Table of Content

25 January 2020, Volume 0 Issue 1

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Progress and thought of navigation and location servicesin of China

JIANG Weiping, GUO Chi, ZUO Wenwei

2020, 0(1):  1-4,25.  doi:10.13474/j.cnki.11-2246.2020.0001

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Navigation and location service is another emerging information industry with rapid development after the mobile communications and mobile Internet. This paper first analyzes the development status and characteristics of navigation and location service industry in detail, expounds the industry chain of the navigation and location serviceand its industrial layout. Then, the advanced technologies and development trends of navigation and location service industry are further elaboratedaccording to the current characteristics of the industry. The advanced technologies include precise cooperative positioning, social perception and computation,integration of satellite navigation and 5G mobile communication, intelligent navigation combined with unmanned robot system. Finally, the paper puts forward some suggestions on the development of the navigation and location service industry in China to meet the great needs of China's modernization development. The suggestions include five aspects:key techniques extension, personnel training, major strategic planning, core chip and software platform, standard setting.

Precise positioning of smart phones and results analysis

HU Ningsong, FANG Wentao, GU Shengfeng, LOU Yidong

2020, 0(1):  5-9.  doi:10.13474/j.cnki.11-2246.2020.0002

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With the development of mobile internet and the popularity of smart phones, the demand for high-precision location based services is increasing. Google Inc announced the possibility to retrieve GNSS raw data from smart phones and tablets equipped with Android Nougat (version 7) operating system or later. Thus, high-precision positioning technology such as PPP and RTK for geodetic receivers will be used for public terminal, such as smart phones. In this paper, we use the real time precise satellite orbit、clock offset and ionosphere correction from collaborative precision positioning service to achieve PPP high-precision positioning of smart phones. Two smart phones, Xiaomi 8 and Huawei P10, are tested to evaluate the performance of PPP, the results show that the horizontal positioning accuracy is better than 1 m under the open sky. Compared with standard single-point positioning, the horizontal accuracy improves 36% and 47%.

A real time semantic segmentation method based on multi-level feature fusion

ZHOU Jimiao, LI Bijun, CHEN Shizeng

2020, 0(1):  10-15.  doi:10.13474/j.cnki.11-2246.2020.0003

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Road scene understanding is an important module in autonomous driving as it can provide rich information for other modules like high-res map and dynamic planning. Semantic segmentation classifies each pixel in an image and it is often used in scene understanding. However, common segmentation algorithms cannot balance the accuracy and speed. In this paper, we first extract features with light-weight backbone MobileNetV2, and then introduce a new feature fusion module to combine multi-scale features efficiently, which can makes a good balance between accuracy and speed. Finally, we evaluate our method on the Cityscapes dataset.

Lane detection with double vanishing points estimation

CHEN Shizeng, LI Bijun, ZHOU Jimiao

2020, 0(1):  16-20.  doi:10.13474/j.cnki.11-2246.2020.0004

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In automatic vehicles or advanced driving assistance systems, lane detection provides a way to guide the vehicle to drive along its own lane. An efficient lane detection method is proposed in this paper. Firstly, the lane features are extracted, and the lines are generated from vanishing points to image bottom. Then the lines crossing most features are selected and vanishing points are updated by the overlap between features and selected lines. Last step will be repeated until stable vanishing points are obtained. The last selected lines are most likely to be lane lines. Finally, validate and select the best lane lines. The proposed method has been tested on a public dataset. The experimental results show that the method can improve robustness under real-time automated driving.

UGV's automated driving navigation and localization in closed areas with pre-established high precision planar map

WANG Yiwen, QIAN Chuang, TANG Jian, WEN Jingren, NIU Xiaoji

2020, 0(1):  21-25.  doi:10.13474/j.cnki.11-2246.2020.0005

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Aiming at the application of UGV automated driving in closed areas,a high precision planar map based navigation and localization method is proposed in this paper. This method establishes multiple resolution grid maps of pre-defined probability with the 3D laser scan, which improves the localization efficiency and insures the map accuracy at the same time. Maximum likelihood estimation is adopted to obtain the initial pose of the carrier, IMU data is used to obtain a reasonable starting value of the carrier's pose for Gauss-Newton search. Field experiment proves it a proper method which efficiently resolves the quick accumulation of scan-scan matching's localization errors that locating with LiDAR scan and the prior map, it's able to provide the carrier's continuous location of high accuracy.

