最新刊期
卷 14 ， 期 5 ， 2010
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Preliminary comparisons of the typical polarized radiative transfer models: precision and efficiency
摘要：Radiative transfer models are key tools in the remote sensing and parameterization of climate radiative forcing, while polarized radiative transfer models can provide more accurate insights into the radiation processes in the earth–atmosphere system. PolRadtran/RT3 （Polarized Radiative Transfer, based on the adding-doubling method）, SOSVRT （Vector Radiative Transfer, based on successive order of scattering）, and VDISORT （Vector DIScrete Ordinate Radiative Transfer, a polarized version of DISORT based on the inverse of matrix method）, are three of the most common radiative transfer models, each with polarization based on different physical principles. A comparison of their accuracy and efficiency reveals that SOSVRT is the most efficient, with the time consumed remaining almost invariable with the increase of stream numbers, but increasing with the optical depth of the layered atmosphere. For example, the time consumed for an optical depth of 1.0 was found to be two times that for an optical depth of 0.5 for the Mie scattering atmosphere. The efficiencies of RT3 and VDISORT in modeling polariza- tion with a large stream number were found to be low. For example, under the Rayleigh scattering atmosphere at 400nm and a stream number of 40, the time consumed was 23 times and 7 times as much as that of SOSVRT, respectively. The computation time for the two models was found not to be sensitive to the optical depth, but increased greatly with the increase in stream number. All three models were found to be of the same order of accuracy, but VDISORT showed a fluctuating result for simula- tions with large streams.关键词：polarized radiative transfer;adding-doubling method;successive order of scattering;DISORT- 189
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发布时间：2021-06-10 - 摘要：In this paper, new solar radiation modeling based on stepwise regression analysis are put forward for estimating global solar radiation from common climate variables （such as sunshine duration, cloud cover, vapor pressure） and geographical elements （altitude, latitude）, which simplify the simulation process, improve the operational efficiency under the similar preci- sion. Based on these models and the observation data of common meteorological elements at more than 730 stations in China, the resulting 1km×1km resolution（20226531 grids） solar radiation distribution show that in the whole country, the annual solar radiation energy on the land surface is about 52.4×1018 kJ, and the average annual solar radiation lies between 2780— 7560MJ?m?2?a?1. There are regional distribution characteristics of global solar radiation in China; it declines from northwest to southeast. The highest value （≥6700 MJ?m?2?a?1） areas of solar radiation is in the Tibet Autonomous Region, the northeastern of Qinghai Province and the west border of Gansu Province; their total area is about 1300000km2. The lowest value （≤4200 MJ?m?2?a?1） area of solar radiation is in the Sichuan Basin and the gorge area of the Yarlung Zangbo Grand Canyon in the south of Tibetan Plateau; their total area is about 750000km2.关键词：global solar radiation;multiple stepwise regression;spatial interpolation;China
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发布时间：2021-06-10 - 摘要：Some initial investigations are conducted to employ DNA computing for hyperspectral remote sensing data classification. As a novel branch of computational intelligence, DNA computing expresses rich information of spectral features with DNA encoding, and acquires the most typical DNA encoding of each class by DNA modulating and controlling mechanism. For each pixel of the hyperspectral image, computing the distance between the pixel and the typical DNA sequence, finding the class property of the minimum distance, set the class property of each pixel as the minimum distance class. An experiment was performed to evaluate the performance of the proposed algorithm in comparison with other traditional image matching classification algorithms: binary cording, spectral angles and spectral derivative feature coding （SDFC）. It is demonstrated that the proposed algorithm is superior to the three traditional hyperspectral data classification algorithms based on the experiment results.关键词：DNA computation;hyperspectral;spectral matching;classification
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发布时间：2021-06-10 - 摘要：It is necessary to consider the uncertainty of spatial data and fuzziness of relative conception when discussing the description of spatial relation and reasoning because of the complexity of direction relation induced by the fuzziness of direction concept and inherent uncertainty of spatial data. Two fuzzy models are introduced based on classical fuzzy set. In 4-directions fuzzy model the space is divided into four cardinal directions and each direction has equal angle, but each main cardinal direc-tion has 60° and each secondary cardinal direction has 30° in 8-directions fuzzy asymmetric model. Extended 8-directions fuzzy asymmetric model is introduced based on interval type-2 fuzzy sets which takes the positioning error of reference point into ac-count. The primary membership function and the uncertainty of primary membership grade is discussed too. The difference be-tween this model and the cone-based model is comparatively analyzed. Two cases are provided in the last. The first case is used to analysis the attributes of 8-directions fuzzy asymmetric model and the second case shows the process of determining the direction relation between point with positioning error and polygon.关键词：cardinal direction relation;interval type-2 fuzzy set;direction membership grade error
