最新刊期
卷 ， 期 1 ， 2002
- 摘要：Multiangular remote sensing observation can provide more spatial structure information that make it possible to retrieve the 3 D structural parameters of vegetation. Currently, most of the inversion algorithms only use one single band in the field of multiangular remote sensing, the correlation between bands hasn’t been used efficiently for green vegetation. From the reflectance spectrum characteristic of green vegetation, we found that the basic shape of the spectrum can be used as prior knowledge in the inversion of vegetation structure. As a framework in this paper, spectral parameters were regenerated in the band of red, green and near infrared, their difference and ratio are used as the spectral prior knowledge in inversion. Through detailed simulation and inversion, it is clear from the statistical analysis that this method is more stable to observe noise than the single band based method which uses the averaged structural parameters inverted using one single band each time. It is also found that the inversion results tend to be closer to the ground truth than the single band based method after employing this kind of spectral prior knowledge.关键词：prior knowledge;inversion;reflectance spectrum;vegetation structure
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发布时间：2021-06-10 - 摘要：This paper introduces a new Spaceborne Polarimetric SAR Data Simulation system, The siumlation method used in this paper is based on the view of real system; and according to the sequence of the transmit pulses, each return wave formed by the reflection of all the targets which are irradiated by the transmit beam is calculated one bye one, all these return wave data form the result. Compared with the usually used method based on single point target simulation, this method is much more efficient especially in case of simulating a large area. It is also conveniently to simulate all kinds of error and keep the correlation and consistency of the errors. At last, a simulation example is also given.关键词：SAR;polarimetric SAR;SAR data simulation
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发布时间：2021-06-10 - 摘要：Change vector analysis and principal components analysis in NDVI time trajectories space are powerful tools to analyse the land cover change. The length of the change vector indicates the magnitude of the change, while its direction indicates the nature of the change. This change detection method is applied to two remotely sensed indicators of land surface conditions, i.e. NDVI and spatial structure, with aims to improving the capability to detect and categorize land cover change. The magnitude and type of changes and the changes in spatial structure indicator in China from 1983 to 1992 are calculated using the above mentioned analysis methods. Through the research, the main conclusions are drawn as follows:\;1) The change vector magnitude of NDVI is different apparently between East and West China. Larger changes of NDVI lie to the Southeast coastal areas, Taiwan and Sichuan, Yunnan province （monsoon area of Southeast and Southwest China）. The changes in Northwest area and Qinghai Xizang Plateau are little. It can conclude that the monsoon climate and the human activity impact apparently on the land cover dynamic of East area （especially the different kinds of crops）.\;2) NDVI of land cover changes is derived from many factors （climate, hydrology, landform, soil, land use etc.）. Although the basic tendency of the climate in North China is that the temperature becomes increasing and precipitation get decreasing （drying）, no obvious changes are presented in large scale in this region. Landform types and vegetation types in North China are the key factors for NDVI changes.\;3) The spatial structure indicator is able to detect changes in the seasonal ecosystem dynamic for spatially heterogeneous landscapes. Changes of spatial structure indicators of NDVI mainly locate in South China, reflecting the high heterogeneity vegetation during the growth and decay processes. The areas composed of Tianshan Mountains, Changbai Mountains, and Xiaoxinganling Mountains reflect the impact of landform types on the spatial structure index.关键词：vegetation;land cover;NDVI;Change Vector Analysis （CVA）;spatial structure
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发布时间：2021-06-10 - 摘要：Rice is a vital world food crop, and most paddy rice fields distribute in warm, humid environmental regions with heavy cloud cover and rainfall. It is difficult to acquire optical remote sensing data in these regions. So SAR system is used to map and monitor rice crop growth status. It is important for rice monitoring to understand the microwave backscattering. The backscattering is related to the dielectric properties and geometric parameters besides the radar system parameters. The geometric parameters of the rice can be easily measured, but it is very difficult to get the dielectric constant from ground observation due to many influence factors. So it is necessary to compute the dielectric constant using models.\;This paper presents the modeling results of dielectric constants from different rice growth stages in Zhaoqing test site using DebyeCole dualdispersion mode of vegetation. In the test site, two crops of early season rice and late season rice are planted in 1997 and 1996, and the growing period of rice crop is divided into five major stages: transplant, seeding developing, ear differentiation, heading and mature period. Based on the results, the paper discusses the influences from microwave frequency, gravimetric moisture content of rice, temperature, salinity and bulk density of dry vegetation meterials on dielectric constant. The rice crops of different growth stages have the various dielectric constants, and the dielectric constants of early and late season rice crops show the diverse changes. The parameters, including microwave frequency, gravimetric moisture content of rice, temperature and bulk density of dry vegetation materials, have the influence on dielectric constant, but salinity has no effect on the dielectric constant.关键词：rice;growing period;dielectric constant;influence
