最新刊期
卷 16 ， 期 1 ， 2012
- 摘要：Soil dielectric constant is basic for soil water content and soil froze-thaw status monitoring by microwave remote sensing,and also provides underlying boundary condition for plant and snow.However,present research on soil dielectric constant is lack of systematically measurement on high organic matter soils.This research classified soil natural organic matter substance into two types:humus and plant residue.With rigorous controlled-condition experiment,five black soils in the Northeast China with varied organic matter content and the meadow soil in Biandukou mixed with different content of poplar sawdust were measured to study the dielectric effect of humus and plant residue respectively.Results show that humus can decrease the bulk density of dry soil and decrease soil dielectric constant acting as an indirect mechanism.For wet soil under the same bulk density,the dielectric constant of soil with higher humus content is inclined to be larger.Comparison with Dobson model simulation shows that the impact of humus is around ±2 for real part and can reach 1 for imaginary part for wet soil with 25% gravimetric water content under a room temperature of 29℃.Compared with humus,plant residue influences both dry soil and wet soil significantly.Plant residue can effectively loose soil structure and bring in the dielectric property of a plant component.With gravimetric water content of 30%,the dielectric constant of Biandukou soil mixed with 20% poplar content is 4—7 lower for real part and 1—3 lower for imaginary part than pure Biandukou soil in average.Therefore,the natural organic substance in soil can change soil dielectric constant,and show its impact on microwave remote sensing.关键词：soil dielectric constant;organic matter;humus;microwave remote sensing
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发布时间：2021-06-10 - 摘要：This study estimates photosynthetic active radiation（PAR） based on a simplification of the general radiative transfer equations and Moderate Resolution Imaging Spectroradiometer（MODIS） atmosphere products（aerosol,cloud,ozone and water vapor product）.Comparing estimated PAR with field measurements in Tibetan Plateau in 2005,significant linear correlation in order 0.8—0.9 is obtained and relative error is less than 13%.Remaining other condition constant in sensitive analysis,cloud thickness,depth of aerosol and pressure show more important impacts on PAR estimation than water vapor and ozone.Cloud thickness,angstrom turbidity coefficient,atmospheric pressure changes by 30%,25% and 15% will lead to respective changes in PAR of 20%,5% and 5%.关键词：photosynthetic active radiation（PAR）;MODIS atmosphere products;Qinghai-Tibet Plateau;estimated radiation
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发布时间：2021-06-10 - 摘要：Geometric imaging equation is the most fundamental and important formula for photogrammetry,and rigorousness and conciseness are main factors constrain its applicability.In this paper,following the analyzing of attitude influence on sidelooking radar imaging,a rigorous and concise geometric imaging equation based on Range-Coplanarity（R-Cp） condition is proposed using positions and attitudes（e.g.,exterior orientation elements） of the radar sensor as orientation parameters.The equation considers the effect of attitude angles on radar image positioning,reflects the imaging geometric principle of radar images in both distance and azimuth directions,removes the complicated imaging parameters,and realizes the coherence of orientation parameters of rigorous model for optical image and side-looking radar image.Furthermore,it also shows higher positioning experiment precision compared to Konecny G model and Leberl F model.Theory and tests indicate that the equation has potential applications in the field of photogrammetry on radar remote sensing images.关键词：range-coplanarity equation;geometric imaging equation;exterior orientation elements;side-looking radar;rigorous sensor model
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发布时间：2021-06-10 - 摘要：The vehicle-borne laser scanning（VLS） technology can quickly acquire three-dimensional information of earth surface with high precision.As a new technique of data collection acquisition,it has been gradually applied to Geographic Information System（GIS） industry.The classification on laser scanning points（LSP） is the premise and key step to the feature extraction and the model building of urban objects.This paper presents a classification method mainly suitable for the urban’s typical objects.Firstly,it extracts the LSP of the ground surface through taking three items into account,including characteristics of data collection,the vehicle’s GPS trajectory,and the slope relationship between the adjacent LSP in the same scanning line.Secondly,as for the remaining LSP,the object division should be completed first through the methods of Grid and Segmentation,and then performs the objects classification by computing several statistical indicators of the spatial characteristics.Finally,this paper takes the Sanya city as the study area,to verify the effectiveness of this method.The result shows that,this classification method successfully classifies the categories of the ground,buildings,trees and street lamps from the LSP.关键词：vehicle-borne laser;point cloud;classification;grid;segmentation
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发布时间：2021-06-10 - 摘要：In order to overcome the problem of fragmentation of ground objects and low accuracy in the single window texture classification,we present a new method of classification using SVM based on multi-window texture,using the Changjiaoba town of Foping county in Shaanxi Province as the test area.First we established the SVM classification model combined with texture analysis based on texture extraction from SPOT 5 remote sensing image.Then we used the model to classify and analyze the types of land use in the area by comparing it with single window texture classification and single data source（spectrum） SVM classification.The research result showed an overall accuracy for multi-window texture classification of 85.33%,which was 13.11% higher than the single window texture classification and 24.10% than single data source（spectrum） SVM.Therefore,we conclude that the method is effective and could solve the problem of fragmentation of ground objects and low accuracy in the single window texture classification.关键词：support vector machine;texture feature;land use;single window texture;multi-window texture
