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Refined identification method and practice of unmanned aerial vehicle for geological hazards in small-scale mountainous areas HUANG Haifeng, ZHANG Rui, ZHOU Hong, YI Wu, XUE Ronghua, DONG Zhihong, LIU Qing, DENG Yonghuang, ZHANG Guodong Bulletin of Surveying and Mapping    2024, 0 (1): 6-11.   DOI: 10.13474/j.cnki.11-2246.2024.0102 Abstract （152）   HTML （24）    PDF（pc） （6029KB）（239）       Knowledge map    Save In this paper, aiming at the geological disasters in small-scale mountainous areas, such as landslides and collapses, a set of refined hidden danger identification method based on small UAV photogrammetry is proposed. Firstly, carry out at least two drone photogrammetry operations for the work area, and obtain refined results such as realistic 3D models, digital orthophoto images (DOM), and digital surface models (DSM) after processing.Secondly, the main focus is on detecting changes in DOM and DSM in two phases to achieve disaster body recognition.Once again, summarize the common characteristics of disaster bodies and establish identification indicators for typical disasters.Then, based on the identification markers, the three-dimensional visual interpretation method is mainly used to identify the pregnant body. Finally, identify or eliminate potential hazards through ground inspections. Applying this method to the left bank slope area of the Xietan River in Zigui, the head of the Three Gorges Reservoir, and 10 different types of hidden dangers are identified, which proves the feasibility of the method. Reference | Related Articles | Metrics

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Discussion on digital twin and metaverse in smart city construction ZHANG Xinchang, LIAO Xi, RUAN Yongjian Bulletin of Surveying and Mapping    2023, 0 (1): 1-7,13.   DOI: 10.13474/j.cnki.11-2246.2023.0001 Abstract （1789）   HTML （112）    PDF（pc） （1674KB）（839）       Knowledge map    Save With the in-depth integration of urban management and new technologies such as spatial big data,5G and artificial intelligence,the applications related to new smart cities have become the key concerns of the geographic information industry field and society. This paper introduces the background and concept,theory and technology of smart city,describes the relationship among digital city,smart city and digital twin city,summarizes the current situation and trend of digital twin city,and discusses the smart city in the metaverse era. The budding period of smart city relies on spatial information technology,database technology,virtual reality technology and computer network technology to build digital city,the development period integrates artificial intelligence technology,Internet of Things technology,cloud technology and spatio-temporal big data technology on the basis of digital city to build new type of smart city,and the construction period combines new type of smart city related technology and realistic 3D technology to realize digital twin. The cross-era metaverse smart city may integrate technologies or devices such as augmented reality,extended reality,brain-computer interface and somatic devices on the basis of the digital twin to realize the beautiful vision of human living in an amphibious world. Reference | Related Articles | Metrics

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UAV debris flow disaster detection technology based on fine reconstruction of multi-camera ZOU Yang, DONG Xiujun, ZHANG Guangze, LI Jianqiang, LI Xiangdong, LI Tianyu Bulletin of Surveying and Mapping    2024, 0 (1): 1-5.   DOI: 10.13474/j.cnki.11-2246.2024.0101 Abstract （214）   HTML （43）    PDF（pc） （7668KB）（220）       Knowledge map    Save In recent years, geological disasters have occurred frequently in the southwest region, and unmanned aerial vehicle aerial survey technology has obvious advantages in geological disaster detection. This article uses a suspended fixed wing unmanned aerial vehicle as a platform, equipped with a five lens multi-camera to detect and obtain relevant parameters such as debris flow morphology, channels, sources, and zoning in Longmen gully, Liangshan prefecture. The advantages of five lens multi-camera photography and the specific application methods and effects of drone aerial survey technology in debris flow disaster detection are elaborated and discussed. The main understanding is as follows: ① Compared with traditional monocular cameras, five lens multi-camera photography has the advantage of being able to collect data from multiple different angles of vertical and tilt, and the obtained high-definition image data is finely reconstructed to generate orthophoto images. The texture of the 3D model is more comprehensive and has higher resolution.② By using refined reconstruction of orthophoto images and three-dimensional models, a total of 21 sources of landslides, collapses, rock heaps, and dangerous rocks in the debris flow disaster area are interpreted. The net and dynamic reserves of each source material are estimated based on the average thickness and area, providing a data basis for prevention and control design. ③The unmanned aerial vehicle aerial survey technology has advantages such as flexibility, strong emergency response, large survey range, strong traceability, and low flight cost, and has high promotion value and significance in disaster detection. Reference | Related Articles | Metrics

