最新刊期
卷 ， 期 4 ， 2002
- 摘要：The vegetation hotspot dependence on its stucture at various times in one day and various growth periods is investigated in this paper. We simulate the interaction of light and vegetation based on three dimensional plant canopies.Our approach consists of four processes. Firstly,the biophysical parameters,such as corn plant height,leaf base height,size of leaf,and shape of leaf,are measured on field,and the statistics of the parameters is obtained based on the measurement. Secondly,the three dimensional structure of canopy is built by the CSM （Computer Scene Model）according to the statistics under a pixel configuration,such as planting by row or by random. Thirdly,the zenith and azimuth of sun are calculated for the simulated site on earth. Fourthly,hotspots and bi directional reflectance distribution functions are calculated by the LIM （Light Interception Model）under various sun and viewing geometric conditions. Finally we evaluate diurnal consecutive hotspot and seasonal consecutive hotspot. The characteristic and scientific objectives of hotspot satellite Triana also are introduced. The simulated result will improve our understanding about the Triana data,and help us to use the dada effectively.关键词：hotspot;remote sensing physical modeling;computer simulation;vegetation visualization
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发布时间：2021-06-10 - 摘要：Multi angular remote sensing supplies reflectance of land surface in different directions. To simulate the relationship between bi directional reflectance distribution （ BRDF ） and structure of land surface and optical characteristic of objects,more models were developed. Because they are simple,rapid,grasp the main factors affecting BRDF and have some physical meaning,semi empirical models,especially,kernel driven models are applied broadly in data processing in batches. Thus,kernel driven BRDF model was the core of the AMBRALS,an algorithm for MODIS land surface BRDF and albedo products. In the onboard version of AMBRALS,the LiSparseR Gometrical Optical （GO） kernel was used. But a new derived kernel LiTransit kernel is also good at transition from LiSparse kernel to LiDense kernel when zenith angle is large,and accords more to the basic principle of GO model than LiSparseR kernel. Results of validation show:RossThick LiTransit kernels combination has more stability when extrapolated to large zenith angles with LiSparseR kernel. Therefore,we will use the Litransit kernel instead of LiSparseR kernel in the new version of AMBRALS. We introduce the algorithm based on this new kernel in this paper,including the kernel driven model and its inversion,albedo retrieval based on BRDF model,broad band albedo retrieval and realization of this algorithm. The speed requirement of tremendous data processing can’t be met easily,such as MODIS data. Although we can calculate the integration of the kernel beforehand,store up and acquire through look up table method during retrieving albedo,it’s inconvenient for an integrated data processing system. Thus we need to get the simple form of the integration of the kernels. Because the integrations of the kernels are approxinately independent on directions than BRDF ,it’s sufficient to use a polynome dependent on the solar zenith angle to regress the integration of kernel. In this paper, we study the polynome regression of LiTransit kernel to instead LiSparseR, but not affect the systematic of the algorithm at the same time. Comparing the numerical integration of the kernel and the polynome regression result show the relationship is very well,the polynome can be used in the algorithm directly.关键词：albedo;kernel driven BRDF model;LiTransit kernel;MODIS;AMBRALS
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发布时间：2021-06-10 - 摘要：There are nonlinear relations among the bi directional reflectance of rice,its canopy architecture parameters, the spectral characteristics of the different components of rice, and the illumination and viewing geometry. This article explores the use of artificial neural network for both forward and inverse bi directional reflectance modeling of rice based on the data measured in Zhejiang University（Hangzhou,China） for field experiments from 1999 to 2000. The assumption here is that the bi directional reflectance of a rice canopy is the function of the geometry of its constituent elements,the spatial distribution,spectral features of the elements, and the illumination and viewing geometry. This implies that the bi directional reflectance of the canopy is particular sensitive to the canopy’s structural parameters, the spectral characteristic of foliage,and the illumination and viewing direction. It also implies that canopies with different parameters will exhibit different bi directional reflectance. On the basis of these analysis,we decided to have 10 input parameters:model inclination angle of the canopy（ θ ）,eccentricity（ D ）,reflectance of foliage（ R ）,transmittance（ T 1 ）,sun zenith angle（ θ s ）,soil reflectance（ sbrf ）,the ratio of mean length to canopy height（ L 1）and the ratio of width to length（ P ）,leaf area index（ LAI ）,diffuse to total incident radiation（ Q 1）. There are 17 output parameters:bi directional reflectance of the canopy in the principal plane,from -60° in the forescattering direction to +60° in the backscattering direction at increments of 7 5° in forward BP model. On the other hand,there are 3 output parameters:leaf area index,the ratio of mean length to canopy height and the ratio of width to length,and other 22 parameters mentioned above except eccentricity and model inclination angle of the canopy are input parameters in inverse BP model. After model development,the neural network model is tested against the independent data set. The Root mean square error between the bi directional reflectance of rice measured and simulated varies from 4 53×10 -6 to 3 67×10 -3 . The inversion model of artificial neural network is able to inverse the rice canopy structural parameters with 81 8% accuracy. The results of both forward and inverse modeling suggest that the model of artificial neural network is of high precise to simulate the relations of the bi directional reflectance of rice and its canopy structural parameters. Further research is needed to monitor the rice growth by the neural network model.
