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    25 January 2018, Volume 0 Issue 1
    A Review of the Mobile Trajectory Clustering Methods
    MOU Naixia, XU Yujing, ZHANG Hengcai, CHEN Jie, ZHANG Lingxian, LIU Xiliang
    2018, 0(1):  1-7.  doi:10.13474/j.cnki.11-2246.2018.0001
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    Mobile trajectory data is the representation of human mobile behavior.Mining this kind of data and discovering their latent semantic information can map the people's travel patterns and social attribute,etc.The clustering method based on similarity is a common method of data mining.Trajectory clustering can be used to find the object group of the similar behavior,so as to find the relevant moving patterns.According to the characteristics of the trajectory data,the trajectory data model is divided into trajectory point model and trajectory segment model,and the corresponding similarity measure is defined:spatial similarity measure and spatio-temporal similarity measure.Then,the clustering methods of two models are reviewed,and the advantages and disadvantages of the algorithms are also summarized,which provide the basis for effective selection of clustering algorithms.Finally,the development trend of the research on the clustering method of the moving trace data is discussed.

    Summary of the Research Progress of Seafloor Geodetic Control Network
    LI Linyang, LÜ Zhiping, CUI Yang
    2018, 0(1):  8-13,87.  doi:10.13474/j.cnki.11-2246.2018.0002
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    The high-precision seafloor geodetic control network is one of the infrastructures of digital ocean and underwater network centric warfare. However, the construction and research of seafloor control network at present is almost blank in China. To autonomously establish high-precision seafloor geodetic control network, this paper draws on the experience of the developed countries. Firstly, the development and current situation of the foreign seafloor control network are combined, and the composition and development of GNSS/Acoustic system are introduced systematically.Then the key technologies of data processing are studied in detail, the factors that affect the positioning accuracy of seafloor control point and its positioning accuracy are analyzed.Finally, taking the present situation in our country into account, immediate steps should be taken to speed up the construction and research of the seafloor control network.

    The Research Status Analysis on Multi-baseline Tomographic SAR
    XU Xigui, PANG Lei, ZHANG Xuedong, LIU Hui, CHEN Yang, WEI Shiying
    2018, 0(1):  14-21.  doi:10.13474/j.cnki.11-2246.2018.0003
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    Tomographic synthetic aperture radar (tomographic SAR) is an information inversion technology developed from the interferometric SAR (InSAR).Tomographic SAR makes up the shortages of the traditional InSAR resolving ability loss in height direction,which really achieves three-dimensional imaging in the azimuth,range and height direction.This paper introduces the principle of tomographic SAR imaging,and discusses the problems about complex image registration,deramping,phase errors compensation and height direction imaging.In the same time,three types of tomographic SAR algorithms and the applications in various fields are studied and summarized.Eventually,the existing problems and developing trend of tomographic SAR imaging are discussed.

    ISB Analysis and Function Model Design in the Real-time BDS/GPS Clock Estimation
    GU Shouzhou, SHI Chuang, DANG Yamin, BI Jinzhong, XUE Shuqiang, ZHANG Longping
    2018, 0(1):  22-27.  doi:10.13474/j.cnki.11-2246.2018.0004
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    The real-time clock product is the basis products for the high precision wide-area positioning service.Focus on inner-system bias of BDS/GPS,we have studied the ISB difference of BDS GEO/IGSO/MEO with various GNSS receivers,and then proposed three ISB parameters model,finally real-time BDS/GPS clock estimation is achieved with undifferenced method. The BDS/GPS observations of 78 MGEX global sites and 2 Hunan province CORS site are collected to generate the real time clock products that was compared with the final iGMAS precise clock product in two strategies (the old model and the new model). The results show that the accuracy of GPS clock estimation is equivalent with the two strategies,and the accuracy of BDS clock estimation is improved significantly with the new method,especially for the BDS IGSO/MEO satellite,the improvement is more than 20%,which verifies the validity of the algorithm.

