Table of Content

25 November 2020, Volume 0 Issue 11

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Spatial heterogeneity monitoring of temporal variation of vegetation coverage in Shengli mining area

WANG Kewen, LI Jing, WANG Ruiguo, FU Xiao

2020, 0(11):  1-6.  doi:10.13474/j.cnki.11-2246.2020.0344

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By analyzing the geographical location and climatic conditions of the Shengli mining area, in order to get the spatial heterogeneity of the gain scheduling vegetation coverage, this paper uses ENVI, GIS, Matlab and other softwares, based on the Landsat TM/ETM+/OLI remote sensing data of the Shengli mining area from 1985 to 2017 to calculate NDVI, and the binary model is used to calculate the vegetation coverage to obtain the temporal changes of the average vegetation coverage in the study area. The transfer matrix method and Sen+Mann-Kendall method are used to analyze the transfer status and change trend of different levels of vegetation coverage in the study area. Conclusion: The average vegetation coverage in Shengli mining area fluctuates greatly and shows a slight downward trend. During the monitoring period, 68.36% of the areas with high vegetation coverage have degraded, and only about 3.2% of the areas with very low vegetation coverage have been improved. In addition, the vegetation coverage in the study area is affected by structural factors and randomness factors. The spatial heterogeneity is obvious. The vegetation in the irrigation area grows well due to human interference. The extremely low vegetation coverage area is maintained below 3%, and the areas that vegetation coverage decreases significantly is mainly concentrated in mining landscape areas such as open pits and dumps.

Monitoring on spatial-temporal vegetation dynamics based on Landsat time series

WANG Hua, YANG Qianpeng, GUO Shanchuan, DAN Zeng, CIREN Duoji

2020, 0(11):  7-12,38.  doi:10.13474/j.cnki.11-2246.2020.0345

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The purpose of this paper is to analyze the spatial-temporal pattern of vegetation coverage and driving factors in Bayi district, using pixel dichotomy model and correlation analysis methods, from Landsat time series images between 1990 and 2019 based on GEE platform. Research results show: ①The overall trend on vegetation coverage emerged as an approximate stability with a little increasing, among which the valley regions increased significantly while the high mountain regions is relatively stable. ②Temperature in Bayi district increased significantly whereas the precipitation decreased slightly, demonstrating a “warm and dry” feature. The response of vegetation coverage to precipitation is stronger than temperature, but however the relationship between climate change and vegetation coverage is not significant generally. ③A good relationship is found between human activities and vegetation cover, where the non-high vegetation coverage areas presented in significant negative correlation while the high vegetation coverage areas had positive correlation. The proposed methods of dynamic monitoring on vegetation coverage and quantitative analysis using remote sensing big data and geographic cloud computing, can provide technical support and scientific data for ecological assessment and evolution analysis over alpine canyon region.

Object-based Karst wetland vegetation classification using UAV images

GENG Renfang, FU Bolin, JIN Shuanggen, CAI Jiangtao, GENG Wanxuan, LOU Peiqing

2020, 0(11):  13-18.  doi:10.13474/j.cnki.11-2246.2020.0346

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This study aims to classify Karst wetland vegetation on Huixian National Wetland Park, located in Guilin, Guangxi province using object-based image analysis technique, random forest algorithm, image thresholding approach and Boruta all-related features selection algorithm based on UAV images. Results are as follows: the contribution of different feature variables is described as follows: spectral feature (DOM spectral > DSM spectral) > texture feature (DOM texture > DSM texture) > geometric feature > contextual feature; the overall classification accuracy of two UAV data sets is above 85 % as well as Kappa coefficient. This study provides insights into feature variable selection, segmentation parameter setting and classification method selection for karst wetland vegetation classification using high spatial resolution UAV RGB images.

Wetland extraction method combined with Sentinel-2 and AW3D30 data

CHEN Guang, BU Kun

2020, 0(11):  19-22.  doi:10.13474/j.cnki.11-2246.2020.0347

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This paper mainly studies the wetland cover in Liao River estuary. In order to realize dynamic monitoring of large-scale wetland, the Sentinel2-L1C and AW3D30 DSM have been used as basic data and the random forest model has been used for raster classification. The results extracted by random forest model will be further processed by using digital signature of terrain and polygonal shape characteristics. The visual interpretation method has been used for verifying the accuracy of the classification, the results showed: this method has a high degree of automation, which can extract wetland coverage with less manual intervention. The extraction results achieved higher precision with the producer's and overall accuracy of 91.04% and 82.65%, respectively. The Kappa coefficient is 0.599 7, which indicated that the computer classification method this paper used and artificial visual interpretation have good consistency.

