Digital City Construction Research Articles

Hybrid Method of Connection Evaluation and Framework Optimization for Building Surface Reconstruction

The three-dimensional (3D) reconstruction of buildings using photogrammetric point clouds is important for many applications, ranging from digital city construction to urban energy consumption analysis. However, problems such as building complexity and point cloud flaws may lead to incorrect modeling, which will affect subsequent steps such as texture mapping. This paper introduces a pipeline for building surface reconstruction from photogrammetric point clouds, employing a hybrid method that combines connection evaluation and framework optimization. Firstly, the plane segmentation method divides building point clouds into several pieces, which is complemented by a proposed candidate plane generation method aimed at removing redundancies and merging similarities. Secondly, the improved connection evaluation method detects potential skeleton lines from different planes. Subsequently, a framework optimization method is introduced to select suitable undirected polygonal boundaries from planes, forming the basis for plane primitives. Finally, by triangulating all plane primitives and filling holes, a building surface polygonal model is generated. Experiments conducted on various building examples provide both qualitative and quantitative evidence that the proposed hybrid method outperforms many existing methods, including traditional methods and deep learning methods. Notably, the proposed method successfully reconstructs the main building structures and intricate details, which can be further used to generate textural models and semantic models. Experimental results validate that the proposed method can be used for the surface reconstruction from photogrammetric point clouds of planar buildings.

3D urban landscape rendering and optimization algorithm for smart city

3D urban landscape visualization is a key technology in digital city construction. Based on the research and analysis of the three-dimensional space of the urban landscape space, the three-dimensional space can not only allow users to intuitively perceive the development of the city. It also enables decision makers, planners, and users to more intuitively, objectively, and rationally recognize and understand the current urban development and planning design. Defining the data content of the 3D city landscape image model is the basis for creating the 3D city image model. It not only guides producers to select data, but also serves as the basis for sharing data between different applications. With the continuous development of society, the number of people living in rural areas migrating to cities to make a living has increased rapidly, leading to the growing problem of “urban congestion” in many areas. In order to effectively solve these problems, “smart cities” came into being. It quickly triggered a boom in global urban development. Based on a survey of the state-of-the-art in the field of 3D modeling and engineering design visualization, this paper analyzes 3D rendering acceleration algorithms used to speed up rendering and improve the quality of 3D design. By utilizing BSP technology, transparent objects can be drawn in any order in any scene, which solves the problem of incorrectly occluding transparent objects during rendering. This paper also applies collision detection technology, which enhances the user’s immersive feeling when roaming the landscape. In the 3D reconstruction process, it can complete the column and wall recognition for the test image with complex composition. Its recognition rate for various urban features has reached more than 80%.

Automatic extraction and reconstruction of a 3D wireframe of an indoor scene from semantic point clouds

ABSTRACT Accurate indoor 3D models are essential for building administration and applications in digital city construction and operation. Developing an automatic and accurate method to reconstruct an indoor model with semantics is a challenge in complex indoor environments. Our method focuses on the permanent structure based on a weak Manhattan world assumption, and we propose a pipeline to reconstruct indoor models. First, the proposed method extracts boundary primitives from semantic point clouds, such as floors, walls, ceilings, windows, and doors. The primitives of the building boundary are aligned to generate the boundaries of the indoor scene, which contains the structure of the horizontal plane and height change in the vertical direction. Then, an optimization algorithm is applied to optimize the geometric relationships among all features based on their categories after the classification process. The heights of feature points are captured and optimized according to their neighborhoods. Finally, a 3D wireframe model of the indoor scene is reconstructed based on the 3D feature information. Experiments on three different datasets demonstrate that the proposed method can be used to effectively reconstruct 3D wireframe models of indoor scenes with high accuracy.

