Table of Content

25 March 2021, Volume 0 Issue 3

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Analysis on BDS-3 satellite to single base station differential positioning performance

LENG Hongyu, BI Jinzhong, XU Yantian, WANG Duo, LIU Yanhui

2021, 0(3):  1-6.  doi:10.13474/j.cnki.11-2246.2021.0068

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With the continuous advancement of the global networking work of the BeiDou Navigation Satellite System(BDS), it already has global positioning and navigation service capabilities. According to the fact of the RTK positioning performances in the case of BDS-3 is uncertain,this paper puts forward a method to analyze the RTK positioning performance of BDS-3. In order to evaluate this,the observation data collected by the four reference stations in Shanghai on the 305th day of 2019 is divided into two cases with different baseline lengths. The single-baseline RTK positioning solution is performed. This paper analyzes in details on the accuracy improvement of the combined BDS-2 and BDS-3 through experiments. The experimental results show that compared to BDS-2 only, the combined BDS-2 and BDS-3 increases 3~6 visible satellites, which has a great improvement in the satellite space structure. For a short baseline, effectively improves the ambiguities fixing success rate from 89.3% to 92.3%, and the N, E and U components are improved by 4%, 43.23% and 35.60%, respectively. Moreover, more BDS-3 satellites can speed up the convergence of the RTK positioning solution in the case of medium and long baselines and obtain the centimeter-level positioning accuracy.

Accuracy analysis of BDS-3 dual frequency combination precision point positioning

LIU Shengfeng, YANG Wenlong, GU Tao

2021, 0(3):  7-11,17.  doi:10.13474/j.cnki.11-2246.2021.0069

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In view of the difference in the precise point positioning performance of different dual-band combinations of BDS-2, BDS-3, and BDS-2/BDS-3, this paper analyzes the PPP precision of seven different dual-band combinations in BDS-3 and compares it with BDS-2, BDS-2/BDS-3 same frequency dual frequency combination PPP precision comparison. The results show that the precision of BDS-2 and BDS-3 at the same frequency dual-frequency combination PPP is equivalent to the first convergence time. Among them, the precision of B2I/B3I combination PPP is the worst, and the precision of BDS-2/BDS-3 positioning precision and the first convergence time compared with the single situation, it has been greatly improved. In terms of BDS-3 dual-band combined PPP, the precision and first convergence time of the B2b/B3I combined PPP are the worst of the BDS-3 seven dual-band combined PPP, and the positioning performance of the other six dual-band combined PPPs is comparable.

Research on single point positioning of BDS-3 new signal

MU Renhai, DANG Yamin, XU Changhui

2021, 0(3):  12-17.  doi:10.13474/j.cnki.11-2246.2021.0070

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For the current research on the single point positioning of the new B1C and B2a signals of the MEO satellite (BDS-3M) in the BeiDou Satellite Navigation System (BDS-3),this paper conducts a dual-frequency single point positioning experiment based on the new signals of B1C and B2a. Combined with data from five tracking stations of iGMAS for 10 consecutive days, data quality analysis,the dual-frequency single point positioning (SPP) and dual-frequency precise point positioning (PPP) are researched,and compared with GPS L1,L2 signals and BDS-3 B1I,B3I signals.The experimental results show that the accuracy of the new BDS-3 signal in the directions of E, N and U is better than that of 10, 12 and 11 m respectively, and there is some difference between the accuracy of the dual-frequency pseudo-range single point positioning of L1 and L2 GPS and the dual-frequency pseudo-range single point positioning of the old BDS-3. In terms of precise singlepoint positioning, the convergence speed of BDS-3 new frequency point is slightly lower than that of GPS, and the new signal of BDS-3 can reach the accuracy of dm level in the three directions of E, N and U.

