最新刊期
卷 ， 期 1 ， 2003
- 摘要：For a remote sensing pixel with 3D surface, the directionality of thermal emission depends on the component parameters of the pixel, such as component temperatures, component emissivities and structural parameters. The contribution of the multiple scattering between components to the directional thermal emission is mainly affected by the 3D structure of pixel. In this paper, we present an analytical model to describe the multiple scattering between components and its contribution to the pixel’s emission. The modeling work is based on the conceptual geometric-optical thermal emission model. For the non-isothermal pixel with random distributed components, at the pixel’s scale, the openness coefficient and viewing factor is defined, the effect of multiple scattering between components is modeled with the principle of multiple bouncing. Then the directional thermal emission of pixel is derived based on the areal weighted emission of components by taking the ambient radiation into account. The model is validated using measurement data indoor. The two experimental data sets are on different observing object （samples of pingpong spheres and simulated trees made of cotton）. Each set of measurement data includes directional thermal emission of pixel, the emission of components, the ambient thermal radiance, and the structural parameters of the pixel. These measured data of components are as input of the model, the brightness temperature of the pixel is calculated. The model predicted brightness temperatures and their comparison with the measured brightness temperature in pixel scale are presented in the paper. The directionality of the effect of multiple scattering is also discussed. The result demonstrates that in pixel scale the analytical model prediction fits the measurement well. Note that in the multiple scattering effect model, when the samples on the background are very close to each other and the viewing facrot VF 2-2can not be ignored, our modeling methodology can still apply. But the results formula will then be very complicated. In such case, a two layer multiple bouncing model would be more appropriate.关键词：non-isothermal pixel;directional thermal emission;geometric-optics model;multiple scattering
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发布时间：2021-06-10 - 摘要：It is an important field to estimate stand average height using remote sensing technology. SAR interferometry （InSAR） technology uses the phase information of single look complex SAR data to get three-dimensional information of the earth surface. In recent years, this technology has been used widely. Having considered the advantages of InSAR and the characteristics of woodland, this paper focus mainly on using SAR interferometry technology to estimate average height of stand with SIR-C/X-SAR L-band and C-band data. In this paper, after a brief review of InSAR technology and its major application fields, the principles of SAR interferometry are introduced. Then the methods of estimating stand height are given. At last, SIR-C/X-SAR C-band and L-band SLC data of Daxing′anling are processed and the estimated stand height is calculated and analyzed with the field measurements. The result shows that it is potential for InSAR technology to estimate effective stand height. Several conclusions are drawn as follows: （i） It is potential for InSAR technology to estimate effective stand height. Stand height information can be acquired from the digital surface model （DSM） gained from complex SAR data. If the appearance of forests is very regular, the short wavelength SAR data can get better result. But if the appearance of forests is irregular, the more steady result can be obtained using long wavelength SAR data. （ii） Only the method of "differential height between stand and nearby" is useful now. Other methods, which require accurate GCPs during InSAR processing, were not useful in this study. （iii） Different wave band should be selected if the appearance of forests were different obviously. If the appearance of forests were better, the short wave such as X or C band should be selected. Otherwise, the long band such as P or L band should be selected. （iv） SAR interferometry technology can be used to monitor stand height increment. Because the effective tree height can be estimated, we can use InSAR data of multi-year interval to monitor tree height increment during this interval.关键词：InSAR;DEM;DSM;effective tree heigth
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发布时间：2021-06-10 - 摘要：VCIcomputed from NDVIis a recommendatory index usually used in drought monitoring by remote sensing, but it could be different criterion on scaling the drought severity in different region. It is more important to get an objective scaling method forVCIthanVCIitself. By analyzing the historic data （1981-1994） of NOAA AVHRR NDVI（resolution of 8 km） and soil humidity （-20cm） observed by 102 permanent agro-meteorological stations in the whole China, the statistical models have been made out between the vegetation condition index （VCI） and the soil moisture index （SHI）. The scales of VCIin determining the drought severity can easily form the ones of SHIin describing the drought through the models, so drought monitoring in every ten days is practical. Based on that, the operational system of drought monitoring by remote sensing in China has been developed , which can be used to monitor the occurrence of the drought in China for every ten days from March to September. It would be beneficial to policy-maker for disaster reduction.关键词：drought;remote sensing monitoring;NDVI;VCI
