy of the proposed method for waveform decomposition.关键词：LiDAR;EM algorithm;full waveform digitizing;waveform decomposisiton;Gaussian decomposition
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发布时间：2021-06-10 - 摘要：Polarimetric microwave radiometer can be used for remote sensing of ocean surface wind speed and direction.The global minimum of the cost function corresponds to the best estimate of the actual wind vector;but due to the level of noise it may not be the closest ambiguity to the true wind direction.The presence of these ambiguous solutions must be carefully considered in the retrieval of wind vector estimates.Expected errors in wind direction retrievals have been examined using Monte Carlo simulation analysis,as well as the maximum likelihood estimation（MLE）cost function in the presence of noise.An algorithm is proposed to obtain wind direction according to the first and second rank solutions of the first scan and the first rank solution of the second scan.The simulated results show that the algorithm can avoid ambiguous solution,and the cells near the position that along or perpendicular to spacecraft-heading vector give the largest error of retrieved wind direction.These cells can be used for cold and warm calibration,and the residual cells which give smaller direction errors can be used for wind direction remote sensing.A new scanning geometry for conical-scan is put forward.关键词：ocean surface wind direction;polarimetric microwave radiometer;downwind;upwind;ambiguity
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发布时间：2021-06-10 - 摘要：According to TanDEM-X satellite program,this paper studies interferometric capabilities of TanDEM-X mission during an orbit period and tries to get the change of relative height error in a global scope.Firstly,based on HILL-equation of the helix formation,effective baseline,including the range and azimuth effective baseline,which has a great impact on interferometry is analyzed in detail during an orbit period.Then the influence of baseline decorrelation imposing on interferometric phase error is discussed detailedly,which is the most important influence on relative height error.At last relative height model is established and relative height error or TanDEM-X system is presented further.The computer simulating result shows the validity of analysis.关键词：interferometry;HELIX formation;effective baseline;Correlation coefficient;phase error;relative height accuracy
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发布时间：2021-06-10 - 摘要：This paper introduces a procedure of Interferometric SAR（InSAR）processing,including the algorithms of image registration and phase unwrapping.A coarse-to-fine fast registration framework,based on the mean square difference function,is proposed.Aiming at the interferogram with large size and dense residues,two unwrapping algorithms are presented:one is the multi-patches method to connect opposite residues,and another one the center expanding method to search opposite residues.These two algorithms can avoid long branch cuts and excessive connection of residues,and are well employed in the experiments of ENVISAT-ASAR datasets.Compared with conventional methods,our results of registration and unwrapping show good advantages in InSAR data processing.关键词：InSAR;image registration;Phase unwrapping
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发布时间：2021-06-10 - 摘要：In remote sensed images,mixed pixels are always present.Soft classification defines the membership degree of these pixels for different land cover classes.Sub-pixel mapping is a technique designed to use the information contained in these mixed pixels to obtain a sharpened image.Pixels are divided into sub-pixels,representing the land cover class fractions.Evolutionary agent algorithms,combined with the assumption of spatial dependence,assign a location to every sub-pixel through two reactive behaviors which are breeding and diffusion.In the paper,the algorithm is tested on degraded synthetic and real imagery.The obtained accuracy measures are higher compared with conventional hard classifications,so it is proved to be a simple and effective method for sub-pixel mapping.关键词：remote sensed imagery;sub-pixel mapping;evolutionary agent algorithm;breeding;diffusing
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发布时间：2021-06-10 - 摘要：Feature is the most essential attribute for recognizing target in image processing.This paper proposes to recognize ship target by utilizing a fuzzy neural network processing on its geometry,moment and texture features.First,we simply depict geometry feature and moment feature especially Hu moment.After that,we respectively extract and analyze geometry,Hu moment and texture feature of ship target in simulated and satellite observed data,as well as ship target acquired by automatic target detection.By analyzing the ship target’s features,the feature set（or subset）,comprising geometry,Hu moment and texture feature,can be used to recognize ship target.Fuzzy-neural network method can combine fuzzy set’s advantages with neural network’s,by which feature-based classification and recognition for targets in images can be implemented validly.The paper depicts a fuzzy-neural network method with principal-subordinate neuro for classification and recognition at first,and then,utilize the method to classify and recognize,basing on single category feature and multi-source（multi-temporal）data fusion.Experiments’ results indicates that classification and recognition for large ship can be implemented validly by utilizing fuzzy-neural network methods based on large ships’ geometry features,moment features and texture features.Furthermore,using multi-source data fusion,the classification and recognition effect can be improved.关键词：fuzzy neural network;ship target;classification and recognition;feature extraction