Analysis of long-term vegetation change in Ningxia with different trend methods

KANG Xiong, CAO Juntao, CHEN Cheng, YANG Jie, WANG Jianxiong

2020, 0(11):  23-27.  doi:10.13474/j.cnki.11-2246.2020.0348

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Ningxia is located in the Loess Plateau, the trend of vegetation change directly affects the ecological protection in this place. This paper uses MODIS NDVI monthly synthetic products from 2005 to 2015 to get annual NDVI data with the maximum synthetic method, and adopts the unitary linear regression method and the Sen+Mann Kendall method to analyze the vegetation change trend and spatial difference in Ningxia in recent ten years. The results show that the monthly mean value of NDVI presents Gauss distribution, and the best stage of vegetation growth is from July to September. The yearly NDVI value increases significantly in 2005—2007, the yearly NDVI value increases steadily in 2008—2012, and the yearly NDVI value decreases in 2013—2015. The trends in vegetation change obtained by the one-dimensional linear regression method and the Sen+Mann-Kendall method are almost the same, with both the overall improvement of vegetation in the north, but local urban vegetation degradation is more serious; slight improvement in the central region, local obvious improvement. The vegetation in the south is significantly improved and the area of vegetation improvement was larger. The difference between the two methods by differential analysis is only 22.95%, and the Sen+Mann-Kendall method is better for monitoring of areas of slight variation and the trends are more accurate.

Dynamic monitoring of natural resources based on the domestic satellite images

LIN Xiaoping

2020, 0(11):  28-32.  doi:10.13474/j.cnki.11-2246.2020.0349

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It is an important problem of natural resources management to master the overall change of the mountains, rivers, forests, farmlands, lakes and grasslands accurately and timely. With the characteristics of macro, comprehensive, dynamic and fast, satellite remote sensing technology can be applied in the field of natural resources to carry out target identification, information collection and processing, analysis and evaluation. It can be used as an effective means for natural resources monitoring. This paper takes land, mineral and ocean as the research objectives to carry out the dynamic monitoring of natural resources based on multi-source and multi-temporal domestic satellite remote sensing data and kinds of approved and planned data. The results show that it is feasible and efficient to explore the potentials of domestic satellite images deeply as a way to realize the precise remote sensing monitoring of natural resources.

Extraction of Gangnalou glacier velocity based on SAR migration tracking method

ZHANG Shengpeng, ZHOU Zhongzheng, ZHAO Lijiang, ZHANG Yongying

2020, 0(11):  33-38.  doi:10.13474/j.cnki.11-2246.2020.0350

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Glacier dynamic change monitoring helps to reflect global and regional climate change and protect the natural environment and natural resources. In recent years, the research on glacier movement based on SAR data has become one of the mainstream technologies. The extraction of glacier velocity based on SAR mainly includes synthetic aperture radar interferometry, multi-aperture radar interferometry and offset tracking. In this paper, the intensity tracking method of SAR migration tracking method is used to extract the glacier velocity along the distance and direction of Gangnalou glacier in the northeast of Hala lake, Qinghai province. The results show that the extraction effect of the range direction glacier velocity is better, the maximum velocity reaches 15.36 m/a, the velocity decreases from both sides of the central axis, and tends to 0 at the end of the ice tongue; the maximum velocity of the azimuth direction extraction ice velocity reaches 18.27 m/a, but there are some directional streaks in the azimuth velocity diagram due to the ionosphere interference. Inaddition, due to the small component of ice velocity in azimuth and other factors, the accuracy of azimuth velocity extracted in this study is lower than that in distance.

