最新刊期
卷 16 ， 期 2 ， 2012
- 摘要：Large numbers of important researches have been done to estimate regional surface heat fluxes using remote sensing data over the past few decades. Due to the spatial heterogeneity of the land surface on a regional scale, many problems still need to be explored. Clearly, for landscapes with significant variability in vegetation cover, type, architecture, and moisture, due to the large contrasts in surface temperature, vegetation cover, surface roughness length and zero plane displacement height, the application of a land surface model to a mixed pixel causes significant errors. In this paper, we discussed the method of combining the land cover information and remotely sensed vegetation index provided by Landsat data and Moderate Resolution Imaging Spectroradiometer （MODIS） data to correct spatial-scale errors. It makes full use of the advantages of the temporal resolutions of MODIS data and spatial resolutions of Landsat data to construct a regional evapotranspiration model, which meets the requirements of spatial heterogeneity scale and makes the higher frequency of large area flux monitoring more operational.关键词：evapotranspiration;remote sensing;mixed pixels;spatial-scale error;sub-pixel analysis
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发布时间：2021-06-10 - 摘要：This paper presents an improved Empirical Orthogonal Functions （EOF） model for estimating methane profiles from spaceborne hyperspectral infrared observations based on profile dataset from European Centre for Medium-Range Weather Forecasts （ECMWF） and radiative transfer model RTTOV9.3. The model was applied to Atmospheric Infrared Sounder （AIRS） observations, validated by ground-based Fourier Transform Spectrometer （FTS） observations and AIRS v5.0 CH4 products. Compared with FTS measurements, the Root Mean Square （RMS） relative error of CH4 mixing ratio of EOF retrieval was smaller than that of AIRS v5.0 CH4 product for data lower than 300 hPa, and the relative error of CH4 column amount of EOF retrieval was also smaller. Compared with AIRS v5.0 CH4 product, the coefficient of determination for CH4 profiles retrieved from EOF model was 0.9715, and the RMS relative errors were smaller than 2.5%. The validation results show that the EOF model could provide a good initial value for physical retrieval and is a promising operational approach due to high stability and efficiency.关键词：EOF;methane;AIRS;atmospheric infrared remote sensing;physical regression
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发布时间：2021-06-10 - 摘要：Quick and accurate evaluation of the building damages after earthquake in urban area is a critical issue for timely assessing the disaster situation and effectively carrying out rescue mission. Very High Resolution （VHR） optical image is usually a direct way to visually monitor natural disaster occurrence. However, under some serious situations, such as bad weather or difficult geographic conditions, the post-event VHR optical image is not always available over large areas. All day and all weather space-borne Synthetic Aperture Radar （SAR） in operation can provide the reliable and high quality images over a large area. Of course, the relationship between optical image and SAR image is not simply a one-to-one visual correspondence. Microwave scattering and penetration through terrain media, and image speckles of SAR observation with a certain resolution are different from VHR optical imaging. How to make fusion of VHR optical and SAR images under different pre-event and post-event situations can provide a useful and operational approach to make timely and accurate evaluation of earthquake losses.关键词：earthquake;optical and SAR remote sensing;mutual information;detection of building damages
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发布时间：2021-06-10 - 摘要：A method for Synthetic Aperture Radar （SAR） image target recognition based on Principal Component Analysis （PCA）, Independent Component Analysis （ICA） and Gabor wavelet decision fusion is presented in this paper. PCA, ICA and Gabor wavelet transformation were used to extract feature vectors from SAR target images, respectively. Three Support Vector Machine （SVM） classifiers were applied to classify the feature vectors extracted via three algorithms, respectively. Ranking based decision fusion algorithm was then used to fuse the outputs of three classifiers. The final classification decision result was obtained from the output of the fuser. Experiments were implemented with three military targets in MSTAR database. The experimental results show that the probability of correct classification obtained by PCA, ICA and Gabor wavelet decision fusion is better than that attained by any of the individual feature. Therefore, it is concluded that the method proposed in this paper advances the probability of correct classification and can be an effective approach for SAR image target recognition.关键词：SAR;target recognition;decision fusion;PCA;ICA;Gabor wavelet
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发布时间：2021-06-10 - 摘要：Motivated by the fact that image patch can be sparse represented using a suitable over-complete dictionary, a nephogram super-resolution algorithm via sparse representation using over-complete dictionary is presented. During the experiment two dictionaries Dl and Dh for the low-resolution and high-resolution nephogram patches were trained jointly in order to guarantee that the low-resolution and high-resolution patch pair possesses similar sparse representations as to their own dictionary. Through solving optimization problem, the sparse representation for each low-resolution nephogram patch with respect to Dl was obtained, and the representation coefficients were applied to Dh in order to generate the corresponding high-resolution nephogram patch. At the end of experiment the high-resolution nephogram which satisfies the reconstruction constraint was achieved by using gradient descent algorithm. Numerical experiments for infrared and visual nephogram demonstrate the effectiveness of the proposed algorithm. Moreover, the proposed algorithm outperforms interpolation based methods in terms of visual quality and the Peak Signal to Noise Ratio （PSNR）.关键词：nephogram;super-resolution;over-complete dictionary;dictionary training;sparse representation