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发布时间：2021-06-10 - 摘要：We introduce the Advanced Land Observing Satellite and its Panchromatic Remote-sensing Instrument for Stereo Mapping（PRSIM）and use the super-resolution reconstruction approach to improve the resolution of the PRISM images.PRISM is a panchromatic radiometer with 2.5 meter spatial resolution.PRISM instrument belongs to the class of push broom sensor and data are acquired by a linear CCDs array.PRISM product are processed into CEOS format for level 1B1,1B2R,and 1B2G.The image of Level 1B2G is geometrically corrected data.The PRISM sensor can capture three images in the direction of looking forwards,downwards and backwards from the aircraft or satellite at same time.So we can obtain three images of Level 1B2G in the same scene.Super-resolution technique can obtain a high-resolution image from observed multiple low-resolution images.The major advantage of the super-resolution approach is that it may cost less and the existing low-resolution imaging systems can still be utilized.There is a great need to have fine spatial resolution data with high fidelity and consistence in geo-referencing and intensity（tone）in the studies of land cover and land use,and their changes.In view of this,we present a maximum a posteriori estimation framework to obtain a high-resolution image from the PRSIM images of Level 1B2G.This super-resolution method is composed of two main steps.In the first step,we present a hybrid optical flow registration method to deal with the deformation which is brought by hypsography.In order to improve the registration accuracy of PRISM Level 1B2G Images,we propose a new optical flow registration method.This approach uses the Normalized Cross-Correlation registration algorithm before we use Lucas-Kanade optical flow registration algorithm.Optical flow is the distribution of apparent velocities of movement of brightness patterns in an image.Optical flow can arise from relative motion of objects and the viewer.The Lucas-Kanade registration approach divided the original image into smaller sections and assumes a constant velocity in each section.Then it performs a weighted least-square fit of the optical flow constraint equation.It can detect most local distortions of PRISM image in sub-pixel accuracy,but this method may lead to some misregister.The Normalized Cross-Correlation registration algorithm can reduce the misregister.So,we take the NCC registration method to perform coarse registration firstly.The mixture registration method can remove the deformation which is brought by hypsography in a great measure.In this second step,to reconstruct the high-resolution image,we apply an iterative scheme based on alternative minimization to estimate the blur and HR image progressively.It is the combination of the blur identification and high resolution image reconstruction.We also improve the Gaussian PSF assumption model,and introduce the volatile blurs into the PSF model.By Alternating Minimization（AM）algorithm,we can estimate the volatile blurs.Image quality assessment plays an important role in image super-resolution reconstruction.Peak Signal-to-Noise Ratio（PSNR）and Mean Squared Error（MSE）are the most widely used objective image quality indexes.The two indexes are Full-Reference image quality assessment.Unfortunately,we can not obtain the original high resolution image in the super-resolution reconstruction process.So we propose two noreference image quality assessments which are entropy and Mean Grads.Experimental results show that our super-resolution method is effective in performing blind SR image reconstruction with PRISM images and our super-resolution reconstruction algorithm has better performance in edge preserving than bicubic interpretation.The resolution of PRISM image is enhanced effectively.The enhancement show that the mixture registration method can reach sub-pixel precise and the modification of the Gaussian PSF assumption model correspond to the actual PSF of PRISM images.The AM blind super-resolution approach can be used to enhance the resolution of aerial and remotely sensedimages.关键词：superresolution;optical flow;ALOS;PRISM