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Review from vehicle navigation to autonomous driving: the evolution of electronic map ZHAO Mingshu Bulletin of Surveying and Mapping    2023, 0 (6): 6-10,92.   DOI: 10.13474/j.cnki.11-2246.2023.0160 Abstract （201）   HTML （20）    PDF（pc） （4284KB）（193）       Knowledge map    Save Taking the implement of electronic map in vehicle navigation and autonomous driving as the research object, this paper deeply analyzes the closd relationship between the evolution of electronic map and the development of driving technology. The significant characteristics of map data content and model structure at each stage are discussed along with the development of driving technology.In recent years, the iteration of autonomous driving technology has continuously puts forward new requirements for map data, which has further enriched the map content to extent even beyond the scope of traditional geographic information. It requires add more information to spatial dataframe, including environmental perception data, sensor data, driving experience data and so on. Which enables comprehensive management, query and sharing on massive information. This paper proves the rationality and inevitability of the above requirements by reviewing the geographic information transmission model extension. The international data standard NDS is taken as an example to introduce one of the practices. Finally, summarize the relevant progress in brief and presents an outlook of this field. Reference | Related Articles | Metrics

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LiDAR point cloud registration with improved ICP algorithm XU Zhe, DONG Linxiao, WU Jiayue Bulletin of Surveying and Mapping    2024, 0 (4): 1-5.   DOI: 10.13474/j.cnki.11-2246.2024.0401 Abstract （199）      PDF（pc） （3266KB）（192）       Knowledge map    Save The traditional ICP algorithm has long matching time and is affected by initial values in LiDAR target point cloud matching, which leads to low positioning accuracy and poor robustness when applied to unmanned vehicle SLAM technology. Proposes an NDT-ICP algorithm that combines the KD-tree algorithm. Firstly, voxel grid filtering is used to preprocess the point cloud data obtained from LiDAR, and the method of plane fitting parameters is used to remove point cloud of ground. Secondly, use NDT algorithm for point cloud coarse matching to shorten the distance between the target point cloud and the point cloud to be matched. Finally, the KD-tree proximity search method is used to improve the speed of corresponding point search, and the precise matching of the ICP algorithm is completed by optimizing the convergence threshold. Through experiments, it has been shown that the improved algorithm proposed in this article has significantly improved speed and accuracy in point cloud matching compared to NDT and ICP algorithms, and has better accuracy and robustness in map construction. Reference | Related Articles | Metrics

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Dynamic monitoring of wetlands in the Yellow River delta based on multi-source remote sensing FAN Yanguo, WANG Jie, FAN Bowen, XU Ziyao Bulletin of Surveying and Mapping    2023, 0 (6): 27-35.   DOI: 10.13474/j.cnki.11-2246.2023.0164 Abstract （187）   HTML （16）    PDF（pc） （5532KB）（184）       Knowledge map    Save The contradiction between the gradual urban and rural construction and natural ecological environmental protection is becoming more and more intense, and the state and government attach great importance to the development of the Yellow River delta wetland area. Therefore, it is urgent to monitor, extract and analyze the dynamic change information of the Yellow River delta in recent years. In this paper, macroscopic (land use) and microscopic (surface deformation) information of the Yellow River delta wetland region is extracted and analyzed by using 8-view Landsat optical images from 2000 to 2021 and 34-view Sentinel-1 downscaled VV polarized SAR images from 2015 to 2021, combined with socio-economic and natural environment data for driving factor analysis. The results show that the land use pattern of the Yellow River delta wetland region did not change significantly between 2000 and 2021, but the land use degree gradually increased; the spatial distribution of the surface deformation degree of the Yellow River delta wetland region is extremely uneven between 2015 and 2021, with the maximum sedimentation rate reaching -43.643 mm/a and the maximum uplift rate of 0.136 mm/a; human activities and socio human activities and social economy are the dominant drivers of surface information changes in the region. Reference | Related Articles | Metrics

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Research status and prospects of GB-SAR deformation monitoring technology LIU Longlong, ZHANG Jixian, ZHAO Zheng, KANG Qi, XI Xiaofei Bulletin of Surveying and Mapping    2019, 0 (11): 1-7.   DOI: 10.13474/j.cnki.11-2246.2019.0341 Abstract （1191）   HTML （55）    PDF（pc） （1196KB）（465）       Knowledge map    Save Ground-based synthetic aperture radar (GB-SAR) is a ground-based active microwave remote sensing technology developed in recent ten years. GB-SAR system can be used for non-contact, high precision, large-scale and long-distance deformation monitoring, which is of great significance in the field of deformation monitoring. Firstly, this paper introduces the basic theory and research status of GB-SAR. The main GB-SAR systems are summarized and the key parameters of the existing systems are listed in detail. Then we analyze the advantages and disadvantages of GB-SAR technology in the field of deformation monitoring such as infrastructure, landslides, mines, glacier movements and cultural relics protection and summarize the challenges faced by ground-based radar systems in practical applications. Finally, the application prospects are prospected from the aspects of deformation monitoring multi-dimension deformation and atmospheric correction. Reference | Related Articles | Metrics