Lane-level navigation system based on BeiDou high-precision positioning

GUO Jing, WANG Zhengwei, QI Junfeng

2020, 0(1):  26-29.  doi:10.13474/j.cnki.11-2246.2020.0006

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With the increasing number of vehicles operating in our country, various kinds of traffic accidents occur from time to time, which has brought huge losses to people's lives and property. There are many reasons for this. Among them, illegal acts (such as speeding, changing lanes at will, occupying overtaking lanes for a long time, emergency lanes, stopping at will) by drivers of operating vehicles are the important factors leading to accidents on expressways. Based on this phenomenon and reason, a high-precision positioning lane-level navigation system based on BeiDou Satellite Navigation System is studied and implemented, which can strengthen the control of driving behavior of operating vehicles, solve the traffic law enforcement problems and improve the management efficiency.

The real-time PPP precision analysis based on BDS-3

DAI Jinqian, WU Di, DAI Xiaolei, LOU Yidong

2020, 0(1):  30-34.  doi:10.13474/j.cnki.11-2246.2020.0007

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To provide real-time BDS-3 satellite precision orbit and clock products,the daily observations of DOY 143-150 in 2019 from MGEX stations which were recorded in simulated real-time mode were selected to calculate by PANDA in this paper. The evaluation of overlapping arcs of BDS-3 satellite real-time precision orbit products shows that the radial accuracy of real-time orbit is better than 10 cm, and the real-time clock difference STD is better than 0.3 ns. On this basis, the real-time static PPP and real-time dynamic PPP positioning based on the BDS-2, BDS-3 and the fusion of BDS-2+BDS-3 were verified and analyzed. The experimental results show that the horizontal positioning accuracy of BDS-3 static PPP is better than 2 cm and the elevation accuracy is better than 4 cm, the convergence time of BDS-2+BDS-3 combined real-time dynamic PPP is 38.2%, 75.0%, 49.7% higher than BDS-2 respectively. After convergence, the E direction accuracy is better than 3 cm, the N direction accuracy is better than 2 cm, the average improvement is 38.2%.Besides,the elevation direction accuracy is better than 6 cm,which increases 64% averagely.

Land-use information extraction of GF-1 remote sensing image of reservoir area by using object-oriented method

YANG Zhixiang, JIA Dongzhen, ZHOU Hangyu, HU Youneng, LI Guang

2020, 0(1):  35-39.  doi:10.13474/j.cnki.11-2246.2020.0008

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GF-1 remote sensing satellite is the first domestic high-resolution satellite. Due to abundant information included in the images, more and more GF-1 data have been used to extract the information of land-use. However, few application is found in the land-use investigation of reservoir area of hydraulic project. Firstly, take reservoir area of Xiajiang hydraulic project in Jiangxi Province as an example, the images are preprocessed including ortho rectification using RPC model, geometric precision correction and so on. Then, band simulation based pansharpening algorithm by multiple linear regression is used to fuse 8 m multispectral and 2 m panchromatic images, the performance of this method is better than the conventional fused method. Finally, land use information of reservoir area from 2 m fused image by using object-oriented method based on comprehensive utilization of spectral information, texture, shape characteristics and so on. The results show that land-use information could be extracted from GF-1 images of reservoir area effectively; the overall classification accuracy reaches 87.9%, the Kappa index is 0.836, and can meet the requirement of land-use investigation and change motoring in reservoir area.

Monocular SLAM system in dynamic scenes based on image semantic segmentation

SHENG Chao, PAN Shuguo, ZHAO Tao, ZEN Pan, HUANG Lixiao

2020, 0(1):  40-44.  doi:10.13474/j.cnki.11-2246.2020.0009

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The traditional visual SLAM algorithm is based on the static environment assumption when recovering scene information and camera motion. The dynamic objects in the scene will reduce the robustness of the algorithm and the final positioning accuracy. In this paper, we propose to combine the image semantic segmentation based on deep learning method with the traditional visual SLAM to reduce the interference of dynamic objects on the positioning results. Firstly, a supervised convolutional neural network (CNN) is used to segment the dynamic objects in the input image to obtain the semantic image. Secondly, after extracting feature points from the original image, the feature points of dynamic objects are eliminated object feature points according to the semantic image, and the feature points of static objects are saved. Finally, the monocular SLAM method with points is used to track the camera motion based on the saved feature points. Experiments on the ApolloScape datasets show that compared with the traditional method, the proposed method improves the positioning accuracy in dynamic scenes by about 17%.

