Table of Content

25 June 2020, Volume 0 Issue 6

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An indoor localization method based on adaptive particle filter fusion of geomagnetism,WiFi and PDR

LU Yanling, WEI Junling, LIU Caiwei, LI Jingwen, JIANG Jianwu

2020, 0(6):  1-6.  doi:10.13474/j.cnki.11-2246.2020.0170

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With the rapid development of national economy, people spend more and more time on indoor activities, indoor space environment is more and more complex, the demand for location and navigation services for indoor environments is also increasing. Due to the stability of geomagnetic signals and the widespread deployment of WiFi technology, the integration of geomagnetic and WiFi positioning has certain advantages. Therefore, this paper deals with the acquired signals adopting from adaptive particle filter model and random sampling consistency algorithm by fusion of geomagnetism,WiFi and pedestrian dead reckoning(PDR) based on the Android smart phone as the receiver. Experiments show that compared with other single-class methods, the indoor localization method of fusion of geomagnetism,WiFi and FDR can reduce the error of indoor localization accuracy to 1.02 m.

Context-aware landmark detection assists WiFi-PDR indoor localization

HE Xiaona, SONG Binbin, YU Min

2020, 0(6):  7-11,16.  doi:10.13474/j.cnki.11-2246.2020.0171

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Aiming at the instability of WiFi signal and the large cumulative error of PDR(pedestrian dead reckoning) in the current WiFi-PDR indoor localization, a context-based landmark detection assisted WiFi-PDR indoor localization method is proposed. This method uses the context information monitored by smart phones to establish a user model, and uses the user behavior perception based on convolutional neural network and coarse-grained location perception based on WiFi-PDR indoor localization to discover the hidden indoor landmark information, and completes the user's location correction at the landmark location to improve the positioning accuracy. This method reduces the indoor localization error of WiFi-PDR to some extent and improves the indoor localization accuracy of users. The experimental results show that the accuracy of the indoor localization method is 43.62% higher than that of the traditional WiFi-PDR method.

Application of density map based on improved MCNN in indoor localization

ZHAO Qi, SUN Lishuang, XIE Zhiwei

2020, 0(6):  12-16.  doi:10.13474/j.cnki.11-2246.2020.0172

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A large number of shopping crowds in Beijing shopping malls are prone to crowded and trampled accidents, making it necessary to determine the location of high-density population areas. Therefore, population density maps are introduced to determine the distribution of populations in the map, and the location information of indoor populations is obtained. Firstly, the collected crowd video is divided into image frames and divided into training sets and test sets. Then, the human head label processing is performed on the training set image, and the ground truth density map is generated as the training data of the improved multi-column convolutional neural network algorithm and the model is generated, and the model is applied to the test set image to generate the population density map. Finally, use ArcGIS to georeference the population density map and the indoor plan to achieve high-density population positioning. The results show that the position coordinates of the high-density area determined by the population density map are basically consistent with the actual coordinate values, indicating that the new idea of applying the population density map to indoor localization is feasible.

An indoor localization method combining WiFi, geomagnetism and PDR

WANG Zhaoyuan, GAO Jingxiang, LI Zengke, CHANG Mengyang

2020, 0(6):  17-21.  doi:10.13474/j.cnki.11-2246.2020.0173

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This paper proposes an improved particle filtering method that uses indoor WiFi signals, geomagnetic sources, and cheap smartphone sensors to perform indoor localization. WiFi indoor localization has fewer mismatches and geomagnetic fingerprint indoor localization has strong anti-interference ability, this paper uses the advantages of both and combines PDR to provide continuous location information. Compared with traditional particle filtering, MD-DTW (multi-dimensional dynamic time warping) is used to determine the weight of particles, and a segmented particle weighting method is proposed to constrain the length of the particle sequence, which can effectively accelerate the convergence speed of particle filtering. Simulation experiments show that the improved particle filter can achieve a positioning result of 1 m, which has strong practicability.

