20 April 2018, Volume 33 Issue 2
    

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  • Wang Baogang,Jin Rui,Zhao Zebin,Kang Jian
    Remote Sensing Technology and Application. 2018, 33(2): 193-201. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0193
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Surface soil freeze-thaw processes affect the energy and water exchange between the land surface and the atmosphere,hydrological cycle process and ecological system activity.It is obviously important to study the spatial distribution and temporal dynamics of surface soil freeze-thaw cycle,frozen depth,transition water content by the remote sensing technology,and their influences on and feedback with climate change.With the implementation of the SMOS and SMAP satellite projects,the L-band,with lower frequency,deeper penetration depth and stronger dielectric sensitivity,can be used to not only monitor the surface freeze-thaw cycles,but also to estimate the soil frozen depth,frozen velocity and phas-|change water content.Compared with the widely used C,X,Ku and Ka bands,L-band has a wider application potential.As a supplement,this paper reviewed soil freeze-thaw cycle with passive microwave remote sensing,including observation principle and advantage of L band,newly improved and developed algorithms,passive radiometers and so on,particularly focusing on the development and potential of the L-band.
  • Su Yang,Qi Yuan,Wang Jianhua,Xu Feinan,Zhang Jinlong
    Remote Sensing Technology and Application. 2018, 33(2): 202-211. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0202
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    The extraction of land surface coverage is the basis of ecological environment evaluation,vegetation change analysis and regional ecological and hydrological processes.Aerial hyperspectral remote sensing has great advantage in land surface coverage extraction,such as flexible,wide coverage,high spatial resolution and high spectral resolution.Research area has landscape characteristics of vegetation,landscape fragmentation and heterogeneity in Ejina Poplar Forest National Nature Reserve.Comparison and analysis of two methods of dimension reduction based on minimum noise transform and principal component analysis,three supervised classification methods based on maximum likelihood method,support vector machine and object\|oriented classification.Land surface coverage is extracted by NDVI threshold segmentation,minimum noise transform dimensionality reduction method and maximum likelihood classification method according to the characteristics of landscape fragmentation,heterogeneity and high redundancy of hyperspectral data based on the Airborne Hyperspectral Data of Ejina oasis in the lower reaches of Heihe.The land surface coverage results overall accuracy and Kappa coefficient are 87.95% and 0.885 by random sampling based on airborne remote sensing data.The results show that the classification results of high accuracy can provide effective parameters for ecological research.
  • Qin Zhentao,Yang Ru,Zhang Jing,Yang Wunian
    Remote Sensing Technology and Application. 2018, 33(2): 212-215. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0212
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    A new algorithm for Hyper\|Spectral Image(HSI)inpaintingbased on self\|adaptive sparse representation of clustering structure is proposed.The method can adaptively select the block size according to the feature of remote sensing image.After the pixel is clustered,each band image of HSI can been sparsely represent according to the dictionary learning algorithm,and achieve HSI inpainting through the sparse approximation.The experimental results show that the sparse coefficients obtained by self\|adaptive spare representation can better represent the HSI and improve the Peak Signal\|to\|Noise Ratio(PSNR) of the image.The method proposed in this paper has important significance and application prospect in remote sensing image application.
  • Guo Yubo,Zhuo Li,Tao Haiyan,Cao Jingjing,Wang Fang
    Remote Sensing Technology and Application. 2018, 33(2): 216-226. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0216
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    Non-negative Matrix Factorization (NMF)method of blind spectral unmixing can obtain the spectrum and abundance of the endmember by synchronous optimization,without supervising the selection of endmember.Therefore,NMF has been developed rapidly in the application of hyperspectral unmixing.However,traditional blind spectral unmixing NMF method tends to fall into the local optimum and it is difficult to obtain a stable optimal solution.In this paper,we propose an improved Non-negative Matrix Factorization (NMF)method based on Spatial\|Spectal Preprocessing for spectral unmixing of hyperspectral data (SSPP-NMF).First,the SSPP algorithm is used to combine spatial and spectral information to select reasonable and effective dataset.Then,the NMF algorithm is used to unmix this dataset to obtain the final optimized endmember spectrum.Finally,the Non\|Negative Least Squares (NNLS)method is used to obtain the final abundance of the whole study area.The validity and applicability of the proposed method were analyzed based on a set of synthetic hyperspectral data and real hyperspectral images;and then the results were compared with that from three algorithms including the existing NMF algorithm,MVC\|NMF algorithm and ATGP-NMF algorithm.Results show that compared with ATGP-NMF and MVC-NMF,the SSPP algorithm can effectively suppress the influence of noise,significantly improve the performance of the NMF method of blind spectral unmixing algorithm.
