High-precision 3D Model Research Articles

High-precision 3D Modeling of Construction Waste Pile Bodies by Integrating Multi-source Data

Abstract. The instability of construction waste pile bodies, as an increasingly concerning disaster, poses significant risks to the safety of people's lives and property. Currently, there is limited research on high-precision 3D modeling techniques for construction waste pile bodies, which significantly hinders the accuracy and reliability of early detection and risk assessment of pile body instability. Therefore, constructing high-precision 3D models of construction waste pile bodies using multi-source data plays a crucial role in improving the accuracy and timeliness of early warning systems for pile body instability, offering significant theoretical research and practical application value. Building 3D models of construction waste pile bodies solely based on unmanned aerial vehicle (UAV) oblique photography data faces challenges, such as various degrees of data voids and insufficient model completeness, and few methods currently address the construction of 3D models of construction waste pile bodies through the fusion of multi-source data. This paper attempts to use the Iterative Closest Point (ICP) algorithm, combining SLAM laser point cloud data with UAV oblique photography data to fill data voids, and utilizes the fused point cloud to reconstruct the triangulation network, achieving the transformation from 3D point cloud models to 3D surface models. On the basis of texture mapping, a high-precision 3D model of the construction waste pile body is constructed. The research results show that the 3D model of the construction waste pile body, integrated with multi-source data, has a planar error of 0.0187m and an elevation error of 0.0368m, meeting the corresponding model accuracy requirements. It can more realistically restore the fine 3D features of the construction waste pile body, effectively compensating for the shortcomings of single-source data in 3D modeling of construction waste pile bodies, providing a new method for the 3D model reconstruction of construction waste pile bodies, and offering effective data support for construction waste research.

3D Modelling and Measuring Dam System of a Pellucid Tufa Lake Using UAV Digital Photogrammetry

The acquisition of the three-dimensional (3D) morphology of the complete tufa dam system is of great significance for analyzing the formation and development of a pellucid tufa lake in a fluvial tufa valley. The dam system is usually composed of the dams partially exposed above-water and the ones totally submerged underwater. This situation makes it difficult to directly obtain the real 3D scene of the dam system solely using an existing measurement technique. In recent years, unmanned aerial vehicle (UAV) digital photogrammetry has been increasingly used to acquire high-precision 3D models of various earth surface scenes. In this study, taking Wolong Lake and its neighborhood in Jiuzhaigou Valley, China as the study site, we employed a fixed-wing UAV equipped with a consumer-level digital camera to capture the overlapping images, and produced the initial Digital Surface Model (DSM) of the dam system. The refraction correction was applied to retrieving the underwater Digital Elevation Model (DEM) of the submerged dam or dam part, and the ground interpolation was adopted to eliminate vegetation obstruction to obtain the DEM of the dam parts above-water. Based on the complete 3D model of the dam system, the elevation profiles along the centerlines of Wolong Lake were derived, and the dimension data of those tufa dams on the section lines were accurately measured. In combination of local hydrodynamics, the implication of the morphological characteristics for analyzing the formation and development of the tufa dam system was also explored.

Geodatabase, metric reconstruction and a GIS platform of historical-archaeological sites in Aquino