A dynamic spatial-temporal data acquisition and mining method based on ELK stack

WU Jiaqi

2020, 0(1):  45-49,81.  doi:10.13474/j.cnki.11-2246.2020.0010

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This paper attempts to extract the ability of ELK inprocessing large-scale and real-time log files, combines its superiority with geographic information technology, and provides a dynamic spatial-temporal data acquisition and mining method based on ELK stack. The method dynamically collects massive unstructured data and screens spatial-temporal information related to geographic elements in real time, so as to realize real-time dynamic analysis and mining of spatial-temporal geo-information data under massive analysis samples, and takes the traffic flow of Shanghai expressway which is used to verify the method model as a research object. The experimental results can reflect certain social potential laws and provide relevant guidance value, prove the method is feasible, and the advantages and disadvantages of the method are recorded and analyzed.

RSSI indoor ranging algorithm based on wavelet transform and neural network

ZHU Menghao, LU Xiaoping, LU Zezhong, LI Yaping, TAO Xiaoxiao

2020, 0(1):  50-54.  doi:10.13474/j.cnki.11-2246.2020.0011

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A WiFi-based RSSI indoor ranging algorithm based on wavelet transform and neural network is proposed. The method is to correct the RSSI data and path loss model by wavelet transform and neural network. Using wavelet decom position and single-reconstruction reconstruction method, only a single-branch reconstruction of the approximate part of the low-frequency, discarding the high-frequency details, and using the neural network to train the path loss model in a speci fic environment. The example shows that the maximum ranging error, minimum ranging error and average ranging error of the algorithm are 1.206, 0.037 and 0.692 m. The average ranging error is 1.846 and 0.469 m compared with the path loss model and BP neural network model.

Research on GPS/BDS/GLONASS dual-frequency RTK positioning algorithm

CHEN Wentao, CHENG Pengfei, XU Yantian

2020, 0(1):  55-60,70.  doi:10.13474/j.cnki.11-2246.2020.0012

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In the double difference observation equation, the double difference ambiguity loses the whole circumference characteristics for using FDMA technology for GLONASS. To solve it, this paper proposes a method based on the interstation single difference ambiguity, and additional ambiguity parameters Kalman filter, it implements GPS/BDS/GLONASS combined RTK positioning. The RTK program is used to solve measured short baseline data of the GPS, BDS and GLONASS dual-frequency, and the stability and positioning accuracy in other RTK modes are compared and analyzed. The results show that the fixed rate of ambiguity of GLONASS single frequency and dual frequency positioning is 99.8% and 99.7%, respectively, and its positioning accuracy is not much different from BDS and GPS. In single-frequency or dual-frequency RTK positioning, the stability and positioning accuracy of the dual-system and three-system combined positioning are significantly higher than that of the single system. The stability of the three-system combined positioning is the best and the highest precision. As the frequency increases, the initialization time is significantly reduced, providing the possibility to achieve a fixed solution for a single epoch.

Monitoring the land subsidence in Hexi area of Nanjing by using Sentinel-1A

YANG Zhen, XU Jia

2020, 0(1):  61-65,75.  doi:10.13474/j.cnki.11-2246.2020.0013

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The Hexi area of Nanjing is a floodplain developed by the deposition of the Yangtze River and the Qinhuai River. Due to the large-scale development and construction of the Hexi New City and the impact of geological conditions, land subsidence has become a problem that cannot be ignored in urban development in the region. Sentinel-1 data is the free SAR data currently running. It has a short revisit cycle and a large width, which provides an important data source for wide-area long-term surface deformation monitoring. The short-baseset set interference (SBAS-InSAR) technique is used to process the 19-story Sentinel-1A data covering the Hexi area from April 2015 to April 2018, and the ground subsidence results of the study area from 2015 to 2018 were obtained and combined. Urban development, population distribution and other information have in-depth analysis of the distribution characteristics and causes of land subsidence.

