最新刊期
卷 ， 期 2 ， 2003
- 摘要：In this study using PROSPECT Model and in situ optical measurement of corn leaf, mesophyll structure parameter N of different growth phase as calculated. Based on this, given different chlorophyll and water content, corn leaf optical characteristics were modeled. It is found that in the visible region, chlorophyll dominates the optical characteristics, with the increasing of leaf chlorophyll content leaf reflectance and transmittance decrease and accordingly leaf absorptance increases while in the infrared region, water’s effect prevails, with the increasing of water content leaf reflectance and transmittance decrease and accordingly leaf absorptance increases. At the same time, given fixed chlorophyll and water content, leaf optical characteristics varying with different mesophyll structure were simulated. It is found that with the increasing of N , leaf reflectance increases and reaches an asymptote while leaf transmittance decreases and reaches an asymptote also.关键词：single leaf;optical characteristics;simulation
- 164
- |
- 397
- |
- 9
发布时间：2021-06-10 - 摘要：Aided by raster-based Geographical Information System （GIS） function, one method for terrain based landslide risk assessment for Lantau Island of Hong Kong was given in the paper. In this method, slope, aspect, vegetation covered, geology, elevation and distance to drainage line were considered as landslide related elements, and each element as given different weight in landslide risk assessment matrix. In raster based landslide risk assessment methodology, the grid size （pixel） selection for dataset concerned is a key task and must be solved. To find the most appropriate grid size for each elements, 5m, 10m, 20m, 40m and 80m five kinds of grid size were tested in this study. Following the state that landslide risk assessment result is the key to evaluate the appropriate grid size, landslide risk assessment parameters characteristic, risk assessment results were analyzed and compared thoroughly, 20m grid size was found the appropriate grid size for the pilot area according to most features described in the paper such as area frequency for each kind of grid size, landslide frequency under each grid size, area frequency for each class landslide susceptibility under different grid size. Generally, the appropriate grid size selection for certain cases are connected to area of pilot region, user requirement, gromorphology and topography characteristics of pilot region, and other case sensitive elements. Based on the results obtained in the pilot area, one experimental formula was given for grid size selection of landslide risk assessment.关键词：appropriate grid size;landslide risk assessment;raster GIS;Lantau Island Hong Kong
- 235
- |
- 1528
- |
- 47
发布时间：2021-06-10 - 摘要：The multi-scale representation model of complex landform based on two-dimensional wavelet transformation is proposed in this paper. The new idea and principle of this model can completely get rid of intersection of different contours which commonly occurred in almost all models used before. Thus, it could be said that by theory and method the model can preserve the veins of landform, maintain the coordinate relations among the contour lines, besides, it has adaptive property. The experiments on that model give the following conclusions:① The landform characteristics such as the peaks, saddle points, valley lines, intersections of valleys, ridge lines of mountains can be preserved very well, so the structure and roughness of the global landform will be retained.② The relative positions of the contour lines are maintained precisely, so the shape of the landform such as the outines of mountains, the directions of ridges and valleys are retained quite well.③ The rates of changes of the amount of information, the simplification of the contour lines, the extent of landform generalization for different levels of decomposition or reconstruction are consistent and stable,besides,they coincide with the visual feeling and standard of the ordinary people.④ The Lipschitz index, which is related to the roughness of the landform, is used to calculate the threshold value in the model, thus the threshold which control the amount of information being retained is directly linked with the complexity of the landform and could be adjusted adaptively.⑤ Because of the flexibility of the threshold value and the stability of the method, the multi-scale representation based on that two dimensional wavelet model is suitable for more kinds of landforms.关键词：complex landform;multi-scale representation;Wavelet analysis;Lipschitz index
- 137
- |
- 233
- |
- 4