  • Liu Ailin,Guo Baoping,Li Yanshan
    Remote Sensing Technology and Application. 2018, 33(2): 227-232. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0227
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    Piecewise COnvex Multiple\|Model ENDmember(PCOMMEND) spectral unmixing can well solve unmixing of the nonconvex hyperspectral data,which improves the calculation accuracy of the standard linear mixed model based on the convex geometry model.the number of piecewise convex is not sure in the practical application,which limits the calculation ccuracy of unmixing and the wrong endmembers will sometimes extracted,in view of the situation,the Discrete Particle Swarm Optimization(D\|PSO)is proposed to unmix the piecewise convex mulutiple\|model hyperspectral imagery,D\|PSO is the intelligent algorithm of random search,and is able to find the global optimal solution of convex function,which reduce the unmixing error caused by the uncertainty number of the convex section,experiments on the simulative data and real data has indicate D\|PSO improves the accuracy of the extracting endmember and estimating the proportion.
  • Wu Xing,Zhang Xia,Sun Xuejian,Zhang Lifu,Qi Wenchao
    Remote Sensing Technology and Application. 2018, 33(2): 233-240. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0233
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    The quality evaluation of remote sensing data is a bridge for development of sensor and data application.In this paper,we focused on the hyperspectral data acquired by China's self\|developed SPARK satellite launched in December 2016,and evaluated the radiation quality of SPARK 1A data using four objective indicators,namely radiation accuracy,signal\|to\|noise ratio(SNR),information entropy and sharpness.According to the results of each indicator,variance and information entropy show that the main information of SPARK data is concentrated in 81~152 band(542~985 nm),and the average entropy,signal\|to\|noise ratio and definition of this bands are higher than those of other bands,which are 6.28,47.63 dB and 179.5 respectively.The data quality of this spectral data is better than that of other bands,which is beneficial to the spectral identification and spatial feature extraction of different objects.The average SNR of 1~80 band(411~539 nm) was 38.23 dB,and the entropy was 5.28.Image enhancement can be used before processing for the low gray level and smaller gray range of the image in this bands.Because the 153~160 band(1 000~1 105 nm) was uncalibrated,its average SNR is less than 15 dB,and it has the lowest clarity,the spectrum and spatial information are seriously damaged,it is recommended to remove this bands.

     
  • Hou Haiyan,Hou Jinliang,Huang Chunlin,Wang Yunchen
    Remote Sensing Technology and Application. 2018, 33(2): 241-251. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0241
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    Based on the characteristics of the microwave signal responding to the snow depth,we use AMSR2 brightness temperature,geo\|location and terrain factor as the inputs of ANN,and snow depth as the desired output to develop an efficiency snow depth retrieve model.We compared the influence of combinations of TB,geo-ocation and terrain factors on the retrieve of snow depth.It is reviewed in this article that,TB of horizontal polarization,latitude perform better than vertical polarization and longitude respectively.Combination of slope and aspect is superior to other combinations of terrain factors.Besides,there are equivalent influence on snow depth of geo\|location and terrain factors.Finally,we compare the performance of four optimal ANN models under different input combinations.At last,we found that the ANN consists TB,latitude,longitude,slope and aspect as inputs is the best model which might fairly simulating the snow depth of Beijiang.
  • Duan Jinliang,Wang Jie,Zhang Ting
    Remote Sensing Technology and Application. 2018, 33(2): 252-258. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0252
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    Vegetation cover fraction is an important control factor in the process of simulating surface vegetation transpiration,soil water evaporation and vegetation photosynthesis.Based on the TM image data of two different types of vegetation cover,a collaborative sparse regression algorithm based on the spectra normalization framework is proposed to retrieve the vegetation cover fraction,which solves the problems such as the error of the endmember variability and the efficient of the algorithm arisen from many spectral mixture analysis algorithms used to retrieving vegetation cover fraction.And also by contrast to the dimidiate pixel algorithm,the accuracy of the algorithm is indicated.The experimental results show that the normalization of the image and endmenbers can effectively reduce their heterogeneity and improve the retrieval precision and the algorithm has higher accuracy than the dimidiate pixel algorithm.