The effect of Beidou antenna phase center offsets and variations correction on precise single point positioning

GU Shiming, DANG Yamin, WANG Hu, GU Shouzhou, XU Changhui, REN Zhengzhao, ZHANG Jinxu

2020, 0(1):  66-70.  doi:10.13474/j.cnki.11-2246.2020.0014

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In this paper, the manufacturer's model, MGEX model and ESA model are used to correct the antenna phase center offsets and variations of BDS satellites in precise point positioning. The results show that the three models improve the accuracy of BDS precise point positioning, with an improvement of 1~2 cm and from 1 dm to centimeter level in the horizontal and vertical directions. Meanwhile, the ESA model is better than the other two models. For the receiver phase center offsets and variations, the BDS is corrected by the GPS correction model. Compared with the uncorrected model, the accuracy improvement varies with antenna types, which can be millimeter level in the horizontal direction, whereas it can be centimeter level in the vertical direction.

Study on the performance of BDS-3 multi-frequency pseudo-range single point positioning

ZHANG Qiankun, LIU Xiaosheng, HE Qimin

2020, 0(1):  71-75.  doi:10.13474/j.cnki.11-2246.2020.0015

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Currently, the study on BDS-3 pseudo-range single point positioning (SPP) is insufficiency and there are no comparative analyses about the results of multi-frequency SPP in BDS-3. In this paper, the performance of multi-frequency SPP in BDS-3 are analyzed by using the measured data. In addition, the same frequency SPP experiment of the combination with BDS-2, Galileo are carried out in this paper to analyze the results of the same frequency combination of multi-frequency SPP. The experimental results show that the BDS-3 is unsuitable to positioning independently due to its limited positioning ability at present. The same frequency SPP of the combination BDS-3/Galileo can compensate the poor positioning accuracy caused by the inadequate number of satellites (NSAT) and incomplete data in BDS-3 new frequency SPP, and improve the SPP accuracy of Galileo. The positioning accuracy of the frequency B3I in BDS-2/3 and the frequency B2b in BDS/Galileo are similar to that of the frequency L1 in GPS.

Simulation of urban population distribution grid by integrating geodetector and random forest model

CHENG Fanglong, ZHAO Guanwei, YANG Muzhuang, LIU Yueliang, LI Fang

2020, 0(1):  76-81.  doi:10.13474/j.cnki.11-2246.2020.0016

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Fine population distribution is important to urban resource allocation and management.In this paper,we take the Yuexiu District, Liwan District, Tianhe District, Haizhu District, Baiyun District and Huangpu District of Guangzhou city as the research areas,and base on multi-source data such as demography, night lighting, interest points and land use,using the geodetector to identify the influencing factors of population distribution,and simulate the population distribution grid by using random forest model.The results show that compared with the traditional correlation analysis, the geodetector can identify the important factors of spatial distribution of population more accurately.The correlation coefficient between the results of population distribution grid simulation based on random forest model and the actual population of streets (towns) is 0.774, with an average relative error of about 30%.Compared with the simulation results based on linear regression model, the accuracy of the stochastic forest model is significantly improved.

Spatial location advantage analysis for university campuses in Nanjing, China using multi-source spatial big data

HUANG Sheng, ZHANG Jiajie, RONG Dongchao, XIA Zelong, CHEN Yuehong

2020, 0(1):  82-88.  doi:10.13474/j.cnki.11-2246.2020.0017

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Based on multi-source spatial big data, this paper proposes an evaluation model of spatial location advantage for university campuses in Nanjing, China. The evaluation model considers four factors including living, transportation, environment and population and they are combined by experts scoring and entropy weight methods. The evaluation results show that:①The comprehensive spatial location advantage of university campuses in Nanjing presents a spatially decreasing trend from the central area of Nanjing and has significant differences between districts; ②The spatial location advantage of living factor presents "one superpower and multi powers" structure and its spatial pattern is related to Nanjing metro network, the spatial location advantage change of living factor is positively correlated with the commercial radiation capacity; ③The spatial location advantage of transportation reaches the highest in Xinjiekou area and has a strong relationship with Nanjing metro network; ④Jiangning higher education mega center has the highest comprehensive evaluation score, followed by Xianlin higher education mega center and the Pukou higher education mega center withthe lowest comprehensive score, but they have a large gap to university campuses in the central area of Nanjing. The evaluation analysis can provide a valuable decision-making support for the construction of urban in Nanjing and the improvement of higher education mega centers in future.