GLIBERTY-DSAIL coupled model inversion of vegetation LAI in southern mixed forest

GUO Yunkai, LIU Jianqin, GUO Yanqing, CAO Xiao, XIE Qiong

2020, 0(11):  39-42,75.  doi:10.13474/j.cnki.11-2246.2020.0351

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In order to solve the problem of low leaf area index (LAI) inversion accuracy and little research in the coniferous-broadleaved mixed forest in the southern hilly areas, this paper proposes a GLIBERTY-DSAIL coupling model combined with multiple linear regression inversion LAI method. In this study, the GLIBERTY-DSAIL model selects simulated spectrum and vegetation measured hyperspectral as data sources. Through the correlation analysis, the vegetation index with high correlation about LAI is selected as the inversion factor, a multiple linear regression model is constructed to quantitatively invert vegetation LAI. The paper evaluates the accuracy. The results show that: RVI, DVI, GNDVI, and MSAVI vegetation indexes that are significantly related to LAI are used as inversion factors, combined with the model proposed in this paper to invert LAI, the model prediction coefficient R² is 0.708 6, and the root mean square error RMSE is 0.302 1. The accuracy is higher overall. This combined method can be used to invert vegetation LAI of coniferous-broadleaved mixed forests, and provide new ideas for the study of mixed forest LAI in southern areas.

Urban impervious surface information extraction based on random forest algorithm: taking Changchun as an example

CHANG Xiangyu, KE Changqing

2020, 0(11):  43-49.  doi:10.13474/j.cnki.11-2246.2020.0352

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In order to quickly and accurately grasp the spatial distribution and dynamic change information of impervious surface, based on the idea of multi-classifier ensemble learning, random forest algorithm is introduced in eliis paper. Landsat 8 image is used as data source and Changchun city as experimental area. 25 feature variables, such as spectral indices, texture measures and independent components after spatial transformation are selected to classify. The importance of variables calculated by out of bag error is analyzed and the optimal classification model is obtained through many experiments. The extraction of high-precision impervious surface is also realized. Finally, random forest algorithm is compared with the traditional parameter classifier. The result indicated that the overall accuracy of random forest algorithm can reach 94%, which is higher than 5.9% of maximum likelihood classification, 0.77% of support vector machine algorithm, 0.914 3 of Kappa coefficient and 0.104 3 of root mean square error. The extraction accuracy of impervious surface is 95.54%, which can not only accurately extract impervious surface but also provide effective thematic information for urban construction and planning.

The vector field consistent matching of FAST and opposite color features is improved

ZHANG Jin, ZHAO Xiangwei, LUAN Jishan, FENG Kang, AI Bo

2020, 0(11):  50-54.  doi:10.13474/j.cnki.11-2246.2020.0353

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In order to solve the problemswith traditional image matching algorithms, such as too many false matching point pairs, and poor robustness in complex environment, an image matching algorithm is proposed based on improved FAST to extract feature points, combing with opposite color features.First, the corner points extracted by the improved FAST algorithm are used as feature points, and the feature points are described by combining with the improved Opponent SIFT algorithm. Then, the extracted feature point pairs are roughly matched based on the character location algorithm, to reduce the risk of false matchingof the feature point pairs in the whole matching process. Finally, in order to avoid the problem that the correct point pairs are mistakenly removed caused by the RANSAC algorithm easily falling into the local optimal solution, the vector field consistency is used instead of RANSAC for purification of matched point pairs to reduce the false matching rate. The comparison experiments show that the accuracy of the improved algorithm is greater than 91%, and it has good robustness and adaptability for the variation of differences.

Method for evaluating the accuracy of point cloud matching positioning results based on composite multi-attribute decision making

WU Yuhan, LI Chaoyang, XUE Qingquan, QIE Xiaobin, ZHANG Yabo

2020, 0(11):  55-60.  doi:10.13474/j.cnki.11-2246.2020.0354

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LiDAR point cloud matching and inertial integrated navigation technology are hot topics in the field of high-precision positioning and navigation. The accuracy in the evaluation in matching positioning results directly affects the accuracy of integrated navigation positioning. Especially, outdoor actual road scenarios, the environment is complex, so the probability of mismatches is high. Only if evaluating the matching positioning results accurately can improve the integrated navigation positioning accuracy. Therefore, it is great significante to study evaluation models. In this paper, the construction of the evaluation model is abstracted as a multi-attribute decision problem. A compound multi-attribute decision algorithm is used to identify factors that influence the positioning results and give a weight. The quality of the positioning results is evaluated quantitatively, and the model is verified with using actual road data. The results show that the algorithm is reliable and effective, could reflect the quality of mateling positioning results actually.