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Improved multi-task road feature extraction network and weight optimization ZHU Wenjie, LI Hongwei, JIANG Yirui, CHENG Xianglong, ZHAO Shan Bulletin of Surveying and Mapping    2023, 0 (12): 1-7.   DOI: 10.13474/j.cnki.11-2246.2023.0350 Abstract （177）   HTML （41）    PDF（pc） （4324KB）（180）       Knowledge map    Save In order to address the challenges of autonomous driving in complex road environments, the need for collaborative multi-tasking has been proposed. In the fields of natural language processing and recommendation algorithms, the use of multi-task learning networks has been proven to reduce time, computing power, and storage usage in multiple task coupling scenarios. Due to this characteristic of multi-task learning networks, in recent years, it has also been applied to visual-based road feature extraction. This paper proposes a decoder head structure combined with the FPN network and applies it to a YOLOv4-based multi-task learning road feature extraction network. Additionally, the paper optimizes the multi-task network algorithm through investigating the impact of multi-task weight settings. The effectiveness of the weight settings was also verified among similar algorithms. The experimental results obtained on the BDD-100K dataset show that the proposed structure has better accuracy while still ensuring real-time performance compared to similar methods. This paper's method provides new ideas and methodologies for vehicle autonomous road perception and high-precision map generation in visual-based autonomous driving processes. Reference | Related Articles | Metrics

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Spatial and temporal dynamic change and influencing factors of ecological environment quality in Chaohu Lake basin based on GEE WANG Ying, LI Daiwei, ZHANG Fan, ZHU Huizi, LI Longwei, LI Nan Bulletin of Surveying and Mapping    2023, 0 (7): 7-13.   DOI: 10.13474/j.cnki.11-2246.2023.0193 Abstract （258）   HTML （19）    PDF（pc） （6645KB）（174）       Knowledge map    Save Taking Chaohu Lake basin as the research area, remote sensing ecological index (RSEI) is constructed through Google Earth Engine cloud computing platform, and large-scale and long-time dynamic monitoring analysis and evaluation of ecological environment quality in Chaohu Lake basin are carried out by means of spatial autocorrelation and geographic detectors based on Landsat TM/OLI series remote sensing data from 2000 to 2020. The results show that:①The average value of RSEI increased from 0.70 in 2000 to 0.74 in 2020, showing an overall improvement trend, and the ecological environment level is mainly excellent and good. ②The global Moran's I index of the study area is all greater than 0, and the ecological environment quality in Chaohu Lake basin presented a clustering trend on the global autocorrelation, with a significant spatial positive correlation. In the past 20 years, the low-low aggregation area had a trend of increasing firstly and then decreasing. ③The ecological environment is affected by many factors, among which human factors had a great impact on the ecological environment of Chaohu Lake basin in 2010, which leaded to the decline of ecological environment quality. Reference | Related Articles | Metrics

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Monitoring and evaluation of environment effect of photovoltaic power station construction using MODIS satellite data WANG Yiting, WANG Xinyue, ZHAN Yinggang, ZOU Rui, YANG Lixiang Bulletin of Surveying and Mapping    2023, 0 (8): 108-112.   DOI: 10.13474/j.cnki.11-2246.2023.0241 Abstract （148）   HTML （10）    PDF（pc） （5722KB）（166）       Knowledge map    Save This paper selects Gonghe Photovoltaic Industrial Park in Qinghai province, the largest photovoltaic industrial park in China as the study area, uses the MODIS medium resolution satellite data and meteorological data, and investigates the ecological and environmental effects of photovoltaic power station construction from 2010 to 2020. The M-K spatio-temporal trend analysis method was used to analyze the spatial and temporal variations of land surface biophysical parameters after the solar panels were built. Then the Granger causality test method was used to investigate the causal relationship between the changes in land surface parameters and meteorological factors. The results showed that the vegetation in the study area are increasing, while the surface temperature and albedo decreasing. Vegetation growth under photovoltaic panels is slightly better than that outside the panels. The increase of construction area is the Granger cause of the increase of vegetation in the study area. The study indicates that the establishment of photovoltaic can promote the growth of vegetation, reduce albedo and cool the surface temperature. Reference | Related Articles | Metrics

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Real-time Observation Decoding and Positioning Analysis Based on Qianxun BeiDou Ground Based Augmentation System HUANG Yongshuai, SHI Junbo, OUYANG Chenhao, LU Xingning 测绘通报    2017, 0 (9): 11-14.   DOI: 10.13474/j.cnki.11-2246.2017.0277 Abstract （807）   HTML    PDF（pc） （3924KB）（1935）       Knowledge map    Save As the first commercial BeiDou ground based augmentation system (GBAS) in China, the Qianxun location network announced in May 2016 is able to provide high-precision positioning service for users in majority territory. This paper first introduces the message formatting and decoding broadcast by the Qianxun Beidou GBAS, and then evaluates the RTK and RTD positioning performance in Wuhan and Chongqing. Numerical results show that the positioning precision can reach centimeter for RTK and sub-meter for RTD, respectively. The aim of this paper is to provide a basis for the promotion of BeiDou GBAS. Reference | Related Articles | Metrics