Mixed noise denoising method for remote sensing images combining BM3D and multi-level nonlinear weighted average median filtering

REN Chao, LI Xianguang, DENG Kaiyuan, PAN Yalong, ZHU Zilin, ZHANG Zhigang, SHI Xianjian

2020, 0(1):  89-93.  doi:10.13474/j.cnki.11-2246.2020.0018

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A mixed noise denoising method for remote sensing images based on BM3D and multilevel nonlinear weighted average median filtering is proposed. The bior1.5 and hear parameters in the traditional 3D block matching algorithm are replaced by coief3 wavelet and sym2 wavelet, and the 3D block matching algorithm and multistage nonlinear weighted average median filtering are combined to improve the denoising ability of the algorithm for mixed noise. A simulation comparison experiment and a real remote sensing image denoising experiment are carried out. The experiment shows that the method proposed in this paper is better than the traditional mixed noise denoising method in the aspect of remote sensing image mixed noise denoising.

Methods and application of impervious surface information extraction in plain river network based on multi-temporal landsat imagery

ZHOU Feng, LIAO Yubing, LI Na

2020, 0(1):  94-97,106.  doi:10.13474/j.cnki.11-2246.2020.0019

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Impervious surface is recognized as the key indicator of the urban ecological environment. To improve the accuracy of the impervious surface information extraction in plain river network area, according to analysis of the seasonal spectral characteristics of the pixels in the rapid urbanization area of North Jiangsu derived from the multi-temporal Landsat imagery, this study proposes a new decision tree model based on the NDVI, NDWI and NDBI time-series datasets. Using the novel established decision tree model, the change of the impervious surface is also analyzed. The result shows that the Kappa coefficient and the overall accuracy of the impervious surface classify are both larger than 0.85, implying that the method is potentially useful for the detection of the impervious surface. With the process of the urbanization, the region has undergone a rapid expansion of the impervious surface with a increasing rate of 7.0 km²/year. In addition, a more rapid development trend towards the southeastern direction has been found during the period 2005-2016. Our investigations could provide scientific basis for the urban ecological environment research and provide a technical support for the impervious surface extraction in other plain river network area.

Inversion of urban buildings height based on Google Earth remote sensing images

CHEN Chong, YANG Zhiyong, SHI Xiaoliang, SHANG Yu

2020, 0(1):  98-101.  doi:10.13474/j.cnki.11-2246.2020.0020

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Based on the distribution of building shadows in optical remote sensing images, the relationship between building height and shadow distribution is derived. Based on this, the buildings height inversion method is established, and the height information inversion of the typical buildings in Beijing is realized. The results show that the height of the building is extracted using the full length of the shadow of the building in summer or the length of the visible part in the winter, 90.9% and 84.8% of building calculation errors are controlled within 5% of the height of the building. When extracting the height of residential areas or high-rise buildings, summer remote sensing images should be used as much as possible to reduce the shadow occlusion. When the height of the low building is extracted, it is better to use the shaded part of the winter image to perform the inversion calculation. In the absence of image parameters such as satellite orbit, use the height of the typical known building to reverse the relevant parameters, and it is feasible to use those parameters to estimate the height of other buildings in the same scene image, providing the possible of using the typical urban buildings to estimate the height of buildings.

UAV image coverage analysis method considering terrain fluctuation

ZHANG Heng, LI Xiao, YE Pengfei

2020, 0(1):  102-106.  doi:10.13474/j.cnki.11-2246.2020.0021

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Because of the low relative altitude of UAV, ground fluctuation will have an adverse effect on the resolution, coverage and overlaps of UAV images when using UAV for aerial photography of surveying and mapping. There will be some defects in the aerial images, such as insufficient resolution, insufficient overlap, coverage loopholes and so on. In order to solve this problem, this paper proposes a method to calculate the coverage of each image accurately with the help of DEM by using digital differential correction, and uses FME to efficiently generate the coverage of all images. It is verified by some pracise project that the method can accurately predict the coverage and overlap of all images in the the designed air routes. So the design defects can be found and corrected in time. This method can effectively reduce the image coverage defects caused by terrain undulation, so as to avoid rework and improve the efficiency of aerial photography.