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发布时间：2021-06-10 - 摘要：Beijing-1 small satellite was launched in October 2005.It includes two sensors,32m three bands multispectral（green,red and near-infrared）and 4m panchromatic.Its revisiting period is very short,which was planned about 3—5 days depending on latitude at 32m resolution.Another important advantage of this satellite is the large area collection capability of 32m multispectral image,600km width imaging swath and more than 4000km stripe.These allow us to efficiently collect a large amount of imagery data,covering every region of the world.Due to the advantages of 32m multispectral image,it is obviously suitable for mapping,especially for large area,such as the whole country of China.So Beijing-1 small satellite will challenge the predominant role of satellite image data,such as TM and SPOT in Chinese large-area mapping work.Beijing-1 small satellite ground station is the first one in China that integrates satellite supervising and controlling,task planning,data acquisition,data preprocessing and mosaic,etc.Because of the incorporate working mode,the image data of Beijing-1 small satellite was obtained and processed.By the date of Nov.20th 2006,the obtained image data has more than 1000 orbits,which covers the whole country of China,and about 20 times for some area.Based on the abundant image data,the study of China’s digital mosaic map of Beijing-1 small satellite was promoted.This paper introduces the methods of image enhancement,geometric correction,image mosaic,and color adjustment,which led to a successful China’s digital mosaic map based on multispectral images of Beijing-1 small satellite.As to image preprocessing,destriping,band registration and MTF restoration was applied.Moreover,in order to improve the quality and efficiency,data preprocessing and geometric correction was done on every orbit.During the color adjustment,the image data was divided into many rectangle cells with the same area,with overlapping area between any joined cells.In practice,the data cell was 17125 pixel 17700 pixel,about 870MB,with 1000 pixel overlapping between any joined cells.There are 53 cells covering the land of China.Due to same small cells,it was obviously to decrease the cost of hardware for data processing,to improve the effect of color adjustment.According to the above mentioned approach,it will take less than half a year to obtain the Beijing-1 small satellite image data covering the whole country of China,and then only two months are needed to finish the whole mosaic work.As the result of study,by Dec.2006,two pieces of digital mosaic image of China has been achieved.The digital mosaic map is being and will be used in many fields,such as forest monitoring,land use and land cover change study,resource research,digital mapping and so on.Moreover,the experience to achieve the 32m mosaic image map is useful for other similar projects.关键词：Beijing-1 small satellite;multispectral images;image process;Mosaic
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发布时间：2021-06-10 - 摘要：Filtering is an important method to extract digital terrain model（DTM）form Light Detection and Ranging（LIDAR）data and has made some good effects in application,but existing filtering methods are deficiency in certain applications,especially unsuitable for undulated terrain.In this paper,a new filtering method which is based on contours is developed.The method mainly consists of three steps:Firstly,digital surface model（DSM）is generated from raw LIDAR data by surface interpolation methods,such as the nearest neighbor interpolation method,and then contours of DSM are generated.Secondly,these DSM contours are separated into three groups:ground contour,which only consists of points on ground;object contour,which only consists of points off-ground,such as on trees or roofs;and mixing contour,which consists of points on ground or off-ground.According to some properties of contours,including closeness,start-to-end distance,length of curve,denseness,ground contours and ground contour section of mixing contours are extracted and then some ground points are obtained,finally an initial approximation of the DTM is determined by interpolating those ground points.Then a refined DTM is obtained by an iterative method:comparing the approximate DTM with the original DSM and if the difference is below a predefined threshold the original DSM points are selected and made into DTM data points.Otherwise,the location is marked as no data;and then the no data points are interpolated using the selected DSM data.Comparisons between initial and refined DTM obtained by methods proposed previously is done.To calculate the accurate probability,the objects obtained by new filter is compared with standard objects obtained from aerial images manually.All the experimental results show that the proposed method is a simple and practical one needing little calculation,and can be used in undulating terrain area.关键词：lidar;filtering;contours;DSM;DTM
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发布时间：2021-06-10 - 摘要：For most of the traditional image fusion methods,the spectral distortion of the fused images is a common problem.The major reason relates closely to the different spectral characteristics of sensors.In this paper,a novel spectral preservation fusion method for remotely sensed images is presented by considering the spectral characteristics of sensors.The method is mainly based on the fast IHS transform.After analyzing the spectral response of the multispectral and panchromatic sensors,the IHS fusion method has been improved in two parts:the construction of intensity component and the injection method of detail information.In the proposed method,the spectral distortion is reduced significantly and all the multispectral bands can be fused at the same time.To evaluate the performance and efficiency of the proposed method,two experiments are carried out on IKONOS and ETM+ images respectively.The results show that the proposed method is better than other methods.It can keep almost the same spatial resolution as the panchromatic images and minimize color distortion.关键词：image fusion;intensity-hue-saturation （IHS） transform;spectral response;spectral preservation