A city 3D model construction method based on 3ds Max and Smart 3D

XU Jincai, LI Chaokui, CHEN Jianhui

2020, 0(11):  61-65.  doi:10.13474/j.cnki.11-2246.2020.0355

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Based on the point cloud data and aerial photos of a university library, the 3D model is constructed by using 3ds Max and Smart 3D. On the one hand, the method of human-computer interaction is adopted for modeling, and the 3D laser point cloud data is imported into 3ds Max software to establish the 3D digital model. On the other hand, the semi-automatic manual mode is used for modeling, and the Smart 3D software is used to model the building entity after the aerial camera data is encrypted, automatically modeled, mapped and other operations. The characteristics and differences of the two modeling methods are compared in terms of modeling efficiency, model aesthetics, modeling accuracy and applicable objects. The research shows that 3ds Max is more suitable for regular body and high-precision modeling, while the efficiency of modeling is relatively low; Smart 3D modeling is more efficient and more suitable for rapid modeling in a large range of scenes. The conclusions are helpful to the selection of modeling methods under different requirements, and provide a reference for the selection of 3D modeling methods for research, engineering and experiment.

Research on cloud detection method of domestic high-resolution satellite images

LIU Yunfeng, YANG Zhen, HAN Xiao, FU Jun

2020, 0(11):  66-70.  doi:10.13474/j.cnki.11-2246.2020.0356

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Most cloud detection methods aim at specific sensors or rely on multiple bands, which require high parameters. However, domestic high-resolution satellite images usually contain a small number of bands, and most cloud detection methods are not applicable. In this paper, the deep learning method is adopted, the fused GF-1 images are innovatively applied to the “dualattention mechanism” model for cloud detection,and compared with the test results of manual drawing and full convolutional network model. Theoretical analysis and research results show that: first, the cloud detection efficiency results of the “dual attention mechanism” model are compared with the results of manual drawing, the accuracy rate is 0.986 4. Second, by increasing the number of cloud samples and the number of non-cloud samples, the model can effectively solve the problem of misdetection of roads, rivers, residential areas. Third, compared with the full convolutional network model, the dual attention mechanism model has more accurate cloud boundaries and stronger model applicability. Using less band information for cloud detection provides a reference for other domestic high-resolution satellite images cloud detection.

An improved EMD noise reduction method based on noise statistical characteristics

LU Tieding, QIAN Wenlong, HE Xiaoxing, LE Ying, HUANG Jiawei

2020, 0(11):  71-75.  doi:10.13474/j.cnki.11-2246.2020.0357

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The GPS elevation time series usually contains noise, which easily affects the accuracy of GPS signal solution. In view of this problem, this paper proposes an improved EMD noise reduction method based on the statistical characteristics of noise. Firstly this method decomposes the signal by EMD to obtain two parts of low-frequency signal and high-frequency noise. Then randomly shuffles the high-frequency noise part twice and accumulates with the original high-frequency noise to obtain the average value. Finally, it compares with the low-frequency signal add up to form a new signal and perform EMD decomposition again to extract the useful signal. Verification is performed using simulated data and measured GPS elevation time series data from WUHN stations. The experimental results show that when the signal-to-noise ratio is relatively high, the noise reduction effect obtained by this method is better.

Research on real-time positioning of pseudorange smoothing for smart phone observations

CHEN Bingzhu, ZHENG Zuoya, GU Shouzhou, CHEN Chong, BEI Jinzhong, SHAN Rui

2020, 0(11):  76-79,89.  doi:10.13474/j.cnki.11-2246.2020.0358

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Due to the limitations of the internal antenna structure and GNSS receiving chip of the smart phone, the original observation value of the phone is easily affected by the external environment, and the observation noise is large, which leads to the problem of poor positioning accuracy. In order to improve the accuracy of mobile phone's pseudorange single point positioning, this paper studies and analyzes the performance of pseudorange single point positioning based on smoothed carrier and smoothed Doppler on the basis of detecting the cycle slip of mobile carrier observation value. The experimental results show that both carrier smoothed pseudorange and Doppler smoothed pseudorange can effectively improve the positioning accuracy,however, Doppler smoothed pseudorange has better stability and better positioning accuracy, the statistics showed that the RMS values in the three directions of east (E), north (N), and high (U) are respectively increased by 52%,62%,60%, and the planar accuracy entered 1.5 m.