Summary of road information extraction methods

LI Xiaolong, ZHANG Yun

2020, 0(6):  22-27.  doi:10.13474/j.cnki.11-2246.2020.0174

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Road information extraction aims to extract information on a road by using relevant data and methods, such as the number of lanes, centerlines and boundary lines. Road information extraction has important application value in transportation planning and vehicle navigation. With the wide application of various sensor devices, the explosion of traffic data and the method of road information extraction are changing rapidly. This paper reviews the research progress of road information extraction recently. The road information extraction method is divided into three categories based on video and data, high-density point cloud data and floating vehicle trajectory data according to the data source, and these three categories are discussed in depth. The main implementation algorithms of the method, and the comparative analysis of these algorithm models, finally explored the future research trends and challenges of the existing road information extraction methods.

Forest resource data obtained by UAV stereo photography

HE Cheng, DONG Zhihai, WANG Yue, LI Jin, LI Kaiping, HOU Senlin

2020, 0(6):  28-31.  doi:10.13474/j.cnki.11-2246.2020.0175

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The aerial photogrammetry technology of UAV makes traditional forest survey methods develop towards digitalization and intelligence. In order to improve the precision and efficiency of forest resource information collection, reduce field work time and work intensity, the method and precision of obtaining forest resource data by UAV stereo photography technology are studied in this paper. A three-dimensional stereo image of the study area was acquired by using a rotorcraft equipped with a five-eye camera. The tree height, three-dimensional coordinates, crown width, and area were extracted from the image by software. All these was y=0.998 9x+0.068 5, the correlation coefficient R²=0.98,indicating a high precision of crown width obtained by UAV stereo photography. The true error interval of the three-dimensional coordinate positioning was between -13 and 17, in which the discrete interval of the elevation coordinate was greater than the planar coordinate, the precision of the planar coordinate is about 3 cm, while elevation coordinate is about 10 cm. The sample area values obtained by the stereo photography technology were close to true values and the correlation coefficient is 0.98. It could be obtained that the UAV stereo photography technology had a high precision of obtaining forest resource information data, which improved efficiency, saved costs, reduced work intensity, and had higher practical promotion value.

A method for “Island” class patchsymbol filling of constrained Delaunay triangulation

MAO Wenshan, LIU Tao, DU Ping

2020, 0(6):  32-38,44.  doi:10.13474/j.cnki.11-2246.2020.0176

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The traditional method of map symbol filling on the “island” class patch will cause unreasonable symbol layout or symbol space conflict in sensitive areas, missing object attribute quantitative or sequential description. To this end, this paper proposes an “island” class patch symbol filling algorithm based on the constraint Delaunay triangulation. Firstly, regular meshing and irregular triangulation of discrete point groups corresponding to “islands” class patch, used to calculate equivalence points. Secondly, add “convex” and “concave” attachment points according to the additional criteria,connect equivalence points and additional points in sequence as the constraint boundary of Delaunay triangulation. Finally, construct a uniformly varying constrained Delaunay triangle network, integrate the primitives in the triangular network, and fill in the “island” class patch symbols. Experimental analysis using island boundary point data in electronic chart, compared with the traditional method, the “island” class patch symbol filled by this method is uniform various. Strong interactivity, easy for users to modify and switch, and perform secondary filling. The result shows that the method proposed in this paper is suitable for symbol filling of “island” class patchs.

Change conalysis of chlorophyll concentration in the East China Sea and its response to seawater temperature

JIANG Shan, WANG Yicheng, MA Renfeng

2020, 0(6):  39-44.  doi:10.13474/j.cnki.11-2246.2020.0177

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The analysis of temporal and spatial pattern of ocean chlorophyll concentration and its response to sea water temperature are of great significance for the development and protection of ocean resources and the prevention of red tide. Based on the data of chlorophyll concentration and sea water temperature in the East China Sea from 2004 to 2018, the paper uses the trend analysis and ArcGIS10.2 software, does the space-time analysis of Chlorophyll concentration in the East China Sea, and combines with the water temperature carried on the regression analysis to explore the Chlorophyll of the response mechanism of the water temperature changes. The results show that: ①Chlorophyll concentration in the East China Sea shows no significant interannual variation between 2004 and 2018.Chlorophyll concentration in the East China Sea fluctuates up and down during the year, with peaks in winter and troughs in summer. The closer to the coastal zone, the higher the chlorophyll concentration.②The sea water temperature in the East China Sea area fluctuates on an interannual scale, with a higher temperature in summer and autumn on a seasonal scale, followed by spring and the lowest in winter. Sea surface temperature rises gradually from the coast to the open sea. ③In terms of spatial correlation, chlorophyll concentration in the East China Sea is negatively correlated with seawater temperature as a whole, and the degree of correlation is different in different sea areas. There is a strong correlation between chlorophyll concentration and seawater temperature in the Yangtze River Delta and offshore area. In coastal areas, due to the influence of urban environment, economic development and human production and life, the correlation between seawater temperature and chlorophyll concentration is not obvious.