    Height Anomaly Fitting Based on EGM2008 Model and Weighted Composite Model
    LUO Taorong, WANG Zhongyuan, LIANG Ning, MA Xiaoshen
    2018, 0(1):  28-32.  doi:10.13474/j.cnki.11-2246.2018.0005
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    Height anomaly fitting is an important technical means that the value of GPS height measurement is applied in practice.In this paper,the height anomaly fitting method based on EGM2008 gravity field model is proposed that the long wave item of height anomaly is calculated through EGM2008 gravity field model and the residual height anomaly is fitted through weighted composite model.The measurement data is used to verify the performance of weighted combination model based on EGM2008 gravity field model in the city of Jiangsu province.Numerical results show that the method proposed can increase the performance of this method by 30% and reach centimeter-level in height anomaly fitting.

    Accuracy Analysis of Network RTK Interpolation Models for Rover Station Tropospheric Delay Correction
    LI Ying, CHEN Mingjian, ZUO Zong, YAO Xiang
    2018, 0(1):  33-37,43.  doi:10.13474/j.cnki.11-2246.2018.0006
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    The accurate correction of the double-difference tropospheric delay error between the rover station and the reference station is key to the network RTK technology.In this paper,the experiments are based on the observation data from seven reference stations of Henan province ground based augmentation system (GBAS).The linear interpolation method (LIM),the linear combination model (LCM),the low order surface fitting model (LSM) and the kriging interpolation method model (KRG) are selected as the research object.Each model are analyzed for the effect of the correction of tropospheric delay error in several rover stations with different elevation difference level.The experimental results indicate that the LIM and the KRG are more accurate in correcting the tropospheric delay among the four conventional interpolation models.When the height difference between the rover station and the main reference station reaches to 400 meters,the interpolation accuracy of the model is reduced to the decimeter level for the low altitude angle satellite,in which the demands of high precision positioning in rover station cannot be met.

    Co-seismic and Post-seismic Gravity Changes of the Japan Mw9.0 Earthquake from GRACE RL05 Data
    YIN Peng, ZHANG Yongzhi, JIAO Jiashuang, NAN Kangkang, WANG Huiling
    2018, 0(1):  38-43.  doi:10.13474/j.cnki.11-2246.2018.0007
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    Based on the RL05 earth gravity field model released by GFZ,considering the influence of the terrestrial water reserves in the global land data assimilation system,the co-seismic and post-seismic gravity changes caused by the 2011 Japan Mw9.0 earthquake is successfully extracted by using the method of stacking and 300 km fan filter.The gravity annual variation rate of the two characteristic points around the epicenter is calculated as well by using the method of least squares fitting in 85 months before and after the earthquake.The results show that the gravity change caused by the soil moisture content and accum snow is -0.34~0.09 μgal; the co-seismic gravity changes from the GRACE RL05 data is -5.3~4.2 μgal,which is consistent well with the result based on the PSGRN/PSCMP model in spatial distribution and order of magnitude; the gravity increasing trend is showed in the area around the epicenter in 5 years after the earthquake,the maximum increase in gravity of the Sea of Japan the upper plate locates and the Pacific Ocean the subduction area locates is 2.6 μgal and 4.5 μgal,respectively,the gravity of the subduction area increases greater,indicating that the viscosity of the subduction area is relatively lower than that of the up-lift zone.