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Method and application of dynamic generation of local relative position based on high precision map FEI Wenkai Bulletin of Surveying and Mapping    2023, 0 (6): 1-5.   DOI: 10.13474/j.cnki.11-2246.2023.0159 Abstract （212）   HTML （24）    PDF（pc） （2027KB）（161）       Knowledge map    Save For the application of information sharing and transmission between roadside intelligent devices and self-driving vehicles equipped with high precision maps, this paper proposes a method of dynamic generation and expression of high precision relative positions. The method relies on the common key information of high precision map to encode and decode, and realizes relative location information transmission through geometric matching technology, which improves the security of high precision location information transmission and the compatibility between different maps. This paper gives a complete information generation method, encoding and decoding flow scheme, and obtains good experimental results. Reference | Related Articles | Metrics

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A method for constructing true 3D models of complex scenes based on multi-source spatial data ZHOU Baoxing, WANG Bing, ZHANG Hangfan, MA Dengyue, LIU Xizhu Bulletin of Surveying and Mapping    2024, 0 (4): 13-17.   DOI: 10.13474/j.cnki.11-2246.2024.0403 Abstract （99）      PDF（pc） （11003KB）（156）       Knowledge map    Save The 3D models of cities have been widely applied in various fields such as urban construction and social services. In order to rapidly and accurately construct 3D city models to meet the needs of urban detailed planning and management,this article focuses on the main theme of fast,reasonable,and precise construction of true 3D models,with city terrain and urban features as the research objects. It proposes a fast construction solution for city 3D models,starting from terrain to features,and from rough to precise. It realizes the rapid modeling of urban basic terrain,buildings,and other 3D scenes. The proposed modeling approach is specifically implemented using the Skyline platform,forming a complete operating process. Reference | Related Articles | Metrics

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Lunar impact crater detection based on multilevel segmentation LI Haipeng, DONG Youfu, ZHANG Hao Bulletin of Surveying and Mapping    2023, 0 (11): 18-22.   DOI: 10.13474/j.cnki.11-2246.2023.0321 Abstract （78）   HTML （10）    PDF（pc） （2171KB）（152）       Knowledge map    Save The extraction of craters of different sizes on the lunar surface is of great value. Currently, crater detection algorithmsare effective for craters less than one kilometer, but the detection rate of largercraters needs to be improved. We propose an automatic crater detection model with good robustness.Firstly, we generate the terrain parameters based on the who lelunar DEM published by LOLA, then detect craters by object-oriented multilevel sesgmentation combined with machine learning.Three typical regions are selected for experiment and analysis, the recall and accuracy rates for craters between 1~120 km in diameter are 86.5% and 81.2% respectively, with a good detection rate. Reference | Related Articles | Metrics

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Front-of-vehicle road extraction method based on feature fusion difference of vehicle LiDAR HE Guangming, HAN Shiyuan, CHEN Yuehui, ZHOU Jin, YANG Jun Bulletin of Surveying and Mapping    2023, 0 (12): 13-18.   DOI: 10.13474/j.cnki.11-2246.2023.0352 Abstract （66）   HTML （19）    PDF（pc） （1515KB）（149）       Knowledge map    Save In order to cope with the changing road environment during driving and divide the drivable area of the current road in front of the vehicle, this paper proposes a detection method for the road in front of the vehicle based on multi-feature fusion difference. This algorithm extracts the ground point cloud from the original point cloud by morphological filtering method, statistically summarizes the ground point cloud data to define the operation domain, divides the differential element size and starting point of different depths in the operation domain, fuses the characteristic parameters in the differential element, forms a feature matrix, solves the differential matrix, and performs threshold filtering, so as to realize the extraction of the point cloud in front of the vehicle. In this paper the extraction algorithm of the relevant road point cloud is compared to,which highlight its excellent performance and then the road extraction effect of different depths of the collected data is compared to prove the effectiveness of the algorithm. Reference | Related Articles | Metrics

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Multi-source POI location fusion considering address semantics and geospatial features LI Pengpeng, LIU Jiping, WAGN Yong, LUO An, SANG Yu, YAN Xuefeng Bulletin of Surveying and Mapping    2023, 0 (11): 54-60.   DOI: 10.13474/j.cnki.11-2246.2023.0327 Abstract （80）   HTML （7）    PDF（pc） （1392KB）（147）       Knowledge map    Save Multi-source POI location fusion is one of the key technologies for geospatial data matching and fusion. However, due to the difference of location coding and location error between different POI data sources, location fusion becomes more difficult. Multi-source POI location fusion considering address semantics and geospatial feature is proposed. Firstly, semantic features of address attributes are extracted by TextRCNN and graph attention network. Then, Multi-layer perceptron is used to extract geospatial features of location attributes. Finally, multi-source POI location fusion is realized by feature aggregation based on self-attention mechanism. We conduct experimental verification on the POI data of Baidu map, Tencent map and Amap in Chengdu. The results show that this method is significantly superior to the existing methods, and the average location fusion accuracy is better than 12 m. Reference | Related Articles | Metrics

