最新刊期
卷 ， 期 3 ， 2007
- 摘要：The spectral characteristics and the interaction between leaf and light were analyzed based on the optical absorption coefficients of foliar biochemical contents,and the method and equation to calculate the radiative-equivalent water thickness（REWT） of leaves were presented based on the reflectance difference between 945nm and 975nm bands.Because of surface direct reflectance and multi-scatter in the leaf,the REWT derived from Beer principle was quite different from the biochemical equivalent water thickness（EWT）.The leaves spectra of different species at different water status were measured by our experiment and Lopex93,and the REWT values at 975nm band were calculated based on the presented method.The relation between leaves’ EWT and REWT was analyzed and tested from our experimental dataset and Lopex93 dataset.The REWT was 3.3 times larger than EWT with a significant correlation coefficient（R2） of 0.80 for our dataset and 0.86 for Lopex93 dataset.The results show that:（1） the REWT can be calculated from the reflectance difference between 945nm and 975nm,and it was reliable and significantly correlated with EWT;（2） the relation between REWT and EWT reflected the leaf internal light transfer,and multi-scatter path-length in near-infrared bands was quite different from leaf thickness.关键词：equivalent water thickness（EWT）;radiative-equivalent water thickness（REWT）;Beer principle;spectral reflectance
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发布时间：2021-06-10 - 摘要：The bidirectional reflective characteristic of objects plays an important role not only in models of remote sensing but also in inversion,consequently,it is the base of quantitative analysis in remote sensing that chooses the appropriate method of acquiring the bidirectional reflective characteristic of ocjects in natural environment.For a long period,BRF（Bidirectional Reflectance Factor） acquired in natural environment is taken as the expression of bidirectional reflective characteristic of objects,but the definition of BRF doesn’t prescribe radiant circumstances explicitly.Actually,BRF acquired in natural environment is related to radiant environment,so it is unsuitable to describe the reflective characteristic of objects with BRF.This viewpoint is testified in this paper by field data,meanwhile,we established the truth that BRDF（Bidirectional Reflectance Distribution Function） has nothing to do with the radiant environment.This paper provides a new method of acquiring BRDF data of objects in natural environment in order to arouse more pondering over the difference between BRDF and BRF.As it is indicated in the result of the experiments,with this method,we can acquire BRDF of objects in natural environment exactly.关键词：Bidirectional Reflection;BRDF;BRF
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发布时间：2021-06-10 - 摘要：Phase Congruency was introduced as a new method to detect features from high-resolution remotely sensed imagery.Three objects i.e.paddy, road,and factory,were selected from the IKONOS Pan imagery of Nanjing.The Phase Congruency feature images were obtained by applying Phase Congruency model to the images with two-octave Log Gabor wavelets filters over 5 scales and 6 orientations.For qualitative comparison,the outputs of the Sobel and Canny detector were also presented.The results show that Phase Congruency response value was invariant in image local illumination and contrast.The other obvious difference was that the Sobel and Canny detector produced responses on each side of linear features,whereas the Phase Congruency produced a response centered on the line.The effects of varying filter orientation or scale and the effect of adding noise in the feature detection between Phase Congruency and Canny method then were compared.It was found that Phase Congruency could obtain more accurate localization because it does not need low-pass filter to restrain noise first.It was also shown that noise had been successfully ignored in the smooth regions of the image,unlike the Canny detector results fluctuated all over the image.With this invariant image feature detector,better image segmentation and object-oriented image recognition are possible.关键词：edge feature;feature detection;Phase Congruency;Log Gabor wavelets;high-resolution remotely sensed imagery
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发布时间：2021-06-10 - 摘要：Topological relations have been recognized to be very useful for spatial query,analysis and reasoning.This paper concentrates on the topological relations between two lines in IR2.The line of thought employed in this study is that the topological relation between two lines can be described by a combination of finite number of basic（or elementary） relations.Based on this idea,a hierarchical approach is proposed for the description and determination of basic relations between two lines,where the topological invariants,including dimension,the number of separates,type of components,and sequence of components in the intersection of two lines,are defined and utilized.Seventeen（17） basic relations are identified and eleven（11） of them form the basis for combinational description of a complex relation,which can be determined by a compound relation model.关键词：topological relations;line object;topological invariant