Context aware derivation of linear object entities

ZHANG Honggang, LI Chengming, YIN Yong, WU Wei, GUO Man

2020, 0(11):  80-84.  doi:10.13474/j.cnki.11-2246.2020.0359

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In view of the problem that there is no space entity topology for the line data and area data found in the automatic synthesis of cartography, this paper proposes a context aware method for deriving linear object entities.First, establish a spatial topology proximity to fencelines, ancillary facilities, and buildings, clustering direct neighboring groups, it is divided into three modes, namely the topological connection between the two walls, the topological connection between the wall and the building, and the topological connection between the hanging wall line near the building and buildings; Finally, the shortest path, contour and the nearest point are used to connect the three models. Experiments with Fujian province data as an example show that this method can effectively build a spatial entity topology connection, help improve automatic map synthesis, at the same time can meet the requirements of production practice, with a high degree of practicality.

A stylized filters and middleware technology of web map

LI Hang, MA Yan, ZHANG Xiang

2020, 0(11):  85-89.  doi:10.13474/j.cnki.11-2246.2020.0360

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To meet the increasing requirement of customized maps in web mapping environment, and to overcome the limitations of the current vector-based web mapping pipeline, this paper proposes a stylized map filter method based on image processing. We show that this filter is able to customize existing map images/tiles through the proposed image processing pipeline, and can be used as middleware for commercial web map services (WMS). This paper describes in details the pre-processing, image processing stack, and map tile storage of the framework. Finally, we use a watercolor map style as an example to demonstrate the proposed method, which shows its feasibility to improve the diversity and effectiveness of web map design.

An optimization algorithm to enhance efficiency of weighted total least squares

NI Fuze, WANG Jianmin

2020, 0(11):  90-92,103.  doi:10.13474/j.cnki.11-2246.2020.0361

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At present, the weighted total least-squares (WTLS) adjustment is a relatively rigorous method used for estimating parameters in the errors-in-variables (EIV) model. However, the required matrix operations involved in the iteration process are extremely time-consuming, particularly when processing large data sets. Using partial errors-in-variables (PEIV) is conducive to improve the computational efficiency of WTLS. Based on the PEIV model and the least squares criterion, this study derived an algorithm for weighted total least squares problemin a concise way. The algorithm is simple in the concept and involves fewer matrix operations because it doesn't demand matrix reconstruction in the iteration process. Finally, simulated experiment is used to test the performance of the proposed algorithm. The results show that the proposed algorithm can achieve the same results as the existing algorithms and has higher computational efficiency.

Analysis on urban expansion and ecological pattern based on geographical condition data: taking Wuhan as an example

LI Fangting, ZHANG Guo, JIA Jipeng

2020, 0(11):  93-98.  doi:10.13474/j.cnki.11-2246.2020.0362

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Urban expansion is the main characteristic of urbanization. The study of urban expansion law provides decision-making basis for urban spatial planning and high-quality development. In this paper, we select Wuhan as the study area, and take the results of geographical national conditions survey from 2015 to 2018 as the main data source, the characteristics of urban expansion and ecological pattern change in the study area are analyzed by data collation and extraction, urban expansion index calculation, urban pattern change extraction and ecological landscape index calculation. The results show that Wuhan's rapid expansion from 2015 to 2018 slowed and its compactness declined. The expansion of central cities is mainly at the expense of the destruction of cultivated land. The forest and grass area in far-away district is expanding rapidly at the expense of decreasing. In the ecological index, the fragmentation of each ecological landscape type decreased, but the water area maintained well.

Research on topological relation self-adaptation in DLG data update

CHEN Nan, ZHANG Biao

2020, 0(11):  99-103.  doi:10.13474/j.cnki.11-2246.2020.0363

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Aiming at the problem of maintaining the consistency of the topological relationship between geographical elements when heterogeneous vector data is converted, a method of adaptively updating the topological relationship is proposed. Based on the analysis of the topological relationship between geographical elements, the change of the topological relationship caused by its spatial changes is researched. Taking the rationality of the changed topological relationship as the basis of judgment, an adaptive strategy for the topological relationship corresponding to the geographical elements is proposed. The theoretical research is applied to engineering applications. Firstly, the topological relationship adaptive strategy of geographic features is converted into an editable XML document, and then a plug-in tool is developed using the ArcGIS Add-in method. It realizes the self-adaptive updating of topological relations amony geographical features, reduces manual operations and improves update efficiency.