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发布时间：2021-06-10 - 摘要：Fast transferring between geodetic coordinates and sphere triangle facets is of the same importance as properties of equal area and shape for global grid using for spatial information.Based on the spherical icosahedron case of Equal Angle Ratio Projections（EARP）,a new Spherical Triangle regional Quadtree（EARPIH）is constructed.There are two ways to build up the partition model:one is to evenly discompose the triangle projection plane and the other is to discompose the sphere directly.The coordinate transformation can deduce to locate a point into the evenly triangle network.The partition model is compared with several famous models such as SQT,QTM and ISEA by the indices,including distribution of chords,compaction,and area.关键词：global grid;projection;coordinate transfer;equal-area partition;equal-shape partition
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发布时间：2021-06-10 - 摘要：Motion compensation is a key factor in SAR imaging.Generally speaking,there are two kinds of motion compensation.One is based on measured data and the other is based on echo data.In this paper we focus on the latter one.The Doppler rate is an essential parameter in the process of the motion compensation;the instability in both forward velocity and acceleration of aircraft is regarded as vibrations of the Doppler rate.In the high-frequency band SAR,synthetic aperture is narrow and the hypothesis is tenable that the slant range is longer than the length of synthetic aperture.Basing on the hypothesis,the Doppler rate in the high-frequency band SAR has nothing to do with the position of the object.Thus the formation of the Doppler rate is comparatively simple,and the motion compensation is easy to operate.However,in Ultra Wide Band Synthetic Aperture Radar（UWB SAR）,the length of synthetic aperture is relatively long,so that the hypothesis that the slant range is longer than the length of synthetic aperture is unreasonable.In the meantime,the Doppler rate in the high-frequency band SAR matters with the position of the object.Due to the above reasons,we need to re-analyze the formation of the Doppler rate in UWB SAR and study new motion compensation.Out of this aim,the paper tentatively studies motion compensation of UWB SAR in wide swath.First,We obtain the Doppler rate of different range from linear fitting,and then compensate the phase error directly instead of separating the motion parameters from Doppler rate.In the section of experiment,in order to verify the theoretical part,according to the simulated data,a quantity analysis was made on the difference of the Doppler rate in the short and long pole of mapping band respectively.Then based on UWB SAR’s echo data of Aircraft Y7 and following the theoretical instruction stated in the former part,we make motion compensation successfully.Using the method of direct average we get the result images.Finally,a comparison is made between the results obtained from two kinds of motion compensation.It turns out that the method used in this paper is effective.
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发布时间：2021-06-10 - 摘要：Multi-temporal remotely sensed imagery change detection is a hot topic in recent years.Most researchers pay attention to statistical pattern recognition principal to solve the problem.In this paper,we discuss the problem from three aspects.Firstly we focus on GMM model statistic coefficients resolve method.The Expectation Maximization（EM）is the most commonly method to calculate GMM coefficients.However,EM algorithm often converges to local value.So we combine genetic k-means algorithm（GKA）with EM to modify it.Using the initial clustering result obtained by GKA,we are able to initialize EM globally.The combination helps EM search out globally optimal solution and enhances the automatic degree.When we get the global optimal results,it is easy for us to obtain change detection result using Bayes Rule for Minimum Error（BRME）.However,the BRME doesn’t take into account the image’s contextual information.It is well known that one pixel belongs to "change" or "no change" depends not only on itself,but also on its neighbor pixels.There are two ways to model contextual information.The first is probability relaxation iteration,and the second is Markov Random Field（MRF）.MRF has two commonly used solution methods;one is Iterated Conditional Method（ICM）,and the other is Simulated Annealing（SA）.In this paper,we compare the three spatial contextual change detection methods using visual effect and kappa coefficient.The experiment shows that MRF based on simulated annealing has better performance than the other two.Through the above experiments,we find that traditional MRF deals all pixels equally and ignores the neighbor local features.In fact,in different region,the spatial information has different impact.We analyze the impact and propose variable weight MRF method.It can adaptively vary spatial impact according to different image local features.It has virtues of preserving structural change and filter noises.The experiment proves that variable weight MRF gets the best result.关键词：change detection;gaussian mixture model;genetic K means clustering;expectation maximization algorithm;markov random field