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发布时间：2021-06-10 - 摘要：The movement of clouds is qualitative analyzed by forecasters with satellite images currently,which is,however,lack of objectivity and quantitativity.In this paper,based on the stationary satellite infrared（IR） channel（10.3—11.3 μm） images of FY-2C and FY-2D with the time resolution of 15 minutes,brightness temperature（BT） and area threshold are selected to identify the severe convective cloud（SCC）.We then use the SCC matching algorithm of maximum correlation to track the shorttime automatic prediction of SCC systematically.The experiment results show that the tracking method proposed in this work has higher matching accuracy and efficiency compared with the traditional cross-correlation approach.The cloud center of gravity（CG） extrapolation is markedly superior to the minimum temperature,and the mean temperature,area and roundness all have better indications to the cloud split and merge.Tested by contingency table,the automatic identification and tracking technology has high prediction accuracy and timeliness.In addition,the research of this paper provides a scientific basis for the objective and quantitative application of satellite images to SCC short-time prediction in operation.关键词：FY-2C and FY-2D;severe convective clouds;cloud threshold identification;maximum correlation tracking algorithm;short-time automatic forecast technology
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发布时间：2021-06-10 - 摘要：An image obtained by a satellite in orbit may reflect a variety of inaccurate observations and different forms of interference,such as image rotation,the bow effect,and non-uniform stripes phenomena.These are attributed to the inherent characteristics of the Earth.These types of redundancy and stripes can be foreknown,and the image can be restored using design optimization,the satellite orbit ephemeris and image processing methods.The restoration of a periodic or aperiodic interference newly introduced in orbit requires the integrated use of multiple data sources,prior knowledge on the principle of interference,and appropriate image processing methods.Meanwhile,the authenticity of the original radiation information should be preserved for follow-up quantitative studies.In the present study,a new destriping method was introduced for processing of Mid-Infrared images.Using on-board calibration data and analysis of the stripes phenomenon and mechanism,a new spatial domain compensation algorithm was explored for the removal of image interference stripes.Results show that the image quality can be substantially improved by the proposed method.When compared with the frequency domain filtering algorithm,it is better in terms of both the dynamic range index and radiation information preservation.关键词：spatial domain compensation;mid-Infrared image;interference strips destriping;evaluation
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发布时间：2021-06-10 - 摘要：The speckle in polarimetric Synthetic Aperture Radar（SAR） image has seriously affected the effectiveness in extracting information.For this reason,a novel method based on the similarity of the scattering for speckle reduction is proposed.This method combines the similarity of the scattering properties and the redundant information in SAR image,and applies the Wishart distribution of SAR data to implement the measurement of the similarity.It then averages the covariance matrices with the weights according to the similarity between the matrices,leading to efficient reduction of the speckle in SAR image.The method processes each element of the covariance matrices,given its advantage in preserving polarimetric properties.Compared with the existing methods,including the Polarimetric Whitening Filter（PWF） and the polarimetric Lee filter,the implementation result indicates that the proposed algorithm is effective in improving the performance of despeckling and details preservation.关键词：SAR;multi-polarimetric;speckle reduction;scattering character;similarity
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发布时间：2021-06-10 - 摘要：As the continuous development of sensor technology to improve spatial,temporal resolution and spectral resolution of remote sensing images and to increase the amount of information,thus the storage and transmission of remote sensing image has brought significant challenges,so traditional image coding strategy is difficult to adapt to the applications of remote sensing images based on the uplink demand.This paper presents a coding scheme which is based on wavelet low-frequency sub-band prediction of distributed remote sensing images,using interpolation prediction method to get the auxiliary information which is used to decode the Wyner-Ziv.low-frequency information of images use embedded zerotree wavelet（EZW） coding scheme,while the prediction-error image use the Turbo hybrid coding scheme based on uniform quantization and the bit plane.At the decoder,the stream of prediction-error image is considered as an auxiliary information and the stream of low-frequency information are joint decoding.Experimental results show that the proposed method has high coding efficiency,small distortion,high compression ratio,strong ability of error control and scalable bit stream with quality and other characteristics.关键词：remote sensing image;distributed coding;predictied error;bit plane;error control
