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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 （264）      PDF（pc） （3266KB）（227）       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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Evaluation of regional landslide susceptibility based on convolutional neural network: a case study of Wanzhou district of Three Gorges Reservoir area YANG Yanchen, ZHOU Chao, SHI Jiamei Bulletin of Surveying and Mapping    2023, 0 (11): 1-6.   DOI: 10.13474/j.cnki.11-2246.2023.0318 Abstract （258）            Knowledge map    Save Carrying out regional landslide susceptibility assessment is the key to landslide meteorological early warning and risk assessment. Aiming at the fact that many current susceptibility studies do not consider the relationship between the occurrence of landslides and adjacent environments, a regional landslide susceptibility modeling framework based on convolutional neural network (CNN) is proposed. Taking Wanzhou district of the Three Gorges Reservoir area as an example, 12 factors such as slope and aspect are selected to construct an evaluation index system, and the influence of factors on landslide development is analyzed by information method. The local two-dimensional matrix is used to construct the dataset, CNN is used for susceptibility modeling. At the same time, the impact of the size of the local two-dimensional matrix to the accuracy when constructing samples is explored. The results show that landslides are more likely to occur the closer to the reservoir zone, and the water system and human engineering activities have a greater impact on the development of landslides. The accuracy of the CNN model is 0.925, which is significantly higher than that of the machine learning model, and the accuracy can be improved by increasing the local two-dimensional matrix size when constructing the sample. The CNN model has advantages in multidimensional spatial data processing, considering the influence of landslide location and its adjacent environment, and it is an accurate and reliable regional landslide susceptibility evaluation method. Reference | Related Articles | Metrics

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Multi-source remote sensing landslide hazard identification method driven by knowledge graph LI Yongxin, WANG Defu, MA Zhigang, FAN Yajun, YANG Benyong, LIU Li, LUO Chao Bulletin of Surveying and Mapping    2024, 0 (1): 12-18.   DOI: 10.13474/j.cnki.11-2246.2024.0103 Abstract （239）      PDF（pc） （4718KB）（82）       Knowledge map    Save Remote sensing technology plays an important role in the field of geological disaster prevention and control. With the development of aerospace technology, more remote sensing data can be obtained and effectively applied to the identification of geological hazard bodies, especially in the identification of landslide hazards. Comprehensive use of InSAR and optical remote sensing data to identify geological hazards is a hot topic in recent research. The traditional recognition process relies entirely on the work experience of interpreters, with strong subjectivity and no fixed recognition logic to follow. Based on SBAS-InSAR and optical satellite imagery, this paper analyzes the process of landslide hazard identification, and constructs the Knowledge graph and identification extraction matrix model of landslide identification. Under the logic drive of the Knowledge graph, the regional spatial characteristics of landslide hazards identified by the combination of “optical remote sensing+InSAR” are analyzed, providing a reference implementation scheme with the significance of semi quantitative extraction of indicators for landslide wide area identification, and realizing the identification process of landslide hazards from completely subjective to semi quantitative. Experiments show that this method can provide reference for relevant research and practical engineering applications, and has certain application value. Reference | Related Articles | Metrics

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A deep neural network model for road extraction of MLS LiDAR point cloud LIU Jin, YANG Ronghao, WEN Wen, TAN Junxiang, LAN Qinglong, GAO Xiang, TANG Hong Bulletin of Surveying and Mapping    2023, 0 (12): 8-12,18.   DOI: 10.13474/j.cnki.11-2246.2023.0351 Abstract （189）            Knowledge map    Save PointNet++ has shown better performance than traditional methods in MLS LiDAR point cloud road extraction, but there are still the phenomena of over segmentation or under segmentation for road edge extraction.To address this issue, an improved neighborhood enhancement coding network E-PointNet++ is proposed. By introducing a neighborhood enhancement coding module before feature extraction, the connection between local neighborhood points is established to improve the network's road edge segmentation ability.Comparative experiments are conducted on two datasets, and E-PointNet++ shows significantly better performance than other methods, with accuracy, integrity and detection quality all exceeding 97%. This method performs robustly on different datasets and scenarios. Reference | Related Articles | Metrics