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发布时间：2021-06-10 - 摘要：In order to raise signal-to-noise ratio（SNR）of InSAR interferograms,this paper proposes a Wavelet-Wiener combined（WWC）filter in view of the respective merits of Wavelet transform and Wiener filter.The WWC algorithm and its computer program are developed to raise SNR of interferograms.To validate the proposed filter,the localized area around Phoenix in Arizona of USA is selected as the testing site and the ERS-1/2 C-band interferogram is utilized as the source data for filtering.Several indicators,including visualization effect,standard deviation of phase derivatives,number of residues and accuracy in DEM derived interferometrically,are taken into account to assess the effectiveness of this filter.The tested results show that WWC filter has some prominent advantages in terms of denoising,edge protection and improving DEM accuracy,if compared with two typical approaches presented previously,i.e.,Wavelet soft-threshold filter and Goldstein filter.关键词：INSAR interferogram;wavelet-wiener filter;algorithm;assessment
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发布时间：2021-06-10 - 摘要：This study is devoted to the regional validation of POLDER-2/PARASOL aerosol retrieval scheme over land surfaces against independent automatic sun-photometers located at Beijing and Xianghe sites both included in AERONET（Aerosol Robotic Network）/PHOTONS（PHOtométrie pour le Traitement Opérational de Normalisation Satellitaire）.Analysis of the AERONET/PHOTONS volume size distributions shows that the fine mode is very well defined with size-cut of about 0.3μm over Beijing area.POLDER-2/PARASOL aerosol optical thickness（AOT）is shown to be quite consistent with the fine fraction of the size distribution（radius <0.3μm）.In other words,POLDER-2/PARASOL retrieval over land is mainly sensitive to the anthropogenic aerosols which are known to have important impacts on the climate,environment as well as human health.However,the Angstrom exponent used in the POLDER retrieval algorithm is much higher than the statistic of the AERONET/PHOTONS measurements over Beijing.Thus the derived AOT have been underestimated and the Angstrom exponents have been overestimated.关键词：aerosol;POLDER;PARASOL;volume size distribution;polarized reflectance
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发布时间：2021-06-10 - 摘要：Synthetic Aperture Radar Interferometric（InSAR）processing depends on phase unwrapping to convert phase to topographic height.However,in rugged terrain the signal decorrelation caused by layover and shadow is one of the limitations for InSAR topographic height reconstruction,because the phase unwrapping is difficult.A new algorithm is proposed in this paper to reconstruct high resolution digital elevation model（DEM）with the help of existing coarse SRTM DEM（about 90m×90m）.Firstly,the simulated phase from coarse DEM is removed from the ERS-1/2 interferogram.Thus the residual interferogram is easier for phase unwrapping.By calculating the variance of unwrapped residual interferogram,a proper threshold is selected to extract the noise phase of layover and shadow,and then the noise area are substituted by surrounding average phase to recover the phase approximately.After converting the residual phase to height,SRTM DEM is added to reconstruct the topographic height.The result shows that this method can not only solve the problem of phase unwrapping for layover and shadow in rugged terrain,but also improve the height accuracy and topographic detail feature of coarse resolution DEM.关键词：InSAR;SRTM DEM;Phase unwrapping;Topographic height reconstruction
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发布时间：2021-06-10 - 摘要：A decision tree algorithm was developed to classify the freeze/thaw status of the surface soil based on the cluster analysis of samples such as frozen soil,thawed soil,desert and snow,along with microwave emission and scattering characteristics of the frozen/thawed soil.The algorithm included five SSM/I channels（19V,19H,22V,37V,85V）and three crucial indices including scattering index,37GHz vertical polarization brightness temperature and 19GHz polarization difference,and took into consideration the scattering effect of desert and precipitation.The pureness of samples is essential to the analysis of the microwave brightness temperature characteristics,which is prior to deciding the thresholds of each node of the decision tree.We have selected four types of samples,including frozen soil,thawed soil,desert and snow.The frozen soil has some special microwave emission and scattering characteristics different from the thawed soil:① lower thermodynamic temperature and brightness temperature;② higher emissivity;③ stronger volume scattering,and the brightness temperature decreased with increasing frequency.The threshold of each node of the decision tree can be determined by using cluster analysis of three vital indices,and calculating the average and standard differences of each type and each index.The 4cm-depth soil temperature on the Qinghai-Tibetan Plateau observed by Soil Moisture and Temperature Measuring System of GEWEX-Coordinated Enhanced Observing Period,were used to validate the classification results.The total accuracy can reach about 87%.A majority of misclassification occurred near the freezing point of soil,about 40% and 73% of the misclassified cases appeared when the surface soil temperature is between-0.5—0.5℃ and-2.0—2.0℃,respectively.Furthermore,the misclassification mainly occurred during