Digital surface model refining using projected images

CHEN Yannan, WANG Jiali

2020, 0(6):  45-48,56.  doi:10.13474/j.cnki.11-2246.2020.0178

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With the wide use of photogrammetry technology and the increasing demand for photogrammetric products, true orthoimages (orthoimages generated by using digital surface models (DSM)) play an increasingly important role in many engineering applications and lives. How to obtain a highly accurate DSM is the key for true orthoimage generation. The current means of obtaining DSM is mainly through either digital photogrammetry technology or 3D laser scanning technology. For many reasons, the DSM obtained has more or less various error sources. The common methods to correct those DSM errors (DSM obtained through digital photogrammetry technology) are mainly manual editing or reprocessing the troubled images. These methods are time-consuming or/and labor intensive, low-accuracy and random. In this paper, a new method is proposed to correct some DSM errors to improve the quality and accuracy of DSM. The new method is based on the concepts of projected images and the projected loci of a spatial point on the projected images as the geometry constraint, employs some popular image matching techniques to find the correct elevations. The details of the method are given and results from two experiments demonstrate that the proposed method is effective and very promising in correcting and refining DSM, and has certain potentials in practice use.

Typhoon center location method based on FY-2 remote sensing data

LIU Jia, WANG Xudong

2020, 0(6):  49-52.  doi:10.13474/j.cnki.11-2246.2020.0179

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Typhoon center location hasthe problem of low accuracy in formation and dissipation period. For this problem, a novel method based on cloud motion wind is proposed using infrared remote sensing data from FY-2 geostationary meteorology satellite. First, pyramid decomposition is performed on remote sensing infrared sequence images. Second, the optical flow model with weighted median filtering is developed to build cloud motion wind field. Third, the density matrix method is used to calculate typhoon center. Rammasun and Halong that formed in the Pacific Northwest in 2014 are selected for case study. Results show that the method is accurate for the whole life cycle of typhoon.

UAV image matching in Karst area using A-AKAZE algorithm

LI Chuang, WANG Xiaohong, HE Zhiwei

2020, 0(6):  53-56.  doi:10.13474/j.cnki.11-2246.2020.0180

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The terrain in Karst area is complex, and UAV image matching is difficult and time-consuming. Aiming at how to improve the matching efficiency of UAV images in this area, this paper proposes an improved algorithm based on AKAZE. The algorithm firstly uses the complete affine invariant framework to simulate the original image. Then the AKAZE algorithm is used to extract and describe the feature points of the simulated image, and obtain the feature points and descriptors of the original image. Finally, the original image is matched precisely by using the RANSAC algorithm based on homography matrix, and then eliminated error matching point pairs. In this paper, the improved algorithm is experimentally studied and compared with ASIFT and AKAZE. The experimental results show that, compared with ASIFT algorithm, the total matching time based on A-AKAZE algorithm is about 50% of the total matching time of ASIFT algorithm, and the total matching time can be greatly reduced under the same matching accuracy. Compared with AKAZE algorithm, the total matching logarithm and correct matching logarithm based on A-AKAZE algorithm are at least 7 times of the total matching logarithm and correct matching logarithm of ASIFT algorithm. Considering the matching time-consuming and the correct matching logarithm, this algorithm is better than AKAZE and ASIF, and more suitable for UAV image matching in Karst area.