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发布时间：2021-06-10 - 摘要：With the development of the technology of remote sensing, the demand the high data rate has been steadily growing. It is very important to design,develop and test a stable, high-speed, great-capacity and real-time recorder,because it is a necessary device in remote sensing for the raw data recording and the system testing. This paper introduces a high-speed, great-capacity and real-time recorder which is based on a personal computer the detail of design, the configuration, the development, the testing, and the verification of the Digital Recorder are presented in this paper. It basically consists of one data-acquiring card and several SCSI-adapter cards, which are added in the PCI bus of a personal computer. The data-acquiring card is a data input device. There is a SCSI hard disk on each SCSI adapter. All the SCSI adapters and disks compose a disk array as the storage device of the recorder. It can reduce the disk transfer delay by increasing the amount of SCSI disks, and improve the efficiency of disk array by balancing the load of disks, and extend the SCSI bus transfer speed by increasing the amount of SCSI adapters. The recorded data from the acquiring card is transferred to the computer memory, and then to the SCSI-adapter cards by DMA mode. The SCSI-adapters will write all the data blacks to SCSI disks. There are many buffer cells with a same size in memory to smooth the inadaptability between input data rate and storing data rate. And the buffer cells are dlvided into two parts, conventional memory buffers and extended memory buffers, since the extended memory can’t be accessed directly under DOS system. Because of accessing conventional memory may have more efficiency than the extended one, the extended memory will not be used unless the conventional memory has been exhausted. Because of the especial access rules to disks and buffer cells, the position of a data blocks in the disk array may be uncertain. An index to all input data blocks enable the data blocks to be written to any disk randomly,but the data can still be restored in original order according to the indexes of each data block. Data acquiring and disk writing is driven by interrupt, which is the protection of real time. Rational layout of the data acquiring and writing disk enhances the performance. Because of the flexible structure, it has good practicability, and is easy to be developed economically.关键词：PCI bus;SCSI bus;disk array;high speed;real time.
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发布时间：2021-06-10 - 摘要：The development of high-resolution sensors provided more methods for remote sensing mapping. High-resolution satellite imagery refers to those images of which spatial resolution is less than 10m. Information of linear features of landscape in high-resolution satellite images is very prolific. However, every part of a whole scene has different characters in spectrum space or gray space, because of immoderate specializations and influence of noise disturbances. This made it difficult to detect and recognize the linear features of landscape objects. The traditional single filtering method used to extract linear features of objects was confronted with some problems such as feature specializations. BRDF influences, geo-procedure scaling dependence etc. Method about extraction of structure information from high-resolution imagery is a key for application of this imagery. In this paper, we discussed a method based on image texture characters through designing filter cluster for the automatic detection and recognition. The filter cluster includes two filters, one is the high pass filter through which the borderline characteristics of the object in imagery can be detected, another is the statistical filter through which some noise made by high pass filter can be abated. In process of high pass filtering, how to select the size of filtering window is very important to precision. We had designed a proportion factor η to depict processing result. The test result indicated that the 7×7 filter window was the most appropriate in this research. After being transacted by the filter cluster, through selection of threshold on the test image which could control dividing pixels of background and objects, a vector layer that describing the linear features of object in landscape could be acquired through linear detection and tracking. A comparison of differences was finished between the results by traditional single filter and by multi-filter. The vector layer gained through multi-filtering has fewer noises than those only through single filtering. The result of test indicated that multi-filtering method could improve the precision of analysis, illustrate the possiblity of extracting automa- tically the vector information layers from high resolution satellite imagery, and provided technology basis for application of high-resolution satellite imagery.关键词：multi-filtering;linear feature;hihg-resolution satellite imagery
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发布时间：2021-06-10 - 摘要：The relationship between attenuation coefficient, k, and radar reflectivity factor, Z, as well as that between k, Zand rainfall rate, I, is influenced by the shape of precipitating raindrops and the orientation of their rotatory axes respect to the polarization direction of the incident radar wave. Provided that the orientation of rotatory axes of poly-disperse small spheroid particles is known, correctable thickness of radar echo for attenuation depends mainly on rainrate. The heavier the rainfall rate, the thinner the correctable thickness. For an 80mm/hour precipitation uniformly distributed along a radial direction, correctable thickness of radar echo is more than 120km for 5.6cm wavelength and about 50km for 3.2cm if correction algorithm R2or R3is used. Orientation information is critically important during attenuation correction. Right k-Zrelationship must be coupled with right orientation status.