An ontology-based methodology to establish city information model of digital twin city by merging BIM, GIS and IoT

With the development of digital city and smart city construction, the City Information Model (CIM) has played a critical role as a container of spatial–temporal data to establish the Digital Twin City. For a digital twin city, a virtual high-fidelity CIM model that corresponds closely to the real physical world is the premise and cornerstone of its construction. Therefore, the integration of BIM, GIS and IoT has become the preferred topic for researchers and has received much more attention from a wide academic circle. However, traditional integration mainly focuses on the conversion of both IFC and CityGML, and IoT data are also often used as visualizations. More importantly, the underlying data formats of GIS, BIM and IoT are still independent of each other without a unified data structure expression, so real data-driven analysis and decision-making cannot be implemented. This study aims to establish a general CIM ontology to integrate heterogeneous BIM, GIS and IoT data. First, the related work of BIM, GIS and IoT integration is studied and analyzed. A comparison of three mainstream approaches, data conversion, standard extension and data linking, is conducted, and it illustrates the advantages of ontology techniques in solving data interoperability problems. Second, a technical framework of BIM, GIS and IoT data integration based on ontology technology is proposed. The approach is mainly divided into five steps: geometry processing, data instantiation, ontology construction, ontology mapping and querying application. On the basis of the CIM ontology, an application ontology is built for a specific application domain to illustrate rule-based mapping, querying and inferring. Finally, the case study shows that the Ontology-based methodology in this paper has contributed to establish a general pattern for CIM data integration by mapping and linking concepts from the semantic level. It avoids changes in the original data sources and the missing data problem.

Does Digital City Construction Contribute to Air Pollution Control? Evidence from China

With the quick advancement of new generation information technologies like the Internet, big data, cloud computing, artificial intelligence, and blockchain, digitalization is emerging as a crucial tool for restructuring factor resources, reshaping the economic landscape, and altering competitiveness. However, there is no literature on the impact and mechanism of digitalization on environmental pollution management. Thus, this study measured the level of digital development in each province using principal component analysis based on panel data of 30 Chinese provinces during 2006–2019. On this basis, the impact of digitalization on haze and its mechanisms were explored using regression models and mediating effect models, respectively. The findings demonstrate that (1) haze pollution may be reduced through digital progresses, and there is an inverse U-shaped non-linear link between them, that is, as digital technology is refined, its impact on haze pollution shifts from facilitation to suppression; (2) digital development can reduce haze pollution by promoting technological innovation and improving the efficiency of environmental management; and (3) there is regional heterogeneity in the influence of digitalization on air pollution. In heavily polluted areas, the suppression effect of digital technology on air pollution is more than three times that of other areas. The goal of this study is to investigate how digitalization affects haze pollution and its mechanisms, as well as to offer some scientific guidance for China’s efforts to build a “Digital China” under the banner of digitalization.

Urban building extraction based on information fusion-oriented deep encoder-decoder network in remote sensing imagery

The building extraction technology in remote sensing imagery has been a research hotspot. Building extraction in remote sensing imagery plays an important role in land planning, disaster assessment, digital city construction, etc. Although many scholars have explored many methods, it is difficult to realize high-precision automatic extraction due to the problems in high-resolution remote sensing images, such as the same object with different spectrum, the same spectrum with different object, noise shadow and ground object occlusion. Therefore, this paper proposes an urban building extraction based on information fusion-oriented deep encoder-decoder network. First, the deep encoder-decoder network is adopted to extract the shallow semantic features of building objects. Second, a polynomial kernel is used to describe the middle feature map of deep network to improve the identification ability for fuzzy features. Third, the shallow features and high-order features are fused and sent to the end of the encoder-decoder network to obtain the building segmentation results. Finally, we conduct abundant experiments on public data sets, the recall rate, accuracy rate, and F1-Score are greatly improved. The overall F1-score increases by about 4%. Compared with other state-of-the-art building extraction network structures, the proposed network is better to segment the building target from the background.

Digitalization and carbon emissions: How does digital city construction affect china's carbon emission reduction?