Quality assessment of BDS-3 real-time precision product and analysis of PPP performance

XU Xintong, YANG Zhixin, ZHANG Linjie, YANG Ying, WANG Yixin, QIAN Chuang, LIU Hui

2021, 0(3):  18-22,74.  doi:10.13474/j.cnki.11-2246.2021.0071

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With the official opening of the BDS-3, various data analysis centers have successively begun to provide real-time precision products of the BDS-3 system, making real-time precise point positioning (PPP) based on the BDS-3 is possible. The quality of real-time precision products is an important factor affecting real-time PPP positioning performance, and directly determines the availability, convergence time and positioning precision of real-time PPP. In order to promote the research and application development of real-time PPP based on BDS-3, this paper evaluates the quality of the existing BDS-3 real-time precision products, including data integrity rate, clock bias precision, and orbit precision, combined with observation data from 5 reference stations evenly distributed around the world, and analyzes the real-time PPP of BDS-3 performance. Experimental results show that the real-time data integrity rate of BDS-3 is 98.3%, and the precise clock bias and orbit precision are 0.8 ns and 8 cm respectively.Compared with GPS, the real-time PPP convergence speed is increased by 30%, and the positioning precision is increased by 8% after joining the BDS-3 system.

SPP accuracy analysis of BDS-3 under different masking angles

ZHU Yuxiang, CHEN Yonggui, AN Chunhua

2021, 0(3):  23-27.  doi:10.13474/j.cnki.11-2246.2021.0072

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Aiming at the BDS-3 positioning performance under the condition of low satellite visibility and epoch availability, this paper analyzes different altitude angles (10°, 20°, 30°, BDS-3 and GPS measured data from MEGX tracking station). 40°) SPP positioning accuracy of BDS-3 satellites B1I, B1C, B2a, B3I and GPS system L1 frequency. It is found through research that the average number of visible satellites and satellite spatial geometry of BDS-3 are better than GPS, and it changes linearly with the increase of the altitude angle. The SPP positioning accuracy of the four frequencies of BDS-3 increases first and then decreases with the increase of the altitude angle. When the altitude angle is 20°, the positioning accuracy is the highest. When the altitude angle reaches 40°, the positioning accuracy is the lowest, and the epoch availability rate is also the lowest. But the availability rate of the B1I and B3I epochs is still greater than 90%, while the availability rate of the B1C and B2a epochs is greater than 70%. Both the SPP positioning accuracy and the epoch availability are better than the GPS system L1 frequency.

Automatic recognition and positioning of overpass based on Faster R-CNN

MA Jingzhen, CHEN Huanxin, ZHU Xinming, ZHANG Fubing

2021, 0(3):  28-32,86.  doi:10.13474/j.cnki.11-2246.2021.0073

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The automatic recognition of overpass structures is of great significance for multi-scale modeling, spatial analysis and vehicle navigation of road network. The traditional method of overpasses recognition based on vector data relies too much on the characteristics of manual design and has poor adaptability to complex scenes. In this paper, a method for overpasses identification based on the target detection model Faster R-CNN is proposed. This method uses convolutional neural network to learn the deep structural characteristics of samples, and then realizes the automatic recognition and accurate positioning of the overpasses. The experimental results show that the method has a good recognition effect on overpasses, and can accurately determine their positions in the complex road network, avoiding the influence of human intervention on the uncertainty of results, and has a strong anti-interference.

Thin cloud removal in remote sensing images based on noise-adjusted principal component transform

ZHANG Yu, JIA Suimin

2021, 0(3):  33-37.  doi:10.13474/j.cnki.11-2246.2021.0074

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To solve the problem of attenuation of the earth's surface reflectance in optical remote sensing images due to cloud cover, a thin cloud removal method based on the noise-adjusted principal component transform (NAPCT) model is proposed. Firstly, a NAPCT cloud removal model is constructed through noise estimation to realize the conversion of cloud images. Secondly, it corrects the turbid pixels on NAPC1 by using the cloud distribution information provided by the first component of NAPCT (NAPC1) and merging the cloud mask. Finally, the inverse transform is applied to the cloud covered area and mosaic with the original clear pixels to obtain a cloudless image. The performance of the method proposed in this paper is evaluated qualitatively and quantitatively using simulated and real Landsat 8 images. The experimental results show that the NAPCT method proposed in this paper provides better uniformity compared with other methods. The root square error and the peak signal-to-noise ratio have a better effect on removing clouds.