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发布时间：2021-06-10 - 摘要：This paper presents a novel method for automated extraction of building footprints from mobile LIDAR point clouds. We first generate the georeferenced feature image of mobile LIDAR point clouds using an interpolation method, and adopt image segmentation and contour extraction and tracing to extract building boundaries in the geo-referenced feature image as the coarse level of building footprints in Two-dimensional imagery space. Then, the coarse level of building footprints is further refined by applying planar segmentation on the extracted point clouds in the building boundaries. Finally, the triangulated irregular network （TIN） is used to achieve the fine level of building footprints. Dataset of residential areas captured by Optech’s LYNX mobile mapping system was tested to check the validities of the proposed method. Experimental results show that the proposed method provides a promising and valid solution for automatically extracting building footprints from mobile LIDAR point clouds.关键词：mobile LIDAR;footprints extraction;image segmentation;point cloud segmentation;triangulated irregular network
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发布时间：2021-06-10 - 摘要：According to analysis of the limitations of traditional algorithms, such as local points fitting and frequency domain signal analysis, a typical noise removalremoval algorithm of LIDAR point clouds based on three-dimensional finite-element analysis is proposed. Firstly, point clouds is partitioned into smaller and similar units by finite elements named space hexahedron model. And then, all of the units are classified into noise units or non-noise units with adjacency-based reasoning rules. Finally, the low noise is removed by iterative processing with finer threshold. In this approach, we did experiments with a real strip data which is obtained by an international mainstream system. The result shows that finite-element analysis has good performance in noise removal.关键词：LiDAR;space distribution;finite-element analysis;triangular mesh;SNR
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发布时间：2021-06-10 - 摘要：In order to analyze the characteristic of large attitude angle errors of CBERS-02B satellite imagery, this paper proposes a specific strategy and algorithm to improve the point determination accuracy by using block adjustment. First, the errors of attitude angles are calibrated according to four Ground Control Points （GCPs） around the four corners of each image. Then the Rational Polynomial Coefficients （RPCs） of each imagery are solved using terrain-independent approach. The Rational Function Model （RFM） with the affine transformation parameters is applied for the bundle block adjustment of CBERS-02B satellite images. Two CBERS-02B stereo pairs in level 0 acquired by a single CCD are selected in our test. The experimental results have shown that an accuracy of ±3 pixels can be attained both in plane and elevation. Moreover, the elevation accuracy is better than the planimetric accuracy. Comparing to the bundle block adjustment without pre-correction, the method proposed in this paper can improve the accuracy both in plane and elevation to a similar accuracy level of foreign High-resolution Satellite Images （HRSIs）, which indicates that Chinese satellite images have good potential for geometric positioning. These experiments further show, the pre-correction before bundle block adjustment is necessary and feasible for the images in geometric processing.关键词：CBERS-02B;High-resolution Satellite Images （HRSI）;block adjustment;accuracy
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发布时间：2021-06-10 - 摘要：Comparative analysis of cloud fraction obtained from Moderate-resolution Imaging Spectroradiometer （MODIS） and ground observations shows the existence of considerable deviations. Five correction methods, based on cloud fraction observed from ground meteorological stations, have been proposed in this paper, including difference correction, ratio correction, difference-mixed correction, ratio-mixed correction and normalization-mixed correction of MODIS cloud product. The results show that all of the five correction methods are workable. Comparatively, the ratio correction method has the highest precision and is easy to be implemented. Hence it is the best recommended correction method for MODIS cloud product. After correction, the cloud fraction of MODIS is identical with that of ground observations, both in spatial distribution and quantitative analysis. Furthermore, intensive observations test show that monthly Mean Absolute Bias Error （MABE） of cloud fraction obtained from MODIS after ratio correction is less than 5%. This study gives a reference for relative researches using ground observation data to correct the related satellite products, which is of great significance to the related investigations of plateau, mountains and desert with sparse stations.关键词：cloud fraction;MODIS;correction methods;spatial distribution;ground observation data;correlation;difference
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发布时间：2021-06-10 - 摘要：We proposes a novel fusion method for multi-sensor image fusion, whose basic thought comes from Brovey transformation. This method exploits a new calculation formula of the product coefficient in Brovey transformation through considering spectral range differences and spectral response differences of different sensors in multi-sensor image fusion.Based on the spectral range differences and spectral response differences of various sensors, the inferential reasoning formula was proposed. The relationship between panchromatic and multi-spectral images was built using weighting coefficient β and proportion coefficient w. Finally, the product coefficient in Brovey transformation was rebuilt by the two factors.The novel multi-sensor image fusion method has greatly reduced spectral distortion in Brovey transformation. To evaluate its performance and efficiency, four experiments using proposed fusion method, Brovey transformation and Modified IHS were carried out, including fusion of Beijing-1 small satellite （BJ-1） multi-spectral （MS） image and SPOT 5 panchromatic （PAN） image, the SPOT 4 MS image and BJ-1 PAN image, the Landsat 5 （TM） MS image and BJ-1 PAN image, and the HJ-1A MS image and SPOT 5 PAN image. Qualitative and quantitative evaluations of the tests were also conducted. The results showed that the proposed method is better than the other two methods generally. It shows good ability in spectral preservation and high spatial details immersion. The simpleness and timesaving make it high potential in future applications.关键词：multi-sensor;spectral range differences;spectral response differences;product coefficient