This paper presents the contents of a geodatabase developed from the outcomes of survey operations carried out, in several stages since 2015, within the archaeological context of the Roman city of Aquinum, in southern Lazio. The proposed geodatabase integrates traditional topographic surveying techniques with total station, GPS and GNSS geodetic receivers with photogrammetric surveys and terrestrial laser-scanner (TLS) measurements, including the realization of HBIM (Historical Building Information Modeling) models, to investigate some specific historical-archaeological evidence useful to understand the Roman and medieval urban structure of the city. The processing and management of the metric and information datasets were entrusted to a GIS platform, implemented in the opensource Quantum-GIS software, to optimize the flowchart of the acquisition/processing process and to realize an intra-site Web-GIS useful for the visualization and dissemination of the results. The methodological-operational approach applied in the research activities highlights the fundamental contribution that the technological innovations of geomatics can provide for the construction of elaborate knowledge concerning cultural heritage, also becoming the base for the elaboration of more complex and detailed analyses. In this case, for example, the HBIM digital model of the Church of Santa Maria of Libera was also used for an in-depth study in the field of structural engineering, as input to model the masonry vaults of the aisles of the church and assess their structural safety through the analysis methodology denominated "Thrust Network Analysis (TNA)." In addition, the high-precision 3D models developed from detailed photogrammetric measurements of the archaeological fragments and human remains found in the excavation areas made it possible to create interesting "visual digital products" that are immediately understandable even for non-experts, and thus particularly useful for wide-ranging knowledge dissemination.

3D modelling method and application to a digital campus by fusing point cloud data and image data

ObjectiveThe use of single-source data for real-world 3D modelling currently faces problems such as deformation, pulling and fuzzy texture at the bottom of buildings in some feature models because of the lack of images. Moreover, LIDAR generates a huge amount of data, and the massive raw data processing and point cloud parsing puts high demands on the hardware arithmetic and algorithms. Aiming at the deficiencies and defects of the two data sources of inclined photogrammetry and airborne laser point cloud in the construction of high-quality and high-precision city-level 3D models. Methodsthis study uses a university library building as an example and proposes the main technical process and method of modelling after fusing the point cloud data acquired by inclined photogrammetry and 3D laser scanning technology. This is accomplished in the reconstruction stage of multi-source data fusion through data spatial alignment, coordinate system unification and data spatial integration. At the stage of multi-source data fusion and reconstruction, through data spatial alignment, coordinate system unification, point cloud coarse alignment and the iterative closest point (ICP) algorithm, a realistic 3D model of a building is constructed to verify the effectiveness of the modelling method. ResultsThe method can effectively improve the accuracy of the real-life 3D model, repair the deficiencies in the model and optimise the details of the model. It can also significantly improve the fineness of the tilt photography model and perfectly present the geometric and texture information of the building, making it a superior method for fine 3D reconstruction. ConclusionThis 3D reconstruction method of buildings, which integrates low-altitude inclined photogrammetry and airborne light detection and ranging (LiDAR), has high positional accuracy and can provide new methods and new ideas for the construction of digital campuses as well as for other engineering applications.

A Super-Resolution and 3D Reconstruction Method Based on OmDF Endoscopic Images.

In the field of endoscopic imaging, challenges such as low resolution, complex textures, and blurred edges often degrade the quality of 3D reconstructed models. To address these issues, this study introduces an innovative endoscopic image super-resolution and 3D reconstruction technique named Omni-Directional Focus and Scale Resolution (OmDF-SR). This method integrates an Omnidirectional Self-Attention (OSA) mechanism, an Omnidirectional Scale Aggregation Group (OSAG), a Dual-stream Adaptive Focus Mechanism (DAFM), and a Dynamic Edge Adjustment Framework (DEAF) to enhance the accuracy and efficiency of super-resolution processing. Additionally, it employs Structure from Motion (SfM) and Multi-View Stereo (MVS) technologies to achieve high-precision medical 3D models. Experimental results indicate significant improvements in image processing with a PSNR of 38.2902 dB and an SSIM of 0.9746 at a magnification factor of ×2, and a PSNR of 32.1723 dB and an SSIM of 0.9489 at ×4. Furthermore, the method excels in reconstructing detailed 3D models, enhancing point cloud density, mesh quality, and texture mapping richness, thus providing substantial support for clinical diagnosis and surgical planning.