High-precision lane-level map elements extracting based on high-resolution remote sensing image

HOU Qiaochu, LI Bijun, CAI Yi

2021, 0(3):  38-43.  doi:10.13474/j.cnki.11-2246.2021.0075

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High-precision map is automatically under the city road scene driving one of the necessary infrastructures. Aiming at the problems of the high acquisition cost, long period, and complicated data processing in the production and update of the static layer of high-precision map, the lane-level element extraction scheme of high-precision map static layer based on high-resolution remote sensing image is proposed. Firstly, multi-temporal images are registered by the SURF algorithm, and pixels are judged by combining the spectral information of the image, thus realizing the detection and removal of dynamic vehicles in the lane.Secondly, based on the object-oriented method, a feature selection method of element objects is proposed, and the threshold analysis of each element is carried out in combination with the statistical theory to realize the detection and extraction of lane-level elements such as the dashed lane line crosswalk.Finally, combined with experimental data, the effectiveness of the proposed lane-level elements extraction scheme based on remote sensing image is verified.

Acquiring high-precision DEM in high altitude and cold area using InSAR technology

DU Qingsong, LI Guoyu, PENG Wanlin, ZHOU Yu, CHAI Mingtang, LI Jinming

2021, 0(3):  44-49.  doi:10.13474/j.cnki.11-2246.2021.0076

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Using Sentinel-1A SLC data as the original image, based on InSAR technology, the DEM data of the central small area located in West Tianshan, Xinjiang, a typically high and cold region is obtained in the paper. Then it compares the data with the commonly used SRTMDEM v4 DEM and GDEMDEM. The results show that:applying InSAR technology can obtain high-precision DEM with the resolution of 15 m by processing sentinel-1a SLC data. The DEM data precision is better than SRTM V4 DEM and GDEMDEM, which can better describe the details of the surface topography, can be used as input data to obtain high-precision deformation information of the ground, and can provide important basic data for engineering construction and geological disaster evaluation. In addition, this method is of great significance for DEM data updating.

Improved method of UAV 3D path planning

FENG Zhaohui, HAN Liusheng, LI Qin

2021, 0(3):  50-54.  doi:10.13474/j.cnki.11-2246.2021.0077

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In order to adapt to the changing natural environment, it is necessary to develop three-dimensional path planning for remote sensing observation mission in the complex environment of undulant terrain. It is valuable to reduce the flight time and energy consumption to improve the observation efficiency. This paper proposes an algorithm called curved surfaced flattening algorithm (CSFA). The algorithm uses quasi-uniform B-spline curve fitting algorithm to interpolate the DEM of target area processed by CSFA algorithm to build the terrain model of regional natural environment. Then it uses the vertex-edge algorithm to calculate the optimal flight direction and obtain minimum number of turns in order to reduce the time and energy consumption. Finally, the three-dimensional(3D) airstrips and exposure points can be calculated according to the overlap constraint in photogrammetry and regional environment terrain model. In the experiment, 3D path planning simulation is carried out by establishing constraints at different fly heights. The results show that method proposed in this paper can shorten the length of 3D airstrips, reduce the energy consumption and improve the efficiency of observation task obviously.

Building facade classifying and DIM point cloud filtering

CUI Ying, HUANG He, LIU Xianglei, LUO Dean

2021, 0(3):  55-59.  doi:10.13474/j.cnki.11-2246.2021.0078

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Aiming at the distortion of building façade TIN grid model which caused by the dense image matching (DIM) point cloud with noise, this paper references the idea of sample learning and proposes the corresponding DIM point cloud filtering method to remove the noise point and improve the model distortion after classifying the facades. Among them, for the facade with planar structure, this paper first learns and calculates the parameters of mathematical facade model from the selected point cloud sample, and then sets the threshold for the model to filter; for the façade with curved structure, after analyzing the characteristic of the facade DIM point cloud, this paper first marks the selected point cloud sample as two types of façade point and non-facade point, then learns the feature of the marked sample and calculates the optimal regression coefficient needed for the filtering classifier by the logistic regression algorithm to remove the noise point cloud. Finally, the experimental result showed that the filtering method can effectively identify and segment the noise point cloud from the whole facade point cloud, and the facade model which built by the filtered point cloud was be refined and optimized.