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发布时间：2021-06-10 - 摘要：Clouds and their shadows in remote sensing images bring many troubles to image interpretation and application.It is important to detect and repair these regions rapidly.An efficient method was proposed to detect and repair the unwanted clouds and shadows using two images of the same site acquired in adjacent time.At first,the cloud and shadow regions were enhanced by fusing multi-spectral data and then detected automatically using Otsu’s algorithm.Since the clouds and their shadows will lead to obvious differences in brightness between the two images,false detection of highlighted objects and water regions can be easily discarded,and then the normalized cloud and shadow density map can be built.Linear combination of two images and histogram matching algorithm were adopted to repair the shadow and cloud regions.Experiments on SPOT 4 multi-spectral remote sensing data show impressive results which will benefit several applications.关键词：Automatic detection;image repairing;histogram matching;cloud and shadow density map;multi-spectral
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发布时间：2021-06-10 - 摘要：We focuse on simulation principles and techniques of GNSS-R in sea surface wind field（SSWF） retrieval based on airborne remote sensing,and analyze the relationship among ocean wave spectrum,sea surface slope,wind speed and direction.We not only carry out a numerical simulation on the condition of various wind speeds and directions,receiver altitudes,and flight speeds,but also have completed a corresponding simulation software.The simulation results indicate that all the parameters above can affect the peak value and the trailing slope of the relative power waveform of the reflected signals from sea surface.Simulation study of this paper establishes a theoretical basis for the SSWF retrieval using GNSS-R.关键词：GNSS-R;ocean microwave remote sensing;sea surface wind field;relative power waveform
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发布时间：2021-06-10 - 摘要：This paper provides wind and wave observation results detected by high frequency surface wave radar OSMAR071 during Typhoon Fung-Wong.Methods for extracting ocean surface parameters from HFSWR sea echo are introduced.The Stewart Barnum and Maresca SBM method combined with multi-beam sampling method is used to invert wind direction.A modified Barrick’s model is proposed to obtain significant wave height and the SMB formulation is used to extract wind speed information.Compared with buoy data of wind and wave,radar inversion results show good agreement with in-situ observations.The root-mean-square error RMSE of significant wave height,wind speed and wind direction between radar-derived and those from the buoy are 0.48 m,3.5 m/s,27.7°,and the coefficients of determination（R2） are 0.72,0.60 and 0.97,respectively.Factors affecting detecting accuracy are also discussed in this paper.关键词：Typhoon;high frequency surface wave radar（HFSWR）;OSMAR071;Significant wave height;wind field
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发布时间：2021-06-10 - 摘要：Based on the analysis of results of radiative transfer simulation,a method for ground-based infrared remote sensing of cloud based on height is proposed according to the monotonic relationship between Cloud Base Height（CBH） and the downwelling infrared radiance.A preliminary comparison experiment is conducted with cloud base height measured by laser ceilometers.The results show high accuracy of CBH of middle and low cloud determined according to the proposed method with an average error of 107 m.关键词：cloud base height;infrared remote sensing;downwelling infrared radiance;ground-based remote sensing;laser ceilometer
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发布时间：2021-06-10 - 摘要：We designed a new device which can be used to measure the absorption coefficient of pure water directly.First,we measured the irradiance of direct light penetrating through different thicknesses of water layers.Then we used the ratio method to eliminate the impact of measuring instruments on experimental results.Finally,we acquired the extinction coefficient.The extinction coefficient experiment proved that extinction coefficient of suspended substance in water can be calculated by formula of ?ngstrom.We therefore put forward a method on how to eliminate the impact of suspended substance in pure waters.Eventually,we determined the absorption coefficient of pure water from 400 nm to 900 nm.Comparing with previous studies,overall results are consistent,but with better precision in the long wave length.The absorption coefficient of pure water can be used as the normal data for water quality remote sensing.关键词：absorption coefficient;pure water;suspended substance;extinction coefficient
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发布时间：2021-06-10 - 摘要：According to the extreme large and mutable characteristics of water absorption coefficient in the infrared spectrum,a device for measuring thin thickness of water layer is developed on the basis of the previously presented system for measuring water absorption coefficient in the optical region,in order to change the thickness of water layer from 0.04 mm to 350 mm.Then water absorption coefficient is measured with water layers of different thicknesses between 0.04 mm to 150 mm.After the effect of impurity was removed,measured data is integrated effectively and the absorption coefficient of pure water in spectrum from 900 nm to 2500 nm is obtained.Because the pure water absorption coefficient of each section in the spectrum is measured accurately under optimum detecting range of the instrument,the result is more reliable and agrees well with previous measurements.It can be used as basic data in quantitative remote sensing applications.关键词：absorption coefficient;pure water;near-infrared spectrum;extinction coefficient
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发布时间：2021-06-10
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