The Application of Laser-Scanning 3D Model Reconstruction Technology for Visualizing a Decommissioning Model of the Heavy Water Research Reactor

Currently, over 100 nuclear power units globally have been in operation for more than 40 years. Hindered by the limitations of computer technology at the time, these nuclear facilities lack detailed electronic drawings. Activities such as equipment replacement and process circuit system modifications during operation result in discrepancies between paper drawings and actual conditions. Given the complexity and irreversibility of nuclear facility decommissioning activities, virtual simulation technology is often employed before the decommissioning process begins to assist in designing and validating decommissioning plans. Consequently, the creation of high-precision 3D models is crucial for subsequent decommissioning designs. Through innovatively utilizing laser-scanning 3D model reconstruction technology in the reconstruction of the model of China’s first heavy water research reactor undergoing decommissioning, this paper provides an overview of the process of laser-scanning 3D model reconstruction and its application in reconstructing the heavy water research reactor model. Using a 3D laser scanner, four decommissioning areas of the heavy water research reactor, including the reactor building, secondary water pump room, ventilation center, and low-level radioactive wastewater storage tank area, were subjected to 3D laser scanning. The acquired point cloud data from 572 scanning stations were processed using point cloud processing software for denoising, stitching, and triangulation. The triangulated model was then imported into modeling software for 3D reconstruction, ultimately establishing a digitalized model of the heavy water research reactor suitable for subsequent decommissioning simulation and design.

Застосування та опрацювання результатів лазерного сканування в цивільному будівництві.

The goal of this work is to create a 3D model and detailed drawings of the structural components of a kindergarten building in the city of Truskavets, based on laser scanning. The methodology is based on using laser scanning to create detailed 3D models and drawings of buildings. This process involves several stages: performing laser scanning of the object, processing the obtained data to create an accurate 3D model, analyzing the model to identify necessary changes or improvements in the structure, and finally, developing detailed drawings based on this model. The method also includes assessing the accuracy and quality of scanning to ensure the reliability of the final results. Results As a result of this work, detailed 3D models and drawings of the construction object were created using laser scanning. The results demonstrated high accuracy and quality of the models, enabling their effective use in reconstruction and repair works. The study also showcased how this technology can enhance design and planning in construction, particularly in the context of renovating existing buildings. These outcomes affirm the efficacy of laser scanning as a tool for modern construction design. Scientific novelty and practical significance. The importance of this work lies in the creation of a high-precision 3D model from laser scanning results, enabling the development of a detailed plan for the reconstruction of the kindergarten. This was the first time a comprehensive set of tasks for creating a 3D model of a kindergarten in Truskavets was carried out, based on laser scanning technology.

Full-automatic high-precision scene 3D reconstruction method with water-area intelligent complementation and mesh optimization for UAV images

ABSTRACT Fast and high-precision urban scene 3D modeling is the foundational data infrastructure for the digital earth and smart cities. However, due to challenges such as water-area matching difficulties and issues like data redundancy and insufficient observations, existing full-automatic 3D modeling methods often result in water-area missing and many small holes in the models and insufficient local-model accuracy. To overcome these challenges, full-automatic high-precision scene 3D reconstruction method with water-area intelligent complementation on depth maps and mesh optimization is proposed. Firstly, SfM was used to calculated image poses and PatchMatch was used to generated initial depth maps. Secondly, a simplified GAN extracted water-area masks and ray tracing was used achieve high-precision auto-completed water-area depth values. Thirdly, fully connected CRF optimized water-areas and arounds in depth maps. Fourthly, high-precision 3D point clouds were obtained using depth map fusion based on clustering culling and depth least squares. Then, mesh was generated and optimized using similarity measurement and vertex gradients to obtain refined mesh. Finally, high-precision scene 3D models without water-area missing or holes were generated. The results showed that: to compare with the-state-of-art ContextCapture, the proposed method enhances model completeness by 14.3%, raises average accuracy by 14.5% and improves processing efficiency by 63.6%.