Land surface temperature inversion and change analysis of Dongguan using Landsat images

CHEN Minghui

2021, 0(3):  60-68.  doi:10.13474/j.cnki.11-2246.2021.0079

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With the rapid urbanization process, a large number of construction land has been added in some cities along the southeast coast of China, and the urban human settlements have been affected causing urban thermal environment problems. It is of great practical significance for the sustainable development of cities and the improvement of the quality of human settlements to study the spatial and temporal distribution and change characteristics of urban thermal environment and analyze the causes of changes. In this paper, taking 8 temporal Landsat satellite images from 1986 to 2017 as data sources, the surface temperature of Dongguan city is quantitatively inversed by single channel algorithm, and the spatial-temporal distribution pattern and change characteristics of the thermal environment of Dongguan city are analyzed and the influencing factors are analyzed. The results show that in the past 30 years, the urban thermal environment in Dongguan city has developed from scattered point distribution to belt distribution along the main traffic routes; the surface temperature in the town/street center of Dongguan city is significantly higher than that in the suburbs and villages, and there is a strong heat island effect; the proportion index of heat island in Dongguan city has an overall upward trend, from 0.06 in 1986 rose to 0.15 in 2017, with the highest heat island effect in Dongguan in 2009. The results of the study are of great significance to the rational planning of Dongguan city construction and the sustainable development of urban construction.

Pedestrian road network extraction based on crowdsourcing trajectory data

ZHENG Tianjing, HUANG Jincai, ZHOU Baoding, ZHANG Dejin

2021, 0(3):  69-74.  doi:10.13474/j.cnki.11-2246.2021.0080

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At present, the routes provided by the navigation location service application are mostly based on the data of the vehicle road network, which is difficult to meet the needs of pedestrian navigation. The complete pedestrian network has become an important factor restricting the application of pedestrian navigation. Therefore, this paper proposes a pedestrian network extraction method based on Morse theory. First, the trajectory is preprocessed to remove redundancy and noise in the trajectory data, and the original trajectory is divided reasonably to form a clear trajectory set. Secondly, Morse theory is used to extract the "ridgeline" in the density map of walking track and reconstruct the pedestrian network. The experimental analysis uses the walking GPS track data of Shenzhen university campus to extract the pedestrian network. By qualitative and quantitative comparison of the extracted pedestrian network results with OpenStreetMap (OSM) data, the effectiveness of the method in this paper is verified. At the same time, compared with the current typical road network extraction methods, the proposed method can extract high quality pedestrian network.

An algorithm of indoor spatial topological model based on building plans

HAN Litao, ZHOU Lijuan, GUO Jia, SUN Xianlong

2021, 0(3):  75-80,86.  doi:10.13474/j.cnki.11-2246.2021.0081

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When taking building plans as the data source to construct indoor navigation models, the building plans lack topological information, especially the topological description of polygonal objects such as rooms and corridors.Therefore, an algorithm for automatically constructing the indoor spatial topological model is proposed.According to the characteristics of CAD building plans, the algorithm abstracts the wall line as an arc segment, the door and window as a point, and the room as a polygon. Then, starting from the starting wall line, the algorithm calculates the first wall line encountered clockwise or counterclockwise as the first edge of the target room or corridor, and so on, and finally returns to the starting wall line, completes the extraction of a room or corridor. Repeat the above process until all wall lines are marked twice, indicating that all rooms or corridors are extracted successfully. The topological relationship between doors and windows and rooms is based on the topological relationship between doors and windows and wall lines, and the topological relationship between doors and windows and rooms is deduced. Taking the building plan of a university teaching building as an example, the experiment show that the algorithm can effectively realize the automatic generation of indoor space topology model.

Cultural landscape map design: visualization objects and artistic style

SU Shiliang, WU Linying, DU Qingyun, KANG Mengjun, WENG Min

2021, 0(3):  81-86.  doi:10.13474/j.cnki.11-2246.2021.0082

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Using a typical case of West Lake cultural landscape, with a predominant focus on the visualization objects and artistic style, this paper, firstly establishes a theoretical framework for guiding the selection of visualization objects, according to the landscape gene theory and the image associated with Chinese cultural landscape. Then proposes a logic for transferring the artistic style of landscape maps in Song Dynasty following the idea of "past for present". And finally explains the design strategy involved of the specific steps in visual hierarchy, color, symbol and outlay design, aiming to providing references for cultural landscape map design both in theory and in methodology.

