最新刊期
卷 15 ， 期 4 ， 2011
- 摘要：Mars rover Spirit landed in Gusev Crater on January 4, 2004. It became a stationary science platform on 26 January 2010 after NASA’s efforts to free it from a sand trap had been unsuccessful. During its six years of exploration of the red planet, Spirit traveled 7.73 km and made significant discoveries, e.g. detection of deposits of salts and minerals such as sulfur and opaline silica that only form in the presence of water. This paper presents a brief review of Spirit’s six years of Mars roving and major scientific discoveries. In particular, it demonstrates how planetary mapping and remote sensing technologies have been greatly supporting the mission to achieve its science and engineering goals.关键词：Mars rover Spirit;roving Mars;scientific discoveries;planetary mapping;remote sensing
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发布时间：2021-06-10 - 摘要：The mixels in the hypersepectral images not only influence the accuracy of target detection and classification, but also greatly hinder the development of quantitative remote sensing. The typical endmember extraction algorithms now available are analyzed and summarized. These algorithms can be classified into two types based on the hypothesis of the existence of the pure pixels: endmember identiflcation algorithm and endmember generation algorithm. Six endmember extraction algorithms, including N-FINDR, VCA, SGA, OSP, ICE and MVC-NMF, are introduced and compared using experimental data, which further show their advantages and disadvantages. With results of various methods, the future perspective is proposed for further study.关键词：hyperspectral image;mixel;linear spectral mixing model;endmember
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发布时间：2021-06-10 - 摘要：Traditional airborne SAR （Synthetic Aperture Radar） makes use of the GPS/INS to compensate the platform motion error to acquire high resolution images. GPS data with geographical coordinates （consists of longitude, latitude and height） is converted to a local Cartesian coordinates, under which raw radar data is processed with some imaging and motion compensation algorithms to create an image with the local coordinates. However, it is not easy to be understood for other departments who need an image located by geographical coordinates. This paper presents a novel SAR imaging algorithm derived from Back-Projection that can be processed directly under the geographical coordinates and avoid coordinates transformation. Each pixel of the im- age obtained via this algorithm is located with geographical coordinates, which is convenient to be applied by the intelligence or other survey departments. Images obtained under geographical coordinates by this algorithm are as clear as traditional algorithms that been proved by simulations and an outside experiment.关键词：synthetic aperture radar;motion compensation;geographical coordinates;coordinates transformation;elevation calibration
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发布时间：2021-06-10 - 摘要：The microwave calibration target’s surface temperature is simulated using the computational fluid dynamics simulation technologies, which overcomes the difficulties of traditional methods in measuring the small wedge of calibration targets at a high precision. An evaluation method to calculate the calibration target’s equivalent output temperature is introduced and the ref- erence depth value of embedding the temperature sensor is applied, which efficiently reduces the difference between the sensor’s measurement value and the calibration target’s equivalent output temperature. The uncertainty of the calibration target’s bright- ness temperature can be reduced within 0.5 K, which highly increases the measurement evaluation precision of the radiometer’s calibration system.关键词：calibration target;blackbody;brightness temperature;radiometer;microwave remote sensing
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发布时间：2021-06-10 - 摘要：This study analyzes the main phase contributions of ScanSAR-Stripmap interferometry and further points out the special component caused by unsynchronized echoes, which is then verified in the experiment. The whole process of ScanSAR-Stripmap interferometry has been proposed and implemented with the help of relating modules of the Repeat Orbit Interferometry Package （ROIPAC） developed by Jet Propulsion Laboratory （JPL）. Coregistration and improvement of coherence are solved emphatically. Finally, ScanSAR-Stripmap interferometry is realized using Envisat ASAR data and the results are compared with those of traditional Stripmap-Stripmap interferometry for validation.关键词：InSAR;interferometry;ScanSAR;stripmap;burst;synchronized