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发布时间：2021-06-10 - 摘要：This paper is about the processing of the burst mode Space borne ScanSAR data There are many algorithms developed for processing the strip mode space borne SAR data,for example;the RD algorithm,the Specan algorithm,the Chirp Scaling algorithm,the Ω k algorithm However,due to the bursting characteristics of the ScanSAR data and the operation mode of the ScanSAR,none of the above algorithms can be used directly in the processing of the Space borne ScanSAR data In this paper,the time domain and the frequency domain characteristics of the ScanSAR echo were analyzed Based on the understanding of RadarSAT ScanSAR data and the characteristics of the ScanSAR echo,the full swath RD algorithm,fast SPECAN algorithm and Chirp Scaling algorithm were developed The RD algorithm for whole scanned swath is an effective algorithm,the SPECAN algorithm can provide a high resolution image quickly and the chirp scaling algorithm has an excellent phase preserving ability In the real data processing,some methods like the side lobe control of point target echo,the fast range walk correction,the scalloping weakening,the range ambiguity control,the azimuth false target elimination and the Doppler centroid frequency estimation were discussed and verified关键词：space borne SAR;ScanSAR;image processing algorithm
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发布时间：2021-06-10 - 摘要：An effective algorithm for suppressing speckle in synthetic aperture radar（SAR）images utilizing the empirical mode decomposition（EMD）method is presented in this paper.The EMD was proposed by Norden E Huang et al .,with which any complicated data set can be decomposed into a finite and often small number of intrinsic mode functions.Contrary to almost all previous methods,this new method is intuitive,direct,a posterior and adaptive,with the basis of the decomposition based on,and derived from,the data.So EMD is quite suitable for analyzing nonlinear and nonstationary data.A line of digital SAR images can be decomposed into a series of modes whose characteristic space scale defined by the space lapse between the extrema is different.The speckle noise is defined by the mode whose space scale is not more than 4.The SAR speckle suppression is implemented by smearing short space scale component in the spatial domain via the EMD.As the EMD is onedimensional method,we use EMD in the following way.First we process each horizontal row of pixels,then process each column pixel of image. EMD is based on and derived from the data,thus it is adaptive and can preserve the edge information.Application to SAR images has shown that the performance of the algorithm is satisfactory in both smoothing and edge preservation.关键词：SAR;EMD;speckle;space scale
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发布时间：2021-06-10 - 摘要：Metadata is a kind of data coming from some data collection,and it is a description or direction of the data collection.The advantages to utilize the metadata are as follows:（1）the speed of selecting and indexing from large volume of data in the geo spatial database can be improved;（2）it will promote the sharing of geo spatial information and propel the progress of Chinese standard;（3）it will be advantageous to evaluate the geo spatial data and control their quality;and（4）taking advantage of the metadata may be helpful to store and manage the geo spatial information.The General Provincial Situation GIS（GPSGIS）is a kind of GIS reflecting the comprehensive and general situation in some province,and the content contains:（1）the general geographic information（such as rivers,lakes,topology and so on）;（2）natural resources information;（3）economic information;（4）social development information;and（5）others.So,the development and application of GPSGIS should be supported by metadata for geo spatial data.On the basis of analyzing of the present standards for metadata,the contents of metadata in GPSGIS are put forward.The metadata is stored by a new method that is based on the relation database.Certainly the metadata is organized and managed by related tables to build the metadata database.The database is composed of some metadata tables as given belaw:（1）the top metadata table,located in the most top level of the all geo spatial databases;（2）the sub top metadata table,located in the lower level than the top one,so it is less important than the top metadata;and（3）the data collection metadata tables,located in the equal rank to the one geo spatial database.It is of importance that the management of the metadata databases is based on the management of the topologic data,but both of them must be coordinated.关键词：general provincial situation GIS;metadata;related table
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发布时间：2021-06-10 - 摘要：Striping is an important factor that influences image quality acquired by linear array CCD blocks.This may be more crucial for spectrometers because of the imperfect calibration of the detector characteristics and the necessity of higher CCD quality,which results in the most common striping.This paper firstly discussed the main reason causing stripes.Then we compared some striping removal algorithms and their limitations.Based on this consideration,we point out that the standard moment matching method changes the mean value distrbution of image in line or column arrangement.This is especially the case for small size images.We present some approaches to simulate and calibrate the image gray value distribution.The purpose of these methods we embraced here is to recover the truth of the mean value distribution of ground radiance.As an emphasis,we mainly discussed the theories and processes of three kinds of mean value fitting approaches:the mean value compensation method,Fourier transformation method and correlation method. After discussing the methods,we used an 890×770 size test image acquired by an imaging spectrometer to experiment our theories.Through combining moment matching with these post-processing techniques,we successfully reduced stripes and improved the image quality.Finally,we visually and quantitatively assessed the quality of the resulted images.关键词：spectrometer;striping noise;moment matching