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发布时间：2021-06-10 - 摘要：Modulation transfer function（MTF） is an essential parameter which characterizes imaging quality of satellite optical camera.We present a review of techniques for modulation transfer function in-flight measurement and emphasize the technique of knife edge according to situation of developing ground sample distance.The important techniques of data fitting and frequence augment are discussed on the bases of mathematics and digital signal processing theory.These techniques are important to improve accuracy of acquired modulation transfer function.关键词：modulation transfer function;in-flight measurement;technique of knife edge
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- 550
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发布时间：2021-06-10 - 摘要：We present a method for detecting shadows and changes of manmade objects based on background model.Original object detection method based on background model assumes that image pixels of nature background can be modeled as a Gaussian distribution,however regions containing man-made objects do not match with this model.So objects can be detected from the nature background.Our tests proved this background model is not applicable to medium scale aerial photos because in that scale man-made objects take up more percentages in the image and cannot be reqarded as a tail in Gaussian distribution.This paper improves the background model,and treats both nature and man-made objects as background,and shadows as detection objects.Using this model,we firstly detect object’s shadows from anomaly of Gaussian distribution and use some filter operators to eliminate those shadows not from man-made objects.Our tests proved that the detection effect of man-made object’s shadows is quite impressive.Then the original images were compensated using the shadow images.After compensating,we got images without shadows.At last change detection was made base on those compensating images.For convenience of the experiment,images were partitioned into several areas of interest（AOI）,and coarse matching of counterpart AOIs of old and new images was made.And then we detected man-made objects’ shadows in AOIs,and those containing man-made objects are remained and those shadows detected will be considered as man-made objects information and be discarded.Then we compensated the AOIs with shadows detection images,and used difference change detection method to compare these AOIs and got the final change detection results.Our tests used aerial images taken at the year 2000 as old images,whose scale is 1∶8000,and aerial images taken at the year 2002 as new images,whose scale is 1∶15000.Experiment results prove our method is effective.关键词：shadow detection;change detection;background model;gaussian distribution
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发布时间：2021-06-10 - 摘要：Urban heat island（UHI） is one of the main factors influencing the weather,climate,and environment over the urban and its surrounding area.In the present study,MODIS land surface temperature retrievals at 1 km resolution produced by the split-window algorithm during the year of 2000—2005 are used to investigate the UHI over Beijing Metropolitan.It was found that the daytime UHI demonstrates distinctive seasonal variation,with the maximum during summer being larger than 10℃ and the minimum during winter being negative,which it is called urban cool island hese.Numerical simulation shows that the urban cool island mainly results from the difference of the surface thermal characteristics between urban and rural area.The seasonal variation of nighttime UHI is much less,being about 5℃ throughout a year.Beijing is surrounded by mountainous area in the west,the north,and the northeast,whose height reach up to 2000m（See Figure 1）.In the east and south of Beijing,the elevation is close to sea level with the complexity of the underlying surface.The different rural baseline not only influences the value of UHI but its seasonal variation.Three typical areas with different land surface types are selected to study the influence on UHI.The results show that the cropland area near Beijing city has uniform vegetation and is suitable to be studied as rural area.The cool island during winter（spring） maybe increase the near surface air stability and aggravate the air pollution over Beijing urban area.关键词：urban heat island;urban cool island;land surface temperature;Thermal inertia;air pollution
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发布时间：2021-06-10 - 摘要：Wildfires release large amount of green house gas,smoke and aerosols which strongly impact on global climate.In China,wildfire in steppe area caused greatly economic loss.Remote sensing is a powerful tool to monitor fire and estimate burn scar area.Based on GEMI（Global Environment Monitoring Index） and spectral characteristics of burn scar in short wave region,a new index GEMI-B（Global Environment Monitoring Index-Burn scar） is proposed to extract burn scar in steppe area.In order to avoid the daily disturbance of cloud,aerosol,sensor zenith and sunglint,new multi-temporal composite methods based on maximal GEMI-B are proposed in the study to composite time series MODIS data.Based on active fire（hotspot） map,an automated extraction procedure has also been developed.A case study is carried out for the wildfire occurred in May,2003 on the border area between China and Mongolia.It is suggested by the results that the GEMI-B index,compositing algorithm and automated extraction method have potential to be applied on burn scar mapping in the semi-arid or arid areas.关键词：burn scar;MODIS;GEMI-B;time series data composite;automated extraction