Change detection of remote sensing imagein dense urban area based on IR-MAD and mean shift algorithm

NIE Qian, ZHAO Yanfu

2020, 0(6):  57-62.  doi:10.13474/j.cnki.11-2246.2020.0181

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Change detection of different phase remote sensing image has become one of the indispensable technical means for land use change survey, urban expansion analysis, natural disaster analysis and other environmental issues.This paper proposes a method for detecting remote sensing image changes in dense urban areas based on a combination of IR-MAD and mean shift algorithm. The relative radiation correction of the two-stage image is completed based on the pseudo-invariant feature method, which effectively reduces the registration error between images. Then IR-MAD algorithm is used to perform iterative operation on the corrected image,the mean shift clustering algorithm is used to classify the iterated images, the morphological methods are used to process the segmented images, and finally the change maps are obtained.This paper shows that this method can effectively detect the change area and can be applied to urban change detection and disaster monitoring.

Retrieval of precipitable water vapor by using combined GPS/BDS/GLONASS/Galileo PPP method

LI Hongda, ZHANG Xianyun, LIAO Liufeng, LI Ting, NIE Shihai

2020, 0(6):  63-66,98.  doi:10.13474/j.cnki.11-2246.2020.0182

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In order to further improve the performance of detecting precipitable water vapor (PWV) by using precise point positioning (PPP), this paper proposes a method of retrieval PWV by using GPS/BDS/GLONASS/Galileo combined PPP technology. Based on the measured data of three domestic multi-GNSS experimental project observation stations, the performance of GPS/BDS/GLONASS/Galileo combined PPP in atmospheric water vapor detection was evaluated. The experimental results show that: Compared with GPS PPP, GPS/BDS combination PPP and GPS/GLONASS combination PPP, GPS/BDS/GLONASS/Galileo combination PPP estimates the zenith tropospheric delay (ZTD) initialization time increased by 33%, 26%, 20% respectively, and it can obtain more accurate ZTD estimates and PWV information, and has better performance in atmospheric water vapor detection.

A mounting-attitude estimation algorithm for low-cost vehicle IMU

FENG Muju, GAO Di, HE Wentao

2020, 0(6):  67-70.  doi:10.13474/j.cnki.11-2246.2020.0183

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The mounting-attitude values of IMU to vehicle is a necessary condition for applying the non-holonomic constraints of vehicle, and such constraints can effectively solve the problem of precision reducing of the low-cost INS/GNSS integrated navigation system, when the GNSS signal is interrupted for a long time. This paper proposes an algorithm for estimating the mounting-attitude of the low-cost consumer-grade IMU based on Kalman filtering and particle filtering in the scene of vehicle, which does not need to limit that the attitude of the IMU to the vehicle is a small angle. Subsequently, based on the simulation platform, a low-cost consumer-grade IMU is modeled, and the algorithm is verified by using the generated IMU data of different sets of different mounting-attitude. Finally, an on-board test was conducted. Both the simulation results and the on-board test results show that the algorithm can accurately estimate the mounting-attitude of the IMU relative to the vehicle, which has a practical significance for the improvement of precision of low-cost INS/GNSS integrated navigation system.

Analysis of multi-source geospatial vector data association

GUO Li, JIANG Jingli, LI Hao, WANG Yunge

2020, 0(6):  71-76,86.  doi:10.13474/j.cnki.11-2246.2020.0184

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Aiming at the present situation that multi-source geospatial vector data is multi-source and difficult to integrated and comprehensive utilization, multi-source geospatial vector data association technology is proposed, and a association visual and computational query system of multi-source geospatial vector data is constructed based on the technology. Firstly, the concept and classification of multi-source geospatial vector data association is defined. And then the construction technology of association relation which includes adaptive quadtree coding technology, scanning line technology, geometric matching and semantic matching technology is introduction on the basis of the concept and classification.Finally, to display association relation visually, prototype system is designed. The proposition of association technology can build association relation amang multi-source geospatial vector data, the establishment of prototype system offers a platform for users to use multi-source geospatial vector data integrated, and it has improved the utilization ratio of data and the effectiveness of searching.