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发布时间：2021-06-10 - 摘要：We propose a method to extract the feature of Bi-directional Reflectance Distribution Functions （BRDF） over Badain Jaran Desert using Landsat-TM/ETM+ and ASTER GDEM data. Badain Jaran Desert is characterized with homogeneous and rugged terrain, which forms a natural Bi-directional Reflectance data sets with hypotheses that the surface structure of each slope element does not vary with the variations of slope and aspect. Therefore, we use nadir view Landsat-TM/ETM+ imagery to reconstruct the BRDF characterization of this experimental site. To begin with we use ASTER GDEM product to retrieve the sun-view geometry for each slope element corresponding to one pixel in remotely sensed imagery. Then the observations from Landsat-TM/ETM+ imagery and the retrieved sun-view geometries are used together to extract the BRDF feature of the experimental site. Finally, we simulate surface reflectance for 25 scenes of different Landsat-TM and ETM+ images and compare the simulations with the actual Landsat-TM and ETM+ imageries. Results show that the difference between the simulation and "true" surface reflectance are 2.80%, 1.92%, 2.68% and 2.32%, respectively, which is higher than the radiometric calibration error requirement of 5% to 7%. Therefore, the combination of nadir viewing Landsat-TM/ETM+ imagery with ASTER GDEM data can be used to cross-calibrate remotely sensed imagery with large viewing observation.
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发布时间：2021-06-10 - 摘要：The detection of oil content in soil has an important practical significance in oil pollution prevention and control. We measure the hyperspectral reflectivity and the oil content for soil samples in Gudong Oilfield. Using variable forecast model and stepwise regression method, we analyze the linear and nonlinear relationships between soil spectral characteristic parameters and oil content. The experiment shows that there is a significant correlation between the third broken line segment slope of envelope line analysis and the oil content. The cubic function of this section slope is the best single variate estimation model. The standard normal variate transformation has the best effect on spectrum pretreatment. When the transformed spectral are used to build multivariate regression model, the adjusted coefficient of determination is 0.826, and the total RMSE is 0.531, which is the best forecast model. The method of using hyperspectral data to detect the oil content will provide an effective new way for detecting the oil pollution in soil.关键词：Gudong Oilfield;soil;oil;hyperspectral
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发布时间：2021-06-10 - 摘要：Using the Ozone Monitoring Instrument （OMI） to obtain the long-term SO2 concentration, we analyzed the near-surface SO2 concentration variation before the 2010 Asian Games and the space distribution of Pearl River Delta SO2 concentration during the period of the 2010 Asian Games. It shows that OMI has the ability of monitoring near-surface SO2 concentration variation. Because of linkage air quality guarantee measures in the Pearl River Delta, during the 2010 Asian games, the air quality of Pearl River Delta is better than historical periods.关键词：the 2010 Asian Games;Pearl River Delta;sulfur dioxide （SO2）;OMI remote sensor
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发布时间：2021-06-10 - 摘要：First, a binary image containing only land and ocean pixels is generated by intersecting the LiDAR-derived shore digital surface model （DSM） and the ocean surface derived from tidal gauge data. Then a series of image processing algorithms are applied to extract preliminary high and low tide lines. Since LiDAR pulses can not penetrate into water, some regions near the low tide line may have invalid DSM values. In order to overcome this disadvantage, a mobile trend surface fitting method is used to extrapolate the DSM near low water lines, hence more accurate low tide lines can be extracted. Experimental results show that this method can extract high and low tide lines effectively with less manual labors.关键词：LiDAR;high tide line;low tide line;combined extraction;mobile trend surface fitting
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发布时间：2021-06-10 - 摘要：The parameters of backscattering coefficient model have significant temporal and spatial variability. In order to overcome this limit, a classification algorithm based on spectra dominant factors for Taihu Lake is established to classify the water reflectance spectra into three types. Quasi-analytical algorithm and optical closure are used in this paper to stimulate the back-scattering coefficient for three types of water reflectance spectra in Taihu Lake according to the field measurement reflectance data. The properties of backscattering coefficient are also analyzed synchronously. On this basics, the backscattering coefficient parametric model for three types of water in Taihu Lake are established. As a result, the difference of the backscattering properties in different time and space is converted into the difference of bio-optical properties of dominant factor in water. Thus, the parametric models of backscattering coefficient are demonstrated to be suitable for different parts and different seasons of Taihu Lake.关键词：taihu lake;spectral classification;Quasi-analytical algorithm;optical closure;Backscattering coefficient
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发布时间：2021-06-10
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