The rise and vigorous development of digital technology and digital economy provide huge potential for carbon emission reduction globally and in China. However, the current research on digital technology and carbon emissions is still in its infancy, and there is a lack of empirical conclusions between the two. Therefore, this paper investigates the impact of digital city construction on carbon emissions in China and its transmission mechanism using the panel regression models and mediating effects models, respectively. In particular, this paper constructs a measurement system for the level of digital city construction in China from four dimensions: digital infrastructure, digital economy, digital industry, and digital application. Then, the relationship between urban digital development and carbon emission reduction in China was investigated. The results show that: firstly, regional digital development significantly reduces carbon emission intensity, and the impact on total carbon emission shows an inverted "U" curve relationship of increasing and then decreasing. Second, digital development affects carbon emissions through three paths: technological innovation, industrial structure and energy structure. Third, the heterogeneity analysis shows that the impact of digitalization is more significant in the central and western regions than in the eastern regions, which highlights the late-development advantage of these regions in terms of carbon neutrality and carbon peaking targets. Based on the above conclusions, specific policy recommendations are proposed for region development in the future.

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.

Application of Urban Planning Surveying and Mapping in Digital City Construction

Application of Urban Planning Surveying and Mapping in Digital City Construction

A fine construction method of urban road DEM considering road morphological characteristics

Urban road DEM is not only an important basic geographic information data of the city, but also an important element to describe and express the urban topography, and it is an indispensable part of the construction of the smart digital city, urban planning and urban surface process simulation. Previous methods for constructing urban road DEMs do not sufficiently consider the actual morphological characteristics of urban roads, and morphological distortion is evident in the expression of urban roads, seriously affecting the application of urban rainfall flood simulation and urban pipe network design. In response to these problems, this study proposed a considering morphological characteristics fine (CMCF) method of urban road DEM construction, selected a typical urban road area in the Jianye District of Nanjing City in China as the study area, used the 1:500 digital line graphic as data source, hierarchized roads in accordance with different morphological characteristics from the perspective of DEM construction, constructed the corresponding DEMs, and finally merged all levels of road DEMs to produce a complete high-precision urban road DEM. Results showed that the DEM constructed using the CMCF method not only exhibited higher elevation accuracy than the urban road DEM constructed using previous methods, i.e., inverse distance weighting (IDW) and triangulated irregular network (TIN) methods, with a mean error and a root-mean-square error of 0.015 and 0.060, respectively, but it can also accurately express the spatial element composition form and road morphological characteristics of urban roads, avoiding the distorted expression of road morphological characteristics. This study can provide a reference for a new DEM construction method and data support for smart digital city construction and urban surface simulation.

Rendering and Optimization Algorithm of Digital City’s 3D Artistic Landscape Based on Virtual Reality

“Digital city” in a broad sense refers to urban informatization. That is to say, the digital city will gradually realize the informatization of the urban national economy and society by building infrastructure platforms such as broadband multimedia information network and geographic information system, integrating urban information resources, establishing e-government, e-commerce, labor, social insurance, and other information communities, to make the city in an invincible position in the competition of the information age. The virtual reality technology of urban three-dimensional landscape, or the establishment of a virtual city, is an important part of the vast project of digital city construction. This research mainly discusses the rendering and optimization algorithm of digital city 3D artistic landscape based on virtual reality. The article uses image stitching technology. Clean up unnecessary furniture in the CAD floor plan, and try to keep only the wall structure. Export drawings and save as dwg files for 3DMAX modeling. For adjacent overlapping images, the common features of the overlapping parts are determined by image matching, so that the images taken at different shooting positions and different viewing directions with a small angle of intersection are calculated to be unified. Take the photo coordinate system, and then find out the overlapping range of each direction for splicing. In the actual data acquisition process, most of the spatial data such as existing maps are used. It mainly includes topographic maps and the latest planning drawings, as well as planning and design drawings of various residential areas. In addition to determining the specific location of each feature, various maps are used to make a surface image (texture) of an urban area based on these data using Photoshop. The editing of roaming space is the key to realizing 3D panoramic virtual city browsing. Combined with the navigation of 3D panoramic map, using key technologies such as hotspot connection and command button, the 3D panoramic images collected in different places in the city can be effectively integrated into one, assisting with various multimedia elements, such as background music, animated videos, and language commentary, show the true appearance of the virtual city in all directions. Compared with the SURF algorithm, the SIFT algorithm extracts more feature points and more correctly matched point pairs, and the minimum time is 0.524 s. This research will contribute to the construction of the three-dimensional landscape of the digital city.