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发布时间：2021-06-10 - 摘要：There are a lot of differences in multi-source remote sensing images from various sensors about the same scene. Maximization of mutual information can be used for the multi-source image matching, but the accuracy and efficiency of image matching need to be further improved. Therefore, an algorithm for multi-source remote sensing image matching was proposed in this paper, based on contourlet transform, Tsallis entropy based mutual information and improved particle swarm optimization. Firstly, the target image and reference image were decomposed to the low resolution image using contourlet transform, respec-tively. Then, a new image similarity measure criterion, the Tsallis entropy based mutual information, was used to achieve the global optimization. Meanwhile, a modified extremum disturbed and simple particle swarm optimization algorithm was applied to match the lowest resolution remote sensing images. Based on the preliminary result, the matching between the higher resolu-tion images could be implemented stepwise up to the full resolution images. The experimental results show that, compared with those of other existing remote sensing image matching methods, the proposed algorithm has the high accuracy, strong robustness and requires much fewer operations.关键词：multi-source remote sensing image matching;contourlet transform;Tsallis entropy;particle swarm optimization
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发布时间：2021-06-10 - 摘要：In this paper, we analyze the directional characteristics of contourlet coefficients in high frequency subbands of remote sensing images. And then we find that each coefficient in these subbands has obvious directionality. Based on this direc-tional characteristic, this paper proposes a novel image fusion algorithm for remote sensing images. First, we separately perform contourlet transform on the intensity component of the multi-spectral remote sensing image obtained by IHS transform, and the panchromatic remote sensing image. Second, we choose the low frequency coefficients of multi-spectral image’s intensity component to form the low frequency subband of target image. Subsequently, we compare the directional matching degree of the high frequency coefficients of the panchromatic image with those of the multi-spectral image’s intensity component to determine the high frequency subbands of target image. Finally, the target image is obtained by inverse contourlet transform and inverse IHS transform. Extensive experimental results show that the proposed method is superior to conventional methods in terms of entropy, joint entropy, and average gradient. It can enhance the spatial resolution of target images. Meanwhile, it well preserves the color information of multi-spectral images.关键词：remote sensing image fusion;contourlet transform;correlativity of directional region;fusion operator
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发布时间：2021-06-10 - 摘要：In the process and analysis of high-resolution remote sensing image, segmentation is the key step of extracting information from image data to image object. For the image segmentation tasks of large amount of data, data paralleled computing model is generally used. In this process, the effect of merging segmentation results when data gathering is related to the precision and accuracy of the subsequent object-oriented analysis. In this paper, data paralleled segmentation of remote sensing image is adopted, and a new algorithm named data sewing is proposed to solve the problem of merging segmentation results. Experiments, such as comparison of final segmentation results and assessment of computing efficiency, show that the algorithm im-proves the efficiency of image segmentation process. Meanwhile it guarantees the correctness of the boundary thus to ensure the credibility of the final segmentation result as well.关键词：image segmentation;parallel computing;data sewing;mean-shift;object extraction
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发布时间：2021-06-10 - 摘要：As one of the key techniques for high-resolution remote sensing target recognition, feature selection focused on how to find the critical features in the feature set to represent the target. Generally, the classical methods for feature selection were as follows, principal component analysis, empirical method, etc. When using these classical methods, recognition accuracy was not guaranteed. In this paper, a new method was proposed, the main idea of which was to couple GA （Genetic Algorithm） and SVM （Support Vector Machine） for feature selection, and using recognition results to guide the revolution direction of GA. Meanwhile, to reduce the risk of premature convergence of the traditional GA, some modification had been made. The experi-ment demonstrated the effectiveness of the proposed method.关键词：genetic algorithm;support vector machine;target recognition;feature selection