发布时间：2021-06-10 - 摘要：A new adaptive approach combined with Media filter and gradient-based adaptive filter is presented for removing the noise in the interferogram. Filtering phase noise in an interferogram is an important aspect in INSAR data processing. But any improper altering of the wrapped phase may influence the quality of derived DEM because the interferometric phase contains the topographic information. Therefore one of the difficulties in phase noise filtering is how to remove the noise and preserve the sharp sawtooth profile of the fringe effectively. The interferometric phase image behaves with the fringe in the form of modulus 2π wrapped phase. Filtering directly in interferogram may smooth the sharp edge of the sawtooth in the fringe and damage the unwrapped phase contribution. Some investigators have shown that the processing should not be conducted directly in the phase image, but in the complex plane. With the filtering presented in this paper is done in the complex plane before the phase image is formed by means of the arc tangent operator, i.e. in the real and imaginary component of the interferogram respectively.The gradient-based filtering is an iterative algorithm. In the iteration, the moving window average with adaptive weight is conducted. The weight is varied with the gradient contribution of phase image. The less of the weight is corresponding to the larger gradient value so that the boundary of the fringe is not blurred. Additionally, the moving window is small to avoid the average of the phase values belonging to the different sides of the boundary. But the algorithm is not effective for the spike-like noise because it may also arose the great gradient and be treated as the boundary. To suppress the spike-like noise, the small window Media filtering is applied before the gradient-based average.Compared with existing approach for phase noise filtering, the presented approach does not need complex procedure for the parameter estimation and are easy to be implemented. The effectiveness is verified with the interferogram generated from SIR-C/X-SAR repeat-pass INSAR data.关键词：SAR;INSAR;filtering;adaptive algorithm;speckle
- 140
- |
- 680
- |
- 21
发布时间：2021-06-10 - 摘要：SAR image usually becomes very difficult when precise orbit data of SAR platform is not available. A SAR rectification method based on image simulation is proposed in this paper. The simulated SAR image is generated by means of Digital Elevation Model （DEM） and the known orbit data, then image matching is performed between the simulated and the real SAR image to identify some pairs of corresponding points. The position differences of these corresponding points are caused by the imprecision of the orbit data, and can be used to correct the rectification residuals. In this paper, the common SAR image simulation algorithms are introduced briefly, and then the algorithm used to match real to the simulated image is presented, as well as the SAR rectification method based on simulated image. At last, an experiment on the proposed rectification method is made, in which a RADATSAR SGF image is rectified precisely by means of simulated SAR image. Moreover, except the image matching stage, all the procedures of this rectification can be done automatically, which is significant to the large-volume SAR image processing.关键词：synthetic aperture radar;geometric rectification;image simulation;image matching
- 210
- |
- 734
- |
- 12
发布时间：2021-06-10 - 摘要：SAR （Synthetic Aperture Radar） images have been widely applied because of the development of SAR remote sensing techniques. The theories and techniques of SAR image rectification have been paid attention to in the application field of RS （Remote Sensing） and GIS （Geographic Information System）. It was noticed that why there are different mathematical models in describing the relationship between SAR image points and their corresponding ground points, and which one is better.Based on a long time study on SAR image application, this paper recapitulated three mathematical models—F. Leberl Model, Konecny Model and Polynomial Model, which were ever used for the SAR image processing in the world. The characteristics of the three models were analyzed and tested in the experiments of rectification with the image information acquired by China-made SAR system and America-made GEM system. After the experimental results were compared, it comes to some conclusions:1.The simplest model—Polynomial Model adapts to the rectification with the SAR images of flat terrain regions under the condition of enough control points distributed averagely, in which the amount of calculation is the least and the accuracy of rectification is acceptable.2.The accuracy of rectification acquired by Leberl Model is better than the one acquired by Konceny Model—the simulation of traditional form.3.Leberl Model is more adaptive and simpler than Konceny Model.4.Leberl Model was recommended for real-time monitoring and assessing natural disaster
- 189
- |
- 537
- |
- 10
发布时间：2021-06-10 - 摘要：In this paper, a kind of SAR image segmentation method based on the criterion of likelihood difference function is proposed. At first, based on the distribution property of SAR image, we get the following conclusions by simulation: After merging of two regions with same distribution, the difference of likelihood is approximately independent of the regional size and regional mean value, and only depends on the look number. On the basis of this conclusion, we simplify the likelihood difference function, and the analytic form of the probability distribution function is obtained. Giving the false alarm probability, we can calculate the threshold which indicates whether the adjacent regions can be merged. Then we construct merging cost according to the likelihood difference function and region shape constrains, and make regions to be merged with order. When there are no regions which can be merged, the final segmentation result is achieved.关键词：SAR;likelihood difference;false alarm probability;segmentation