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Monitoring and analysis of landslide deformation based on SBAS-InSAR YANG Chunyu, WEN Yi, PAN Xing, YUAN Debao Bulletin of Surveying and Mapping    2023, 0 (11): 12-17.   DOI: 10.13474/j.cnki.11-2246.2023.0320 Abstract （185）            Knowledge map    Save Taking the mountain landslide occurred in Zaoling township in Shanxi province on March 15, 2019 as the research object, using Sentinel-1A SAR image data from July 5, 2018 to June 30, 2019 (a total of 30 scenes) before and after the landslide, this papere monitors the deformation data of landslides with the support of SBAS-InSAR technology. The results show that the deformation range of the study area is -52.03 to 33.77 mm/a, and the overall environment is relatively stable. The deformation rate and cumulative deformation variables of the long-term loess plateau are analyzed. The causes of landslides are analyzed based on relevant geological data from the research area. Using the standard deviation ellipse algorithm, it analyzes the spatio-temporal evolution characteristics of surface deformation in the loess plateau area where the landslide is located. The results show that the center of gravity of the standard deviation ellipse shifts to the northwest, the elliptical area decreases slightly, the deformation intensifies in the northwest southeast direction, and the deformation development in the northeast southwest direction is relatively gentle. The azimuth angle rotates counterclockwise, and the displacement is about 17.03 °. Reference | Related Articles | Metrics

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Forest canopy height and biomass estimation based on LiDAR satellite (GEDI) in Guangdong province WU Zhenjiang, ZHANG Jiahua Bulletin of Surveying and Mapping    2023, 0 (12): 102-105.   DOI: 10.13474/j.cnki.11-2246.2023.0366 Abstract （183）            Knowledge map    Save Forest canopy height and biomass estimation play an important role in estimating forest carbon expenditure. In this study, the forest canopy height and biomass in Guangdong province use the global ecosystem dynamics survey (GEDI) LiDAR satellite as the data source, regression tree and Kerry kin interpolation algorithm, respectively. The results show that the height of trees in Guangdong province is generally between 10 and 20 m, accounting for more than 50%. The tree height high value occurs in Shaoguan, Zhaoqing and other cities in northern Guangdong province, and the tree height is generally 15~20 m, while the average tree height in Zhanjiang city is the lowest, generally less than 10 m. The maximum forest biomass in Guangdong province is 335.85 t/hm 2, the minimum value is 5.25 t/hm 2, and the average value is 98.27 t/hm 2.The areas with high value of forest biomass are mainly distributed in the eastern and western Guangdong province, while the forest biomass is lower in the plain and urbanized areas of Guangdong province. The results provide a scientific basis for estimating carbon absorption of forest ecosystem in Guangdong province. Reference | Related Articles | Metrics

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Review of the current research status of subway deformation monitoring HEI Junmiao, WANG Li, LI Ang Bulletin of Surveying and Mapping    2024, 0 (2): 39-44,79.   DOI: 10.13474/j.cnki.11-2246.2024.0207 Abstract （172）      PDF（pc） （1655KB）（90）       Knowledge map    Save This article includes the deformation monitoring techniques during subway construction and operation respectively, and then sorts out the current research status of subway deformation monitoring data processing methods. It summarizes the existing problems in the current research of subway deformation monitoring, and prospects the development direction of subway deformation monitoring research, providing some ideas for the systematization and automation of subway deformation monitoring research. Reference | Related Articles | Metrics