Framework design of full-feature adaptive field survey for natural resources

LIU Li, LIU Juan, CHEN Hongyu, LI Weiqing

2020, 0(1):  107-110,114.  doi:10.13474/j.cnki.11-2246.2020.0022

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In view of the different classification standards, investigation caliber and investigation methods in the investigation of full features of natural resources, resulting in the repeated development and construction of the software platform for each department's investigation and the unclear expression of the data geographic information features of the investigation results, this paper combines the actual needs of the field investigation of full feature of natural resources, and unifies the life community of mountains, rivers, forests, lakes and grasses. This paper constructs a semantic feature model of natural resources, proposes an adaptive field investigation method to represent different types of natural resources, realizes a flexible and excellent performance natural resources investigation technology platform, and forms a unified field investigation framework of all elements of natural resources, which can effectively enhance the ability of basic investigation, professional investigation and dynamic investigation of multiple categories of natural resources. The level provides a reliable technical guarantee for the modernization of natural resource management ability.

Performance analysis of high-precision regional reference frame establishment using BDS data only

LIU Quanhai, WANG Yankai, CHEN Hua

2020, 0(1):  111-114.  doi:10.13474/j.cnki.11-2246.2020.0023

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Nowadays, GPS is the main technology for the establishment of regional high-precision coordinate frame. Since BeiDou Satellite Navigation and Positioning System (BDS) is developed by China independently, it is very important to assess the possibilities to establish a high-precision reference frame using the BDS only. In this paper, a high-precision regional coordinate frame of Changzhou city is established by using BDS data from Changzhou Continuously Operating Reference Stations (CZCORS), where an un difference data processing strategy is adopted. The results are compared with those of GPS. It is found that the difference between them is quite small. The average RMS values in the horizontal and vertical directions are 3.1 and 4.2 mm, respectively. These confirms the potential for BDS to establish the regional reference framework.

Application of digital orthophoto image combined with LiDAR data in mountain surveying

YAN Huimin

2020, 0(1):  115-119.  doi:10.13474/j.cnki.11-2246.2020.0024

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With the advent of information society, modern water resources surveying and mapping has developed from traditional surveying and mapping to information surveying and mapping. Application of UAV technology in surveying and mapping industry promotes the process of informatization surveying and mapping. This paper discusses how to effectively use UAV technology to solve the problems encountered in the field of surveying and mapping in mountainous areas. Fixed-wing UAV can acquire the digital orthophoto image data of the ground in time to capture the plane and elevation problems of the bare ground, but the elevation information of the ground under vegetation coverage can not be obtained. At this time, LiDAR point cloud data under vegetation coverage can be obtained by airborne LiDAR. Combining the two data, the three-dimensional surface model generated by EPS software can quickly obtain the topographic and topographic data of any surveying area, which not only improves the efficiency of water resources surveying and mapping, but also reduces the intensity of field work.

Key technologies of service-oriented dynamic mapping service system

LIAN Xu, TAN Ming, WU Dandan

2020, 0(1):  120-123,163.  doi:10.13474/j.cnki.11-2246.2020.0025

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First of all, this paper analyzes the disadvantages of traditional thematic mapping technology in the development of surveying and mapping information. And then, based on the rapidly developing WebGIS technology, we explore the online mapping technology based on Web services, and propose the interactive custom mapping based on online map from the aspects of symbol construction, mapping service model, data service and so on. Finally, an interactive cartography system based on Web services is designed and developed, which realizes online subscription cartography for ordinary users and online customization cartography for professional users. Our practice shows that the dynamic thematic mapping system is flexible in function, diverse in expression and high in communication efficiency, and can meet the needs of users with different backgrounds.