A new ground-like flight method based on contours to construct drone routes

WANG Bingqian, CHEN Chao, WANG Huajun, CHEN Jianhua, TANG Qiao, WU Sen, WU Yao

2020, 0(11):  104-107,115.  doi:10.13474/j.cnki.11-2246.2020.0364

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The upright surface information of targets such as building walls, cliffs or dangerous rocks plays a very important role in the fine modeling of objects and investigation, analysis, evaluation and prevention of geological disasters. The images obtained by traditional oblique photogrammetry lack a detailed description of the vertical surface information of the target, and in areas with large changes in height difference, modeling may fail due to different image overlap rates. The ground-like flight strategy solves the above problems to a certain extent, but for areas with sudden changes in altitude, it is often unable to meet the requirements of refined modeling. This paper proposes a new ground-like flight method based on contour lines to construct drone routes. This method generates contour lines based on the DSM of the target area, and completes the design of the drone route through contour simplification and offset. The model results constructed by this method are compared with the modeling results of the traditional ground-simulating flight method. The experimental results show that the method proposed in this paper is more realistic for portraying dangerous rocks on cliffs. Moreover, compared with the traditional ground-like flight method, the flight route designed in this paper avoids frequent altitude changes, which is beneficial to extend the time for the UAV performing flight tasks. Therefore, the new ground-like flight method based on contour lines to construct drone routes proposed in this paper is a very effective and practical flight route design method.

Spatiotemporal fractal characteristics analysis of land-use in Xishuangbanna

SUN Yumei, SHI Baolin, XU Yujing, JIA Qingtang

2020, 0(11):  108-111.  doi:10.13474/j.cnki.11-2246.2020.0365

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In this study, remote sensing images of Xishuangbanna region in 2009, 2014 and 2018 are interpreted to obtain land use data. The transfer matrix and fractal theory are used to quantitatively analyze the complexity, stability and change rules of spatial structural of land use in different periods. The results indicate that the areas of residential land and rubber plantation have increased in the past ten years, while the area of forestland has decreased. The residential land is mainly transformed from rubber plantation and cultivated land, and rubber plantation is mainly transformed from dryland and forestland. In addition, forestland is mainly transformed into shrub and rubber plantation. According to the fractal dimension and stability index of fractal theory, the spatial structure of residential area is the most regular and the spatial distribution is the most stable. However, the spatial structures of forestland and rubber garden are relatively simple. The internal mosaic structure of dryland is complex, with rough edge and random distribution law.

3D modeling of ancient buildings based on UAV close-range photography

LIU Yang, LIAO Dongjun, WANG Chaogang, TAN Tian, LIU Yunfeng, HOU Tenghui

2020, 0(11):  112-115.  doi:10.13474/j.cnki.11-2246.2020.0366

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Three-dimensional modeling has been widely used in cultural relics protection, engineering surveys, urban services, emergency disaster relief, forestry protection and other aspects. Based on actual engineering experience, this paper studies the three-dimensional modeling of ancient buildings for close-range photography of multi-rotor drones, and proposes a three-dimensional modeling method for ancient buildings that combines autonomous flight with manual multi-height and multi-angle photography. The experimental scene verifies the accuracy and quality of the 3D model. At the same time, the control points placed on the ground are introduced, aerial triangulation and dense matching technology are used to obtain the three-dimensional coordinates of each feature point on the ancient building, which provides a new idea for the study of close-range photogrammetry in the deformation monitoring of ancient buildings.

The impact of ionospheric VTEC and meteorological elements on GPS positioning results

LIU Yanchun

2020, 0(11):  116-119,123.  doi:10.13474/j.cnki.11-2246.2020.0367

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The positioning errors sequences of FJCORS reference stations are analysed in the paper, it's found that the observation errors show obvious seasonal variation, and the peak value appears in July for each station. By analyzing the relationship between the positioning errors and ionospheric VTEC and meteorological elements respectively, it shows that the positioning error is not related to VTEC, but has a strong correlation with meteorological elements. The decrease of air pressure or the increase of air temperature and vapor pressure will directly lead to the linear increase of errors.

Application of attitude correction technology in the Yellow River estuary test

SONG Zhonghua, TIAN Hui, WANG Jing

2020, 0(11):  120-123.  doi:10.13474/j.cnki.11-2246.2020.0368

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In order to solve the effect of the ship survey attitude on the single beam digital sounding data in the sea area test near the Yellow River Delta, the attitude sensor is used to effectively correct the ship survey attitude. We draw a conclusion by comparing the test data: the result of the posture correction technology correcting the instantaneous water depth of the digital sounder is compared with the result of the traditional artificial water depth curve, the median error is 0.089 m, and the difference between the areas below the 0 m line of the test section does not exceed 0.22%. The result meets the requirements of national regulations. This paper improves the accuracy of the sounding results in the sea area test and provides a technical guarantee for the application of digital technology in sea area measurement.