- 167
- |
- 307
- |
- 5
发布时间：2021-06-10 - 摘要：The Advanced Very High Resolution Radiometer （AVHRR）on board the TIROS-N/NOAA series of operational meteorological satellites has both visible and thermal infrared channels,which enable sea surface temperatures （SSTs） and other parameters related to water quality to be derived. An artificial neural network （ANN） method for detecting red tides with AVHRR imagery has been developed in this paper. The detection of red tides is based on the fact that 1) the seawater has higher concentration of phytoplankton pigments when red tides occur and 2) the occurrence of red tides in associated with sea surface temperature. The ANN method uses reflectivity in AVHRR visible channels and SSTs derived from AVHRR thermal infrared channels as inputs with five nodes in a single hidden layer to model the nonlinear transfer function between red tides and AVHRR data. The ANN method has been trained and tested using in situ and airborne measurements. The ANN method has been applied to detect red tide events occurred in the Bohai Sea of China in 1999.The results have illustrated good performance of the ANN method with a detection accuracy of 78.5%.关键词：red tide;Artificial neural Network;BP model;NOAA AVHRR
- 238
- |
- 564
- |
- 9
发布时间：2021-06-10 - 摘要：As the composition of China-Germany cooperation project“Land use and Sustainable Development （SILUP）”,Jiangning county of Nanjing,in the South of China,was selected as a test area. The SPOT-2 and SPOT-4 remotely sensed images were used for deriving such thematic information as landuse,water bodies,roads and settlements and their thematic mapping. In this paper,some comprehensive methods and techniques of extracting the information from SPOT data were described,specially a improved method of land use/land cover classification by using SPOT images and ancillary data. In the land use/land cover classification,the feature sets containing the SPOT original band,and a digital elevation model were tested using MLC clustering. Incorporation of slop data generated from DEM was found to be able to improve the classification accuracy of land use. Further land cover discrimination was improved when using fusion images of PAN and XI. The study also put forward techniques of screen display editing to get the thematic maps. Some thematic maps were generated and their accuracy was assessed and discussed. The results showed that much good thematic information can be derived from SPOT images by using the methods and techniques introduced in this paper,and some extracted information can be used for drawing thematic maps in a scale of 1∶50000.
- 147
- |
- 841
- |
- 13
发布时间：2021-06-10 - 摘要：Based on fractal geometry method and land use graphics database, this paper describes an algorithm for fractal dimension of land use types. The algorithm is a fractal dimension expression about area and perimeter. And this algorithm is applied to analyze the change feature of land use types. The experimental results indicate that fractal dimension （ D ） values vary from 1 to 2 and the certain land use types is associated with the fractal dimension D . The D of land use types reflects the degree of complexity, stability and change tendency of land use change. When the value of D is 1.5, namely D is critical value; the change mode of land use types is Brown random movement. The more the value of D is closer to the critical value, the more the stability of land use type is worse, and the complexity of land use type is higher; verse vice. Moreover, the D change or certain land use type reflects the change tendency of this type in different time periods. When the D of certain land use type increases, its area also increases; verse vice, its area decreases. The experiment has been done and supports this conclusion.关键词：Fractal;land use types;fractal dimension
- 197
- |
- 548
- |
- 27
发布时间：2021-06-10 - 摘要：Thermal remote sensing oil-gas exploration is based on the theory on hydrocarbon micro-seepage over oil-gas field. Hydrocarbon moves upward along cracks and fractures in the form of micro-hydrocarbon from oil-gas field and interacts with surrounding material, resulting in round-like hydrocarbon alteration area and a series of indicators on surface and subsurface concerned. Remote sensing data in the range of infra-red band （8—14μm） can be used to attract the information of thermal anomaly because hydrocarbon that reaches the surface and subsurface causes changes of physical and chemical properties of surface material, such as reduction of thermal conductivity and increase of thermal capacity, or production of oxidant heat. The thermal anomaly over