    Color Remote Sensing Imagery Segmentation Based FCM within a MAS Framework
    LI Yu, LIN Wenjie, ZHAO Quanhua
    2018, 0(1):  44-49,71.  doi:10.13474/j.cnki.11-2246.2018.0008
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    For the large-scale remote sensing imagery which has large data and local feature heterogeneity, this paper presents a color remote sensing imagery segmentation method based FCM within a multi-agent system framework. Firstly, dividing the image domain into several sub-domains with rule division tecnology and each segmentation agent controls one sub-domain. And then, the segmentation agent executes the segmentation of its sub-domain by FCM to get the initial local segmentation result within MAS framework, via the harmonizing the local result with the global segmentation result to obtain the true local class number and unify the local label. Finally, the coordinate agent is employed to eliminate the local feature heterogeneity of remote sensing imagery via coordinating the cluster centers of each segmentation agent with its neighbors. The experiments are carried out on the synthetic imagery and the color remote sensing images. The results are qualitatively and quantitatively evaluated and certify the efficiency and effectiveness of the proposed algorithm.

    A New Semi-supervised Change Detection Method of Fusing Spatial Information
    XIE Fuding, YU Shanshan, YANG Jun
    2018, 0(1):  50-54.  doi:10.13474/j.cnki.11-2246.2018.0009
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    Based on the improved semi-supervised fuzzy c-means (SSFCM) algorithm and Markov random field, this paper presents a new semi-supervised change detection method considering spatial information. The difference image is firstly obtained by subtracting two original remote sensing images, and a novel labelling method is introduced by the values of band 4. Then difference image is clustered by SSFCM and labeled samples. To find good monitoring result and remove noise points, this work considers the spatial information of pixels and markov random field. The final monitoring result is obtained by updating the membership matrix. In order to show the validity of the proposed method, two TM remote sensing images are chosen to feed our method to detect the change of forest. The experimental results indicate that the improved semi-supervised FCM algorithm can reduce the missed alarm rate, and Markov random field method can remove the noise points in the process of clustering and reduce the false alarm rate.

    Hyperspectral Image Dimension Reduction Based on Manifold Learning Approach DLA and Tree Species Classification
    WANG Shaohua, YANG Ting
    2018, 0(1):  55-61.  doi:10.13474/j.cnki.11-2246.2018.0010
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    Hyperspectral image has great potential in the classification and recognization of different objects, whose inherent physical and chemical properties can be reflected by the spectral features of the image bands. In order to overcome the high redundancy among the large number of bands of hyperspectral image, efficient dimensional reduction algorithms should be applied to improve the performance of image classification. In this paper, we present a modified manifold learning algorithm termed discriminative locality alignment (DLA) for the dimensional reduction of Hypersion image data. The proposed method transformed the original spectral feature space into the optimal low dimensional subspace by imposing discriminative information which from given raining samples in the manifold learning framework. In this subspace, the maximum likelihood classifier was then used to classify each pixel of the Hypersion image.Meanwhile,the classifycation results based on the dimensional reduction algorithms of principle component analysis (PCA) and original spectral were compared with the performance of classification based on DLA. The experiments showed that DLA can effectively improve the classification accuracy of hyperspectral image data, and obtained satisfactory classification results for tree species.

    Remote Sensing Image Classification of GABA Algorithm
    NIU Yingchao, ZHOU Zhongfa, WANG Li, WANG Xiaoyu
    2018, 0(1):  62-66,71.  doi:10.13474/j.cnki.11-2246.2018.0011
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    In order to make up for the shortcomings of bat algorithm optimization in late, which convergence rate is slow, the accuracy is not high, and easy to fall into the local optimum, this paper proposes a new classification algorithm-GABA algorithm for remote sensing image, and in the algorithm, the operations of genetic algorithm, including selection, crossover, mutation operator are applied to the bat algorithm. It turns out that the bat algorithm with mutation mechanism to avoid the population into local optimum, improve the ability of global optimization algorithm to increase the diversity of bat algorithm. As the same time, in order to highlight the advantages of this algorithm, experiments compared the results of bat algorithm, K-Means algorithm, particle swarm algorithm and the algorithm, analyze and evaluated the classification results of remote sensing images. And experiments show that in the application of remote sensing image classification, this algorithm can not only improve the classification accuracy, but also reduce the classification time. It is a feasible and effective method for remote sensing image classification.