Construction of spatio-temporal big data platform in natural resource management

YANG Junyan, FAN Di, HUANG Guoping

2020, 0(1):  124-127.  doi:10.13474/j.cnki.11-2246.2020.0026

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Due to the reform of natural resources institution, surveying and mapping geographic information work has become an integral part of the unified management of natural resources. The spatio-temporal big data platform how to work under the new organization is an issue that is urgently needed for research. To this end, after analyzing the requirements of natural resource management, this paper puts forward the technical route of the construction of spatio-temporal big data platform and the construction idea of spatio-temporal big data service natural resources management.

Research on the change of built-up land in China from 1980-2015

FAN Yong, HE Zongyi, LI Minmin, HE Biao

2020, 0(1):  128-131.  doi:10.13474/j.cnki.11-2246.2020.0027

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The spatial pattern and change of land use, especially the built-up land, has become the focus of urban research. This paper uses Chinese land use remote sensing data in 1980, 1990, 1995, 2000, 2005, 2010 and 2015, analyzing the change of built-up land from 1980 to 2015. A systematic analysis is carried out. The main research work is:① Calculating the area and growth rate of urban land, rural residential areas, other built-up land and total built-up land in China from 1980 to 2015, and obtain the rate of change of built-up land in China from 1980 to 2015. ② Using the GIS software joint analysis tool to obtain the change pattern of Chinese built-up land from 1980 to 2015. ③ Making the land use transfer matrix, so that the structure of Chinese built-up land change from 1980 to 2015 can be obtained. The research shows that Chinese built-up land as a whole shows a trend of continuous expansion. The eastern and coastal areas are growing at a faster rate, the Qinghai-Tibet Plateau is basically unchanged, the central and northeastern regions are growing at a slower rate, and the northwestern region has a small increase. The built-up land is mainly transferred, mainly cultivated land.

Pedestrian dead reckoning based on ambient light correction

TAO Xiaoxiao, LU Xiaoping, DAI Wenchen, YU Zhenbao, ZHANG Dongmei

2020, 0(1):  132-135,141.  doi:10.13474/j.cnki.11-2246.2020.0028

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Aiming at the problem of low positioning accuracy, high combination positioning cost and difficulty to realize in indoor positioning, a method of correcting pedestrian track calculation (PDR) using ambient light assistance is proposed. This method uses the acceleration, gyroscope and magnetometer datacollected by the smartphone to realize the PDR position estimation. At the same time, the light intensity sensor of the mobile phone is used to obtain the ambient light intensity information of the location in real time, the collected indoor ambient light intensity information is used to correct the cumulative error generated in the PDR trajectory. After the experimental data analysis, this method can effectively solve the cumulative error produced in the PDR trajectory, it can provide positioning technology for large supermarkets, underground parking lots, tunnels, mines and other areas with stable indoor illumination intensity.

Progress and prospect of engineering control network for particle accelerator

GUO Yinggang, LI Zongchun, LI Guangyun, LIU Zhonghe

2020, 0(1):  136-141.  doi:10.13474/j.cnki.11-2246.2020.0029

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As the increasing demand of particle collision energy in high energy physical research, the size of the particle accelerator is increasing, which puts forward a challenge to the design, measuring and maintenance of engineering control network. For this purpose, on the basis of summarizing and sorting out the research status at home and abroad, this paper refines the key technologies of structure and accuracy requirement, the selection of geometric reference framework, measuring instruments and markers, net form of control network and observation scheme, and the reduction and adjustment of observed value for giant particle accelerator control network. At last, some technical prospects and research ideas of the high precision three-dimensional control network construction technology are put forward for giant accelerator engineering.

Design and implementation of BDS one network business management and service system

TANG Xiaofei, CHE Yiming, SUN Xiaochao, WEI Yikuan, ZHAO Peng

2020, 0(1):  142-145.  doi:10.13474/j.cnki.11-2246.2020.0030

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According to the actual demand and current situation of BDS one network system construction and operation project, this paper integrates the existing infrastructure resources, deeply studies and mines the potential information resources, builds a unified platform for standardized management and service application. The business management and service system improves management ability, increases management level, raises service efficiency, and changes the management and operation mode of traditional CORS. It also provides a more efficient and convenient personalized service for massive user, and truly realizes system's standardization, systematization and convenience from the application level. Under the support of this system, BDS one network service system has established a brand-new management mechanism, which also lays a solid foundation for the wider popularization and application of BDS in the future.