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发布时间：2021-06-10 - 摘要：Accurate and timely updated-information for plant area of wheat is essential to yield estimation,agricultural management,optimizing the spatial pattern of winter wheat and food security.On account of the mutual restricting problems among the acquisition ability of RS images,spatial resolution and accuracy in the measurement of wheat plant area in large scale,this paper introduced the technology of support vector machine（SVM）,and developed the model of consistency check used in operational measurement and accuracy verification by integrating the multi-temporal full-covered data（MODIS） and medium resolution sample data（TM）.The paper chose the middle part of Henan province in China as a typical experimental region,where winter wheat is the main crop.By pixel accuracy and regional accuracy,the paper analyzed the consistency of measuring results of winter wheat between MODIS and TM with different sample amount.By consistency check between different proportion of TM sample and measuring result,the study draws the conclusions that when the sample proportion reaches 5 percent of whole samples,the pixel accuracy is higher than 82 percent,and the region accuracy is about 90 percent.Moreover,when sample proportion reaches 40 percent,region accuracy in non-sample region stabilizes over 97 percent.The study result shows that the model in the paper can be regarded as the theoretical and experimental groundwork of the operational measurement of wheat plant area by remote sensing.In practical application,if high or moderate resolution image covering 40% of whole investigating region can be obtained,the accuracy can reach the criterion of operational crop area measurement using the method brought forward in this paper.关键词：winter wheat;plant area;TM sample proportion;MODIS;consistency check
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发布时间：2021-06-10 - 摘要：Energy conservation and accurate angular distribution of radiance are the basic requirements for simulation of radiative transfer processes.Current climate model and operational remote sensing technique demands fast and accurate radiative transfer algorithm.To improve the computational efficiency,the scattering phase function is expanded and truncated as the summation of orthogonal polynomials such as Legendre function.Based on mathematical theory,number of polynomials must agree with streams（number of grids in angular integration） to satisfy the integration conservation,inappropriate truncation of scattering phase function results in considerable errors,especially for strong forward scattering media such as cloud particles and dust aerosol in the atmosphere.The truncated scattering phase function of dust or cloud,which fluctuate with scattering angle,results in false fluctuation in angular distribution of radiance,the fluctuation could be removed through taking huge number terms in expansion of scattering phase function,but energy conservation is broken,radiation flux is wrong and the results are unstable.Based on mathematical and radiative transfer theory,the phenomenon of false fluctuation and the stability of radiative transfer algorithm are analyzed,several fast and accurate methods are compared.Finally,two fast and accurate algorithms,satisfying the energy conservation and using less streams,are given,which is of significance in remote sensing,parameterization of radiative forcing in global climate models,energy budget estimation of the earth-atmosphere system,in particular,the effect of clouds and dust events.关键词：radiative transfer;scattering phase function;flux;radiance
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发布时间：2021-06-10 - 摘要：Atmospheric water vapor is highly variable in both space and time,and the accuracy of Interferometric synthetic aperture radar（InSAR） is limited by the effect of the atmosphere,especially the atmospheric water vapor on repeat-pass InSAR measurements.In order to assess the competence of the MODIS（the Moderate-Resolution Imaging Spectroradiometer） near-infrared water vapor retrieval and gound meteorological model estimation for correcting atmospheric effects on InSAR measurements,coincident observations obtained from Global Positioning System（GPS） measurements at five sites in Fangshan Beijng over a month period（April 2004） are used for time series and spatial comparisons.Comparisons of PWV between MODIS and GPS show that their correlation coefficients are high although MODIS appeared to overestimate PWV against GPS;The wet components of tropospheric delay estimated using two empirical models from the ground meteorological data obtained at the GPS sites show low correlation coefficients with the results derived from GPS.关键词：MODIS;GPS;precipitable water vapor（PWV）;InSAR