    AOD Data Fusion Method Based on Quadratic Polynomial
    LI Guangchao, LI Ruren, ZHAO Yangyang, YANG Zhen, LU Yueming
    2018, 0(1):  67-71.  doi:10.13474/j.cnki.11-2246.2018.0012
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    Aiming at the problem that Aqua and Terra MODIS AOD data are not accurate enough by linear regression algorithm,this paper proposes a quadratic polynomial regression algorithm to fit it,the quadratic polynomial means that the polynomial has more than 1 number and the highest square number is 2.The quadratic polynomial regression and linear regression algorithm were used to fit the randomly selected day and the AOD data from April to June respectively,and the results of the two methods are compared and analyzed.The results show that the RMSE,MAE,R values obtained by the quadratic polynomial regression method are much better than those obtained by the linear regression fitting method for the fitting of the same group of Aqua and Terra MODIS AOD data.It is shown that the quadratic polynomial regression fitting method is better than the fitting of the linear regression method in the fitting of Aqua and Terra MODIS AOD data,and it is proved that the quadratic polynomial regression fitting method is suitable for this research and can improve the accuracy of Aqua and Terra MODIS AOD data fitting results.

    Response Analysis of Land Cover Types on Urban Heat Island Effect
    YI Chuanxiang, HU Jichao, LI Xiaojun
    2018, 0(1):  72-76,116.  doi:10.13474/j.cnki.11-2246.2018.0013
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    This paper uses MODIS surface temperature data and land cover products in summer, combines with Landsat and other remote sensing data to extract the information of land cover and land surface temperature in Jinan, Wuhan and Chongqing in 2003,2008,2013,to determine the distribution of heat island grades in the three cities in different years. On this basis, it analyzes the relationship between the characteristics of land surface temperature, the distribution of heat island and the factors of land cover types in Jinan, Wuhan and Chongqing. The results show that urban land use is the main contributing factor of urban heat island, and the correlation coefficient is 0.42.The most effective way to alleviate the urban heat island effect is forest land, and the average correlation coefficient is -0.41.The best land type to alleviate the urban heat island is not exactly the same in three cities:Jinan's is forest land and cultivated land,Wuhan's is water,Chongqing's is forest land.

    Object Detection in High Resolution Remote Sensing Images Based on Fully Convolution Networks
    XU Yizhi, YAO Xiaojing, LI Xiang, ZHOU Nan, HU Yuan
    2018, 0(1):  77-82.  doi:10.13474/j.cnki.11-2246.2018.0014
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    Object detection is one of the research hotspots in remote sensing image analysis and processing,and has very important research and application value.Traditional remote sensing image target detection method uses the shallow artificial feature,and combines with classifiers,such as support vector machine,random forest and Adaboost,to realize object detection task.In recent years,deep learning,especially convolution neural network (CNN),has achieved great success in image recognition.In the field of target detection,the Faster R-CNN algorithm has made a breakthrough,the detection accuracy has been greatly improved,and the detection procedure has achieved nearly real-time performance.However,the Faster R-CNN algorithm uses RoI (region of interests) pooling layer,the RoI-wise calculation is not shared,so the detection speed is still unsatisfying.R-FCN,however,is based on the fully convolution network structure,and the position-sensitive pool is used to tackle the translation variance problem,which is concealed by the convolution neural network,thus lead to performance improvement.In this paper,the principle of R-FCN is described and applied to the detection of high-resolution remote sensing images.Different parameters and network structure are analyzed to find the best configuration.The performance of three popular algorithms,including Fast R-CNN,Faster R-CNN and R-FCN are compared.Experimental results show that R-FCN can achieve 99.3% precision and achieve at a test-time speed of 180 ms per image.