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发布时间：2021-06-10 - 摘要：Remote sensing images contain a lot of mixed image cells, and it is difficult to classify these cells. Mixed image cells decomposition algorithm based on principle component analysis is a widely used algorithm, but the large computation amount and less flexibility are its main drawbacks. By researching the curve fitting （approximation）theory of the radial basis function neural networks, and the principles of the mixed image cells decomposition algorithm based on principle component analysis, the paper proposes a new decomposition algorithm, which uses the radial basis function neural networks to fit （approximate） the hyperplane of the decomposition results of the principle component analysis algorithm. Experimental results prove that the results of the new algorithm are almost the same with the results of the principle component analysis algorithm （correlation coefficients are above 0.99）. However, the new algorithm has much less computation complexity and more flexibility than the principle component analysis algorithm.关键词：mixed image cells;principle component analysis;radial basis function neural networks （RBFN）;curve fitting （approximation）
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发布时间：2021-06-10 - 摘要：In order to enhance the sensing power of precipitating clouds, a dual polarization radar is developed to be added in an active and passive microwave dual wavelength （X/Ka band） remote sensing system. After this upgrading of dual polarization function, the advanced properties of the principle of the former remote sensing system are augmented. This upgraded system becomes a new capability of synthetical sensing clouds and precipitation, and will play an important role in precipitating cloud structure studies and all kinds of major science projects concerning obtaining quantitative distribution of clouds and precipitation, The working principle, the upgrading method and the specifications of the new system and its main components are given here. An emphasis is laid on the description of the design and implementing means of the antenna feeding unit, the control unit and data acquisition unit. A preliminary rainfall observation test of the system is also presented in this paper.关键词：microwave remote sensing;dual polarization;radar;radiometer
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发布时间：2021-06-10 - 摘要：Yanggong River is a tiny anabranch of upper reaches of the Changjiang River. Its drainage are consists of Lijiang basin and Heqing basin,and is a representative area in northwest Yungui Plateau. Furthermore,there are differeat natiouality and culture background between the upper basin and the lower. Before late 1990s,urbanization process in Yanggong River drainage area is spontaneous,after then,it has been quickened,especially the county seat of Lijiang and Heqing. Spatial pattern of urban and rural residential area has changed greatly, which was reflected mainly in spatial diffusion. With the changes,the problem of how can we realize sustainable development of urban and rural residential area in scale,form,pattern and function in a certain spatial and temporal range shonld be paid attention to. The paper explores the method to extract urban and rural residential information of research area by remote sensing technology,using imitated ratio of vegetation index（RVI）to extract the spatial information from the Landsat TM images of 1996’s and 1999’s,measuring fractal dimensions to explain urban and rural residential area complexity and stability with time out,and comparing the pattern characteristics of the two county seat cities. According to the bigger residential fractal dimension value of total residential area in 1999 than 1996’s and the contrary result while excluding the county seat of Lijiang and Heqing,we find that the Lijiang city and Heqing city become more complex and unstable from year 1996 to 1999 ,but the pattern changes of rural residential area is different. Although the changes of residential area pattern are caused by many factors that interact with each other,the function of various factors is different. We study the dynamic mechanism for facilitating the pattern of the residential area on the bases of research pattern,and find that the earthquake happened in February,1996 and opening of the highway from Dali to Lijiang passing through Songgui basin in 1998 are primary factors influencing the Lijiang and Heqing city and rural residential area along the road. And the flourishing tourism is also important,which leads to the different change rate between Lijiang and Heqing in past three years.关键词：urban and rural residential area;spatial information;remote sensing;fractal geometry;Yanggong river drainage area
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发布时间：2021-06-10 - 摘要：The purpose of this study is to determine the depth of occurrence of groundwater and to evaluate the groundwater level distribution in the oasis and desert ecotone. In this research, on the basis of the regression analysis of groundwater levels and soil water content data measured in the field, a model of groundwater level distribution using remote sensing （GLDRS） was established using Landsat 7 ETM+ image, by dint of practical work and field data examination. To obtain water content of soil precisely using Landsat 7 ETM+image,which is related to the remote measurement of groundwater level, the concept and model of optical vegetation cover is led in. \;The results of the experimental teste of the GLDRS model in the oasis and desert ecotone of Qira county, Xinjiang Uyghur Autonomous Region are discussed. A good correspondence （correlation coefficient is 0.901） was obtained between the groundwater level at control points, where direct measurements were made, and those derived from Landsat 7 ETM+data. Groundwater level distribution in the whole ecotone was evaluated and presented in the form of thematic maps.