Building Image Feature Extraction Using Data Mining Technology.

At present, data mining technology is continuously researched in science and application. With the rapid development of remote sensing satellite industry, especially the launch of remote sensing satellites with high-resolution sensors, the amount of information obtained from remote sensing images has increased dramatically, which has largely promoted the application of remote sensing data in various industries. This technique mines useable information from less complete and accurate data while ensuring low program complexity. In order to determine the impact of data mining techniques on feature extraction of graphic images, this paper explores the relevant steps in the image recognition process, especially the image preenhancement and image extraction processes. This paper develops a preliminary set of relevant data and investigates two different extraction methods based on the availability or absence of nursing information. Aiming at the advantages and disadvantages of the two house extraction methods, this work discusses how to effectively integrate remote sensing data. It uses different data sources to describe different characteristics of buildings, analyzes and extracts effective information, and finally derives building information. The research results show that, using the SVM algorithm in data mining for image feature extraction, in the verified filtering window, the accuracy can be effectively improved by about 20%. Buildings are important objects in high-resolution remote sensing images, and their feature extraction and recognition technology is of great significance in many fields such as digital city construction, urban planning, and military reconnaissance.

Research on digital urban architecture design based on cloud computing data center

Abstract With the acceleration of China’s urbanization process, the scale of cities continues to expand, and urban management issues are becoming increasingly prominent. This research takes the application of digital urban management integration as an example, designs the digital urban management subsystem, combines the design of the system framework, data layer, and integrated public platform layer, and analyzes the data function process of the digital urban management subsystem. Digital cities, as proven by practice, can effectively solve many problems of urban management. The continuous breakthrough of cloud computing has laid a solid foundation for the development of digital cities. The purpose of this article is to study the construction of digital cities based on cloud computing data centers. This article outlines the basic concepts of digital cities, studies related technologies of cloud computing, and introduces related technologies of data transfer in digital cities. Based on the background of digital city construction, a digital city system framework based on cloud computing data center is proposed. Based on the system framework, a digital urban management integrated application system is designed. The test proves that the integrated system can meet the performance requirements of daily business processing. In this paper, the average transaction response time is less than 5 s and the application server utilization is less than 80% as evaluation indicators. By testing the performance of the system, the average response time is 0.436 s and the average CPU utilization is 58.25%

Application of New Surveying and Mapping Technology in the Construction of Smart City

With the rapid development of information technology, the rapid advancement of urbanization and the rapid expansion of urban scale, higher requirements have been put forward for the development of the city, which promotes the continuous acceleration of the urban process, and the construction of smart city has become an inevitable development trend. Smart city is the combination of digital city and Internet of things. Digital city construction uses Remote Sensing, Global Navigation Satellite System, Geographic Information System, Engineering Survey and other Mapping Technology. Therefore, in the construction of smart city, the most indispensable is modern information technology and surveying and mapping technology. Through the analysis of the application of new surveying and mapping technology in the construction of smart city, this paper shows the important role of new surveying and mapping technology in the construction of smart city.

