最新刊期
卷 ， 期 2 ， 1999
- 摘要：The National Spatial Data Infrastructure （NSDI） is the basis of digital earth. It is therefore very essential to develop NSDI in order to implement the vision of a Digital earth. This paper reviews the recent progr ess and future activities of NSDI in China, including the national geodetic fram ework, multi scale geo spatial databases, national efforts on geo spatial dat a standardization, establishment of national geo spatial clearinghouse network, coordinati on of national efforts in acquiring, processing and utilizing geo spatial dada.
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发布时间：2021-06-10 - 摘要：It is still not clear that how high the upper limit of landuse classification accuracy can be reached using TM imagery in southeast p la in areas of China featuring mass irrigation networks and small tracts. In this p aper a result for the upper limit, 65%, is presented based on the GIS layer （as gro und truth） of the detailed landuse inventory map at 1∶10000 scale being well o verlaid with a TM image of the same period, according to the national landuse c lassification system by taking all measures that may make the accuracy higher wi t hin the framework of conventional image classification mathods. The results show that the selection of training samples and reference pixels for accuracy assess ment in a limited part of test area has significant influence on accuracy assess me nt. The limitation of quality and quantity of reference pixels is probably the m a in reason why some early researches of this kind reported higher classification accuracy.关键词：Land use;remote sensing;GIS;classification;Accuracy assessment
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发布时间：2021-06-10 - 摘要：Imaging spectrometer has tens or hundreds of bands. Th us, it provides the opportunity to acquire more volume of information about the surface targets. At the same time it is difficult to process so huge volume of d ata, thus, it is important to find a solution to this problem. Principal Compone nt Analysis （PCA） is a good method to reduce the volume of data at the cost of a little loss of information. But one of disadvantages of PCA is that each PCA tr ansformed component has a blur meaning. Correspondence Analysis （CA） overcomes t his shortcoming. This paper uses CA to process the Laboratory spectra of nine ro cks, which have been resampled on the channels of MAIS, and get a good result. It is also a meaningful attempt to the processing of imaging spectrometer data.关键词：Laboratory spectra of rock;Correspondence analysis
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发布时间：2021-06-10 - 摘要：The backscattering properties of some crops （including paddy, cotton, maize and peanut） from terrain of central plains of China were measured by using multi ba nd polarimetric scatterometer. Backscattering characteristics in different fre quencies and terrain parameters were obtained based on measurement results of ba ckscattering coefficient. 〖WTHZ]关键词：Multi band polarimetric scatterometer;Backscattering coefficient;crops
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发布时间：2021-06-10 - 摘要：It is well established that Synthetic Aperture Radar （ SAR） Interferometry can be used to perform surface elevation mapping and change detection. Among the factors critical to the mapping and detection accuracy is t he registration of the INSAR complex images from repeated orbits. This paper pre sents a method for registering INSAR complex images and two methods for interfer o gram enhancement. When registering complex images, area based registration metho d is used and the correlation coefficient between the corresponding data windows of the complex images is selected to evaluate the registration precision. With the method developed in this paper the INSAR complex images can be coregistered with the precision of subpixel. An interferogram can be obtained from the cor egistered images. To reduce the noise of the interferogram median filter and dir ectional filter were experienced. The advantage of these filters is that the abu n dant fringe information of the interferogram is saved when smoothing the noise. These data processing methods have been applied to the SIRC/XSAR L band interf e rometric data of the Karakax area in the western China, and valuable results hav e been obtained.关键词：Interferometric synthetic aperture radar （INSAR）;Image registration;Interfero gram
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发布时间：2021-06-10 - 摘要：Based on the used degree index of land resources and NDVI （Normalized Difference Vegetation Index）, the present situations of Chinese land use/land cover were analyzed with modeling methods. The conclusions are that the Chinese present la nd cover situation reflects the development and the used level of the Chinese l and used degree index value 202. From the limited value 400 of land used degree index, Chinese land resources have reached the half of its used limited value; i n the eastern China, the land is mainly covered with cultivated land type and th e degree of land use is high; in the western China, the land is mainly covered with unused land type and the degree of land use is low. The relations exist be tween the distribution of Chinese NDVI and the distribution of Chinese vegetatio n types. The distribution of Chinese NDVI is a reflection of the distributive co ndition of Chinese precipitation and temperature. The areas covered with agricul tural vegetation type are almostly situated in the eastern China, and the value of land used degree index is high in this area.关键词：NDVI;Land use/Land cover;Used degree index of land resources