Construction and application of GMG collaborative system for driving remote sensing-based monitoring of agricultural industry in mountainous areas

SUN Junying, LIU Ji, CHEN Zhongchao, CAI Zhongliang, YAN Congzheng

2020, 0(11):  124-127.  doi:10.13474/j.cnki.11-2246.2020.0369

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The karst mountainous areas have fragmented landscape, rugged terrain and cloudy and foggy climate. It is difficult to monitor crops rapidly through conventional remote sensing methods in a large scale. In response to this situation, the GMG collaborative system integrating internal and external industries was developed. Using the precise positioning of GPS, rich semantics of multimedia and advantages of GIS data processing, the remote sensing monitoring of agricultural industry has been driven multi-directionally in Guizhou province. Practice shows that the system quickly realizes the diversity of interpreting samples in provincial monitoring, effectively compensates for the limitations of remote sensing monitoring in local areas and checks the accuracy of interpreted data in real time simultaneously.

A method to correct the logical consistency defect between linear features and land use patch in land survey

ZHANG Jia, BAI Xiaofei, WANG Xiulian, JI Hongwei, YANG Yizhou

2020, 0(11):  128-131.  doi:10.13474/j.cnki.11-2246.2020.0370

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A logical consistency defect between some linear features and patches of land survey data leads to the calculation error of land use patches. To solve the problems, this paper studies the logical relationship between lines and polygons of land survey data, summarizes the defect types of linear features crossing the patches, analyzes its causes and effects, and designs a method to correct the defect by incremental update mechanism. This method does not affect the analysis of land type flow. It can maintain the consistency of statistical results between standard time point of land survey. It is easy to realize the automatic processing of defect correction. And it facilitates data backtracking. The method is applied and verified in the national database quality inspection of land survey. It shows that it is helpful to improve the efficiency of data inspection and has a practical value.

Monitoring and analysis of spatial pattern change of urban expansion in Beijing

YU Yongxin, CHEN Pinxiang, QIN Fei, LIU Bowen, HUANG Yingchun, HUANG Siman

2020, 0(11):  132-136.  doi:10.13474/j.cnki.11-2246.2020.0371

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The paper based on the data of national geographic monitoring, combined with the statistical data of urban economy and population in the same period, uses high-resolution satellite remote sensing image data to extract boundary elements of Beijing built-up area. It combines urban spatial expansion with relevant evaluation indexes to carry out the analysis and research on spatial pattern change. It reveals the spatial pattern and its changing rules of urban expansion in Beijing from 2000 to 2017 and analyzes the reasons for the change, The results can provide a decision basis for scientific planning and sustainable development of Beijing.

Design and application of cloud platform for collaborative work of surveying and mapping metrological verification

LI Wenhui, GUO Longwen

2020, 0(11):  137-139,162.  doi:10.13474/j.cnki.11-2246.2020.0372

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Surveying and mapping metrological verification is an important measure to ensure the accuracy and consistency of surveying and mapping measuring instruments, and it is also an important form of value transmission or valuetraceability. However, at present the metrological verification management software is only limited to the business process, and ignores the digitization, networking, automation, data sharing and later data mining of the metrological verification process, which cannot a greater role in metrological verification in the society. The cloud platform for collaborative work of surveying and mapping metrological verification introduced in this paper uses a cloud server as a carrier and adopts a B/S architecture mode to move all verification services from offline to online. The application model of big data for instrument verification is established and a new mobile interconnection mode for surveying and mapping geographic information metrological verification services is realized.