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发布时间：2021-06-10 - 摘要：Based on the analysis of the information characteristic of image database （IDB） the general relation schema of IDB and the conception of Contentbased Image Retrieval （CBIR） were investigated, and then a set model of CBIR was introduced. Moreover, two classes CBIR system were discussed. Especially, the emphasis was put on the GIS supported CBIR and a set of such querying algebra operators was presented. The system frame and the general schema of CBIR based on image feature index were discussed as well.关键词：image database;contentbased image retrieval;image indexing;spatial relation
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发布时间：2021-06-10 - 摘要：Based on the 12 months’ 1km AVHRR data in China, this paper computes four kinds of vegetation index （VI）, that are ratio vegetation index （ RVI ）, normalized vegetation index （ NDVI ）, soil adjusted vegetation index （ SAVI ） and modified soil adjusted vegetation index （ MSAVI ）. Then, we make the same principal components analysis （ PCA ） to them, and find that the PCA transformed first four principal components （ PCA1, PCA2, PCA3, PCA4 ） contribute about 88% cumulative variance, and PCA1 represents VI cumulation of whole year, PCA2 represents VI difference of winter and summer, PCA3 represents VI difference of spring and summer, PCA4 represents VI difference of spring and autumn. In other words, for multitemporal vegetation index of one year, PCA not only compresses the information to the first four principal components, but also extracts the key change information. The PCA1 expresses the basic land cover information, the others extract the seasonal change information of vegetation. However, the outcome of different vegetation index has some differences. As to the cumulative variance of the first four eigenvectors, the biggest is NDVI , 89.28%, the second is SAVI , 88.40%, and the smallest is RVI , only 87.44%. As to the correlation matrix of four vegetation index, SAVI and MASVI are the most similar, NDVI is much similar with the first two vegetation indices, and RVI is the least similar. Although the primary purpose of VI is to indicate the biomass of vegetation, due to the different features of VI, such as different correlation with leaf area index, different sensitivity to vegetation and different anti disturbance of soil and atmosphere, different VI indicates different biomass for the same vegetation, that is, when we use the same PCA to different VI, the result is not uniform.关键词：vegetation index;PCA;NOAA AVHRR
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发布时间：2021-06-10 - 摘要：Due to the special operation mode of TDI CCD, image shift is resulted from earth selfrotation in polar orbit sensing. This kind of image shift makes image degradation, resolution decrease, and target margin mistiness. Compensating the shifted image is an important problem that must be resolved in the application of polar orbit satellite TDI CCD camera. In this paper, the image shift of TDI CCD camera for polar orbit satellite is forecasted, then the effect of image degradation is calculated. A mathematical model is set up according to the principle of TDI image shift, and an image compensation filter is worked out, which is proved to be valid by computer simulation.关键词：TDI CCD;image shift;image processing
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发布时间：2021-06-10 - 摘要：A method to retrieve the oceanic chlorophyll concentrations in Casse I water based on Aritificial Neural Network （ANN） is presented. The ANN used in this paper is a threelayer feed forward backpropagation network which has 4 neurons in the input layer （corresponding to the ratios of the remote sensing reflectances at 4 wavelengths: 412 nm, 443 nm, 490 nm, 510 nm to the remote sensing reflectance at 555 nm）, 5 neurons in the hidden layer and one neuron for the output layer （Corresponding to chlorophyll concentration）. The training data set and testing data set of the ANN come from SeaBAM data base. 70% of the 919 stations in SeaBAM was used for training data set, the other 30% used for testing data set. At the end, the retrieved results from ANN and from the empirical algorithms were compared. The results show that the accuracy of the ANN is better than the cubic empirical algorithms used widely.关键词：chlorophyll concentrations;Retrieval;Artificial neural Network
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发布时间：2021-06-10 - 摘要：Region is one basic unit of spatial analysis in GIS applications, which is a kind of entity existing widely in many fields such as environment science, land information science and so on. In general, the kind of entity has a common character of continuously spatial distribution, so there is inevitably fuzziness in spatial data used to represent its position when it is abstracted and generalized, and enters into GIS databases. Here, fuzzy set is taken in this paper as a strong and convenient mathematical bridge to model uncertainty and fuzziness under a GIS environment. Firstly, a new method of representing fuzzy region is proposed based on field model, and its spatial uncertainty is analyzed. On the basis of above discussion, we analyze some existing methods on how to describe the point set topology of fuzzy region by referring to some shortcomings and giving a kind of new description method. Thus fuzzy region’s boundary, interior and exterior are defined in detail, and their geometric meanings are given. Finally, this paper ends with the discussion on how to describe uncertain topological relations caused by spatial uncertainty of fuzzy region based on the point set topology, and develops corresponding 9intersection models. It is shown that the point set topology model proposed in the paper is an extension of the 9intersection model by Egenhofer （1991）.关键词：fuzzy region;spatial uncertainty;topological relations