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High-precision 3D modeling technology of urban real scene based on NeRF SUN Jianhua, LI Wei, YUAN Weizhe, WANG Feng, GU Jiaming Bulletin of Surveying and Mapping    2024, 0 (4): 129-134.   DOI: 10.13474/j.cnki.11-2246.2024.0422 Abstract （171）      PDF（pc） （6094KB）（160）       Knowledge map    Save In order to better apply NeRF high-precision 3D modeling in the 3D digital reconstruction of urban real scenes,this paper divides the large scene into sub-NeRF based on NeRF technology,and initializes the polygon mesh by constructing multiple octahedral bodies in the scene. And the vertices of the polygon faces are continuously optimized during the training process. After the training is completed,the weights of the encoder-decoder network are obtained,and different levels of polygon mesh refinement are performed on each independent block through vertex optimization. From satellite-level images that capture city overviews to ground-level images that show complex details of buildings,multi-scale data for urban detail and spatial coverage are constructed through progressive learning. The neural network voxel rendering model uses a multilayer perceptron (MLP) to realize the parameterization of volume density and color,and uses a hierarchical sampling method to realize the sorting distance vector of rays between the near plane and the far plane of a predefined viewing angle,so as to realize real-time interactive rendering of large-scale scenes. Then,GIS and NeRF are fused to provide a new solution for tasks such as multi-data fusion,query,analysis,measurement,annotation and sharing,so as to achieve instant and smooth dragging,zooming and 360° browsing and viewing of scenes without dead ends. This fusion makes it easy to integrate various data sources for spatial analysis in 3D scenarios such as urban planning,land management and environmental monitoring. Reference | Related Articles | Metrics

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Design and implementation of the GNSS/INS integrated software for bridge monitoring based on GINav MA Weihao, DAI Wujiao, YU Wenkun, LI Xin Bulletin of Surveying and Mapping    2024, 0 (8): 1-7.   DOI: 10.13474/j.cnki.11-2246.2024.0801 Abstract （167）      PDF（pc） （6633KB）（151）       Knowledge map    Save In large-scale bridge monitoring,the accuracy and reliability of GNSS positioning are severely affected by environmental factors such as obstruction from bridge cables,towers,fences,and reflections from passing vehicles.INS technology operates autonomously after initial alignment,eliminating the influence of external environmental factors.By combining GNSS and INS technologies,GNSS's resistance to interference and positioning accuracy can be significantly improved.Therefore,targeting the requirements and characteristics of bridge deformation monitoring,we have designed and implemented GNSS/INS bridge deformation monitoring software based on the open-source navigation software GINav.This software includes features such as visualization of monitoring sites,automatic matching of raw data,IMU downsampling,GNSS/INS combined solution computation,and result analysis and evaluation.Vibration table simulations of bridge vibrations show that compared to GNSS-RTK technology,the GNSS-RTK/INS combination achieves significantly improved accuracy,with a mean error reaching 1/20 of the allowable deformation value for deformation monitoring,meeting the precision requirements of bridge deformation monitoring. Reference | Related Articles | Metrics

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Satellite images stereo matching algorithm based on deep learning LI Dongrui, TONG Xin, LI Wentao, SONG Xinyu, LIU Jiebing Bulletin of Surveying and Mapping    2024, 0 (1): 83-88.   DOI: 10.13474/j.cnki.11-2246.2024.0114 Abstract （166）      PDF（pc） （2453KB）（66）       Knowledge map    Save Satellite images stereo matching is one of the important steps for large-scale earth surface reconstruction, there are relatively few existing studies, and there are problems such as poor matching effect and poor model generalization ability. A deep learning-based satellite image stereo matching algorithm is proposed to perform stereo matching, including dataset construction, building stereo matching network, multi-level transfer learning and post-processing. Dataset construction contains disparity offset and and cropping. The cropped patches are then fed into attention volume network, which includes deep feature extraction, attention volume construction, disparity estimation. The network is trained by multi-level transfer learning, adapts to different data sources, and predicts the disparity maps. The false matches are filtered out by post-processing. The experiments were carried out with Jilin1-GF02 and Jilin1-GF04 images. The accuracy of the disparity maps obtained from the experimental results is better than one pixel. It shows that the algorithm proposed in this paper can obtain accurate and efficient results, which determines the generation of subsequent high-quality digital surface model. Reference | Related Articles | Metrics