ICP parallel registration of multiple point clouds with MPI

CUI Jiawu, ZHOU Boyang, ZHANG Xingfu, CHAI Xianghao, FAN Shuchun

2021, 0(3):  87-90.  doi:10.13474/j.cnki.11-2246.2021.0083

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Iterative closest point (ICP) algorithm is a classic algorithm for precise point cloud registration. In this paper, in order to solve the problem of time-consuming and low efficiency in ICP registration of multiple point clouds, the message passing interface (MPI) is proposed to perform batch parallel registration for multiple point clouds. First, the adjacent transformation matrix of two adjacent point clouds is solved in parallel, then the local transformation matrix of each point cloud in the current batch is calculated, and finally the global transformation matrix of each point cloud is obtained. 65 chip point clouds with a total size of over 40 million points in space are registered in batch parallel with DELL PowerEdge R730 server as the computing platform. The results show that batch processing of multiple point clouds using MPI can significantly accelerate the registration speed, and the acceleration ratio is 5.3 when the optimal number of processes is the kernel of the computer.

Annual change detection of land use status based on siamese neural network

ZHANG Weiliang, LIU Qi, WU Changbin, YANG Guangdi

2021, 0(3):  91-95,104.  doi:10.13474/j.cnki.11-2246.2021.0084

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In recent years, multi-phase high-resolution remote sensing images are used to build an annual change detection model of land use status and support the intelligent development of annual change detection of land use status on this basis, which is exactly the difficulty of current research. This paper discusses the construction of land use status quo of annual change detection model. Through the land information and data preprocessing, change detection based on twin neural network model being constructed, and the result of the model output optimizing GIS in to obtain the variation spot target area achieves rapid extraction according to current situation of land use change area. The experimental results show that this method can quickly find the change locations of land use status in the images in different periods, which effectively improve the intelligent level of annual change detection of land use status, and can serve the daily annual change detection of land use status.

Photovoltaic roof extraction from material and angle attribute filtered method

WANG Shouzhi, ZHANG Fukun, ZHU Pengfei, ZHAN Hao, ZHANG Yunjiao, XI Ge

2021, 0(3):  96-99,151.  doi:10.13474/j.cnki.11-2246.2021.0085

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Aiming at the high-resolution satellite image photovoltaic roof extraction problem under the background of sample imbalance caused by various types of urban photovoltaic roof, a material and angle attribute filtered method is proposed. By selecting satellite images of Nankai district, Hongqiao district, Heping district, and Hedong district in Tianjin, the sample balanced data set is acquired using the two filtered material and angle attributes labeled on the photovoltaic roof. This paper finally gets the photovoltaic roof extraction result by properly setting parameters of the U-Net algorithm integrated under the TensorFlow framework. As a comparison, the photovoltaic roof is extracted without using two filtered material and angle attributes at the same time. The experiment shows that the method proposed in this paper has higher extraction accuracy, and especially for the uncommon photovoltaic roof in the study area, it can extract more complete and accurate result with clear boundary.

River surveying based on UAV PPK technology and precision analysis

REN Gaosheng, LI Mingfeng, CHEN Ningning, ZHANG Shiquan

2021, 0(3):  100-104.  doi:10.13474/j.cnki.11-2246.2021.0086

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Aiming at the difficulty of laying control points on the river's belt-like complex terrain and high-precision measurement requirements, a non-GCPs monitoring method for rivers and lakes combined with PPK technology is discussed. The DJI Phantom 4 RTK UAV is used as the research object,the key technologies that affect the accuracy of aerial surveys, such as high-precision POS assisted airborne triangulation based on PPK, camera lens distortion correction, and route designare analyzed,ground base station and UAV POS data by UAV-PPK software calculated, combined with the GNSS post-difference processing technology to obtain high-precision POS data to assist aerial triangulation. Combined with Zhuangmu River regulation project to carry out experiments,the analysis of POS data and mapping accuracy shows that based on PPK's Non-GCPs UAV aerial survey, high-precision POS data assisted aerial three surveys are obtained, and the precision of the results meets the requirements for 1:500 large-scale mapping of river channels. PPK aided UAV for aerial survey improves the precision of surveying and mapping of complex terrain, and provides accurate data support for subsequent comprehensive river regulation work.