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发布时间：2021-06-10 - 摘要：Spatial outlier detection has been a hot issue in the field of spatial data mining and knowledge discovery. Spatial outliers may be utilized to discover and predict the potential change laws or development tendency of geographical phenomenon in the real world. Among the existing spatial outlier detection methods, there are mainly two aspects of issues. On the one hand, these methods primarily consider that all the entities for outlier detection are correlated. Actually, spatial correlation decreases with the increase of distance. Entities will become independent with each other at a distance of rang. Thus, current methods can only discover the obviously outliers in the whole, some local outliers may not be detected. On the other hand, the spatial outlier measures are not enough robust, which are seriously influenced by the construction process of spatial neighborhoods of spatial entities and the possible outliers in spatial neighborhoods. To overcome these two limitations, spatial clustering as a means is firstly employed to extract the local autocorrelation patterns, called clusters. Then, a robust spatial outlier measure is proposed to determine spatial outliers in each cluster. This method is able to detect spatial outliers more accurately. Finally, a practical ex-ample is utilized to demonstrate the validity of the spatial outlier detection method proposed in this paper. The comparative experiment is also provided to further demonstrate the method in this paper to be superior to classic SOM method.关键词：spatial outlier detection;spatial clustering;spatial outlier measure;spatial data mining
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发布时间：2021-06-10 - 摘要：This paper takes the delta oasis of Weigan and Kuqa rivers in Xinjiang as the study area. Fusion image of SAR （Radar-sat image） combined with visible spectrum remote sensing image （TM image） is used to extract soil and vegetation water content in arid oasis. Based on the Normalized Difference Moisture Index extracted from homochronous visible spectrum remote sensing data, this thesis utilizes "water-cloud model" to wipe off vegetation influence from total backscattering coefficient of radar data and sets up the relationship between soil backscattering coefficient and soil moisture. Correlation coefficient for HH Polarization is R2 =0.5227, for HV Polarization is R2 =0.3277. Result shows that in arid and semi-arid area where the main crops are cotton and corn, the combination of C-band HH polarization radar data with visible image performs well in the study of removing vegetation influence while retrieving soil water content in medium vegetated areas.关键词：soil moisture;remote sensing;vegetable;backscatter coefficient;water-cloud model
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发布时间：2021-06-10 - 摘要：In this study, six different land cover datasets were employed in conjunction with MODIS 1km reflectance data to inverse LAI of forests using an algorithm based on the 4-scale geometrical optical model in Jian City, Jiangxi Province, China. Land cover datasets used in this study include five global land cover datasets （Three were produced by the United States Geo-logical Survey （USGS）, University of Maryland （UMD）, and Boston University （BU）, respectively. Two were constructed in Europe.） and a regional land cover map produced using Landsat TM images. For assessing the impact of land cover on the in-version of LAI, LAI images inversely produced with different land cover datasets were compared with LAI data sampled from a 30 m LAI map at 1 km and 4 km scales, respectively. The 30 m LAI map was produced with TM reflectance images and ground measurements of LAI. The results show that the land cover datasets of TM and GLOBCOVER which was created by European Space Agency are the best for the inversion of LAI in this study area. At 1 km scale, the R2 values of LAI inversed using TM and GLOBCOVER land cover datasets with TM LAI estimated using an statistical model are 0.44 and 0.40, respectively. At 4 km scale, these R2 values increase to 0.57 and 0.54. The MODIS land cover data of BU is the third best data for the inversion of LAI, the R2 values between LAI inversed using this land cover dataset and TM LAI are 0.38 and 0.51 at 1 km and 4 km scales, respectively. The land cover datasets of UMD and European GLC2000 resulted in large discrepancies between inversed LAI and TM LAI. The averages of LAI inversed using these two land cover datasets are about 20% lower than TM LAI at 1 km and 4 km scales. Sensitivity analysis shows that inversed LAI is sensitive to clumping index. This study proved that reliable land cover data is required for improving the accuracy of inversed LAI at regional/global scales.关键词：leaf area index;land cover data;4-scale model;accuracy of inversion
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发布时间：2021-06-10 - 摘要：Typhoon has different characteristics, such as texture, shape, and area, in different development stages. We could not automatically recognize the typhoon clouds in all stages based on these features. During different development stages, ty-phoon all has helicity and non-typhoon has no helicity. Based on this, we extract boundary information of clouds and statistics of the rotation degree of boundary clouds in single satellite image. In this paper, we use curvature curve of Bezier histogram to ob-tain two segmentation thresholds, iteratively segment the satellite image, and combine typhoon’s geometric features, such as ro-tation, area and shape to recognize the typhoon. Experimental results show that the typhoon can be recognized effectively in all different development stages.关键词：typhoon recognition;geometric features;Bezier histogram;curvature;circle-like;rotation