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Study on land use change and spatiotemporal variation of carbon storage in Beijing-Tianjin-Hebei based on InVEST model PENG Yunni, SANG Huiyong, ZHAI Liang, ZHANG Ziyi, DUAN Jinjiang Bulletin of Surveying and Mapping    2024, 0 (1): 19-24,31.   DOI: 10.13474/j.cnki.11-2246.2024.0104 Abstract （164）      PDF（pc） （3110KB）（69）       Knowledge map    Save The increase in atmospheric CO 2content is an environmental issue of widespread international concern, and human activities change land use patterns, and land-use/land-cover (LULC) changes further affect terrestrial ecosystem structure, function, and carbon cycling. With the support of global land cover data GlobeLand30, This paper analyzed the land use changes in Beijing-Tianjin-Hebei from 2000 to 2020, used InVEST model to imitate the Spatiotemporal changes of carbon stocks, and used the spatial autocorrelation analysis to study its zoning. The results show that:①From 2000 to 2020, the largest change area in Beijing-Tianjin-Hebei region is cultivated land and artificial surface, with an area decrease of 340 222.124 hm 2and an area increase of 246 333.493 hm 2respectively. ②The total carbon reserves of Beijing-Tianjin-Hebei in 2000, 2010 and 2020 are 1 666.47×10 6、1654.63×10 6、1632.88×10 6 t, the main reason for the decline in carbon storage are the loss of arable land and the expansion of artificial land surface. ③The high value of carbon storage is mainly distributed in mountain and forest areas with relatively high altitude, while the low value areas of carbon reserves are mainly concentrated in central Beijing, the coastal zone of Tianjin and Hebei and the eastern Cangzhou, southern Tangshan. ④The results of local autocorrelation show that the high value areas of carbon reserves are clustered in the north and west of the study area. Among the regions with low to low aggregation, Dongli district of tianjin city and Hanshan district of Handan city, Hebei province show a relatively obvious weakening trend. Reference | Related Articles | Metrics

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Application of multi-source data fusion in 3D reconstruction of Guangfu ancient city ZHANG Xinhang, ZHANG Pei, QI Liang, CHEN Yongli Bulletin of Surveying and Mapping    2023, 0 (11): 112-115.   DOI: 10.13474/j.cnki.11-2246.2023.0337 Abstract （158）            Knowledge map    Save Due to the limitations of objective factors such as object occlusion and aerial photography blind area in the data acquisition process of traditional tilt photography, which cause problems such as 3D model distortion, holes, texture rasping, etc., the method of laser point cloud and tilt photography multi-source data fusion is selected for fine modeling of ancient buildings, which can improve the visual effect and accuracy of 3D models and expand the application field of achievements. In this paper, taking the historical block of guangfu ancient city as an example, through the fusion of multi-source data such as tilt photography, airborne LiDAR, ground hand-held radar and UAV re-shooting, the 3D real scene fine modeling is carried out, and good experimental results are obtained. Reference | Related Articles | Metrics

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Key technologies and applications of 3D terrain modeling for landslide simulations LÜ Yijie, YE Jian Bulletin of Surveying and Mapping    2023, 0 (11): 7-11,17.   DOI: 10.13474/j.cnki.11-2246.2023.0319 Abstract （155）            Knowledge map    Save High-resolution landslide terrain data is an important guarantee for the accuracy and visualization effect of landslide simulations. However, rendering all high-resolution landslide terrain data will cause the landslide simulation program to run slowly, managing terrain data hierarchically and loading terrain data blocks into memory in batches for combined rendering will lead to discontinuity and inconsistent resolution of terrain data participating in landslide simulation calculations. To solve the above problems, an improved quadtree LoD terrain modeling method for landslide simulations is proposed in this paper. Based on this method, terrain data is completely read into memory for numerical calculations, and terrain data blocks of different resolutions are dynamically constructed from the terrain data for combined rendering during the visualization stage, which not only provides complete and continuous terrain conditions for landslide simulations, but also ensures 3D visualization effect of landslide terrain, and effectively improves the running speed of simulation programs. More importantly, by using this method for modeling, the results of landslide simulation will not be affected when browsing the simulation scenes during the landslide simulation processes. The experimental results of landslide simulation show that the method proposed in this paper is effective and practical in 3D terrain optimization modeling for landslide simulations. Reference | Related Articles | Metrics