A feature selection-based deep learning model for urban street trees classification

QIAO Lianhua, LIU Minshi

2020, 0(6):  77-80.  doi:10.13474/j.cnki.11-2246.2020.0185

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In order to manage urban trees in an efficient way, this paper studies the classification of urban street trees. Aiming at the complex problems such as learning multi-classification model optimization of urban street trees, an adaptive deep learning method is proposed by considering the multi-classification characteristics of urban roadside trees. The feature engineering method based on random forest learning is adopted to calculate and analyze the feature importance of urban roadside trees, and the unimportant features are discarded by recursive feature elimination method. Moreover, to improve the performance of multi-classification learning algorithm for urban street trees, an adaptive deep learning method is further constructed on the basis of urban tree feature learning. Furthermore, the proposed deep learning model is evaluated and improved by cross-validation and parameter search methods. The simulation results show that our proposed algorithm has superior performance and effectively to solve the problem of accuracy and generalization of multi-classification of urban street trees.

Management and similarity analysis of trajectories with NoSQL database

HUANG Yafeng, XIANG Longgang, GAO Meng

2020, 0(6):  81-86.  doi:10.13474/j.cnki.11-2246.2020.0186

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Based on the dynamic and semi-structured trajectory data, this paper makes full use of the characteristics of the document-type non-relational database MongoDB, proposes a layered, partitioned and sliced storage strategy, and designs a non-relational organization with the whole trajectory as the basic unit. The model can effectively cope with the massive and dynamic challenges of trajectory data. On this basis, this paper studies the trajectory similarity calculation, and proposes a trajectory similarity measurement method DTWEUCLI that takes into account both time information and trajectory shapes, which can effectively calculate the similarity between trajectory data with different lengths and noises. Finally, based on trajectory-based non-relational storage and similarity calculation, this paper carries out the experiment and analysis of trajectory cluster. The trajectory cluster computing framework based on trajectory similarity calculation is proposed. Experiments based on three data sets show that the DTWEUCLI algorithm can effectively calculate the trajectory cluster of multi-source trajectory data sets and export the trajectory cluster.

Design and implementation of unmanned helicopter aviation emergency surveying and mapping system

ZHU Jie, WANG Junwei, WANG Zhongxiang, WU Hao, ZHANG Ronghui

2020, 0(6):  87-92.  doi:10.13474/j.cnki.11-2246.2020.0187

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Unmanned helicopters have the advantages of strong environmental adaptability, flexibility, and fixed-point hovering, and have broad application prospects in emergency mapping geographic information security. This paper starts with the integration relationship between UAV platform, task sensor and data processing software, and proposes an integrated design scheme including multi-load integration of structural design, electrical design and control flow design, as well as covering aerial photography design, video data processing, Software system integration solution for optical area array image processing. The Z-5 unmanned helicopter aviation emergency mapping system is implemented by this scheme, and the flight test is carried out in Mingguang City, Anhui Province. The results show that the system can simultaneously acquire video and optical images by real-time processing to meet the real-time provision of emergency mapping geographic information support.

Evaluation on grid scale ecological carrying capacity based on ecological footprint: taking Hengshui for an example

ZHOU Yu, WANG Liang, LI Xican, ZHANG Yu, LI Bin

2020, 0(6):  93-98.  doi:10.13474/j.cnki.11-2246.2020.0188

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Aiming at the problem that the evaluation of regional ecological carrying capacity of administrative units can not reflect the differences of ecological conditions and local details of the administrative units, and can not meet the needs of the construction of the control mechanism of differentiated ecological carrying capacity, the paper proposes an evaluation method of ecological footprint model. Based on the ecological footprint model, combined with the population spatial distribution model, GIS spatial analysis technology is used to quantitatively estimate the demand and supply of ecological carrying capacity and ecological footprint from the grid scale and analyzes the spatial pattern. Hengshui city is used as an example to verify the experiment. The results show that the grid scale ecological carrying capacity evaluation method is more consistent with the real situation than the regional ecological carrying capacity evaluation method. From the grid scale, the ecological footprint distribution presents the characteristics of the circle; the ecological carrying capacity presents discrete distribution characteristics. The situation of ecological deficit shows obvious heterogeneity, with banded distribution along the Fudong Paihe River and Fuyang River. Most areas of Hengshui city are in a critical state of ecological deficit, and the ecological status needs to be protected.