    A Method of the Transformation from DDM for Non-navigation to DDM for Navigation
    CAO Hongbo, ZHANG Lihua, HUANG Wenqian, JIA Shuaidong, LIU Xianpeng
    2018, 0(1):  83-87.  doi:10.13474/j.cnki.11-2246.2018.0015
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    Aiming at the problem that digital depth model (DDM) for non-navigation can't be directly applied to navigation, a method of the transformation from DDM for non-navigation to navigation based on the fitting surface of depth uncertainty is proposed. Uncertainty propagation of modeling point of DDM for non-navigation is calculated by the original depth uncertainty based on uncertainty synthetic method. Terrain representation uncertainty of DDM for non-navigation is estimated based on test point method, and then comprehensive uncertainty of modeling point is acquired. The uncertainty fitting surface is constructed based on grid bilinear method by comprehensive uncertainty of modeling points of DDM for non-navigation, and depth uncertainty at any point in the DDM is estimated to improve the probability of an adequate depth of DDM for non-navigation. The experimental results demonstrate that the proposed method is feasible and can greatly improve probability of an adequate depth of DDM for non-navigation, so as to meet the requirements of the safety of ship navigation.

    Application of Large Elliptic Ellipsoid Gauss Projection in High-speed Railway
    FENG Ligang, YAO Dexin, JIN Lixin
    2018, 0(1):  88-91,124.  doi:10.13474/j.cnki.11-2246.2018.0016
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    In order to reduce the problem of projection band transformation of the control point data in the east-west long projective engineering when Gaussian transformation is performed, the paper proposes to establish a large elliptical ellipsoid with the large elliptical line near the center line of the engineering line or its neighborhood. The large elliptic ellipsoid parameters are obtained according to the nonlinear programming optimal theory and ellipsoid transformation is finished,and then the Gauss projection is based on the new ellipsoid.

    Research on Gate Opening Measurement Based on Image Analysis of Bar Code
    XI Xiuxiu, SUN Jiuyun, WANG Yunjia, ZHANG Xinnai, LIU Keqiang
    2018, 0(1):  92-96.  doi:10.13474/j.cnki.11-2246.2018.0017
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    The gate opening measurement is one of the basic indicators of hydraulic gate monitoring.The traditional gate opening measurement method has low measurement accuracy and large measurement difficulty.To solve the problem of measuring gate opening,this paper researches the measurement methods of image analysis based on bar code.Aiming at the limitation of three cycle spacing bar code encoding,a new coding and decoding method is proposed.Finally we establish a complete set of gate opening measuring and monitoring system.The results show that this system can real-time automatic measure gate opening,whose accuracy is high and stability is strong.And the improved coding and decoding method of the bar code image analysis method can obtain better gate opening measurement results,provide effective solutions for the actual engineering measuring gate opening.

    An Improved Map Matching Algorithm for Floating Car
    ZHAO Shuxu, ZHANG Jinqiu, QU Ruitao
    2018, 0(1):  97-102.  doi:10.13474/j.cnki.11-2246.2018.0018
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    The existing map-matching algorithm can not take into account the matching accuracy and matching efficiency when it applies to the floating car GPS data of low frequency sampling.Based on this,an improved map matching algorithm is proposed in this paper.The set of candidate road is determined efficiently based on the improved adaptive electronic map mesh partition method.The optimal matching section and the matching point are determined accurately based on the weighted sum,including the shortest distance weight,the weight of the vehicle heading,the weight of the shortest path and the weight of the track direction.The experimental results show that the proposed algorithm can improve the matching accuracy and the matching efficiency at the same time.

    A Viewshed Analysis Algorithm for 3D Urban Buildings
    JIN Hailiang, LI Liulei, YUAN Songhe, GENG Wenxuan
    2018, 0(1):  103-106.  doi:10.13474/j.cnki.11-2246.2018.0019
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    As a kind of spatial analysis method of 3DGIS, viewshed analysis has a wide application in urban planning,military and archaeology. And its realization is mainly based on visibility analysis. In this paper, the minimum rectangle bounding box of one building is extracted based on the relative regularity of the shape of three-dimensional models of most urban buildings. Based on the position of the viewpoint and the building models, the visible points of each building model are extracted.Then we connect the viewpoint and the visible points of the building model in turn to generate a cone.We make the difference set between the projection area on the plane of one cone bottom surface and the polygon of the other one cone bottom surface as the visible surface of one building model, thus avoiding calculating the visibility of every point of the building model and reducing the computation amount.The final visualization of the results also proves the feasibility and effectiveness of the algorithm.