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发布时间：2021-06-10 - 摘要：The radioactive transfer process in the surface-atmosphere-remote sensor can be simulated by the atmospheric radioactive transfer model MODTRAN 4, thus the top of the atmosphere （TOA） radiance with the corresponding atmospheric parameters can be acquired. Based on the look-up table （LUT） which is generated by simulation, the surface reflectance from CCD data of HJ-1 satellite can be retrieved. Then, the effect of atmospheric correction on CCD data of HJ-1 satellite is analyzed in terms of the spectral curves, comparison with MODIS surface reflectance products, and the normalized difference vegetation index（NDVI）. The results show: （1） Atmospheric correction on CCD data of HJ-1 satellite can eliminate the "increase" effect of the atmosphere. （2） The refl ectance of vegetation and settlement place from atmospheric corrected CCD data of HJ-1 satellite is well consistent with those from MODIS surface reflectance data products, with less than 20% in error between these two surface features for the four bands of CCD data of HJ-1 satellite. （3） The difference of NDVI between vegetation and other objects after atmospheric correction has been increased, which indicates the atmospheric correction can highlight the vegetation information.关键词：HJ-1 satellite;atmospheric correction;MODTRAN 4;MODIS
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发布时间：2021-06-10 - 摘要：Karst rocky desertification is the most serious problems of land degradation in karst regions, southwest China. Remote sensing technique is the promising method to assess and monitor the degree and extent of karst rocky desertification at large scale. In this study, based on field spectral reflectance measurements, the traditional vegetation indices （VIs） and linear spectral unmixing （LSU） are assessed to extract the key indicators of karst rocky desertification. Karst rocky desertification synthesis index （KRDSI） has been developed with the unique of spectral features observed in non-vegetation land cover types. The results show that VIs could be used to extract the fractional cover of green vegetation, and they are not sensitive to soil background. Both VIs and LSU can efficiently extract the fractional cover of non-green vegetation. Compared with LSU, KRDSI shows more consistent results with the field measurement of non-vegetation land cover fractions. This study indicates that evaluation indicators of karst rocky desertification can be extracted from the Hyperion image with the combination of vegetation indices and KRDSI values.关键词：spectral indices;linear spectral unmixing;KRDSI;karst rocky desertification
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发布时间：2021-06-10 - 摘要：A coastline detection method using synthetic aperture radar （SAR）images based on local statistical active contour model has been proposed in this paper. The method incorporates the local statistical active contour model to detect the coastline in SAR images. In order to remove the limitation of a rigid initial contour being requested in the local statistical active contour model, this method firstly utilizes a C-V model to gain an approximate segmentation. Thereafter, a local statistical active contour model based on G0 distribution is proposed to achieve the accurate segmentation results. The new model adopted G0 distribution to fit each neighborhood along the contour, enhancing the fitting ability for SAR images and improving the detection accuracy of the coastline. Through combining a penalizing term of level set function, the model eliminates the need of re-initialization procedure. The experiments of real SAR images demonstrate the proposed method has accurate coastline detection ability.关键词：SAR;coastline detection;statistical active contour;C-V model
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发布时间：2021-06-10 - 摘要：At present, most of the traditional filters such as Goldstein, Lee, Median, Mean, and Periodic filter, can not meet the demand of noise suppression for interferograms contaminated by phase noise. Repeat filtering, however, will result in serious loss of fringe pattern. In this paper, a two-step filter is presented. The filter inherits the good edge preservation characteristics of the Contoured window fi lter and the strong smoothing capability of the Goldstein filter. In addition, it introduces the pseudo- coherence of interferogram to improve the adaptiveness of the Goldstein filter. Experimental results with both simulated and real data show that the proposed filter performs quite well both in noise reduction and in detail preservation. Moreover, it can partially recover continuous interferometric fringes from area without signals, and is applicable for interferograms with very dense and heavily curved fringes.关键词：InSAR;strong noisy;Contoured median Filter;Goldstein Filter;noise reduction;fringe preservation