Application of UAV aerial survey technology in sewage outlet investigation

ZHANG Yuanmin

2020, 0(1):  146-149,153.  doi:10.13474/j.cnki.11-2246.2020.0031

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In recent years, the marine environment pollution is increasingly serious, pollution control is imminent. Investigation of sewage discharge outlets entering the sea is the first priority of pollution control. However, due to the large number of sewage discharge outlets, wide distribution, different shapes and strong concealment, conventional investigation is extremely difficult, with large investment, long cycle and many omissions. UAV aerial survey technology can quickly acquire high-resolution true color images and thermal infrared images. The color image is bright and legible, and can be directly interpreted as exposed sewage outlet. Thermal infrared is sensitive to temperature and has strong penetrability. It can identify hidden objects through temperature anomalies. The combination of the two images can effectively search the source of pollution discharge. It is a major technical breakthrough since the investigation began, and it will provide a strong technical guarantee and support for the smooth development of Marine pollution control.

Application of UAV technology in island surveying and mapping

LI Xuerui, WEI Zheng, TIAN Song, LI Mingjie

2020, 0(1):  150-153.  doi:10.13474/j.cnki.11-2246.2020.0032

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In order to improve the technical means of island survey, the UAV technology is introduced into the topographic survey of islands. Taking the large scale mapping of Huzhou island in Dayawan, Huizhou based Swallow-P small fixed wing UAV as an example, this paper summarizes the specific process of external data acquisition and internal data processing, makes DEM and DOM. Precision analysis is provided of measured ground points, the plane position error and elevation error of the large scale mapping results of Huzhou island UAV meet the accuracy requirement of 1:1000 mapping.

Open,open source and development of GIS undergraduate education

REN Fu, ZHANG Chen, DU Qingyun, SHEN Huanfeng

2020, 0(1):  154-157,163.  doi:10.13474/j.cnki.11-2246.2020.0033

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With the continuous development of the knowledge structure of geographic information, the demand for social talents is diverse, and traditional undergraduate teaching methods are not sufficient to cope with high-level scientific research and work requirements. More scientific and efficient undergraduate training programs need to be proposed. For implementing the basic concepts, professional knowledge and methodologies of GIS into the teaching of undergraduates, this paper puts forward three ideas of GIS undergraduate education:open, open source and development, and creates a set of "multi-disciplinary, multi-method, multi-technique" three-dimensional training program to response to the teaching guidelines called "adults to talents". Based on the existing teaching methods, this program brings breakthrough ideas and reforms by combining with the professional characteristics of geographic information science and GIS undergraduate teaching will become a model of professional training that is more comprehensive in the subject area, more advanced in method and technology, and more various in practice and internships. This teaching concept is beneficial to undergraduate students to fully understand the knowledge they have learned, and to improve the spatial thinking level and enhance the practical development ability in the support of theoretical foundation. It is a useful exploration of GIS undergraduate education methods.

Research on aircraft position NRTK-PPK system based on multi-constellation

WANG Mingjia, LU Yongdong

2020, 0(1):  158-163.  doi:10.13474/j.cnki.11-2246.2020.0034

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In order to obtain high-precision aircraft position, the handheld GNSS receiver is taken on the aircraft, satellite data is received during the flight of the aircraft, and the GNSS data received by the receiver is subjected to difference using NRTK-PPK system. Since the handheld GNSS receiver is placed next to the window of the passenger aircraft, it can only receive the satellite data of the half-day sky. It needs to optimize the PPK algorithm and compare it with the ground RTK difference result to achieve the decimeter-level high-precision positioning effect.

Application of 3D laser scanning technology in building facade lighting design

YUAN Lingyun, LI Hui, LI Jie, HAN Weitao

2020, 0(1):  164-166.  doi:10.13474/j.cnki.11-2246.2020.0035

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The building elevation is the basic data of the facade lighting design, which directly affects the design accuracy and effects. Aiming at the problems of low efficiency and low reduction degree on traditional facade measurement, a building facade measurement scheme based on 3D laser scanning technology is proposed. Combined with the actual case, the method of traversing 3D laser scanning and point cloud drawing is mainly discussed. The application case shows that 3D scanning technology can provide accurate and detailed building elevations for facade lighting design.