Analysis of rural cadastral survey mode based on multi technology integration

JIN Bingbing, LIU Yang, WU Ziwei, ZOU Lianzhao, JIN Ting, HUANG Yunpeng

2020, 0(11):  140-144,150.  doi:10.13474/j.cnki.11-2246.2020.0373

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It is the foundation of rural land management to speed up the rural cadastral survey and establish a cadastral management system of “consistent map and urban-rural integration”. Taking the rural cadastral survey project of Guangzhou as an example, this paper puts forward many technical means, such as the traditional analytic method survey, the innovative mode of real estate integrated ownership survey, UAV incline photogrammetry, the whole process supervision and inspection mechanism, FME data inspection and warehousing, etc., to build a high-quality, efficient and refined management oriented technical mode system. Effectively ensures the precision of the survey and the quality of the results, and comprehensively find out the scope of the whole city's rural areas the ownership, quantity, quality and distribution of land and houses, which has laid a solid foundation for the registration work of rural real estate integration, and also provided the reference for carrying out cadastral investigation in the future.

Study on the integration of Nanjing planning and natural resources system

DOU Wei, CUI Lixin, YANG Lijun

2020, 0(11):  145-150.  doi:10.13474/j.cnki.11-2246.2020.0374

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In the context of the merger of planning and land department, the original planning and land system also need to be integrated. Taking Nanjing as an example, combined with the requirements of “engineering construction reform” and “integration of multiple reviews”, this paper analyzes the intersection of the original Nanjing planning and land business, studies the key process and technology of system integration, and puts forward the scheme of system integration.

Study on the approaches of integration of surveying and mapping work and monitoring and warning for geohazard work

WANG Shuo, WANG Chenyang, CHEN Changsong

2020, 0(11):  151-154.  doi:10.13474/j.cnki.11-2246.2020.0375

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Focusing on breaking through the limitations of traditional methodology on early detection of hidden hazardous locations, strengthening the monitoring and warning capacity of potential geohazards, enhancing comprehensive prevention ability against natural disasters, facilitating the cooperation between geological work and surveying and mapping work, promoting the modernization of natural resource management capacity, this paper analyses the current situation of foundation and technical advantages of surveying and mapping, puts forward the general idea. It makes it clear that building an multi-source stereo monitoring integrated space-air-ground investigation system and establishing a classification monitoring and warning geohazard system with the cooperation of the state, province, city and county, and then makes relevant policy suggestions.

Upgrading and transformation of natural resources archives management system based on space time big data platform of smart city

QI Wenlai, HAN Juan

2020, 0(11):  155-157,166.  doi:10.13474/j.cnki.11-2246.2020.0376

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With the completion of the smart city space-time big data platform, relying on its time traceability, spatial comprehensiveness, and diversity of data types, there is a large space for upgrading and transformation of the natural resources archives management system. In this paper, through the construction of the smart city big data platform in four aspects: spatiotemporal information big data, spatiotemporal information cloud platform, supporting environment, and smart application demonstration. Through the analysis of capacity, this paper studies how to upgrade the file data sorting and storage function in the natural resources archives management system, and transforms the system function modules, so as to realize the integrated management of the map, number and file of the natural resources archives, and meet the management and use needs of the natural resources departments.

Research on GIS engineering coordinate system

LIU Xiaohua

2020, 0(11):  158-162.  doi:10.13474/j.cnki.11-2246.2020.0377

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So far, there are many papers on how to establish a planar coordinate system. However, most of them have studied the establishment of a planar coordinate system in a small area. It's relatively simple. A planar coordinate system that meets the required precision can be established by using height compensation plane, translating central meridian or both. There are few researches on how to establish a planar coordinate system in a large area (nearly ten thousand square kilometers). This paper makes a detailed study on analysis and discussion this complicated problem, and obtains reasonable results. The method and process of induction can enlighten similar problems and can be taken as a reference.

Tree extraction and analysis based on vehicle point cloud data

LIAO Xiaohe

2020, 0(11):  163-166.  doi:10.13474/j.cnki.11-2246.2020.0378

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This article bases on high-precision point cloud data of highways. Firstly, the point cloud data is extracted through the classification processing of point cloud data, and then the point cloud of the tree is projected to the horizontal plane, and the DBSCAN density clustering algorithm is used to realize the extraction of a single tree. Secondly, there is an area where the tree canopy point cloud overlaps in the data-intensive area. This paper extracts the position information of the trunk and calculates all points by combining the geometric features of the trunk The Euclidean distance froms the cloud to the center of the trunk classifies all point clouds to the nearest trunk for coarse segmentation. Finally, the crown model and crown center are determined based on the rough segmented tree contour features. A grid competition algorithm based on density features is proposed to finely segment the overlapping regions. Experiments show that the tree segmentation method used in this paper can achieve accurate extraction of a single tree.