Automated building extraction using satellite remote sensing imagery

Automatic extraction of buildings from remote sensing images plays a critical role in urban planning and digital city construction applications. In real-world applications, however, real scenes can be highly complex (e.g., various building structures and shapes, presence of obstacles, and low contrast between buildings and surrounding regions), making automatic building extraction extremely challenging. To conquer this challenge, we propose a novel method called Deep Automatic Building Extraction Network (DABE-Net). It adopts squeeze-and-excitation (SE) operations and the residual recurrent convolutional neural network (RRCNN) to construct building-blocks. Furthermore, an attention mechanism is introduced into the network to improve segmentation accuracy. Specifically, to handle small buildings, we highlight small buildings and develop a multi-scale segmentation loss function. The theoretical analysis and experimental results show that the proposed method is effective in building extraction and outperforms several peer methods on the dataset of Mapping challenge competition.

3D building fabrication with geometry and texture coordination via hybrid GAN

3D building plays the essential role in digital city construction, city augmented reality and smart urban planning & design. Conventional building construction is accomplished by modeling software which requires significant human intervention. In this paper, a method of 3D building fabrication via Hybrid generative adversarial network (GAN) is proposed, in which a loss function with the introduction of cycle consistency loss and perceptual loss is given, a multi-properties GAN chain is built to create the building with complex architectures. Additionally, a mixed GAN network to generate the geometry and texture coordination is put forward. The discussed method can refine rough architectural models for outputting realistic buildings. Experiments show that generated 3D buildings utilizing the presented method are realistic, with geometry and textural consistency, which improves performance by 20% over traditional methods.

Laser Point Cloud 3D Visual Intelligent System Based on B / S Architecture

In the mid-1990s, the ground laser scanning technology based on B / S architecture began to be widely used in modeling various complex scenes and spatial entities. The massive point cloud data based on the B / S architecture collected by this technology is an important source of information in the three-dimensional space coordinate system, and plays an important role in marine survey, geographic information system, and digital city construction. To this end, how to use the existing computer processing capabilities to efficiently organize and index massive point cloud data and more quickly and accurately complete the three-dimensional visualization modeling of point cloud data has become an important research topic. This paper proposes a "Hilbert-Improved Quadtree" structure to organize point cloud data. In this structure, the node order of the improved quadtree is changed, so that the node order obtained by traversing the quadtree in the middle order completely conforms to the characteristics of the Hilbert curve. Reorganizing the point cloud data based on the B / S architecture in this order can effectively reduce the number of I / O interactions performed by the computer when reading massive point cloud data based on the B / S architecture, and improve the spatial index efficiency of the point cloud data; At the same time, the Hilbert curve is used to reorganize the quadtree to convert single-resolution data into multi-resolution data. At the end of this paper, how to use existing computer resources to more efficiently process massive point cloud data based on B / S architecture Outlook.

Geographic Visualizing Some Municipal Data of Chengguan District

Optimizing information management play an important role in safeguarding administrative functions for city government. Meanwhile, integrating service data with fundamental geographic data is an important way to construct digital city. This article focuses on the geographic visualizing methods of several important municipal data, which improve the operable of digital city construction. KeywordsDigital City; Smart City; Geographic Information System; Geographic Visualizing; Municipal Data Processing

The Developing of Query and Analysis System for 3D Digital City

With the maturity of 2D GIS technology, and the development of 3D GIS and digital city, Not only can it browse roaming system, but it is more important in spatial analysis ability. The development of digital city technology for urban planning provides an effective way, with the 3D visualization technology, virtual reality technology and the applied 3D GIS spatial analysis function of 3D digital city construction. The development of the digital city faces the opportunity in this paper under the background of this 3D digital city is put forward the development and implementation of query analysis system.

Research on the Digital City Geospatial Framework Construction

With the development of urbanization process, the city scale has become more extended. The traditional city manage method can not meet the request of the modern city management. As the "digital China" stratagem advanced, "Digital City" appeared. The" Digital City " as a symbol of the city informatization construction is quickly developing. The network infrastructure and spatial information infrastructure both are the most important infrastructure in the digital city construction, and the geo-spatial framework is an important composition part of the spatial information infrastructure and the foundation supporting platform of the economic society informatization development. The paper explores the process of construction digital city geospatial framework.