Prediction of Heavy Metal Pollution in Soil Based on SSA-XGBoost Model and 3D Geological Model

ABSTRACT The problem of soil heavy metal pollution in decommissioned sites has become an environmental threat and challenge faced by countries around the world. Establishing a high-precision 3D model of contaminants is essential for pollution risk assessment and accurate monitoring of contaminated sites. In this study, 3D geological model and SSA-XGBoost model are proposed to predict heavy metal concentration in a site. These models can effectively improve the prediction accuracy of soil heavy metals, and the RMSE of the XGBoost model optimized by the SSA algorithm is reduced by 24.3%-34.3%. Compared with other machine learning models, the SSA-XGBoost model has optimal performance in improving the prediction accuracy of soil heavy metals. It is suitable for the areas with significant spatial heterogeneity of soil heavy metals. Using the SSA-XGBoost model and 3D geological model, the 3D spatial distribution characteristics of heavy metals in contaminated soil are determined. The concentration of soil pollutants ranked as As>Pb>Mo, and the overall pollution degree decreases gradually from top to bottom. The pollutants are mainly distributed in the production workshop area in the southwest of the site, and the miscellaneous fill layer is the main soil layer that needs to be remediated.

Optimization of Digital Inheritance of Meishan Folk Woodcarving Skills in the Information Age

Abstract This study delves into the digital preservation of Meishan folk woodcarvings, emphasizing the use of virtual reality (VR) technology to enhance the transmission of this traditional art. Utilizing 3D modeling and VR platforms, the research scans and rebuilds wooden carvings for digital exhibition. The realism and interactivity of the virtual environment are improved through collision detection algorithms such as Orientation Bracketing Box (OBB) and Axial Bracketing Box (AABB), complemented by high-precision 3D models created with LIDAR scanning technology. Findings indicate that the VR system significantly enhances the efficiency and quality of digital preservation, offering a robust solution for safeguarding Meishan folk woodcarvings.

A new approach to surveying cliff-dwelling endangered plants using drone-based nap-of-the-object photography: A case study of Clematis acerifolia

Cliffs are essential refuges for endangered plants, but their inaccessibility and inadequate reliable survey methods make the assessment of the survival status of these plants difficult. We employed the drone-based Nap-of-the-Object Photography (NoOP) technique, which involves flying close to an object's surface to automatically capture high-precision images of the object surface, to investigate an endangered cliff plant, Clematis acerifolia, in North China. A drone (DJI M300 RTK) equipped with a visible-light mapping camera (DJI Zenmuse P1) was used for automated NoOP flights, enabling the collection and reconstruction of millimeter-level, high-precision three-dimensional (3D) models of the cliff plots. Across 12 cliffs, we identified and measured the precise coordinates and values of eight microtopographical and five morphological characteristic factors for 1444 C. acerifolia plants. The Ground sampling distance (GSD) of the high-precision 3D models reached 0.10 cm/pixel, and the mean value of the root mean squared error of the sampled positioning coordinates was 4.65 cm/pixel. Correlation and correspondence analyses were used for data analyses. The results indicated that the growth status of C. acerifolia was significantly influenced by a complex factor interaction, particularly plant altitude, crevice width, and crevice length. This method for cliff plant surveys using drone-based NoOP determines the parameters for such surveys and demonstrates the effectiveness and potential of this method for cliff plant investigations. The primary microtopographical factors affecting the growth and distribution status of C. acerifolia were identified, providing pointers for translocation conservation and propagation reintroduction of this endangered plant.