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发布时间：2021-06-10 - 摘要：This paper takes offshore sandbanks in Jiangsu Province as a typical study area.The reflectance of red and near infrared bands is sensitive to water depth based on the analysis of situ water depth and synchronously measuring water reflectance spectra.The linear correlation between depth and reflectance of Landsat TM1 and TM2 is-0.561 and-0.694 respectively.The water depth derived method based on the multispectral remote sensing transfer model shows that depth has linear relationship with the logarithm form of ratio of radiance（or reflectance） differences between deep water and two bands respectively,which are sensitive to water depth.TM4 and TM3 were found to be sensitive to water depth according to former analysis in this study and depth retrieval model was developed using reflectance of these two bands.The model（R2=0.4793） was tested to have good accuracy for depth less than 15m,whereas the predicted accuracy is unaccepted.The reflectance of TM5 combined with the spectra comparison between seawater and sand bank can be used to find the limit between seawater and other objects,which can be used to extract seawater in TM image.Then,water depth was computed by depth retrieval model in the study area.Fathom lines with 5m intervals can be detected through image managing software.With the development of high spatial,spectral and radiant resolution remote sensing technique,the research on shallow water bathymetry remote sensing method and its application will be under continuing investigation.关键词：remote sensing;water depth;TM;coastal zone;Spectra
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发布时间：2021-06-10 - 摘要：Delay doppler radar altimeter（DDA） is a new radar altimeter,which utilizes aperture synthesize to improve the measurement performance.Compared with conventional radar altimeter,DDA has the resolution along track being increased by 10 times,the transmitted peak power being reduced by 10dB,and the measurement precision of altitude being improved to 2cm.The higher measurement precision,the higher space resolution,and the lower transmitted power make DDA feasible to realize miniaturization.DDA represents a new generation of radar altimeter,and it is suitable to survey ocean,coastal zone,and polar ice.In this paper,the mechanism,the simulation of waveforms,and the precision analysis of DDA are discussed.关键词：Radar altimeter;delay doppler;aperture synthesize
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发布时间：2021-06-10 - 摘要：With the development of the remote sensing technology,many new types of remote sensing sensor are being developed immediately and used for earth observation.Large numbers of earth images,which are very important to research earth,are obtained.As remote sensing satellite data has a tendency to become high temporal,spatial and spectral resolution,its volume is increasing sharply.It is a great problem on how to efficiently restore,manage and search mass of remote sensing satellite data.And satellite data catalogue and archive system,a mass storage and searching web-based system,is just the tool to solve the problem.In order to develop high efficient,high reliable and maintainable archive and catalogue system,the characteristics of satellite data’s metadata are analyzed in the paper firstly,which determine the structure of storage organization.Then some critical technology on developing new type of archive and catalogue system are provided,including mass storage,spatial data storage,the implementation of high reliable system,archive and catalogue database’s optimization.At last,archive and catalogue system’s hardware structure is shown and its main functions are introduced briefly and an example of searching RESOURCESAT-1 satellite data is given.关键词：catalogue and archive system;catalogue and browse;mass storage
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发布时间：2021-06-10 - 摘要：Atmospheric correction is one of the key techniques in ocean color remote sensing.Over case 2 waters near shore,atmospheric correction meets two challenges: the nonzero water-leaving radiances in NIR atmospheric correction bands caused by turbid water;aerosol with strong absorption over nearshore regions.In this paper,based on radiative transfer simulations and neutral network techniques,an atmospheric correction algorithm is established for HY-1A CZI in case 2 waters.Water-leaving reflectance and aerosol optical depths can be retrieved from TOA reflectance of band 1 to 4.The algorithm performance is evaluated using simulated data.Satellite data processing experiment shows that the retrieved result seems reasonable except for very turbid waters.关键词：Atmospheric correction;case 2 waters;neutral network;HY-1A CZI;6S
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发布时间：2021-06-10 - 摘要：Snow/ice,one of the most important earth circles,is very significant to climate research and earth environment study.Snow cover,a basic parameter in snow study,can reflect snow amount most directly.The method of detecting snow cover using satellite data automatically is a very interesting topic for snow study.FY-2C,the third geostationary meteorological satellite launched by China in 2004,has 5 channels in its scanning radiometer,including 3.5—4.0μm,water vapor,visible and split infrared channels,which makes snow detection possible.This paper mainly introduces the principle theory and method of snow detection using FY-2C satellite data.Multi-channel thresholds method is a very common way in snow and cloud detection.However,this method has some randomicity in thresholds choosing properly.To avoid the randomicity caused by multi-channel thresholds method,this paper uses threshold functions to take instead of traditional method for snow detection,which uses altitude,geographical location,season, land cover and so on as the variables.Threshold functions can be established by large amount of sampling to obtain coefficients and their expressions.Compared with NOAA-17 snow detection results derived using interactive method,the precision of FY-2C snow detection using this method can reach up to 85 percents.关键词：FY-2C;snow cover;detection;remote sensing