  • Li Zhaoming,Chen Hongbin
    Remote Sensing Technology and Application. 2018, 33(2): 259-266. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0259
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    Calibration of weather radar has a direct impact on the accuracy of detection variables and therefore is critical for most applications of radar data.In this paper,we will focus on simultaneous calibration of reflectivity (Z),differential reflectivity (ZDR) and radial velocity (V) for X-band solid\|state weather radar.To conducting calibration experiments,detailed calibration implementation plan is formulated,two test points are selected and three kinds of spheres are used.Experiments results show that the theoretically calculated Zth and measured Zm have a mean bias of 3 dB and the bias is more affected by the radius than the material of the spheres.The reflectivity has a downward trend and decreases successively from 0.4 to 0.12 dB along with the decent of sampling number.The mean ZDR is about 1.7 dB,which is large deviation in comparison with the theoretical value.The radial velocity (Ve) calculated from GPS information and observed (Vob) have a difference less than 0.1m/s.It is also found that the radar reflectivity variation of metal sphere with azimuth and elevation angles can reflect radar antenna pattern.This calibration experiments provides reference for Dual\|polarization radar.
  • Remote Sensing Technology and Application. 2018, 33(2): 267-274. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0267
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    Process-based ecological models,which simulate carbon exchange at the land\|surface,were powerful and indispensable tools for calculating regional and global spatiotemporal variations of terrestrial Gross Primary Productivity(GPP).Vcmax(maximum carboxylation rate),one of the most critical parameters in the ecological models,was of significance in accurate calculation of GPP.However,the traditional methods of obtaining Vcmax is time\|consuming and laborintensive.In this study,correlations between three types of chlorophyll index(Modified Transformed Chlorophyll Absorption in Reflectance Index,Transformed Chlorophyll Absorption in Reflectance Index,and MERIS Terrestrial Chlorophyll Index) and canopy Vcmaxwas analyzed for different sites,and correlations between MTCI and canopy Vcmax for different time series of the same site.Results showed there were strong relationships between chlorophyll indices and canopy Vcmax.In the three types f chlorophyll index,the results show the most obvious correlations between MTCI and canopy Vcmax.For different time series of the same site,the relationship varies with different plant type.Results indicated that the remotely sensed chlorophyll index has ability to estimate Vcmax with spatial and temporal variations.
  • Zheng Mingliang,Huang Fang,Zhang Ge
    Remote Sensing Technology and Application. 2018, 33(2): 275-283. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0275
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    Land Surface Temperature (LST) is an important parameter that describes energy balance of substance and energy exchange between the surface and the atmosphere,and LST has widely used in the fields of urban heat island effect,soil moisture and surface radiative flux.Currently,no satellite sensor can deliver thermal infrared data at both high temporal resolution and spatial resolution,which strongly limits the wide application of thermal infrared data.Based on the MODIS land surface temperature product and Landsat ETM+image,a temporal and spatial fusion method is proposed by combining the TsHARP (Thermal sHARPening) model with the STITFM (Spatio\|Temporal Integrated Temperature Fusion Model) algorithm,defined as CTsSTITFM model in this study.The TsHARP method is used to downscale the 1 km MODIS land surface temperature image to LST data at spatial resolution of 250 m.Then the accuracy is verified by the retrieval LST from Landsat ETM+ image at the same time.Land surface temperature image at 30 m spatial scale is predicted by fusing Landsat ETM+ and downscaling MODIS data using STITFM model.The fusion LST image is validated by the estimated LST from Landsat ETM+ data for the same predicted.The results show that the proposed method has a better precision comparing to the STITFM algorithm.Under the default parameter setting,the predicted LST values using CTsSTITFM fusion method have a root mean square error (RMSE) less than 1.33 K.By adjusting the window size of CTsSTITFM fusion method,the fusion results in the selected areas show some regularity with the increasing of the window.In general,a reasonable window size set may slightly improve the effects of LST fusion.The CTsSTITFM fusion method can solve the problem of mixed pixels caused by coarse\|scale MODIS surface temperature images to some degree.