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A deep monocular visual-inertial navigation algorithm with SuperGlue LIU Yibo, WU Chuanwen, ZHOU Zongkun, CHEN Hua Bulletin of Surveying and Mapping    2024, 0 (2): 113-117.   DOI: 10.13474/j.cnki.11-2246.2024.0220 Abstract （155）      PDF（pc） （3472KB）（49）       Knowledge map    Save The deep learning method for images is an effective way to solve the problems of unstable feature extraction and tracking loss of traditional visual positioning algorithms in complex environments. In this paper, we propose a visual-inertial navigation algorithm based on VINS-Mono, which using SuperPoint to get feature points and track them by using SuperGlue. And evaluate it using Open-source dataset and real world experiments. Experimental results show that our algorithm has a significant improvement in positioning accuracy and stability compared with VINS-Mono, and the accuracy improvement can reach 26%. Reference | Related Articles | Metrics

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Research on frost heave deformation prediction of high railway foundation combined with PS-InSAR technology and multivariable LSTM neural network LI Xin, WEI Guanjun, ZHANG Delong Bulletin of Surveying and Mapping    2024, 0 (1): 58-64.   DOI: 10.13474/j.cnki.11-2246.2024.0110 Abstract （153）      PDF（pc） （9400KB）（78）       Knowledge map    Save Aiming at the problem that traditional deformation monitoring and prediction are difficult to achieve large-scale monitoring and accurate prediction, a method combining PS-InSAR technology and multi-variable long Short term memory (M-LSTM) neural network is proposed to monitor and predict the frost heave deformation of high railway foundation. Firstly, PS-InSAR technology is used to obtain the spatial distribution characteristics of subgrade frost heave. Then, Pearson correlation coefficient method is used to optimize three kinds of frost heave induced factors, and the obtained data are preprocessed to compose the training data. Finally, LSTM is introduced to construct an intelligent and multivariable frost heave prediction model to accurately predict the frost heave deformation trend of subgrade. The results show that PS-InSAR technology is reliable in large-scale deformation monitoring. The prediction accuracy of M-LSTM model is higher than that of the traditional neural network model, and the mean determination coefficient ( R 2), mean absolute error (MAE) and mean root mean square error (RMSE) are 0.973,0.024 mm and 0.035 mm, respectively. It shows that M-LSTM model has good application value in frost heave deformation prediction of high railway foundation, and also provides a new idea for frost heave deformation prediction of subgrade. Reference | Related Articles | Metrics

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Urban emergency shelter planning based on GIS spatial quantitative evaluation of flood resilience JIANG Fengshan, FU Xingfeng, ZHAO Lei, XIE Zhiqiang, WANG Zhanhui Bulletin of Surveying and Mapping    2024, 0 (1): 169-174.   DOI: 10.13474/j.cnki.11-2246.2024.0130 Abstract （152）      PDF（pc） （3135KB）（78）       Knowledge map    Save In the context of global climate change and accelerated urbanization, the occurrence of extreme weather leads to frequent urban floods and becomes a major natural disaster threatening public life and property. Therefore, improving the ability of cities to face storm floods is the main task in the process of urbanization. This paper takes the five districts in the main city of Kunming Yunnan province as the research area, through the relevant analysis of flood-prone points and refuge sites, based on the relevant analysis of the shortest escape path planning, health, and medical facilities distance and other factors, studies the effective flood emergency planning method, and improves the flood prevention capacity of Kunming by enhancing the resilience of urban flood. The research results show that there are still some hidden dangers of flood and waterlogging in Kunming. In recent years, with the continuous updating of urban planning, the drainage system of the main urban area of Kunming has a certain resistance to extreme rainstorms, but there is still room for improvement. Reference | Related Articles | Metrics