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发布时间：2021-06-10 - 摘要：Extracting and classifying spatial features from highresolution satellite sensor imagery, especially from the image covering urban areas, is a very significant but challenging task. However, it is very difficulty to be implemented and the main obstacle comes from highdimensional and complicated properties of spatial features. In this paper, the Support vector machine （SVM） is introduced as a new technique for solving a variety of learning and function estimation problems, and it has shown great potential in pattern recognition and computer vision problems. The optimal decision surface of a SVM is constructed from finite support vectors, which are conventionally determined by solving a quadratic programing （QP） problem and independent of the dimension of the features. Based on the idea of SVM, a new approach for spatial feature extraction and classification on highresolution satellite sensor has been developed by the experimental case of spatial feature classification in central urban area of Hong Kong with SPOT Panchromatic image. The algorithms are synthetically compared with other established algorithms which are represented with conventional neural network algorithms including BPNN and ARTMAP. Finally, the conclusions can be drawn that SVM holds some particular advantages on its faster learning speed, selfadaptive and representative capability, no limitation by highdimension property in feature space, etc.关键词：Support Vector Machines;remote sensing image;spatial features
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发布时间：2021-06-10 - 摘要：According to investigation results based on remote sensing technology, This paper discusses the patterns of Cele oasis desertification dynamic change in the south of Tarim Basin. Considering macroscopical research, this paper chooses 4 main land cover types which are desertification, oasis, Ecotone and water body, and they represent distinct characteristics of the local area. To register 3 different time, spatial resolution and spectral resolution satellite images, the paper uses some GCPs registered accurately 3 satellite images （for MSS, TM, SPOT HRV） and fuses a image with these multisource data. The fusion image shows more details than monotime image and plays a assistant revising role to some dynamic change charts as followings. On the basis of field survey and some statistical data, the paper uses PCI soft ware to process these data and produces a series of 4 main land cover dynamic change charts. Through analyzing these charts, the paper has studied the dynamicly distributed data of land covers spanning 21 years and the regulation of the local ecological environmental system. At last the paper points out that the trend of Cele region oasis desertification expansion is derived from two important reasons which have severe influences of nature and humanity. Therefore, in order to ameliorate the local ecological environment, people living in Cele country should work hard to plant more to preserve their homeland and reduce the degree of sandy wind offensive, to develop social economy, and to carry out sustaining development.关键词：multisource remote sensing images;desertification;dynamic change;image registration
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发布时间：2021-06-10 - 摘要：Sea surface temperature （SST） is an important indicator of the climate change. The Along Track Scanning Radiometer （ATSR） onboard the European Space Agency’s first remote sensing satellite （ERS 1） was designed to provide high accurate SST. ATSR SST during the period of 1991 to 1992 was compared with simultaneous in situ SST measured by NOAA’s Tropical Atmospheric Ocean （TAO） Array of moored ocean buoys in the tropical Pacific and JMA’s ocean data buoys in the northwest Pacific. The comparisons show that ATSR SST derived from 3.7 μm, 10.8 μm and 12 μm dual view birghtness temperature in the tropical Pacific has a much higher accuracy, with a bias of -0.22 K and a standard deviation of 0.25 K against in situ SST. While, in the northwest Pacific, the bias is -0.51 K and the standard deviation is 0.61 K. The results demonstrate that ATSR can measure SST with a very high accuracy in the tropical Pacific under the volcanic aerosol contamination due to the eruption of Mt. Pinatubo in June 1991. The accuracy of ATSR SST in the northwest Pacific needs to be improved. Simulation using LOWTRAN 7 was carried out to analyze influence of aerosols on the retrieval of ATSR SST.
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发布时间：2021-06-10 - 摘要：In loess plateau of China, the yield varies from cropland to cropland. It is very important for the agriculture of China that monitoring the changes of cropland in different years with RS information. The paper selects some themes that directly affect the yeild of cropland. Based on the comprehensive thematic information, a large region is divided into several small regions and the cropland from some different region in the remote sensing TM image are classified. The development of the method of divisional compound hierarchical classification has improved the accuracy of remote sensing classification greatly.关键词：RS;cropland;divisional compound hierarchical classification;GIS
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发布时间：2021-06-10 - 摘要：The paper describes several kinds of spectrum dividing techniques used in imaging spectrometers （IS）. Dispersion type imaging spectrometers with a prism or grating have come to maturity, and used widely. The IS using a grating in divergent light is a new application method of the grating, which overcomes the defects of IS using a grating in collimated light. The imaging Fourier transform spectrometers （IFTS） have been a powerful tool to remotely detect visible and weak IR radiation. Wedge imaging spectrometer （WIS） has simple construction, and begins to be applied in practice with the further maturity of the process of variable filter. Owing to the limitation of the tunable filter manufacturing process, the imaging spectrometer using tunable filters will need long time to be used as payloads of satellites. The imaging spectrometer using diffractive optics has compact construction, small volume and rapid scanning speed, and its practical ground manufacture have been visible. The computed tomography imaging spectrometer （CTIS） is in the experimental stage because of its new working principle. 3D imaging spectrometer can be used to measure the objects which often change rapidly, by use of its unique characteristics it can obtain two dimension image and one dimension spectral information.关键词：imaging spectrometer;spectrum dividing techniques;Imaging Fourier Transform Imaging Spectrometer （IFTS）;tunable filter;diffractive optics;Computed Tomography （CT）;3D Imaging Spectrometer
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发布时间：2021-06-10
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