  • Li Shanshan,Jiang Gengming
    Remote Sensing Technology and Application. 2018, 33(2): 284-295. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0284
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    This work addresses the LST retrieval from Landsat\|8 data with the generalized split\|window algorithm.Firstly,radiative transfer modeling experiment is conducted using MODTRAN 4.0,fed with SeeBor V5 atmospheric profile database to build a data set of LST related to brightness temperatures in the bands 10 and 11 of Thermal Infrared Sensor(TIRS) on Landsat-8,Land Surface Emissivities(LSEs),viewing zenith angle and Total Precipitable Water(TPW).Secondly,based on the modeling data set,the unknown coefficients of the generalized split-window algorithm are obtained,and the algorithm sensitivity is analyzed.Then,LSTs are derived from the inter-calibrated and clear sky Landsat\|8 data with the generalized split\|window algorithm,in which LSEs are estimated from Landsat\|8 Operational Land Imager(OLI) data,and TPWs are extracted from the European Centre for Medium-range Weather Forecasts(ECMWF) reanalysis data.Finally,the results are validated with the Moderate resolution Imaging Spectroradiometer(MODIS) LST/LSE product(MOD11_L2 V5).The results show that the generalized split window algorithm developed in this work can accurately retrieve LST from the Landsat\|8 data,and the error is mainly come from the uncertainty of LSEs and TPW.Before and after correction of LSEs and TPW,the LST errors in this work are,respectively,-0.64 ±0.81 K and 0.10±0.68 K against the MOD11_L2 V5 product.
  • Cheng Bo,Liu Yueming,Liu Xunan,Wang Guizhou,Ma Xiaoxiao
    Remote Sensing Technology and Application. 2018, 33(2): 296-304. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0296
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    Coastal aquaculture areas are the important marine disaster bearing body,it is of great significance to carry out the research about automatically extraction aquaculture areas based on remote sensing for master basic information of coastal areas,mitigation and prevention of marine disasters.Used Gaofen-2 images for experimental data,and chose Dongshan Island sea in Fujian province as the experimental area,on the basis of analyzed the spectral characteristics of the aquaculture areas,construct feature index to extract spectral feature,used gray-level co-occurrence matrix method to extract the texture feature of the aquaculture areas,fused spectral features and texture features after feature selection,then used Otsu method to determine the threshold for raft culture area and fishing cage culture area,to achieve high precision intelligent extraction and classification for coastal aquaculture areas.The extraction accuracy of the raft culture area is more than 80%,and the extraction precision of the fish cage culture area is above 90%,and the overall extraction precision of the culture area is up to 87%.
  • Zhang Xia,Tang Senlin
    Remote Sensing Technology and Application. 2018, 33(2): 305-312. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0305
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    Strip noise will cover the real radiation information of remote sensing image,which not only reduces image quality,but also application effect.Aiming at the problem that window moment matching is difficult to remove strip noise thoroughly for the non\|uniform image,the wavelet moment matching algorithm is proposed.Firstly,the low frequency wavelet coefficient and the high frequency wavelet coefficients are separated which based on the wavelet multiresolution characteristic.Secondly,the low frequency wavelet coefficients were filtering by window moment matching,while strip noise of high frequency wavelet coefficients was performed by threshold method.Finally,reconstruction of the wavelet coefficients obtained destriping image.The above mentioned algorithm was evaluated quantitatively by local PSNR,local SSIM,Fuzzy coefficient and goodness of fit index.Results show that the wavelet moments matching algorithm is superior to the moment matching,wavelet soft threshold and window moment matching algorithm.Wavelet moment matching improves limitation of uniform distribution of grayscale value based on window moment matching,combining the advantages of spatial and frequency domain denosing,which can remove the noise while preserving the details of the image.
  • Yang Mengmeng,Wang Huibing,Ouyang Sida,Fan Kuikui,Qi Kaili 
    Remote Sensing Technology and Application. 2018, 33(2): 313-320. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0313
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    In order to solve the ambiguity and uncertainty of high resolution multi\|spectral remote sensing image classification and to better overcome the influence of noise,a new BPNN(Back Propagation Neural Network)classification method of multi\|spectral image,based on DT\|CWT decomposition,is presented in this paper.First,the NDVI and texture features of the image are extracted to reduce the classification uncertainty caused by the problem of different objects having the same spectrum and the same objects having different spectrum in the image,then,the original spectral band,NDVI and texture features of the image are decomposed by DT\|CWT to extract the Low\|frequency information of the image,as well as to reduce the image noise and the presence of “salt and pepper” in the classification.Finally,the extracted low\|frequency sub\|graphs are input to the BP neural network and classified according to the trained network to obtain the final classification result.The results of the comparison show that the proposed method with less miscellaneous points has stronger regional consistency,higher classification accuracy and better robustness.