the transition period between warm and cold seasons,namely April-May and September-October.Based on this decision tree,a map of the number of frozen days during Oct.2002 to Sep.2003 in China was produced by composing 5 days classification results due to the swath coverage of SSM/I.The accuracy assessment for pixels with more than 15 frozen days（less than 15 meaning the short time frozen soil）was carried out with the regions of permafrost and seasonally frozen ground in map of geocryological regionalization and classification in China as reference data（Zhou et al.,2000）,and the total classification accuracy was 91.66%,while the Kappa coefficient was 80.5%.The boundary between frozen and thawed soil was well consistent with the southern limit of seasonally frozen ground.A long time series surface frozen/thawed dataset can be produced using this decision tree,which may provide indicating information for regional climate change studies,regional and global scale carbon cycle models,hydrologic model and land surface model so on.关键词：SSM/I;brightness temperature;surface frozen/thawed;decision tree
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发布时间：2021-06-10 - 摘要：Photomap,as a kind of map that integrates the map with the remote sensing image,has the advantages of both images and Line symbol maps and is the composite of multi-source spatial data.As a formation of map product,image-rich detailed photomap can provide fast and practical geographic information for many industries and communities,and direct its current and potential application in fields such as urban planning,infrastructure construction,disaster prevention and mitigation,environmental protection,agricultural planning,information management and national defense.Therefore,it is essential geospatial information.The Wenchuan photomap productions need to use the photogrammetric information of the earthquake-stricken area and high-resolution satellite remote sensing images.Using the photogrammetry and remote sensing technology,it needs to rapidly produce the orthoimages of the disaster areas,and moderately overlay 1:50000 core elements of the earthquake-stricken area to form sub-county wall photomaps,the region-wide photomaps of 1:25,000-scale and the urban and regional focus photomaps of 1:5000-scale.It can provide geographic information services in a timely manner for post-disaster damage assessment,disaster monitoring and survey,planning,and post-disaster reconstruction work.During the period of disaster emergency,according to the "producing as well as the application" principle,in only a month it has completed the production of 98 county photomaps of the 95 counties of whole coverage,the 2653 photomaps of 1:25,000 scale covering 95 counties and the 2114 photomaps of 1:5000 scale of key areas.They are being provided to the affected areas and government departments,and has played an important role in the analysis of the disaster assessment,planning,and post-disaster reconstruction work.Comparing with traditional types of ordinary maps,thematic maps and the comprehensive maps,photomap has not only the features of the traditional map,using the computer graphics technology,but also a large number of remote sensing image processing technology.It has a new production requirement for the content structure,the means of expression and the production process.关键词：photomap;disaster emergency;photogrammetry;remote sensing
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发布时间：2021-06-10 - 摘要：Based on the airborne X band SAR images,the electromagnetic method was used to analyze the characteristics of the buildings after Wenchuan earthquake in the urban district of high resolution Synthesize Aperture Radar（SAR）images.After the undamaged buildings and damaged building were constructed by 3D models,the ray-tracing electromagnetic method and Image-Domain-Integration imaging simulation method were used to simulate SAR images of buildings with different damage degrees.Comparing with the real SAR image,the algorithm presented in this paper can analyze the backscatter change due to building structure,simulate the main scattering points,and effectively assist the analysis of the urban district SAR image characteristics.关键词：SAR;building;simulation
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发布时间：2021-06-10 - 摘要：In this paper,we study the spatial distribution rules of earthquake-induced secondary geological disasters and the relationships between the disasters and their impact factors,based on multi-source multi-temporal satellite data,which was support in ARCGIS software platforms.The results show that stratum lithology,geology structure,water system and topography are major controlling factors in disasters;mean while,different regions have different controlling factors,The distribution of BEICHUAN disasters is along the BeiChuan-YingXiu fault zone as banded;a mass of disasters develops in Silurian strata because of structural components;a mass of disasters affected by the topography developed in the terrain with slope of 30°—70°.The distribution regularity of disasters can provide scientific foundation for prevention earthquake plans and reconstruction after earthquake.关键词：remote sensing;GIS;earthquake-induced secondary geological disasters;distributed characteristics
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发布时间：2021-06-10
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