Application of industrial camera in digitalization of historical aerial photos

ZHANG Junhua, LING Chunli, YANG Yong, WANG Youkun

2021, 0(3):  105-108.  doi:10.13474/j.cnki.11-2246.2021.0087

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As a kind of historical archives, aerial film records the changes of geomorphic information such as city scale and facilities in detail. Due to the limited shelf life of the film, it is necessary to digitize it for permanent storage. Traditional scanning methods are inefficient, and with the birth of industrial-grade cameras of 100 million and more pixels, it is possible to photographing instead of scanning. In this paper, we use the self-made high-precision large format film reproducer, obtains accurate correction parameters through accurate inspection, and combine with the computer post-processing to complete the digitization of about 8500 historical aerial films in Kunming phase II. The results meet the requirements and achieve the expected purpose.

Analysis of the area difference of different coordinate systems: taking Ningbo city as an example

FU Huanian, ZHANG Xudong, WANG Yanlin

2021, 0(3):  109-112,155.  doi:10.13474/j.cnki.11-2246.2021.0088

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For the integration of land use and planning work, this paper discusses the area difference in different urban coordinate systems and analyzes the theoretical law of area change from the ways of different ellipsoids, different Gauss projection planes and different central Meridians, using the formulas of gauss projection and height reduction. According to the actual situation in Ningbo, considering the central part of the city, the edge of the city and the high mountain area, the paper selects five representative survey areas. Based on the existing Ningbo city coordinate system and the national coordinate system, the paper compares the area difference under various conditions and points out the main reasons and explores the unified calculation scheme of urban area during the merging of different business sectors under the natural resources system.

Monitoring and parameter inversion of ground subsidence in mining area based on SBAS-InSAR method

REN Wenjing, JIA Hongguo, YAN Bin

2021, 0(3):  113-117,155.  doi:10.13474/j.cnki.11-2246.2021.0089

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Coal mining-induced geological disasters have a serious impact on the lives and property safety of people in mining areas. Therefore, monitoring the ground deformation of the mining area and inversion of its mining surface parameters to obtain the deformation trend can effectively prevent the occurrence of geological disasters in the mining area. This study selects the Dianping Coal Mine and Fenyuan Coal Mine in Shanxi province as the study area. Based on the Sentinel-1A satellite image data, the small baseline subset (SBAS) method is used to extract the deformation results of the study area. The Okada model is used to invert and analyze the parameters of 5-101 working face, and the inversion results are compared with the measured data through the coal mining and excavation engineering map. Experiment results show that:① The degree of ground deformation caused by coal mining is proportional to the length of coal mining; ② The degree of ground deformation caused by the mining of steeply inclined thick coal seams is greater than the degree of ground deformation caused by nearly horizontal thin coal seams, and it is more likely to cause ground collapse; ③ The Okada model has a higher accuracy in inversion of mining parameters for short, nearly horizontal thin coal seams, indicating that this model is suitable for inversion of mining parameters in this type of coal mine.

Deformation monitoring of Qinghai-Tibei transmission tower using high resolution time-series InSAR technology

FAN Peng, WANG Shuo, ZHANG Zhengjia, LIU Xiuguo, CHEN Qihao

2021, 0(3):  118-122.  doi:10.13474/j.cnki.11-2246.2021.0090

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With the global climate changing and increasing of anthropogenic activity, the dynamics permafrost environment of Qinghai-Tibet Plateau (QTP) is becoming fragile. As one of the most important infrastructures in the QTP, the Qinghai-Tibet power transmission line (QTPTL) has been constructed since 2011. In some section, the stability of QTPTL has been damaged due to the harsh climate and the effect of freezing and thawing of permafrost. To ensure the safety of the QTPTL, it is necessary to monitor the deformation of QTPTL. Conventional measurement methods (GPS and levelling) have limitations of monitoring deformation of QTPTL. In this paper, structural health and stability of QTPTL are evaluated using time-series InSAR with high resolution TerraSAR-X staring spotlight mode images. The structure feature of the transmission line tower in high resolution SAR image are analyzed. Then the deformation velocity, height and thermal dilation of the QTPTL is retrieved. The results demonstrated that potential for the deformation monitoring of QTPTL using high resolution time-series InSAR.