  • Yan Pengfei, Ming Dongping
    Remote Sensing Technology and Application. 2018, 33(2): 321-330. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0321
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    Segmentation of high spatial resolution remotely sensed image is the important foundation of Object\|Based Image Analysis(OBIA), most of the image segmentation algorithms involve the problem of parameter setting. Self\|adaptive Parameterization is one of the key factors that affect the efficiency and effectiveness of remote sensing image segmentation. Considering that traditional watershed segmentation algorithm is susceptible to noise and the segmentation scale parameter is difficult to be self\|adaptively chosen,this paper propose a scale self\|adaptive method in watershed segmentation. After median filtering in primary image, this paper uses spatial statistical method to realize the self\|adaptive setting of watershed segmentation parameters, and then segments the high spatial resolution remote sensing image. This study uses IKONOS and Quickbird multispectral images as experimental data to testify the validity of the method proposed by this paper. The homogeneity within the segmentation parcels and the heterogeneity between thesegmentation parcels are used to build up a synthetic evaluation model to quantitatively evaluate the segmentation results by the proposed method by comparing with different parameter sequences segmentation results. The comparison result show that the proposed method perform well in high spatial resolution image segmentation. As result, the method proposed in this paper not only improves the accuracy of image segmentation to a certain extent, but also raises the automation of the segmentation parameter selection, which provides a new way for image segmentation and the research of parameterization in the future.
  • Zhang Yizhen,Han Zhen,Zhu Qingyi,Wang Yiqing,Hu Xuran
    Remote Sensing Technology and Application. 2018, 33(2): 331-336. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0331
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    Based on the correlation of the sea surface wind vectors to the sea surface roughness temperature in different seasons,wind field data of the Windsat L2 U10 wind fields in the northwest Pacific in January,April,July and October from 2012 to 2016 were selected,and used sea surface roughness Semi\|empirical and theoretical algorithm,the relationship between the brightness temperature gain caused by wind speed and wind vector under different seasons was analyzed.the results showed that the contribution of wind speed to horizontal brightness temperature gain was greater than that of vertical brightness temperature; the change of horizontal brightness temperature gain was the most significant in January and the least was in July; the maximum and minimum mean values of wind speed to vertical brightness gain were 0.19 K and 0.05 K respectively,indicating that the wind speed had little effect on the vertical brightness gain.It showed that the vertical brightness temperature gain was almost independent of the seasons by the standard deviation calculation; in April and October to form larger cyclone phenomenon in high latitude regions by the Pacific and Hawaii high pressure under the influence,and with brightness gain changes,showing obvious features of the North Pacific gyre.
  • Niu Minghui,Chen Fuchun
    Remote Sensing Technology and Application. 2018, 33(2): 337-341. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0337
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    The quantitative applications of satellite remote sensing,especially the application of detecting trends in environmental parameters,place stringent requirements on the stability of instruments and consistency among different platforms.The stability of lunar photometry in solar reflective bands makes it ideal calibration reference for on\|orbit calibration of satellite radiometers.The principle of lunar calibration is straightforward.Irradiance or radiance of the moon received by the instrument will not change if the relative geometry of the Sun,the Moon and the instrument remains unchanged.So the series of the Moon measurements can monitor the change of the instrument’s responsivity.The same relative geometry is unattainable due to the orbits of the Earth and the Sun and the operation of the satellite.The series of the Moon measurements should be corrected and normalized to the same geometry in order to determine the trend of the instrument’s responsivity.The main procedures of data processing are discussed,including lunar disk\|integrated irradiance calculation or mean radiance calculation,over\|sampling correction,distance correction,lunar phase correction and lunar liberation effect correction.The latter three items are also called geometric effects correction.Key methods of lunar phase correction and lunar liberation effect correction are analyzed,including method of multiple regression and data fitting for raw data and method based on lunar photometric models.The method of quantifying the trend of responsivity for satellite radiometer and the form of correction for calibration coefficients are proposed.