    An Approximate Equal-area Diamond Mesh Model Based on Latitude-ring Method and Triangle Aggregation
    YUAN Zhengyi, ZHAO Xuesheng, ZHAO Jing
    2018, 0(1):  107-111.  doi:10.13474/j.cnki.11-2246.2018.0020
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    The spherical diamond grid has been widely used in space operation and data integration, because of its geometrical features, such as the simple structure, the orientation consistency, and the radial symmetry. In this paper, a QTM subdivision model based on the latitude-ring (L-R) method is constructed. The grid area deformation and its location distributions are also analyzed. Then we find that the grid area deformation of this model has the same direction and the "zigzag" distribution characteristics, which means that the adjacent two grid cells are alternatively distributed, one large and one small. So we obtain an approximate equal-area diamond mesh model by merging the two adjacent grid cells up and down. The results show that, compared to other methods of generation spherical diamond mesh, this one is simple in calculation (the long axis distributes along the north and south direction). At the same time, the grid cell generated by this method has a smaller area deformation and more uniform distribution.

    Impact of Deviation of GPT Model and GPT2 Model on Positioning Results
    ZHENG Yun, WANG Hongdong
    2018, 0(1):  112-116.  doi:10.13474/j.cnki.11-2246.2018.0021
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    The global models of pressure and temperature GPT and GPT2 can be used to obtain meteorological elements such as pressure and temperature of GPS sites,which play an important role in calculating tropospheric delay and are widely used in high precision GPS data analysis.The improvement of GPT2 model to GPT model has been validated in many literatures while there is no detailed analysis on the deviations of coordinate time series obtained by using these two models respectively.In this paper,we use the GPT model and GPT2 model to deal with the same continuous observation data respectively.As a result,we find that the seasonal variation of the deviation of the pressure leads to the seasonal variation of the site vertical positioning estimates,which is one of the sources that lead to aliased seasonal signals.Simultaneously,the influence of the deviation of the pressure on the site vertical positioning estimates is related to the site latitude,showing that the ratio of the deviation of the priori zenith delay to the vertical position is increased as the latitude of the site increases.

    An Ionospheric Delay Correction Model Based on Taylor Series Expansion
    ZHANG Zhaolong, WANG Yuegang, TENG Honglei, WANG Le
    2018, 0(1):  117-120.  doi:10.13474/j.cnki.11-2246.2018.0022
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    Aiming at the effect of ionospheric delay error on the positioning accuracy, a Taylor series expansion model (TSE model) based on Taylor series expansion is proposed in this paper. And we compare this model with the traditional Klobuchar model and NeQuick model in the accuracy of VTEC and positioning accuracy. Using the measurement data provided by IGS website, the simulation results show that the TSE model can improve the accuracy of positioning and have better time adaptability.

    Design of Integrated Application Middleware of Independent Network CORS and Location Service Platform
    SONG Chuanfeng, ZHANG Hongwen, XIAO Qinghuai, ZHOU Yuan, LIU Yuxin
    2018, 0(1):  121-124.  doi:10.13474/j.cnki.11-2246.2018.0023
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    For the realization of the integrated application of independent network CORS and location service platform,this paper has designed and developed a middleware which is location routing tool.Using this tool,forwarding the location information between different networks and at different encoding protocols has been realized,such as HLJCORS and the location service platform in heilongjiang province.The research results of this paper can be used as reference for other similar projects.