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发布时间：2021-06-10 - 摘要：In this peaper, the implement and comparison of different self organizing learn ing algorithm in landcover classification of Landsat TM imagery it is found that , with the combination of unsupervised and supervised learning method and the ne a rest neighbour principle, these algorithms have no significant difference in cla ssification accuracy. The study result shows that the self organizing network i s an another method to classify the landcover type in remote sensing imagery by combining the unsupervised and supervised learning phase with the nearest neighb our principle. Because of the simplicity of the Simple Competivite Learning, the self organizing network can use the Simple Competivite Learning algorithm in re motely sensed data classification.关键词：Self organizing network;Unsupervised and Supervised l earning;Kappa agreement coefficent;Overall accuracy;Z test
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发布时间：2021-06-10 - 摘要：This paper presents a new image fusion scheme based on the combination of multiresolution wavelet decomposition and IHS transform for the fusion of Highresolution Panchromatic and Multispectral images. The Panch romatic high resolution image is firstly decomposed to the wavelet planes, then the wavelet planes are added to the intensity component of IHS representation of th e multispectral image. In the proposed method all the spectral characteristics have been preserved, and the definition and the spatial quality of multispectra l image have been improved. Fusion result keeps the contrast of multispectral i mage. Experimental results including the fusion of blackwhite aerial and Landsa t （TM） images, Landsat TM and SAR images are presented. Compared with the WT and IHS method, the proposed scheme is much better and it possesses more adaptabili ty.关键词：Wavelet decomposition;The wavelet plane;Additive fusi on;IHS transform;WT fusion
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发布时间：2021-06-10 - 摘要：In this paper a novel system of the X band radiometer scatterometer developed by our Institutions is reported. By using this system, multi polarized （VV,HH,VH,HV） backscattering coefficients for active remote sensing and V,H polari zed brightness temperature for passive remote sensing can be measured simultan eously. Some measurements of scattering and emission from tree canopy with and without artificial metal targets are presented. Theoretical study of scattering and emission from a layer of random medium is discussed with data analysis. Ou r approach provides an example of correlated active passive remote sensing and application for target detection in environmental clutters.关键词：Radiometer scatterometer;Background and target;Obser vation and analysis
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发布时间：2021-06-10 - 摘要：Microwave remote sensing information includes active and passive microwave remot e sensing information. Under some conditions, they usually show different chara cteristics of the same object. So acquiring active and passive microwave remote sensing information simultaneously is very important to interpretation, decision and inversion of microwave remote sensing. Scatterometer and radiometer are important sensors for microwave remote sensin g information acquisition. A scattero radiometer composed of a scatterometer an d a radiometer can measure backscattering coefficient and brightness temperature of the same object simultaneously and it is superior in size, weight and operati on. In the paper, the design idea of a scattero radiometer is put forward. In the i dea, a public antenna and a public high frequency channel are used to receive sc attering and radiation signals at the same time. Then, the signals are separate d by filters in intermediate frequency and processed respectively. An X band sca ttero radiometer is developed according to the idea. A simple continuous wave s catterometer and a digital gain compensation microwave radiometer are adopted i n the scattering and radiation mode respectively. The fundamental diagram and th e timing program of the scattero radiometer are introduced. The performance of the receiver has been tested and the results are given. Scattering and radiati on characteristics of soil versus water content have been measured with the sca ttero radiometer. The results have been compared with the analogous results ac hieved aboard and the trends are the same. It shows that each mode of the scatte ro radiometer can work in sequence and they don’t disturb each other. It prove s that it is feasible to develop a scattero radiometer according to the idea.关键词：Scattero radiometer;scatterometer;radiometer
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发布时间：2021-06-10 - 摘要：A three component ocean color model for South China Se a is presented, which takes into account the contributions of chlorophyll, yel low substance and inorganic particles. It is then used to simulate the spectral reflectance just below sea surface based on optical properties of these colored matters. The reflectance spectra are also calculated from in situ measured downw elling and upwelling irradiance. The simulated spectra are validated by the comp arison with those measured in situ. Principal component analysis is carried out on a large number of reflectance sp ectra, and it is used to develop the retrieval algorithms of chlorophyll and d issolved organic carbon. The results indicated that the retrieval accuracy of ch lorophyll and dissolved organic carbon is 17% and 37.4% respectively. It appea r s possible that this full spectral method can improve ocean color remote sensin g accuracy.关键词：Water color;Remote sensing;Principal component;South China Sea.