3D Indoor Crime Scene Reconstruction from Micro UAV Photogrammetry Technique

The application of micro Unmanned Aerial Vehicles (UAVs) in photogrammetry, particularly within the realm of forensic investigation represents a relatively novel approach and has gained increased attention. By measuring the distances and positions of the scene’s components, it is feasible to document and visualize the scene using the photographs that were taken for the purpose of assisting investigators. Capturing accurate crime scene data within a short time frame is always a challenge. Conventionally, photographs were used to document the scene, but the technical qualities of the photographs depended on the skill of the present forensic personnel. The use of 3-Dimensional (3D) photogrammetry enables the production of highly realistic and detailed 3D documentation of a given scene. As this technique involves capturing a series of photographs, it can be a time-consuming process. Therefore, this study aims to explore an alternative approach that enables the rapid acquisition of the scene while preserving the intricate details, thus ensuring efficiency without compromising the accuracy of the resulting documentation. The study employs a methodological approach wherein data are collected from a simulated crime scene situated within a confined and hard-to-reach area. The data collection is facilitated through the utilization of micro UAVs. The acquired data are then processed utilizing photogrammetry software, leading to the generation of a 3D model point cloud. The collected data will be subjected to a comparative analysis with data generated using a Terrestrial Laser Scanner (TLS) as a reference, alongside Vernier Calliper (VC) measurements. The findings indicate that the Root Mean Square Error (RMSE) of the integrated point clouds from TLS and micro UAVs compared to the conventional method is approximately ±0.217 cm. It can be deduced that the integration of data derived from micro UAVs and TLS in forensic photogrammetry within a confined crime scene is viable and yields a high-precision 3D model point cloud.

Application of Airborne Radar Variable Altitude Aerial Survey in High Precision Mapping of Mountainous Areas

This paper studies how to use UAV aerial survey equipment to carry laser radar and high-definition real-scene lenses to achieve high-precision mountain mapping. The study aims to solve the problems of complex terrain, difficulties in surveying, and controlling the accuracy of surveying and mapping in mountainous, canyon, and hilly areas. Firstly, the LK tea production area development project is selected as an example for example analysis. The aerial survey equipment and data acquisition equipment are selected according to the characteristics of the project. Secondly, aiming at the problem that the mountainous terrain undulates greatly and that the accuracy of ground object mapping is difficult to control, this paper puts forward the “variable height aerial survey” method. It collects aerial survey data according to the terrain characteristics. Finally, this paper proposes a “point cloud overlay” modeling method. It combines laser point cloud data with real 3D data to form a high-precision real 3D model point cloud reorganization and establish a high-precision real 3D model.

Integrating vision and laser point cloud data for shield tunnel digital twin modeling

In shield tunnel digital twin modeling, constructing high-precision tunnel digital 3D models is essential but poses a challenging engineering problem that affects efficiency and accuracy. To address this, this paper presents a method based on 3D tunnel information models using image and point cloud data. A 3D Tunnel Information Model Construction Method (3DTIM) is proposed, based on vision and laser point cloud data, encompassing six core processing layers, and employing the YOLO-T tunnel inner wall image target recognition method alongside various point cloud data processing methods. Through this method, critical parameters can be rapidly and accurately extracted from images and point cloud data, enabling the direct creation of high-precision 3D tunnel models on the 3D modeling software with an accuracy better than 0.7 cm. The 3DTIM approach not only solves the problem of constructing high-precision tunnel 3D models, but also provides a valuable methodological reference for digital shield tunnel twin modeling, reducing the need for manual measurement and enhancing the efficiency of tunnel digital model construction. This research provides a new practical framework for future studies on tunnel 3D model construction and digital shield tunnel twin modeling based on image and point cloud data, forming a more valuable methodological reference.