    Application of an Improved ELU Convolution Neural Network in the SAR Image Ship Detection
    BAI Yu, JIANG Dongmin, PEI Jiajun, ZHANG Ning, BAI Yu
    2018, 0(1):  125-128.  doi:10.13474/j.cnki.11-2246.2018.0024
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    With the development of space technology,the SAR load detection system in our country is showing the development trend of variousness and multi resolution.Since the traditional detection identification methods are difficult to satisfy the multiresolution and various characteristics of SAR image data,it's necessary to seek a different method to extract effective features from the multiresolution image data.For the rapidly development of intelligence,our scheme bases on the characteristics of SAR image proposes the convolution of the improved neural network method and utilizes ELU as an activation function to establish the deep learning model,which combined with the ELU and quadratic cost function.At the same time,based on the training sample, we establish the sample characteristics and centric distance functions,and then use the fuzzy support vector machine to classify the extracted characteristics.The experimental results show that the proposed method can improve the noise resistance of SAR image for the ship detection, and the detection rate can reach up to 98.6%.
    Inversing of Vegetation Biomass Based on GPS-R
    ZHOU Xiaomin, ZHENG Nanshan, QI Yun, CHEN Shun
    2018, 0(1):  129-132,137.  doi:10.13474/j.cnki.11-2246.2018.0025
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    To verify the feasibility of using GPS-R technology to inverse vegetation biomass,the principle and method inversing vegetation biomass using GPS reflected signal were introduced.The paper performed an experiment to calculate the signal reflectivity using ICF. Using the relationship between the reflectance signal and vegetation biomass,the vegetation biomass was figured out and compared with the result of NDVI remote sensing.The results indicate that it is feasible to retrieve vegetation biomass using GPS-R remote sensing,which has great significance in vegetation plant and carbon emission investigation.

    Groundwater Storage Changes in Shan-Gan-Jin Plateau Derived from GRACE
    XIE Xiaowei, XU Caijun, GONG Zheng, LI Wei
    2018, 0(1):  133-137.  doi:10.13474/j.cnki.11-2246.2018.0026
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    The GRACE and GLDAS were used to invert variation of groundwater reserves in time and space in the Shan-Gan-Jin plateau.The results show that the groundwater reserves decreased at the rate of 3.6±0.7 mm/a from 2005 to 2014,and the decreasing rate was increasing from west to east in space.By comparing with the TRMM rainfall data and measured wells data,it was found that rainfall was strongly associated with changes in groundwater reserves,but not the cause of reduced groundwater reserves.And the results we obtained were basically the same as those of well water level,the special cases excluded.

    Object-oriented Extraction Method of Typical Urban Features Based on GF-2 Images
    WANG Lei, YANG Wunian, REN Jintong, DENG Xiaoyu
    2018, 0(1):  138-142.  doi:10.13474/j.cnki.11-2246.2018.0027
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    Domestic Gaofen remote sensing images have abundant information,which can provide accurate details of spatial objects.It is of great significance to study Gaofen data processing and the method of extracting urban objects in depth.Taking the remote sensing image of domestic GF-2 as the data source,the optimal segmentation scale is obtained through the ESP scale analysis tool which is based on the object-oriented classification method of rule set.And then the feature system and the classification rules of various features are established to extract the information of typical urban features. The results are compared with the traditional pixel-based SVM supervised classification.The results show that the overall accuracy of object-oriented classification of rule set is 92.23%,and the Kappa coefficient is 0.9,which is significantly improved compared with SVM supervised classification.For high-resolution images such as GF-2,the object-oriented classification method is more accurate and has a better graphical effect,which is an effective method for urban object extraction.