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发布时间：2021-06-10 - 摘要：A new quality map is introduced for wrapped phase image in this paper. In order to reduce the affluence of the slope effect in the conventional quality map and improving edge-detection ability in the steep discontinuity areas where the real phase dif- ference is 2 kπ, a quality map derived from the consistency of normal vectors is proposed. In 3×3 window of wrapped phase image, the center is selected as the reference point and then the local unwrapping is performed in the window. After local unwrapping, eight triangles are formed by the center and every pair of neighboring points on the border of the window, then the syntheti-cal normal vector formed by the eight normal vectors of the corresponding triangles is taken as the normal vector of the local unwrapped surface. Finally, the quality value of the center is defined by the sum of angles between the eight normal vectors and the synthetical normal vector. The tests performed on simulated data and real InSAR wrapped phase image show that the new quality map has the better guiding ability than the conventional quality map in the quality-guided phase unwrapping algorithm.关键词：InSAR;InSAS;quality map;normal vector;quality-guided
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发布时间：2021-06-10 - 摘要：Shadow detection for high spatial resolution remote sensing images is very critical for image segmentation, feature extraction, image matching, automatic target detection and target location. In order to improve the accuracy of shadow detection, we propose a new shadow detection method based on a statistical mixture model, which combines several radial basis function neural networks. Four statistical features, including energy, entropy, contrast and inverse difference moment, extracted from grey level concurrence matrix are used as the model input features. EM-like algorithm is adopted to estimate the model parameters through optimizing the system cost function. Comparative experiments are performed between the Gaussian background model and the histogram threshold method. Experimental results show that higher detection accuracy of the proposed approach is obtained. The proposed method can solve the problem such as high reflective regions and false alarms in the presence of water, as well as the repeated threshold calculation.关键词：shadow detection;radial basis function neural network;mixture model;statistical texture feature.
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发布时间：2021-06-10 - 摘要：In this paper, we evaluate the capability of a mass and energy balance computer modelsnow thermal model （SNTHERM.89） by simulating the snow properties with experimental data measured at Binggou basin, Gansu Province, China, 2008. We also compare the simulated snow water equivalence （SWE） with the product from the advanced microwave scanning radiometer （AMSR-E）.The results show that SNTHERM model could accurately predict the snow evolution process and snow properties at Binggou , and reasonably describe the characteristics of snow evolution, indicating that SNTHERM applied at Binggou successfully. In addition, we conduct the sensitivity analysis of snow properties to the meteorological forcing data and initial input parameters. It has been found that the solar radiation energy flux is the most sensitive parameter to the snow properties simulated by SNTHERM, such as the snow depth, density and the grain size. The snow properties are sensitive to their respective perturbation, while the snow density is sensitive to all the other properties. Hence, in the case that snow density need to predict accurately, or SWE assimilation work is conducting, the initial snow depth, density and grain size should be accurate.关键词：SNTHERM;Binggou;snow properties;sensitive analysis;AMSR-E
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发布时间：2021-06-10 - 摘要：How to extract and calculate subtle spectral feature information of crop under various environmental-induced stresses from hyperspectral remote sensing is crucial for the application of remote sensing in monitoring agricultural pollution. The objective of this paper is to monitor the stress levels of rice under the Pb pollution. Hyperspectral data and heavy metal content were collected in the field experiment. The fifth level high—frequency component （d5） was obtained by performing wavelet transform to hyperspectral reflectance （350-1300 nm） and the fractal dimension of d5 was also calculated. Then the relationship between fractal dimension of d5 and different stress levels of rice was established by the fuzzy logic model. The results showed that: （1） d5 can effectively distinguish the stress levels of rice Pb pollutions; （2） the annual relative variation ratio for fractal dimension of d5 was below 4%, and the classification accuracy of fractal dimension of d5 was above 75%. Namely, fractal dimension values of d5 for rice under high, medium and low pollutions have percentage of 86.7% between 1.160 and 1.200, 75% between 1.220 and 1.275, 91.7% between 1.280 and 1.320, respectively. （3） the high （low） semi-trapezoidal functions were carried out to construct a model to detect stress levels of rice.关键词：hyperspectral reflectance;wavelet transform;Fractal analysis;membership function;rice;Pb-induced stress
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