Multi-scale geometric and semantic modeling of drainage network

LAN Guiwen, TANG Yulong, DU Yongliang, PAN Zhuguang, MO Xuqi

2021, 0(3):  123-127.  doi:10.13474/j.cnki.11-2246.2021.0091

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A multi-scale geometric and semantic model of drainage network involving "source-network-factory-sink" by studying the multi-scale geometric and semantic expression method of drainage network is proposed in this paper to meet the different requirements of drainage network management. Through the systematic analysis of the components of drainage network and their interrelations, the LODs model of the drainage network is designed by referring to the CityGML specification. And then according to the characteristics of the different components of drainage network, the three-dimensional models of the components of drainage networks in different LODs are separately constructed by symbolic modeling and BIM modeling and other methods to realize the multi-scale representation of drainage network. The data of drainage network in a certain area is used to verify the modeling method proposed in this research.

Plane detecting and jumping based on the scene depth image of panorama images

MING Jing, XIANG Zejun, LONG Chuan, TENG Degui, CHEN Han

2021, 0(3):  128-133.  doi:10.13474/j.cnki.11-2246.2021.0092

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In the management of street view facades based on panoramic images, it is necessary to jump to the panoramic image that is closest to the target facade and face it right at the front as much as possible. However, the conventional jumping methods cannot meet this demand. To solve this problem, a new method of plane detecting and jumping for panorama images is proposed. Based on the scene depth image of the panoramic image, calculate the world coordinates of the target point as well as the average normal direction of the patch formed by the target point and its neighboring points, so as to achieve the plane detection in the panoramic image. Starting from the target point, search along the average normal direction for the panoramic image whose viewpoint is the closest to the ray. Switch to the target image, and rotate the angle of view based on the orientation of the target point in the target panorama image. The successful application in practical projects in Chongqing and the case study results show that the proposed new method can meet the requirements of facade management and jump to the better neighboring panoramic image facing the target facade. The application effect of the new method is also better than that of conventional jumping method.

The problems and thinking of surveying and mapping geographic information testing in the era of big data

LI Chong, TAN Mingjian, TAN Li

2021, 0(3):  134-137.  doi:10.13474/j.cnki.11-2246.2021.0093

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In the era of big data, surveying and mapping geographic information data, as an important basic data bearing all kinds of natural resource information, social information, economic information, human information, etc., it has a significant quality. However, the current quality inspection of surveying and mapping geographic information can not fully meet the needs of the times from the theoretical basis, methods, service models and other aspects. This paper analyzes some typical characteristics and ways of thinking in the era of big data, analyzes some problems faced by the quality inspection and detection of surveying and mapping geographic information in the new era from the aspects of quality measurement, sampling inspection and evaluation, inspection and detection, and finally gives some thoughts and suggestions.

Discussion on geographic information cloud platform database architecture

JIANG Aihua, LIU Lihong, TAO Wenjun, MENG Dan

2021, 0(3):  138-141.  doi:10.13474/j.cnki.11-2246.2021.0094

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The article from the concept of "a picture", analyzes the function and main characteristics of cloud platform and geographic information classification, illustrates the geographic information cloud platform database content and data update mechanism and methods. From the perspective of data applications discusses the necessity of the research on geographic information platform data. Widely analyzes geographic information cloud platform database system architecture and the mutual relationship between all kinds of cloud platform, discusses the views of geographic information data cloud platform system.

The government service map under the background of digital transformation

WANG Yanchao, CHEN Zhangjian, LI Aiqin, GONG Lifang

2021, 0(3):  142-146.  doi:10.13474/j.cnki.11-2246.2021.0095

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Nowadays, along with the deep going of the reforms to streamline administration and comprehensively accelerating the construction of online government service platform in China, it puts forward new requirements for surveying and mapping and geographic information work. Taking convenience manual compilation work in the Zhejiang government service networks as a breakthrough point, this paper focuses on process reengineering and data sharing and the collaborative update of the service outlets and service addresses of government affairs, and thereby constructs the map system of government affairs with the geographical location as the core, which have been applied in several modules of Zhejiang government service network and Zheliban APP. It provides a map access of "where to do, what to do, and how to do" services for masses and enterprises, and obtains a good response of application effect in Zhejiang province, which has a significant meaning for other regions.