Methods of rectangular Cartogram automatic construction

WANG Weiming, JIA Fenli

2020, 0(6):  99-103,117.  doi:10.13474/j.cnki.11-2246.2020.0189

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Rectangular Cartogram, as a kind of regional Cartogram which can express topology and data attributes at the same time, has great potential because of its simple and intuitive expression content. Rectangular Cartogram attempts to use simple rectangles to represent the topology and data attributes of complex geography. These two attributes are often contradictory in the process of automatic construction, so there are many different construction methods. The research on the automatic construction method is helpful to the exploration of the integration method of geographic information and statistical data. In this paper, firstly, the research background, research status and significance of rectangular Cartogram are briefly introduced. Then, the characteristics and evaluation criteria of rectangular Cartogram are summarized, and two typical algorithms of constructing rectangular Cartogram are analyzed, and the difficulties of automatic construction algorithm are summarized. Finally, the existing problems in the research of rectangular Cartogram are discussed, and its development direction is prospected.

Building roof reconstruction from airborne LiDAR data based on layer connection and smoothness strategy

XU Hao, CHENG Liang, WU Yang

2020, 0(6):  104-110.  doi:10.13474/j.cnki.11-2246.2020.0190

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For providing 3D building models to construct digital and smart cities, an approach, which uses smoothness strategy and layer connection based on airborne LiDAR data proposed for automatically reconstructing 3D building roof models with precise position and details. It consists of four steps: building roof point extraction, building rooftop patch segmentation, connection between roof layers and 3D building roof model reconstruction. Building roof points are firstly extracted from airborne LiDAR data using the reversed iterative mathematic morphological algorithm and the density-based method. In the process of rooftop patch extraction, the smoothness of the rooftop patch is taken into consideration. The concept of layer-connection-point is proposed to complete building model reconstruction effectively and fast after obtaining the smooth rooftop patches. Experiments are analyzed from several aspects: the completeness and correctness, deviation analysis of the reconstructed building roofs, and the influence of elevation to 3D model roof reconstruction supported by the ISPRS standard data set, compared with the international similar experiment. According to the experimental results, the completeness and correctness of the roof reconstruction results are 90% and 95%, respectively. The average deviation distance and standard deviation are 0.05 and 0.18 m, respectively. The experimental results demonstrate promising correctness, completeness, and deviation accuracy, with a satisfactory 3D building roof models.

Land coverage classification of Sentinel-2A image based on object-oriented and rules: a case study of Duchang county, Jiangxi province

ZHANG Hongtao, HUANG Hongsheng, WEI Kangning, ZHONG Haiyan

2020, 0(6):  111-117.  doi:10.13474/j.cnki.11-2246.2020.0191

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As a comprehensive combination of natural and artificial structures on the surface, land coverage is an important foundation for the development of land science related research. In the background of large remote sensing data, accurate, fast and automatic land coverage extraction technology is focused in remote sensing research all the time. Based on eCognition software, this paper take object-oriented multi-scale segmentation method. Taking account of the spectral, shape and texture characteristics of land objects comprehensively in remote sensing images, established a variety of rules to extract the types of land coverage in the study area by using fuzzy function, support vector machine (SVM) and threshold method. A comparative analysis was also made to compare with FROM-GLC10 data and land use change data in the study area. The results showed that: ① The overall accuracy of land coverage classification in the study area was 97%, Kappa coefficient was 0.96, and the classification accuracy was high. ② Based on 10 m resolution image, the comprehensive use of shape, texture and spectral information had a good effect on the extraction of roads. The Kappa coefficient of road extraction was 0.84. ③ The classification results were better than the FROM-GLC10 data both in area and spatial distribution, as great consistency with the land change data in the study area. The object-oriented and rule-based classification method for feature extraction can effectively utilize a variety of remote sensing image features, and the classification accuracy is high, which has a good advantage for processing high-resolution remote sensing data.

Automatic mosaicking seamline detection for high-resolution remote sensing mapping

WANG Zuoyong, CHEN Wei

2020, 0(6):  118-120,124.  doi:10.13474/j.cnki.11-2246.2020.0192

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To better apply remote sensing technology in urban planning mapping, high-resolution remote sensing image has become the most important data source in urban mapping. Faced with the urban area with complex feature information and a large of buildings, seamline extraction between two adjacent remote sensing images is of great practical significance when practicing the mosaics for urban mapping. GF-2 remote sensing imagery has the highest spatial resolution and the smallest breadth among domestic satellites. To develop the applications in urban research with GF-2 remote sensing imagery, an automatic seamline detection method is needed to avoid buildings in urban region. Based on GF-2 remote sensing imagery and building footprints, this paper converts seamline detection into shortest path search from start point to goal point. The result shows that fusing building footprint data and A* searching algorithm can automatically generate seamline to avoid building in complex urban context. This method can be widely used in urban mapping with high-resolution remote sensing imagery.