  • Xie Jingkai,Wang Fumin,Wang Feilong,Zhang Dongni 
    Remote Sensing Technology and Application. 2018, 33(2): 342-350. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0342
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    The vegetation indices that take the soil adjustment factor into consideration can reduce the influence of soil background conditions and have been widely used in monitoring all kinds of vegetation.However,the rice has been planted in the soil covered by a certain thickness of layer of water,which is different with other various soil backgrounds.Therefore,in this paper,through two years of rice plot experiments,we obtained the rice canopy spectral data and the corresponding leaf area index (LAI) data,and then calculated a series of vegetation indices (EVI,SAVI,WDVI) by using different soil adjustment factors changing within a certain range.We compared the abilities of these vegetation indices for rice LAI estimation,and then determine the optimum soil adjustment factors of vegetation indices to adjust the background of rice.In the study,we found that the best soil adjustment factor L for EVI,L of SAVI,a of WDVI are 0.25,0.10 and 1.25 respectively,and we further compared the LAI estimation results of the best soil adjustment factor with those of the conventional soil adjustment factor.For the model taking EVI as an independent variable,the RMSE of LAI estimation using the best soil adjustment factor is 6.82 % lower than that using the conventional soil adjustment factor;In SAVI model,the RMSE using the best soil adjustment factor is 10.23% lower than that using the conventional soil adjustment factor .These results indicate that the corrected vegetation indices considering the background of rice can improve the accuracy of rice leaf area index using remotely sensed data.
  • Chen Siyu,Gong Yinxi,Liang Tiangang
    Remote Sensing Technology and Application. 2018, 33(2): 351-359. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0351
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    Based on ICESat data and temperature and precipitation from 2003 to 2010 and used ANUSPLINE interpolation method and Theil\|Sen’s method,we analyzed and discussed lake water level change characteristic from 2003 to 2010,as well as the temporal\|spatial response of lake water level to climate changes.the results showed that most of lakes mainly distribute in the central and western region of TP,and their lake water levels are mainly between 4 500 to 5 000 meters.Lake water level of Tak kyel and Yamzhog Yumco in the southern of TP as well as Panggong in the western of TP showed a decreasing trend.Analysis of the relationship between lake water level and climate factor indicated that lake water level in different basin showed different trends because of varied temperature and precipitation.the increasing trend of lake volume was not only dependent on direct supply of precipitation,but also effected by melted water from glaciers and snow due to climate warming.
  • Li Xiang,Liu Kai,Zhu Yuanhui,Meng Lin,Yu Chenxi,Cao Jingjing
    Remote Sensing Technology and Application. 2018, 33(2): 360-369. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0360
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    A hybrid mangrove forest extraction and species classification model for large coastal region was proposed using a ZY-3 (ZiYuan-3) image in the eastern part of Beibu Gulf (located at the junction of Guangdong and Guangxi).Firstly,the coastline was extracted according to the spectral features of ZY-3 image.Secondly,the buffer zone along with the coastline was generated as the suitable area of mangrove distribution.Mangrove forests and non-mangrove areas were then further classified using threshold method based on object-based image classification in these areas.Finally,Mangrove forests were classified at specie level using three pixel-based supervised classification methods,k-Nearest Neighbor,Bayes,and Random Forest.The classification results and accuracies were also compared and discussed.The results indicated that object-based threshold method can extract the coastline accurately and map the mangrove forests effectively.The pixel-based random forest classifier can obtain satisfactory results (the overall accuracy of 82.24%) of mangrove species classification than the other classifiers.In summary,the hybrid mode proposed in this paper is suitable for mangrove forests mapping and species classification in a large region.It is also validated the feasibility application of ZY-3 image in coastal mangrove research.
  • Meng Qingyan,Sun Yunxiao,Zhang Jiahui,et al
    Remote Sensing Technology and Application. 2018, 33(2): 370-376. https://doi.org/10.11873/j.issn.1004-0323.2018.2.0370
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    Taking as Székesfehérvár,Hungary a case study,vertical greenery distribution and spatial allocation is studied.Based on the multi\|source remote sensing data,three-dimensional information of urban green space and buildings is extracted.A height sampling method is used to quantify the vertical distribution of green space and building space.According to the spatial allocation relationship,the vertical space is divided into “Green\|deficient layer” and “Green\|sufficient layer”,and the vertical spatial allocation characteristics of different function zonings are compared and analyzed.Case study findings indicate that:(1) greenery vertical structure of residential area and commercial area are similar,but residential area has greater allocation quantity; (2) the first to third building floors in commercial area are considered green-deficient due to the shortage of green space allocation and its monotonous vertical structure,and there is inadequate green space provision for high\|rise building floors in residential area; (3) the major cause for low\|rise green deprivation in commercial area is the high density of low\|rise building structure,and neglecting skyrise greenery results in the high\|rise green deprivation in residential area.