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The Reform and Practice for Surveying Instrument Curriculum in Surveying and Mapping Department of College YU Teng, HU Wusheng, ZHOU Li, JIAO Minglian, SUN Xiaorong 测绘通报    2017, 0 (5): 147-151.   DOI: 10.13474/j.cnki.11-2246.2017.0176 Abstract （543）   HTML    PDF（pc） （6000KB）（698）       Knowledge map    Save In view of the actual situation of the continuous development and innovation of the surveying instrument,the effect and social evaluation of the curriculum of surveying instrument in the past five years is summarized. Surveying instrument has entered the era of electronic intelligence, the reform of teaching content according to the theory and practice are put forward, the improvement and innovative teaching methods are found, in turn, the curriculum also seeks to a reasonable assessment methods, and puts forward reasonable suggestions to form a complete set of curriculum related condition, finally, after the reform of curriculum, the teaching effect is discussed and analyzed. Reference | Related Articles | Metrics

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Analysis of the effects of UAV-borne LiDAR point cloud density on DEM accuracy XIAO Jie Bulletin of Surveying and Mapping    2024, 0 (4): 35-40.   DOI: 10.13474/j.cnki.11-2246.2024.0407 Abstract （100）      PDF（pc） （5613KB）（146）       Knowledge map    Save UAV-borne LiDAR point cloud data is an important data source for producing DEM. In order to further improve DEM production efficiency,selecting flat terrain and mountainous terrain as test areas,the ground point cloud,which is processed by filtering method,is thinned and simplified according to the a lgorithm based on TIN with seven different the ground point cloud retention rate of 80%,60%,40%,and so on,and the corresponding DEM is generated and its accuracy is evaluated by mean error (ME),standard deviation (SD),and root mean square error (RMSE). The results show that: ①The accuracy of the produced 0.5 m grid-spacing DEM could exceed 0.05 m when the ground point cloud density reached 2 points/m 2 for flat terrain and 9 points/m 2 for mountainous terrain. ②As the density of ground point cloud increases,the DEM accuracy level gradually stabilizes,and the DEM accuracy would decrease rapidly when the ground point cloud density is thinned to 1 point/m 2. For the DEM production tasks in large regions using UAV-borne LiDAR point cloud data,the conclusions of this research have a certain guiding and reference significance in reducing data acquisition costs and improving DEM production efficiency. Reference | Related Articles | Metrics

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Tightly coupled GNSS RTK/INS integration positioning based on MEMS IMU XIE Qing, ZHANG Quan, ZHANG Hongping, CHEN Dezhong, LI Zhijun, CUI Yulu Bulletin of Surveying and Mapping    2024, 0 (1): 89-95.   DOI: 10.13474/j.cnki.11-2246.2024.0115 Abstract （119）   HTML （11）    PDF（pc） （3039KB）（145）       Knowledge map    Save In order to improve the poor GNSS positioning stability in complex environment, a low-cost and high-precision positioning method with IMU assisting RTK for autonomous driving is proposed. MEMS IMU M39 and tactical IMU Pos320 are used in simulation experiments. Through simulating interruption of multiple groups of measured vehicle data, INS position drift error, ambiguity fixing time and fixing accuracy are obtained. The ambiguity fixing time and positioning accuracy under three conditions of no inertial navigation assistance, M39 assistance and Pos320 assistance are statistically and analyzed. The results show that M39 can assist RTK to achieve instantaneous ambiguity fixing with 5 s GNSS outage. When the outage is 10 s it still can reduce the convergence time of ambiguity to 1/4. Also, with assistance of MEMS IMU, the number of incorrect ambiguity is significantly reduced, and the proportion of high-precision positioning within 10 cm is increased from 62.25% to 98.44%. Experiments show that MEMS IMU assisted RTK can accelerate the speed of ambiguity fixing and improve the accuracy and reliability of navigation and positioning in autonomous driving. Reference | Related Articles | Metrics

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Shallow sea water depth inversion from WorldView-3 multispectral images based on seabed sediment classification YAO Chunjing, YU Zheng, WANG Jie, QIAN Chen, XU Junhao Bulletin of Surveying and Mapping    2023, 0 (7): 25-31.   DOI: 10.13474/j.cnki.11-2246.2023.0196 Abstract （140）   HTML （12）    PDF（pc） （1559KB）（143）       Knowledge map    Save In recent decades, sea water bathymetry inversion method based on remote sensing image has been a hot research topic. This paper uses WorldView-3 high-resolution satellite imagery, combined with satellite altimetry data, to focus on Wuzhizhou island which is near Hainan Island, China, and its adjacent waters as the main study area. After data preprocessing and substrate classification, multiple linear regression model, Stumpf logarithmic ratio model and BP neural network model are used to invert and analyze the water depth around the island. Results show that: for the three model, after the bottom sediment classification accuracy will be improved significantly. Among them, BP neural network model has the highest accuracy (root mean square error range of 0.2～0.7 m), followed by multiple linear regression model (root mean square error range of 0.3～0.8 m), and log ratio model has the lowest accuracy (root mean square error range of 0.6～1.1 m). Reference | Related Articles | Metrics