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发布时间：2021-06-10 - 摘要：The soil salinity is an important problem to agriculture production and ecological environment.The salinity has been a key factor to form a lot medium & low yield croplands and to affect the sustainable agriculture development in Yinchuan Plain（YCP）,Northwest China.In the study,the suitable time for receiving the remote sensing data（TM） is selected.Based on the remote sensing data and the some soil investigation,the soil salinity has been extracted and their classification is made.It is found that the soil salinization degree and the total distribution area of soil salinity are being alleviated remarkably from 1985.With the support of the RS and GIS,the thematic information related to the formation of the medium & low yield croplands such as the types of farmland,soil salinity degree;fertility,crop yield etc.,are extracted and are put into the compound classification.Through this method,the present situation including their classification and distribution of the medium & low yield croplands in the area is determined clearly.Finally,some analyses on the causes of the soil salinity change in YCP are brought forward.
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发布时间：2021-06-10 - 摘要：The main objective of this paper is to introduce the implementation of Perpendicular Drought Index（PDI）,a simple,effective drought monitoring tool,in integrated remote sensing supporting system（IRSSS） for parameter retrieval and drought estimation.The quantitative remote sensing models are changing and various and the remote sensing data formats are complex and diverse.The research group used component oriented programming thoughts to solve these problems,making this system extendable in data source and models.The system could deal with various familiar formats of RS image.According to the COM rule,the IRSSS developed a particular interface in order to guarantee the users add new function module or file I/O driver by themselves.This paper introduces the implementation of PDI using C++ program language.There are four steps designed to complete the task.The general process and purpose of every step is explained and especially the method of finding soil point and memory management are introduced as the key technology.Our research group has implemented the drought-monitoring function based on the basis of the IRSSS system.Furthermore,according to the observation data of Ningxia the research group generated many results of various Drought Indices.The paper also presents the results of evaluated drought situation of Ningxia Huizu Autonomous Region of China that indicates the accordance with regional hydro-environmental data.关键词：soil moisture monitoring;quantitative remote sensing supporting system;drought;PDI
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发布时间：2021-06-10 - 摘要：Exotic species invasion has been one of the most dramatic ecological event in human history that threatens our economy,public health and ecological integrity.Explaining the nature of the species and species-environment relationship and predicting the spatial distribution of the invasive exotic plants is of great importance for invasive exotic plants prevention and early warning efforts.One approach to species-specific predictions involves the use of habitat-suitability or niche-based models whereby environmental conditions suitable for maintenance of populations of a species are identified and mapped onto geographic space.These approaches combine herbarium specimen locations data with a suite of GIS layers（e.g.climatic,topographic and land cover） to create the ecological models of the species’ requirements.Coupled with these models,GIS can project the ecology model onto geographic space and mapping the habitat-suitability maps in native ranges and exotic ranges.This paper proposes an improved logistic regression approach in an information theoretic framework to predict the suitability of ragweed in both native and invaded ranges.Information-theoretic approaches computed and assessed the modeling choice as well as produced a weighed-average model based on the multiple-models rather than using the sole model with the lowest AIC value or the highest Akaike weight.This multiple-model inference is useful to reduce model selection bias.Having obtained the weighted average model,the resulting regression equations were applied to the native samples including the present points and pseudo-absence points to produce the output of the logit value.Because of lack in true absence data,we didn’t transform the logit value back to regular space scaled from 0—1 representing probability of a pixel containing the species but regard the logit value as the degree of the suitability for the species.So we proposed a new approach specifically to compartmentalize the habitat-suitability using logit value thresholds and frequency statistics.At last,we used this habitat-suitability model developed in native ranges to "project" onto the exotic ranges to predict the ragweed’s potential distribution in China.关键词：RS;GIS;invasive exotic species;logistic regression;information theory;frequency statistics
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发布时间：2021-06-10
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