oil-gas field caused by hydrocartbon micro-seepage is the most direct and significant criteria for oil-gas remote sensing exploration. It is of great practical and economic significances to identify these criteria and study their temporal effectiveness.It has been revealed by the authors in the former research that Oil-gas Thermal Infra-red Remote Sensing Exploration is more effective in a new site for oil-gas-exploration, where the surface condition of hydrocarbon alteration area is well reserved, than the explored oil-gas field where the surface condition of hydrocarbon alteration area was seriously destroyed.In order to compare the effectiveness of remote sensing data acquired before or at the beginning of and after oil-gas exploration, two sample areas has been chosen over the known oil fields in Erlian Basin of Inner-Mongolia and a set of NOAA data of two dates and of one date, which represent the data respectively taken at the beginning of oil-gas exploration and at the end of the exploration. An integrated analysis has been carried out by overlaying remote sensing data in the studied areas with data of geo-chemical exploration. It was shown that the use of remote sensing data taken before or at the beginning of oil-gas exploration, integrated with other information sources, could receive best economic benefit when thermal infra-red remote sensing is used for oil-gas exploration. This is applicable for not only a new exploration site but also a continuing exploration of the old oil-gas field.关键词：thermal infra-red remote sensing;oil-gas exploration;temporal effectiveness
- 114
- |
- 331
- |
- 3
发布时间：2021-06-10 - 摘要：The entironment problem of Talimu Basin have been regarded highly. Many experts and scholars had investigated and researched the Talimu Basin. In the basin, there are 5 reservoirs. They intercepted large number of supplied waterhead. In this background, we began this research. This article introduces a kind of method. This method is to syntheticallly use RS,GIS and GPS（3S）technology and retrieve remote sensing information according to time sequence about land use/cover, Ⅵ（vegetation index）, and population economy etc. in the middle and lower reaches of Talimu River. In this article, the data were analyzed by using GIS technology and the field sizes were investigated by using GPS instrument. A conclusion was concluded that in the past 11 years from 1990 to 2000,in the region of the middle and lower reaches of Talimu river, the area of farmland had been increased 505.433km 2,the area of nature/planted vegetation had been reduced 943.089km 2,and the area of water body had been increased 80.477km 2. The area of desert of the middle and lower reaches of Talimu river is increasing continually. The main reason is the large number of nature vegetation was died, especially the area of the Huyang trees was declined. Finally, some suggestions were make to recover and father fragile ecosystem.关键词：3S technology;ecosystem factors;remote sensing temporal information
- 205
- |
- 574
- |
- 10
发布时间：2021-06-10 - 摘要：Distributed GIS is a complicated software system. Applying Agent technology into distributed GIS will provide a new concept and method to construct distributed GIS system and applications. In this paper, modeling distributed GIS, searching and retrieving spatial information on Internet, constructing service framework for WebGIS, building spatial decision-support system and interoperating in GIS are introduced.Firstly, an agent-based distributed GIS model named as Geo-Agents is studied, which consists of four types of GIS agent: Facilitator, general agent, GIS functional agent and GUServer. All of these agents cooperate to complete GIS tasks.Combining agent technology and spatial metadata to locate and retrieve spatial information is an effective method to process distributed spatial information. A hierarchical spatial metadata database framework is designed to manage spatial databases, layers and maps on network. With the help of spatial metadata, five agents are constructed to distribute on network, search, locate, retrieve and filter distributed spatial information initiatively and cooperatively.Then, an agent-based common WebGIS service framework is introduced, which is divided into three layers: user layer, application layer and service layer. It can provide GIS services for different applications and different groups of users at the same time.Also, an agent-based intelligent spatial decision-supporting system is presented, which is a federal system consisting of many agents. All of these agents cooperate to complete spatial decision-supporting tasks.Finally, an agent-oriented GIS interoperating specification is explored, which has common spatial data interface, common GIS agent descriptive specification and common agent communication mode.关键词：distributed GIS;distributed computing technology;agent technology
- 161
- |
- 409
- |
- 4
发布时间：2021-06-10
- Postal code：100190
- Tel：010-58887052 Email：nrsb@aircas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备20021838号-9
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0