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发布时间：2021-06-10 - 摘要：For an ideal multi spectral remote sensor, there is a completely linear relat ionship between the output of the sensor and the incident radiation due to the even in band spectral response; but for an actual sensor, the output of the sen sor not only depends on the incident radiation, but also on the spectral respon se of the sensor, this will result in the nonlinearity between the output of th e sensor and the incident radiation. Correcting the output data of the sensor b y the use of the spectral shapes of the calibration source and the measured objec t will effectively reduce the measuring error due to the nonlinear response of t he sensor. We have adopted the measured spectral response of Ocean Color CCD Imager （OCCI）, and calculated the response of OCCI to blackbodies at different temperatures which have been normalized to have the same in band average spectr al radiance. It can be seen from the calculated results that the spectral shap es have great influence on the output of OCCI. To reduce the measuring error due t o the nonlinear response, the nonlinear correction factor has been computed acco r ding to the spectral shape of the integrating sphere and the on orbit spectral shape for OCCI ocean measurement, which can fit a 12000 K blackbody.关键词：Remote sensor;Spectral response;Correction;Ocean color
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发布时间：2021-06-10 - 摘要：It is a hotspot for applying Visualization in Scientif ic Computing （VISC） to Geographic Information System （GIS）. VISC is an effective and efficient method for promoting the capability of processing and visualizing the spatio temporal geo referenced data. In this paper, firstly, after review ing the current data structure and visualization, we focus on volume graphics an d provide a based voxel spatio temporal multi dimension geo referenced datab ase. Secondly, by studying two dimensional rendering, three dimensional renderin g and animation, we initially explore the method of integrating GIS and VISC. Fi nally, the results of the finished database and some methods of spatio temporal visualization will be regarded as the base of the further application of VISC i n GIS.关键词：GIS;VISC;Structure of multi dimension data;Animatio n
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发布时间：2021-06-10 - 摘要：This paper describes the concept and the important sig nificance of the “Digital Earth”. It is pointed out that the earth observing t echnology is the key issue of the “Digital Earth”. It has been suggested that China should develop the national earth observing system. The system should cons ist of three parts, i.e., information acquisition, information processing and in formation application. The development of earth observation technology, in the f irst priority, have been discussed in the article. The national earth observing system could have a great contribution for the Digital Earth.关键词：National earth observing system;Digital Earth
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发布时间：2021-06-10 - 摘要：The newly proposed concept “Digital Earth” was discussed in the perspective of the strategy of development of geosciences. It is pointed out that “Digital Earth” is a reasonable development of high technology from NII and NSDI, refle cting the needs for sustainable development of economy and society. On the othe rhand, however, as a comprehensive technique goal, the “Digital Earth” is fa cing to some challenging problems, such as the technique security and the mana gement of macro complex systems. By analyzing the national interests of China, it is concluded that to develop a “Chinese Digital Earth” or a “Digital China ” will be beneficial for the sustainable development of agriculture, the prote ction of environment, the mitigation of natural disasters, and the development of economy and technology. It is worth pointing out that to develop a “Chinese Digital Earth” or a “Digital China” is a realistic aim in technology, which results from the recent development of space technology and information technolo gy. In the turn of the centuries, one of the most important aims of Chinese ge osciences is to enhance the quality and promote the application of fundamental r esearches, in which the “Digital Earth” will play an active role. It is empha sized that at present, the most important thing is not to discuss the dogmatic c oncept of the “Digital Earth”, or to put forward the “Digital Earth” into a single research project, but to understand the “Digital Earth” as a long ter m strategy of development and handle this concept as a policy of science and tec hnology to promote the development of geosciences, informatics and the associate d industry.关键词：Digital Earth;Digital China;Strategy of development of sciences
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发布时间：2021-06-10
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