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发布时间：2021-06-10 - 摘要：Land covers in urban areas tend to change drastically over a short period of time due to rapid urbanization. Especially, land covers in China are changing more frequently, which have been occurred in urban and peri-urban areas where accompanied rapid economic development. Remote sensing images are ideally used to monitor current land cover changes thanks to their rapid up-date capability. There are two conventional methods in producing land covers from either aerial photographs or satellite images: manual interpretation and computer classification. The conventional methods of converting images into urban land covers have a number of limitations. The first method is tedious and highly subject to the interpretation of the image analyst, and fails to take advantage of all spectral information contained in multi-spectral remote sensing images because only limited number of spectral bands can be used to generate the false color composite. The second method, even though requires much less human intervention, is still subject to many limitations. It is difficult task to achieve a high accuracy level, and the conventional supervised classification method requires the selection of a number of training samples for all those covers whose representativeness directly affects the classification accuracy. In this study we present a new method based on Normalized Difference Built-up Index（NDBI）: NDBI=（TM5-TM4）/（TM5+TM4） This method has been successfully applied to automatically extract the urban land in Wuxi City, Eastern China by manipulating the spectral bands of TM imagery. The results indicate that it can serve as a worthwhile alternative for quickly extracting urban land. This proposed new method has a number of advantages over the conventional supervised classification method. It is very objective because it requires minimun interference from the image analyst, much faster and may acquire a high accuracy. However, the universality of this proposed method needs to be tested further in other geographic areas as the spectral response of the various land covers may vary spatially.关键词：urban land-use;remote sensing;NDBI
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发布时间：2021-06-10 - 摘要：Speckle is an important characteristic of SAR image that obstructs the efficient interpretation and thus its applications. So,the image filtering is indispensable in the SAR related applications.In the SAR filtering,there is a persistent contradiction:constraining noises VS.keeping image details.In other words,the optimal goal of image filtering is to constrain the noises while keeping the image details at the same time. The traditional filters are mostly those in the space domains.Though developments of filters in space domain have gradually shortened the span of the two sides,there still are some difficulties in overcoming such contradiction.So,the filters in frequency domain have attracted more and more attention. In wavelet frequency domain,the image frequency can be efficiently decomposed and then the noise can be restricted.In the paper,the de-noise filters in frequency are analyzed and compared.Then based on the concepts of threshold-optimizing and edge-detecting in wavelet frequency domain,an new wavelet de-noise method is presented.The experiment shows that the new filter is efficient at both noise constraining and image detail keeping.关键词：SAR image;speckle;Filter;wavelet transform
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发布时间：2021-06-10 - 摘要：In the last three decades,sustainable development（SD）has been proposed and developed as a new development model.In China,SD has been confirmed as one of the two basic strategies（the other one is"Developing through science & education"）for national development.We define regional sustainability development as the continuous support of human quality of life within a region’s ecological carrying capacity.To achieve regional sustainability development,one must first assess the current situation.Until now,studies on SD have been mainly focused on two domain,one is the concepts and theory of SD and the other is the effectively realizing processes of SD,while few studies were carried out on evaluation methods of SD.Recently the application of Geo-spatial information technology in SD assessment,has gained great attention,mainly because the conventional statistic methods cannot satisfy the requirements of SD assessments. A concept-ual model of regional SD assessment,using high spatiod-temporal resolution remote sensing satellites as an important data sources,was built based on some essential achievements such as Human Development Index（HDI）and ecological footprint.In the conceptual model,’development’and ’sustainability’ were used as two primary criteria to evaluate the regional SD situation. Evaluation Information System for Regional Sustainable Development （EIS/RSD） was developed based on the above-mentioned conceptual model. The system has a number of application models,which can be used for further analysis of original data. The analysis result can be displayed using map and chart. This paper presents the aim,developing scheme,conceptual model,function and assessment method of evaluation information system for regional sustainable development.关键词：sustainable development;assessment method;conceptual model;system function