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A satellite remote sensing method for detecting marine plastic debirs LI Peng, ZHOU Hongli, LIN Shicong, WANG Houjie, LI Zhenhong Bulletin of Surveying and Mapping    2023, 0 (6): 20-26.   DOI: 10.13474/j.cnki.11-2246.2023.0163 Abstract （197）   HTML （17）    PDF（pc） （13046KB）（141）       Knowledge map    Save Marine floating plastic debris is widely distributed in surface waters such as coastal waters and ocean gyres, which seriously endangers marine life and the sustainable development of human society. Limited by the small-scale, small number of marine plastic target samples and the spatial resolution of satellite remote sensing sensors, accurately detect the spatial and temporal distribution characteristics of marine plastic debris has an important practical significance. Based on the known spectral characteristics of plastic and other floating objects in the sea, this study proposes a reflectance feature classification method based on Sentinel-2 satellite imagery. By combining the reflectance threshold and peak characteristics of different bands, it can effectively detect and identify floating plastic in multiple regions of the world, with an overall accuracy of 98% and an F-score of 0.85, which is better than the traditional machine learning classification method, and is beneficial for the change detection and impact mechanism research of marine plastic debris. Reference | Related Articles | Metrics

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Analysis of spatio-temporal evolution characteristics of water bodies in Dongting Lake Basin based on multi-source time series images ZHOU Zaiwen, HE Zhenming, JIANG Songyu, XIANG Longwei, PENG Li Bulletin of Surveying and Mapping    2023, 0 (10): 20-27.   DOI: 10.13474/j.cnki.11-2246.2023.0290 Abstract （103）   HTML （11）    PDF（pc） （5331KB）（139）       Knowledge map    Save Lakes are important land resources, and the study of the dynamic changes of lake waters is conducive to providing an important guarantee for the development and utilization of regional water resources and the stability of ecological balance. Based on Google Earth Engine, using multi-source remote sensing data from 1989 to 2022 as the data source, in normalized difference water index (NDWI), modified normalized difference water index (MNDWI), automatic water extraction index (AWEI sh) and the water index (WI 2015) selects the optimal water body index from the four commonly used water body indexes to extract the water body of Dongting Lake Basin. Combined with various data such as precipitation, temperature, population density and land use in the basin to explore the Dongting Lake analysis of water body evolution characteristics and driving forces in the lake basin. The results show that, from 1989 to 2022, the water body area in the Dongting lake area showed an overall downward trend in the wet and dry seasons, and the three major lake areas all had different degrees of reduction, with an average reduction of 93.27 km 2and 140.15 km 2. The area of lakes in the basin is the result of the combined effects of natural climate change and human activities. Precipitation and temperature are important natural factors affecting the area of lakes. The increase in population and the transfer of land use types caused by reclamation of lakes are the human factors for the reduction of lake area. Reference | Related Articles | Metrics

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Review of coastal ecological environment monitoring based on unmanned aerial vehicle remote sensing HU Yiqiang, YANG Ji, JING Wenlong, YANG Chuanxun, SHU Sijing, LI Yong Bulletin of Surveying and Mapping    2022, 0 (6): 18-24.   DOI: 10.13474/j.cnki.11-2246.2022.0165. Abstract （370）   HTML （25）    PDF（pc） （1092KB）（264）       Knowledge map    Save In this study, we introduce the history and current situation of development of UAV remote sensing systems by introducing the application status of UAV platform and UAV remote sensors from the perspective of coastal ecological environment monitoring. Then we review UAVRS applications in eight different areas of the coastal ecological environment monitoring, which provides evidence of the potentials and effectiveness of UAVRS for coastal zone management. This study points out that in order to further improve the application effect of UAVRS in coastal ecological environment monitoring, it is necessary to conduct further research and improvement in UAV remote sensors, setting out ground control points (GCPs), spectral data processing and other related technologies. In the future, with the improvement of UAV data transmission speed and the development of UAV AD hoc network technology, it is expected to achieve efficient and intelligent monitoring of coastal ecological environment. Reference | Related Articles | Metrics