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Research on surveying and mapping for 3D cadastre and its standardization XU Hongxiu, YANG Yuzhong, WANG He, WU Hongtao, TAN Xinyu Bulletin of Surveying and Mapping    2024, 0 (1): 136-140.   DOI: 10.13474/j.cnki.11-2246.2024.0123 Abstract （151）      PDF（pc） （2043KB）（52）       Knowledge map    Save In view of the traditional land management mode based on cadastral and cannot well meet the increasingly tense demand of urban space management, this paper first analyzes the research status of 3D cadastre at home and abroad, and puts forward the technical route to solve the difficulties and pain points of three-dimensional land management based on 3D cadastral mapping. Then, based on this research content to conduct the exploration of 3D cadastral standardization, this paper mainly introduces the compilation process and main content for Technical Regulation of 3D Cadastre & Pproperty Unit Surveying and Mapping, and the research route and the standardare applied to the typical cases, so as to prove the feasibility of the technical route and the applicability of the standard. Reference | Related Articles | Metrics

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Production technology of city-level real scene 3D models based on oblique images and airborne LiDAR point clouds ZHU Xuhe, LUO Ningxin, WANG Junyi Bulletin of Surveying and Mapping    2024, 0 (2): 144-147.   DOI: 10.13474/j.cnki.11-2246.2024.0226 Abstract （148）      PDF（pc） （10687KB）（67）       Knowledge map    Save With the advancement of real scene 3D modeling in China, the reconstruction of city-level real scene 3D models has become a key focus of research. However, there are challenges in the process of oblique photogrammetric modeling for urban areas, such as large amounts of data processing, complicated and diverse terrains and occlusion of viewpoints leading to model deformation. To address these issues, this paper summarizes a complete technical workflow for city-level real scene 3D model reconstruction by fusing oblique aerial images and airborne LiDAR point clouds. The proposed workflow is validated using data from Zhongshan city, and the results demonstrate that this workflow can effectively improve the efficiency and quality of city-level real scene 3D model reconstruction. Reference | Related Articles | Metrics

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Construction of city level 3D realistic geospatial scene using tilt photography and laser scanning technology LUO Zhenwei, LI Xiao, LIU Chengcheng, ZHANG Yong Bulletin of Surveying and Mapping    2023, 0 (12): 116-120.   DOI: 10.13474/j.cnki.11-2246.2023.0369 Abstract （146）            Knowledge map    Save The advancement of the “Real 3D China” construction plan is increasing demand for large-scale, high-definition city-level real 3D production. Starting with the top-level design and combining it with oblique photography, laser scanning, and other technologies, this research builds a technical framework for the entire life cycle of urban-level real scene 3D construction, using Chengdu's Tianfu New district as the research area to validate the technical framework's feasibility. The research results indicate that the final 3D real-scene model's accuracy meets the design requirements, the expression quality meets the requirements, and the logic is consistent. Standardizing the technical process has reduced production costs significantly, and it also served as a reference for real-world 3D construction research in other cities. Reference | Related Articles | Metrics

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Application of nap-of-the-object photogrammetry in the 3D modeling of tangible cultural heritage LUO Xiaodan, LAI Mingzhi, LU Yan, Lü Xinqiang, LING Congcong, HUANG Yu Bulletin of Surveying and Mapping    2023, 0 (12): 132-135,152.   DOI: 10.13474/j.cnki.11-2246.2023.0372 Abstract （144）            Knowledge map    Save As a case study, Huashan rock paintings in Ningming county, Chongzuo city, Guangxi are analyzed by using UAV close photogrammetry technology to research 3D model modeling of tangible cultural heritage. The goal is to explore digital archival technology and methods suitable for 3D modeling of cultural heritage, including rock paintings, carvings, and ancient buildings. The study reveals that the initial terrain model is created through the collection of initial terrain image data using close-range photogrammetry technology on unmanned aerial vehicles (UAVs), the planning of refined routes based on the initial terrain model, and the implementation of high-resolution photogrammetry. The resulting refined 3D model has high resolution, clear texture, and accurately restored character information. The research findings can offer precise guidelines on 3D modeling technology for related fields that involve acquiring geospatial information, like safeguarding natural and cultural sites. This technology holds promising potential for wider circulation and usage. Reference | Related Articles | Metrics