    Application of Unmanned Aerial Vehicle Tilt Photogrammetry in Planning Schemes Comparison and Selection
    WANG Baoguo, ZHANG Runke
    2018, 0(1):  143-146.  doi:10.13474/j.cnki.11-2246.2018.0028
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    Based on the 3D model of real environment generated by tilt UAV photogrammetry, this paper imports the 3D model of real environment to planning 3D scheme, and integrates planning scheme 3D model with real 3D model. After achieving seamless integration planning schemes, we can compare and select them from different perspectives, different direction observations.Then we can grasp planning direction well. Finally, the buildings within the whole planning should be in accordance with the surrainding style. In the end, we can choose better planning scheme.

    Study on Prediction Method of Dam Deformation for GNSS Automatic Monitoring System
    HUANG Kai, CHEN Qusen, JU Boxiao
    2018, 0(1):  147-150.  doi:10.13474/j.cnki.11-2246.2018.0029
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    This paper aims to study on prediction method of dam deformation for GNSS automatic monitoring system.According to the GNSS deformation monitoring data's characteristics of large sample,high sampling rate and continuous,a new method combining wavelet analysis with BP and NAR Neural network to predict dam deformation is presented.Firstly,we use multi-scale wavelet analysis to decompose and reconstruct the deformation monitoring data sequences.Then,the BP neural network is used to forecast the low frequency approximation sequences,and the NAR neural network is used to forecast the high frequency detail sequences.Finally,the forecasting results of each scale are accumulated to get the prediction results of dam deformation.The application shows that the proposed dam deformation forecasting model in this paper has high predictive accuracy and great generalization performance,which can be widely used in dam deformation prediction for GNSS automatic monitoring system.

    Design and Implementation of the Hybrid-pattern-based Land Investigation APP:Taking Wuhan City Land Planning Law Enforcement Monitoring Mobile System as an Example
    YU Jian, TONG Qiuying, ZHU Bo, WANG Wenhao
    2018, 0(1):  151-156.  doi:10.13474/j.cnki.11-2246.2018.0030
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    This paper studies the design ideas of land investigation APP,which is based on Hybrid (Ionic+Cordova) development pattern and combined with SOA architecture and WebGIS technology.It introduced the architecture and implementation of the system in details,and described the core functions and key technologies.In the practical application of Wuhan City,the feasibility and correctness of the system are verified.Compared with the traditional system development application system,the system has significant advantages in cross platform,high performance and low cost.

    Optimization of Gaussian Process Model Based on Artificial Fish School Algorithm and Its Application Analysis
    QIU Xiaomeng, ZHOU Shijian, WANG Fengwei, OUYANG Liangyou
    2018, 0(1):  157-160,164.  doi:10.13474/j.cnki.11-2246.2018.0031
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    Based on the Gaussian process,the traditional conjugate gradient method is used to search the hyper-parameters, which has the disadvantages of strong dependence on the initial value and obtain local optimal solution. Artificial fish swarm algorithm is used to optimize the hyper-parameters intelligently, and the Gaussian process model based on the artificial fish swarm algorithm is used to predict and analysize the deformation of deformable body. Through the tunnel and foundation pit examples to compare the calculated results, NN kernel function is the best predictor of NN, SE and RQ, the average relative error is 0.69% and 1.06%. The results show that the prediction accuracy of the hyper-parameters optimization model are greatly improved, and the hyper-parameters solving of the Gaussian process algorithm themselves are improved and the effect is obvious.

    Discussion on Research-based Teaching Methods of Course of Global Navigation Satellite System Principle
    LIAN Dajun, CHEN Guodong, YUAN Ming, ZHANG Xu
    2018, 0(1):  161-164.  doi:10.13474/j.cnki.11-2246.2018.0032
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    In order to solve the problems in the course teaching of global navigation satellite system principle,this paper puts forward a set of teaching ideas which includes emphasizing important points,designing teaching contents,strengthening initiative learning,designed the methods of theory teaching,practical environmental designing, and experimental and practical teaching.By adopting the efficient ways of emphasizing important contents,introducing engineering cases,designing teaching environment,and varying teaching with each individual,it could highlight the design and research-based teaching with a good teaching effect.