Map signs of land type analysis of common identification problems in the third national land survey

LI Zhiyu, TAN Junhui

2021, 0(3):  147-151.  doi:10.13474/j.cnki.11-2246.2021.0096

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The third national land survey in 2019, has been fully developed, and the map signs of land type is the emphasis and difficulty in the work. Based on our experience in the implementation of the multiple projects in the south of China, this paper has developed a set of rules and experience of land category identification aiming to solve the problems with wrong judgment easy to make in the work of the three map signs of land type. They are soil moving, construction land and idle land, according to the analysis results from the comparison of images, scene photos and the basis of asserting releasing by country. It helps people to make the class identification quickly and accurately in the third national land survey,avoiding rework and revising of the database, so as to improve the work efficiency of the operation team and the quality of our work in the third national land survey.

Research on professional master's industry-education integration training mode by the PDCA cycle

SHI Jianqing, DONG Chunlai, FENG Nana, WANG Xinxiang

2021, 0(3):  152-155.  doi:10.13474/j.cnki.11-2246.2021.0097

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In order to meet the demand for excellent engineering and technical talents in the new era. Based on the analysis of the status quo of professional postgraduate training, this paper puts forward the model of deep integration of industry and education based on PDCA concept for talent training program, discusses the model and countermeasures for development of training objectives of industry and education deep integration, the implementation of training plan, the development of curriculum system, the optimization of tutor team and quality assurance construction of practice base.It discusses the quality control system for professional master's degree cultivation, and summes up the continuous improvement process of planning, implementation, examination and treatment of all aspects of education and teaching, providing reference for the high-level training and management of professional masters.

Application of SBAS technology in ground subsidence monitoring of mining area

CAO Fawei, LIAO Weigu

2021, 0(3):  156-158,163.  doi:10.13474/j.cnki.11-2246.2021.0098

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The 8-scenario ALOS-PLASAR data of Xiejiaji mine in Huainan city is processed using the small baseline technology, SBAS-InSAR, from January 2007 to February 2011. Firstly, the SBAS-InSAR technology is used to extract the time-series deformation rate of the mining area to obtain the cumulative overall settlement trend. Then it analyzes the key settlement areas such as roads, railways, new and old mining areas, etc. From the analysis of the monitoring results, it can be seen that the Shijian Lake west road and the dam are in the lower overall. In the sinking state, the western half of the Xizhang railway is in an uplifted state, while the eastern half is sinking severely. The Dongfang mine and the Xiner mining area are in different degrees of decline.

Technical practice of backpack, vehicle-mounted laser scanning combined with UAV oblique aerial survey in community holographic data collection

NING Zhenwei

2021, 0(3):  159-163.  doi:10.13474/j.cnki.11-2246.2021.0099

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With the changes in the use requirements of surveying and mapping geographic information and the advancement of surveying and mapping data acquisition technology, holographic surveying and mapping has become a new idea of basic surveying and mapping data production. In this paper, three collection methods of GeoSLAM backpack, Trimble MX9 vehicle-mounted laser scanning system and DJI M300 UAV oblique aerial survey are used in Guangdong Software Park to obtain holographic data in the park, and then carry out calibration, matching, fusion, classification and processing and carry out elementalization, materialized and three-dimensional production to form the three-dimensional object map data of the park, which provides a basic base map for the location service, management and display of the smart community. The results show that the community holographic map produced by laser combined with oblique aerial survey is better than traditional photoelectric ranging methods in terms of richness, accuracy, completeness and precision.

Application of 3D laser scanning technology in contactless deformation monitoring for expressway operation

NI Fei, WANG Haocheng, YANG Yizhuo, YANG Xiaobo

2021, 0(3):  164-166.  doi:10.13474/j.cnki.11-2246.2021.0100

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Use 3D laser scanning technology to obtain 3D point cloud data in the highway monitoring area in a non-contact manner in this paper. Use the difference comparison method of 3D point cloud between the surface to calculate the deformation difference value of different periods of broken roads. The intuitive color band diagram forms a three-dimensional data result diagram and final report. The results show that the accuracy and measurement efficiency of highway pavement data measured by the three-dimensional laser scanner are relatively high, which can meet the requirements of highway pavement monitoring and provide technical support for fast and efficient highway pavement deformation monitoring.