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发布时间：2021-06-10 - 摘要：The rural settlements of China are picked up from the land use vector map by interpreting the Thermatic Map of 2000. About 7.57×l0 5 rural settlements are calculated by the GIS software. The rural settlements density in the eastern area is larger than that in the western area which corresponds to the population densisy of China. The rural settlement density in the eastern provinces are higher while sparse in Tibet and Qinghai provinces. The average area of the rural settlement is 16.27 hm 2. The regional disparity of the rural, settlement scale is apparent. The average area of Northern China is bigger than that of Southern China. Those in the plain area is bigger than in the mountain area and those in the developed area is bigger than in the developing area. Chinese rural settlements are smaller and about 50.09% is between 2-9 hm 2 29.92% 10-21 hm 2 ,10.32% 22-34 hm 2, 8.67% 35-104 hm 2 and only 1% more than 104hm 2. From the Lorenz curve we can see that about 80% of the rural settlements are 10-21 hm 2 and the number of 2-34 hm 2 takes up about 90%.When the scale is 34 hm 2,the slope of the curve is lowest and nearly smooth. In Hunan province whose average acrage is smaller about 84.76% of the rural settlements are 10-21 hm 2 .In Hebei province about 21.51% of the rural settlements are 10-21 hm 2 .The expotential distribution is calculated and the relevant equation between the area and the number of settlements at least a hm 2 N（a） = ca -1.865 is obtained by the log regression. B of Hunan province is the largest in the selective cases and that of Guangdong is the smallest. Although B of Shandong and Guangdong provinces is of little difference,the number of the settlements between 2-10 hm 2. In North province Shandong takes up 35.91% while that of South province Guangdong takes up 35.91%. The spatial distribution of the rural settlements is measured by the lacunarity index. The lacunarity index correlates with the rural settlement density. In the area where the rural settlement density is high the lacunarity is low, the distribution is even and the gap between the settlements is low. On the contrary, in the area that the rural settlement density is low the lacunarity is high ,the distribution is uneven and the gap is high.关键词：rural settlements;scale distribution;Lorenz curve;expotential distribution;Lacunarity Index;spatial distribution;disparity between provinces
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发布时间：2021-06-10 - 摘要：Massive information and worldcovered network bring out the quickly coming of Digital Earth（DE）,which makes the geospatial information management,sharing and valid using on Internet more urgent than ever.In order to resolve these problems,the authors researched and discussed the definitions,functions and contents of geospatial metadata,and its implementation of management system based on Web and its application integrated with WebGIS in DE in this paper while allowing for the frontier of international geospatial metadata standard.Metadata is the "data about data",it is used to describe the contents,quality,presentation,spatial references and management methods of geospatial data and its other properties.Moreover,the geospatial metadata content standard draft has been proposed here,consisting of 8 standard components and 4 referenced components that can only be used with reference to standard components and can not be used independently.Also by making use of the latest Internet technology and integrating with WebGIS,three solutions,namely CGI,the third vendor application and Z39.50,for geospatial metadata network management system（GeoMNMS）have been proposed here.The authors adopted the Z39.50 solution and implemented the GeoMNMS which is based on the Internet and can be used in DE construction.The system has many functions such as User Authorization,Metadata Catalog, Metadata Inpurting,Metadata Query,Metadata Modifying,Geospatial Data/Information Publishing and Sharing on Internet etc.,all of them can be operated online.And some of demonstrations of various functions of the system have been presented finally.In the era of global informationization and Digital Earth,the GeoMNMS provides the prototype of managing and using geospatial metadata in DE construction,and it will promote the progress of Chinese standardization and propel the DE construction.关键词：Digital Earth （DE）;geospatial information sharing;geospatial data;geospatial metadata, GeoMNMS
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发布时间：2021-06-10
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