High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces

Photogrammetry, reconstructing three-dimensional (3D) models from overlapping two-dimensional (2D) photos, finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects, for example rock fractures. Fracture properties are important for determining the mechanical stability, permeability, strength, and shear behavior of the rock mass. Photogrammetry can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture, which controls the fluid flow, hydromechanical and shear behavior of the rock mass. This research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface. A workflow has been developed to define the physical aperture of a fracture using photogrammetry. Three blocks of Kuru granite (25 cm × 25 cm × 10 cm) with an artificially induced fracture, were investigated. For scaling 3D models, 321 markers were used as ground control points (GCPs) with predefined distances on each block. When the samples were well-matched in their original positions, the entire block was photographed. Coordinate data of the GCPs were extracted from the 3D model of the blocks. Each half was surveyed separately and georeferenced by GCPs and merged into the same coordinate system. Two fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical aperture. Accuracy assessment of the photogrammetric reconstruction showed a 20–30 μm digital control distance accuracy when compared to known distances defined between markers. To attain this accuracy, the study found that at least 200 scale bars were required. Furthermore, photogrammetry was employed to measure changes in aperture under normal stresses. The results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers (LVDTs), with differences ranging from 1 μm to 8 μm.

Simulation analysis of rockfall movement characteristics with debris slope using Unity3D based on UAV remote sensing DSM: a case study of the G318 Highway on the Tibetan Plateau

Rockfalls on debris slopes pose a significant hazard to canyon roads on the Tibetan Plateau. In order to assess risks and develop effective engineering solutions, it is crucial to fully understand the characteristics and processes of rockfall movement. This research utilizes UAVs and three-dimensional (3D) laser scanners to capture images and data, while Pix4D is employed to create a high-precision 3D model from the collected data. Unity3D is utilized to analyze the movement characteristics and deposition positions of rockfall. Various movement characteristic indexes, such as velocity, acceleration, displacement, energy loss, and deposit position, are computed and examined for blocks with different shapes, sizes, instability types on the debris slope, and blocks composed of various slope materials and inclinations. The aim is to obtain insights into the specific movement mechanisms of debris slopes, which differ from conventional slopes. Field experiments have confirmed the effectiveness of the Unity3D simulation approach. Building upon this foundation, a high-precision 3D simulation model for the debris slope of the G318 Highway on the Tibetan Plateau is developed using Unity3D. This model is used to calculate the movement characteristics, energy variation, and deposition positions of rockfall. The findings are then compared with those of common models. The results demonstrate that the high-precision 3D simulation model computed by Unity3D provides more accurate and reasonable results compared to the common model. Moreover, the movement characteristics, energy variation, and deposition positions of rockfall on debris slopes exhibit specific characteristics. By employing Unity3D simulation analysis, a comprehensive understanding of the phenomena and behavior of rockfall on debris slopes can be achieved, enabling the proposal of more reasonable engineering protection measures.

Photogrammetric state of degradation assessment of decorative claddings: the plasterwork of the Maidens' Courtyard (The Royal Alcazar of Seville)

Highlights: The photogrammetric survey demonstrates to be a potential tool in the preventive conservation of ancient plasterworks. The high-precision 3D model allows the study and quantification of alterations (e.g. fissures, deformations, and loss of mass or polychromies). The virtual model and the analysis performed with CloudCompare software provide fast, accurate and accessible results to experts in the field. Abstract: Previous studies and documentation about the state of conservation of architectural or decorative elements are crucial for heritage managers, technicians and researchers to succeed in the maintenance and preservation of the heritage. In this sense, hand tracings, digital drawings, or photographs have traditionally been the methods for alteration and sample mapping. In spite of their effectiveness, these methods have some disadvantages, such as the need for more precision in terms of location, dimensions, quantification and types of alterations. By contrast, high-resolution three-dimensional (3D) models allow us to analyse decorative ancient plasterworks with great precision, offering considerable advantages over traditional tools for heritage documentation. To facilitate stakeholders’ work and enhance the quality of data collected, this work proposes the use of photogrammetry as a tool for the documentation of polychromed ancient plasterworks, taking the upper frieze of the access door to the Charles V ceiling room in the Royal Alcazar of Seville as a case of study. Thus, the work methodology applied has shown several advantages over previous methods. On the one hand, it was possible to obtain a 2D planimetry from the 3D model; this is an essential step for those responsible for heritage, especially in reports prior to restoration interventions. On the other hand, the 3D model created enables present alterations identification, the location of fissures and cracks in their three dimensions (opening, length and depth), deformations measurement and control, the quantification of mass or polychrome loss, and the detached elements digital reconstruction. In this way, highprecision digital results are quickly obtained and accessible to all the experts involved in the heritage conservation and maintenance plan.