Urban reality 3D model construction using inclined photogrammetry and geometric modeling

PAN Jiubao, WANG Wei, HUANG Mingwei, SUN Changkui

2020, 0(6):  121-124.  doi:10.13474/j.cnki.11-2246.2020.0193

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In recent years, digital cities have been widely researched and applied on the basis of real-life 3D models. However, traditional 3D modeling methods are difficult to meet the requirements for faster, more realistic, more accurate, and larger-scale data production in modern digital cities. Taking Jiangba ancient town in Huai'an City of Jiangsu Province as an example, this paper completed the research of urban three-dimensional model, built a three-dimensional model of urban real-life based on inclined photogrammetry technology, and refined the real-life three-dimensional model by geometric modeling method. The results showed that the adopted scheme satisfies the application needs of the real-life 3D model, and it was suitable for the rapid construction of large-scale regional urban 3D models. It had certain reference value for the production of large-scale 3D model data.

UAV image ground control points layout for geological disaster hazards

WU Bo, LI Jun, JIANG Dapeng, FENG Zhi

2020, 0(6):  125-127,140.  doi:10.13474/j.cnki.11-2246.2020.0194

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With the background of 1∶2000 aerial production task of one hidden danger spot of geological disasters in Shaanxi province, this paper combines the technical characteristics of Vtol UAV photography and the geographical situation of the spot area. By comparing advantages and disadvantages of several layouts, it aims to study the influence of UAV photography ground control points on aerial triangulation. Based on the geographical situations of different geological disasters, it comes to conclude the appropriate layouts of UAV photography ground control points for different hidden dangers of geological disasters, providing a reference for the same problem in the future.

Estimation method for surface soil moisture based on GPS-IR

ZHU Xiaoling, WANG Jianhui, XIE Rongan

2020, 0(6):  128-133.  doi:10.13474/j.cnki.11-2246.2020.0195

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Global Positioning System Interferometric Reflectance (GPS-IR) is a new remote sensing technique, which can be used to estimate soil moisture content near the surface. From the view of multi-satellite fusion, an estimating method of surface soil water content based on multi-satellite fusion is proposed. Firstly, the direct and reflected signals of multiple satellites are separated by low order polynomial fitting, and then the sinusoidal fitting model of the reflected signals is established to obtain the relative delay phase. Finally, a multiple linear regression model is established based on the relative delay phase of multiple satellites. Based on the monitoring data provided by the plate boundary Observatory (PBO), the inversion effects of different modeling sequence lengths are compared and analyzed to determine the best modeling length. The experimental results show that multiple linear regression model can effectively integrate multiple satellites, and it is feasible to estimate soil moisture.

Intelligent perfect-information surveying and mapping for digital twin cities

GU Jianxiang, YANG Bisheng, DONG Zhen, YANG Changhong

2020, 0(6):  134-140.  doi:10.13474/j.cnki.11-2246.2020.0196

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The wave of informatization represented by new technologies such as big data, internet of things, artificial intelligence, virtual reality, cloud computing and intelligent driving has swept the world. The digital world and the physical world are forming two systems of parallel development and interaction, and digital twin technology emerges at the right moment. With the development of internet of things (IOT) technology, the concept of digital twinning has been introduced into the construction of smart cities, which has a profound impact on urban planning, construction and governance. The Shanghai institute of surveying and mapping has launched a pilot program of intelligent perfect-information surveying and mapping for digital twin cities in China, aiming at the new demand of surveying and mapping geographic information for digital twin cities and the unified supervision of natural resources. This paper introduces the new demands of digital twin cities on geographic information, the research progress of key technologies of intelligent perfect-information surveying and mapping, as well as the technical system, product system and applications of intelligent perfect-information surveying and mapping.