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发布时间：2021-06-10 - 摘要：Medium Resolution Spectral Imager （MERSI） on board the new Generation Polar-Orbiting Meteorological Satellite of China （FY-3） has five spectral channels with 250m spatial resolution, which enhances the ability to observe fine surface features and provides a new data source for drought monitoring in large area. Drought status of north China is evaluated using FY-3A/MERSI satellite data with Perpendicular Drought Index （PDI）. To validate the performance of PDI in macroscale application, quantitative evaluation of drought conditions and development in Tongliao and Chifeng, two cities located in southeast of Inner Mongolia Autonomous Region of China are carried out by comparing time series drought monitoring results with field observation data. Results show that drought status derived from PDI is highly accordant with field drought observation. Satellite based PDI has significant correlation with 10cm and 20cm depth soil water content. Compared with 10cm depth soil water content, PDI has more stable relationship with 20cm depth soil water content. The drought monitoring application in this study show great potential in future drought monitoring operation using China’s own satellite data.关键词：FY-3A/MERSI;drought monitoring;perpendicular drought index;soil water content
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发布时间：2021-06-10 - 摘要：A system for scheduling of disaster monitoring satellites which follows the tenet and operation mechanism of CHARTER is developed. First, it introduces the significance and mechanism on which CHARTER is running and then details the design and implementation of the system. At the same time detailed function of each module is given out. Great attention is paid to the analysis module of tasks’ time windows. In the process of the computation of the targets’ time windows, a dynamic partition algorithm for area target is introduced. Then a dynamic scheduling algorithm is constructed to create schedule plan for disaster monitoring satellites. Also the paper develops three variables to evaluate the plan created, and gives out the meaning of each variable respectively.关键词：mission planning;satellite scheduling;CHARTER;available time windows;area target
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发布时间：2021-06-10 - 摘要：An earthquake of magnitude 7.1 suddenly occurred in Yushu county of Qinghai province on April 14, 2010. This paper presents the studies of using the data of Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar （ALOS-PALSAR） before and after the earthquake to examine and calculate the co-seismic ground deformation. The dif-ferential SAR interferometry （D-InSAR） technique is used. The results show that the earthquake caused the ground deformation over a large area. The extension of the ground deformation followed the south-east to east direction and along the Yushu-Ganzi fault zone. The largest deformation was found about 350 mm at 33.7°N 96.81°E. It is along the line of sight （LOS） of SAR and can be detected with D-InSAR technique. The detected ground deformation was mainly uplifting. The detected ground deforma-tion has an important value for evaluating the extent of ground damage and seismicity in Yushu after earthquake, inferring the nature of the quake faulting, and studying characteristics of seismic deformation.
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发布时间：2021-06-10 - 摘要：The SAR system with its all-weather and all-time imaging capabilities emerged as a very important remote sensing data source for earthquake monitoring and disaster relief. After the recently occurred earthquake in Yushu county, Qinghai province, an airborne SAR system equipped with X-band dual antenna interferometric sensor and P-band fully polarized sensor has been successfully used in disaster monitoring and relief actions. The system is the first airborne SAR system with full intellectual property owned by China. This paper summarizes the Yushu Earthquake remote sensing monitoring and information ser-vice system, including the data, processing methodologies and information service. The emphasis is put on the application of airborne SAR images to disaster information extraction and assessment. First, the parameters characterizing the content of earthquake disaster remote sensing monitoring are determined, which include the information of urban and rural residence, infrastrcucture, geological disasters and farmland damage. The processing methodologies of optical and SAR data for earthquake disaster information interpretation, mapping and risk evaluation are presented. The process chain consists of quick geometric processing, change detection, quick target interpretation and quick spatial risk assessment for disaster. On the basis of the earth-quake information including those extracted from remotely sensed images and other existing social and geospatial data, a system of Yushu Earthquake disaster situation geographic information service has been developed, to facilitate the management, visualization, and statistical analysis of the earthquake disaster information.关键词：Yushu Earthquake;SAR;remote sensing;disaster monitoring and assessment
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发布时间：2021-06-10 - 摘要：At 7:49 am on April 14, 2010, an earthquake （Ms 7.1） originated （33.2°N, 96.6°E） near Jiegu Town, Yushu Tibetan Autonomous Prefecture, Qinghai Province, China. After the earthquake, we analyzed the geological structure of the disaster re-gion based on the "Beijing-1" images. Using the aerial images after earthquake with high resolution （0.4m） and SPOT ortho-images, we monitored urgently the disaster situation, including the damage degree of the buildings, the damage degree of the lifelines, the field disasters and the secondary disasters. The result could provide the important basis for emergency management and rescue mission.关键词：Yushu Earthquake;remote sensing;urgent monitoring
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发布时间：2021-06-10
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