An Improved Poisson Surface Reconstruction Algorithm based on the Boundary Constraints

The usage of the point cloud surface reconstruction to generate high-precision 3D models has been widely applied in various fields. In order to deal with the problems of insufficient accuracy, pseudo-surfaces and high time cost caused by the traditional surface reconstruction algorithms of the point cloud data, this paper proposes an improved Poisson surface reconstruction algorithm based on the boundary constraints. For large density point cloud data obtained from 3D laser scanning, the proposed method firstly uses an octree instead of the KD-tree to search the near neighborhood; then, it uses the Open Multi-Processing (OpenMP) to accelerate the normal estimation based on the moving least squares algorithm; meanwhile, the least-cost spanning tree is employed to adjust the consistency of the normal direction; and finally a screened Poisson algorithm with the Neumann boundary constraints is proposed to reconstruct the point cloud. Compared with the traditional methods, the experiments on three open datasets demonstrated that the proposed method can effectively reduce the generation of pseudo-surfaces. The reconstruction time of the proposed algorithm is about 16% shorter than that of the traditional Poisson reconstruction algorithm, and produce better reconstruction results in the term of quantitative analysis and visual comparison.

The Key Technology of Oblique Photogrammetry of Assembled Buildings by UAV

In order to ensure the disaster control during infrastructure construction and operation, a method of tilt photogrammetry of prefabricated buildings using UAV is proposed. A comparative study of the key steps in the 3D construction process of building (structure) was carried out, and a set of 3D morphology construction method based on UAV tilt photogrammetry was proposed, and the key steps were optimized to realize automation and visualization in the process of model construction. The experimental results show that in the application case of a school district, the error of the three directions is distributed between -4 cm and 4 cm, accounting for 74%, and that between -2 cm and 2 cm, accounting for 37%; the root mean square error of the three directions was calculated to be 4.0 cm, 3.8 cm, and 2.8 cm, respectively. In an engineering application case, the error size of the three directions distributed between -4 cm and 4 cm accounted for 74%, and that between -2 cm and 2 cm accounted for 50%; the root mean square error of the three directions was calculated as 2.3 cm, 2.5 cm, and 3.3 cm, respectively. Conclusion. This method can not only obtain high-precision 3D models of urban complex and single buildings, but also meet the requirements of digital city construction for 3D model construction and obtain clear and high-precision digital land surface model.

Intelligent City 3D Modeling Model Based on Multisource Data Point Cloud Algorithm

With the rapid development of smart cities, intelligent navigation, and autonomous driving, how to quickly obtain 3D spatial information of urban buildings and build a high-precision 3D fine model has become a key problem to be solved. As the two-dimensional mapping results have constrained various needs in people’s social life, coupled with the concept of digital city and advocacy, making three-dimensional, virtualization and actualization become the common pursuit of people’s goals. However, the original point cloud obtained is always incomplete due to reasons such as occlusion during acquisition and data density decreasing with distance, resulting in extracted boundaries that are often incomplete as well. In this paper, based on the study of current mainstream 3D model data organization methods, geographic grids and map service specifications, and other related technologies, an intelligent urban 3D modeling model based on multisource data point cloud algorithm is designed for the two problems of unified organization and expression of urban multisource 3D model data. A point cloud preprocessing process is also designed: point cloud noise reduction and downsampling to ensure the original point cloud geometry structure remain unchanged, while improving the point cloud quality and reducing the number of point clouds. By outputting to a common 3D format, the 3D model constructed in this paper can be applied to many fields such as urban planning and design, architectural landscape design, urban management, emergency disaster relief, environmental protection, and virtual tourism.