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Reconstruction of high-precision real 3D data of offshore islands based on drone tilt photography and laser scanning ZHANG Shuhang, LI Wangmin, PANG Yinning, CHANG Bingtao, MA Defu, LI Xiulong, ZHANG Wuming Bulletin of Surveying and Mapping    2024, 0 (3): 25-30.   DOI: 10.13474/j.cnki.11-2246.2024.0305 Abstract （154）   HTML （16）    PDF（pc） （5347KB）（137）       Knowledge map    Save This paper addresses the needs and technical challenges of real 3D for offshore islands, taking the Miaowan Island in Zhuhai, China as the observation object, using UAV oblique photogrammetry and laser scanning for real 3D data acquisition of offshore islands. Details of the UAV mission planning, ground control and live 3D data processing work, and DEM generation based on parameter-free cloth simulation filtering are presented. The absolute accuracy of the data is verified by checkpoints. The results show that the total mean square error of the acquired ortho-and oblique images are 14.72 and 6.60cm,respectively; the errors of the point cloud, DSM and DEM elevations are 3.10, 6.20 and 7.11cm,respectively, which meet the needs of offshore island live 3D display and survey management. Reference | Related Articles | Metrics

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Spatio-temporal difference analysis of carbon emissions in Chang-Zhu-Tan urban agglomeration based on multi-source remote sensing data WANG Mengjie, WANG Yanjun, LI Shaochun, LIN Yunhao, TENG Fei, CAI Hengfan Bulletin of Surveying and Mapping    2023, 0 (1): 65-70.   DOI: 10.13474/j.cnki.11-2246.2023.0011 Abstract （252）   HTML （15）    PDF（pc） （1715KB）（257）       Knowledge map    Save The spatio-temporal distribution monitoring and evaluation of carbon emissions is one of the key research topics for sustainable urban development. For the analysis of the differences in the spatio-temporal distribution of carbon emissions in the Chang-Zhu-Tan urban agglomeration, this paper applies the NPP-VIIRS nighttime light images and impervious surface data, combined with county-level carbon emissions data to construct the carbon emission estimation model for the Chang-Zhu-Tan urban agglomeration, and analyzes the spatial and temporal distribution characteristics and changing trends of carbon emissions in this urban agglomeration. The results show that: ① The average and total value of nighttime lights and impervious surfaces data can better reflect the regional carbon emission level of the Chang-Zhu-Tan urban agglomeration.②From 2013 to 2017, the carbon emissions of the Chang-Zhu-Tan urban agglomeration were concentrated, mainly distributed in the middle area of the northern part. The carbon emissions areas expand year by year but the intensity weakened. ③ From 2013 to 2017, the changing trend of carbon emissions in the Chang-Zhu-Tan urban agglomeration was that the central area mainly has negative carbon emissions growth, while the peripheral areas have undertaken some carbon emissions. This study monitors the county-level carbon emissions of the Chang-Zhu-Tan urban agglomeration from 2013 to 2017 based on multi-source remote sensing data, and reveals the changes in the spatio-temporal distribution of carbon emissions, which can provide a scientific reference for carbon emission reduction and regional sustainable development. Reference | Related Articles | Metrics

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Monitoring and analysis of deep foundation pit settlement of underground garage based on BeiDou Navigation Satellite System HUANG Xin, ZHANG Jiwen, YU Yongtang, XU Chuanzhao, ZHANG Shuai, ZENG Tao, WANG Jingge Bulletin of Surveying and Mapping    2023, 0 (9): 18-24.   DOI: 10.13474/j.cnki.11-2246.2023.0258 Abstract （115）   HTML （11）    PDF（pc） （1985KB）（136）       Knowledge map    Save In order to investigate the monitoring accuracy of Beidou deformation monitoring system under construction interference conditions, the BDS deformation monitoring system is applied to an underground garage deep foundation settlement monitoring project in Xi'an, and the settlement monitoring data during the construction period and after the construction period are obtained. According to the wavelet noise reduction principle, the monitoring data are smoothed and noise reduced, and the BDS monitoring data are compared with the level monitoring data for analysis. Finally, the final settlement of the site was predicted. The results show that the construction interference will cause the BDS monitoring data to contain a large amount of noise in a certain wavelength range. However, after the 5-layer decomposition of the original data by Daubechies wavelets, smooth settlement monitoring data can be obtained, and the average relative error of the processed data and the level monitoring data is less than 10.31%. The final settlement at the site was obtained in the range of 100~110 mm based on the noise reduction data using the modified Gompertz function prediction method. The related results can provide a reference for the application of BeiDou positioning system in the ground deformation observation project. Reference | Related Articles | Metrics