Design of space and time dimension seismic catalog display system

LUO Yong, FU Hongyun

2020, 0(6):  141-144.  doi:10.13474/j.cnki.11-2246.2020.0197

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Earthquake catalogue is the most basic research data produced by seismological system. According to the characteristics of earthquake catalogue, a comprehensive display system is designed by the open-source framework of the Amap open platform API, Echarts, Plotly and JpGrid. The front and back ends of the system are separated to make better use of the spatial and temporal information of earthquake catalogue. The system shows the original data of earthquake catalogue and the epicenter location, 3D visualization, dynamic M-T diagram and dynamic frequency diagram generated by earthquake catalogue processing in B/S structure. This platform provides a new mode for seismic data to serve the society.

Application of image recognition in internet “problem map” monitoring

HUANG Long, WU Jiatong

2020, 0(6):  145-148.  doi:10.13474/j.cnki.11-2246.2020.0198

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This paper introduces the development course of internet problem map monitoring, expounds the current national internet problem map monitoring network and its working mechanism, and analyzes two difficulties of current internet problem map monitoring.Too much data is difficult to find in time and accurately, and low illegal cost is difficult to effectively reduce the occurrence of problem map. At the same time, this paper compares and analyses two methods of image recognition technology applied in internet problem map monitoring. This paper analyzes the application of two methods in different scenes, and provides a reference for the competent departments of natural resources at all levels to perform their duties in accordance with the law, and further completes the internet “problem map” monitoring work by using image recognition technology.

Practical teaching reform of engineering surveying under flipped classroom/multi-dimensional assessment system

KONG Weihua, MAO Yingdan, XU Xiaoyu, ZHAO Hong, JIANG Jundi

2020, 0(6):  149-152,155.  doi:10.13474/j.cnki.11-2246.2020.0199

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Engineering surveying is the core course of surveying and mapping engineering, and it is one of the most applied courses in the actual surveying and mapping work. The quality of its practical teaching directly affects the quality of students' employment after graduation. Aiming at the outstanding problems existing in the practical teaching of engineering surveying, a practical teaching model focusing on flipped classroom and a multi-dimensional assessment system is proposed. After two years of teaching reform, A fruitful result is achieved in practical content, practical teaching methods and assessment systems, which is promoted in other courses.

Application of Trimble S9/S9 HP total station in precision settlement monitoring of railway pipe jacking construction subgrade

SONG Zhonghua, TIAN Hui, SONG Shuai

2020, 0(6):  153-155.  doi:10.13474/j.cnki.11-2246.2020.0200

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As a non-excavation construction method, pipe jacking is widely used because of saving resources. However, pipe jacking construction will also cause soil deformation around the pipe, which will cause the soil to move and cause ground settlement. Therefore, an effective and accurate settlement monitoring method is indispensable. According to the general rule of pipe jacking construction, the high-precision Trimble S9/S9 HP total station and the differential presure static level are used to set up the monitoring plan for the settlement in this paper. According to the observation results, this kind of scheme can effectively and accurately reflect the settlement situation, which has great significance in practical production and can be promoted and used.

Mechanism analysis of surface subsidence based on the application of “three under” coal mining technology

ZHAO Yunchang

2020, 0(6):  156-157,162.  doi:10.13474/j.cnki.11-2246.2020.0201

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This paper mainly studies the surface change caused by “three under” coal mining, and then analyzes the subsidence mechanism around the mining area. Five observation lines are mainly arranged for the surface along the mining direction and the vertical direction of the working face. The field observation data are obtained by using the electronic level of trimble. The change curve is analyzed by using the settlement observation analysis software and SPSS data analysis software, and the mining situation is analyzed in time. The data of “three under” coal mining face adopted in time has obtained theoretical and scientific basis for mining subsidence, land compensation and comprehensive utilization.

Application of Leica ScanStation P50 3D laser scanner in building topographic mapping

DUAN Yuehui

2020, 0(6):  158-162.  doi:10.13474/j.cnki.11-2246.2020.0202

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This paper briefly introduces the technical characteristics of Leica scanstation P50 new long range 3D laser scanner. Making the building topographic map, as built drawing, in combination with Leica later stage cyclone point cloud processing software, cloudworx plug-in, etc.