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发布时间：2021-06-10 - 摘要：Backscattering in coastal waters is stronger than that in open sea because of high suspended sediment, and its information is reflected well in remote sensing images. The key to estimate suspended sediment concentration （SSC）from remote sensing images is to establish the relationship between SSC and water reflectance R.Many theoretic or empirical models have been developed for calculating SSC. But most of them need real-time survey data of SSC, which limit the use of these models. In this paper, spectral mixing analysis method, which needs little real-time data, was introduced in detail. The pixels with minimun and maximal SSC were used as endmembers, and other pixels were regarded as the mixtures of the two endmembers. A linear spectral mixing analysis model was as followed:R b=（1-f high）R Lb+f highR Hb+E b b=1,2,...,Bwhere R bwas the bth reflectance, R Lband R Hbwere the bth reflectance for minimum or maximal SSC, f high was the fraction of maximal SSC, E bwas residual error and Bwas the number of bands. In order to get the minimum sum of E b（b=1,2,...,B）,the following model has been developed:f high=∑Bb=1（R b-R Lb）（R Hb-R Lb）∑Bb=1（R Hb-R Lb）2 Based on TM remote sensing images, the quantitative relationship between SSC and spectral reflectance was studied. The distribution of SSCs in coastal waters of Minjiang River was calculated by using spectral mixing analysis and empirical formula respectively. The results showed that:（1） the high SSC regions lay in the mouth of Minjiang River, and the further from the coastal, the lower was the SSC; （2） the distribution of SSC can be estimated quickly and objectly from remote sensing images; （3） spectral mixing analysis is a good method, especially in areas lack of much measured data, for it can make full use of multi-band of images and needs less samples.关键词：suspended sediment concentration;spectral mixing analysis;empirical model;coastal water
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发布时间：2021-06-10 - 摘要：The paper builds the multi-subject spatial database and the numerical analytical method because regional difference of Chinese ecological environment background is prominent. The ecological environment background condition is synthetically appraised and the index is used to reflect the general characteristics and the regional difference by the 9 kinds of spatial raster database i.e.precipitation, accumulative temperature, temperature, slope,aspect,elevation, NDVI,the building of the national appraisal index system of ecological environment background and the combined function of the GIS. The ecological environment index in divided into 10 grades. The higher the grade, the better the ecological environment is. The results will be beneficial to compare the regional difference of the ecological environment and to study the dynamic change in time series since it reflects objectively the natural characteristics and regional difference of China. The average index of Chinese ecological environment is 5 726. The ecological environment index increases and represents the better condition from Northwest to Southeast. Using the index, the numerical method is built to reflect the ecological environment background and to compare the regional ecological environment background that builds the foundation for future dynamic monitoring. The feature value of the subject index of every cell by the GRID module of ARC/INFO can be calculated to analyze the regional law and dynamic change and to study the main factors that have the effect on the background. The ancillary information can be supplied to help make decision on the resource exploitation and environmental protection pertinently and simultaneously by overlaying the data with the especially spatial data such as land use data.关键词：Spatial data;China;ecological environment;integrated assessment
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发布时间：2021-06-10 - 摘要：Metadata of geospatial data is the description of geospatial related data sets and information resource. With Geospatial metadata, geospatial data users can quickly learn about the name, quality, scale, data structure and so on. In particalar geospatial metadata has been extended from a method of data describing and indexing to one of the essential tools which has been involved into the whole internet information procedure, including data finding, converting, managing and using. Geospatial metadata is one part of the core contents of digital earth and geographic information infrastructure. Nowadays, because of the important role bring played by geospatial metadata, it has become a new research topic in geographic information system field. However, the most researches on geospatial metadata is on its standard establishment, management and application. In fact, how to express geospatial metadata is the base of its standard and management. The authors analyze the current situation and the obstruction faced with on metadata research procedure, and point out the limitation existed on how to express geospatial metadata structure and syntax. This paper has made a study on how to express geospatial metadata and its standardization. The authors present a new metadata expression idea based on resource description framework （RDF）, a kind of application language of extensible mark up language （XML）. This paper also give an example based on FGDC metadata standard, at the same time, get a new method of geospatial metadata expression based on XML/RDF. The new expression method with XML can realize the integration of metadata, and while expressing geospatial metadata with RDF resolve the syntax problem of metadata expression. At the end, the paper shows the vital functions and the managing methods of geospatial metadata expression based on RDF.关键词：geospatial metadata;Web GIS;XML;RDF
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发布时间：2021-06-10 - 摘要：Water and nutrient are the main limitation factors for crop production. On-site and precise detection of crop water and nutrient content is necessary for improving crop water and nutrient management, and the use efficiency of water and nutrients;reducing environmental pollution caused by over fertilization; and promoting water-saving agriculture production. In this paper, firstly, a brief introduction to the eco-physiological basis of plant spectral characters and the principles of spectra detection of plant water and nitrogen content were presented. An overview was then given on the developments of the detection of crop water and nitrogen status by remote sensing. Finally, the current research highlight, the existing difficulties, and the future development trends and the prospect of remote sensing of crop water and nitrogen status were discussed.关键词：water;nitrogen;ground remote sensing;spectra detection
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