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Enhanced lane line detection algorithm for curves based on Resa-CC LU Weijia, LIU Zeshuai, PAN Yuheng, LI Guoyan, LI Huijie, CONG Jia Bulletin of Surveying and Mapping    2023, 0 (12): 25-30.   DOI: 10.13474/j.cnki.11-2246.2023.0354 Abstract （68）   HTML （7）    PDF（pc） （1755KB）（135）       Knowledge map    Save A curve enhanced lane detection algorithm based on cyclic feature fusion Resa-CC is proposed to address the issue of reduced accuracy in curve recognition caused by excessive curvature at road turns. This algorithm utilizes the shape priors of lane lines to capture the spatial relationships between rows and columns in image pixels, and fuse information to generate feature maps. The residual network is used as the main framework, and the encoder, decoder and attention mechanism modules are added. The Loss function adds curve structure constraints to improve the recognition accuracy of lane curves. The addition of the cyclic feature fusion module and the self attention mechanism module improved the accuracy by 3.41% and 1.1%, respectively, proving the effectiveness of the two modules. The accuracy of the Resa-CC algorithm can reach 96.83%, with an FPS of 35.68. The false detection rate FP and missed detection rate FN are 0.0315 and 0.0282, respectively. This indicates that the algorithm has high detection performance and can more accurately infer the position of the lane line in the curve when vehicles are driving. Reference | Related Articles | Metrics

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Accuracy evaluation of consumer UAV tilt photogrammetry for spoil area monitoring HU Jinru, LAI Linfeng, LU Zhiyuan, ZHANG Xiaofeng, LI Yuan, ZHAO Tingning, WEI Guangkuo Bulletin of Surveying and Mapping    2023, 0 (11): 36-41.   DOI: 10.13474/j.cnki.11-2246.2023.0324 Abstract （97）   HTML （11）    PDF（pc） （3713KB）（134）       Knowledge map    Save UAV photogrammetry technology plays an important role in the monitoring of spoil ground.Consumer-grade drones have significant advantages of low threshold and low cost,but there are few studies on the accuracy analysis of photogrammetry using consumer-grade drones.In particular,the latest “specifications for office operation of low-altitude digital aerial photogrammetry” issued in 2021 has higher requirements for the accuracy of measurement.This paper takes the spoil ground of highway construction project as the research object,evaluates the accuracy of tilt photogrammetry using consumer-grade drones according to the image control points laid on the ground,and compares it with the traditional orthophoto grammetry.The test results show that the consumer-grade UAV can improve the measurement accuracy by 25.19%～ 90.68% through oblique photography,which is more significant in elevation.At the same time,the influence of large terrain drop on the measurement accuracy is reduced to centimeter level,which meets the mapping requirements of 1∶500 scale in the specification.The reliability and feasibility of consumer-grade UAV in the monitoring of spoil ground are proved. Reference | Related Articles | Metrics

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Lithology classification of large slope geological outcrop based on UAV multi spectral remote sensing CHANG Le, HAN Lei, CHEN Zongqiang, SHENG Hui, LUI Shanwei Bulletin of Surveying and Mapping    2023, 0 (11): 42-47.   DOI: 10.13474/j.cnki.11-2246.2023.0325 Abstract （77）   HTML （1）    PDF（pc） （2775KB）（134）       Knowledge map    Save Aiming at the problems that satellite images are difficult to obtain geological outcrop data with large slopes, and traditional classification methods cannot effectively use image information leading to geological outcrop section lithology classification accuracy being relatively low, this research obtains high-precision field geological outcrop data with large slope based on UAV remote sensing technology and proposes a multi-scale hybrid feature network model. The results show that the combination of UAV and close photogrammetry is feasible in collecting geological outcrop data. The multi-scale hybrid feature network model can effectively extract the spectral features and spatial features from the multi-spectral images of UAV and realize the high-precision lithology classification of geological outcrops with large slopes. Taking an outcrop in Yuntaishan geopark as an example, the overall classification accuracy of the proposed model can reach 89.91%, and the Kappa coefficient can reach 0.85. The general classification accuracy is nearly 15% higher than traditional machine learning algorithms SVM and MLC, about 10% higher than Inception V3 and ResNet18, and 1.5% higher than Hybrid CNN. Reference | Related Articles | Metrics

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PDR algorithm based on Kalman filter for optimizing heading ZHU Juntao, LIN Zhiyu, LI Hailin, REN Zhaocai, CHEN Rongsheng, LAN Rongtian, DAI Chengyuan Bulletin of Surveying and Mapping    2023, 0 (9): 30-34,63.   DOI: 10.13474/j.cnki.11-2246.2023.0260 Abstract （130）   HTML （6）    PDF（pc） （1712KB）（132）       Knowledge map    Save PDR technology based on the smartphone platform has become a hotspot in indoor positioning research at home and abroad because of its mature technical conditions and ease of realization on a wide scale. However, the accuracy of smartphone sensors is limited, and the geomagnetic information in the indoor environment will be interfered with by the indoor electromagnetic environment, which will affect the positioning accuracy of the PDR algorithm. Therefore, this paper proposes a smartphone heading optimization method based on the Kalman filter, with the smartphone as the research carrier. The theoretical study and field test are conducted by fusing the geomagnetic and gyroscope sensor data of smartphones, and the heading accuracy in the PDR algorithm is optimized. The average error of the optimized positioning improved to 1.36 m. Reference | Related Articles | Metrics