3D Urban Landscape Measurement Based On Multi-source Data Fusion And Its Impact On Urban Vitality

With the rapid development of urbanization,the scale of urban population and construction volume continue to grow,the agglomeration of urban space makes the production factors concentrated,the city becomes more and more crowded,the land available for development and construction is less and less,and the built-up area is disorderly.Problems such as sprawl and expansion,loss of cultivated land,traffic congestion,and environmental pollution have gradually attracted the attention of urban residents.The transformation of urban development from "flat" to "three-dimensional" has become a historical necessity.The space formed by the urban landscape is an important place to carry and gather urban elements,and its ideal spatial form and perception are closely related to the rich urban activities.With the continuous development of urban three-dimensionalization,the influence mechanism of urban landscape on urban vitality has undergone significant changes.Facing the high-density and high-volume-ratio 3D city in the future,how to build an ecologically-prioritized,dynamic and livable city has become a proposition of the times in the field of urban construction.Taking urban landscape research as the premise of realizing high-quality and green development of cities not only helps to build a modern society in which man and nature coexist in harmony,but also achieves the goal of urban vitality and livability.At the same time,with the rapid development of multi-source urban data analysis technology,how to carry out 3D urban landscape research scientifically,objectively and accurately,clarify the nonlinear relationship between urban landscape and urban vitality,and respond to the current needs of urban vitality and livable development.The problems existing in the process of urban landscape planning and construction have become the opportunities and challenges faced by the current urban construction and management field.At present,academia has made abundant research results in the research on the morphological representation of urban landscape,measurement calculation,and analysis of the relationship with urban vitality,but the research on urban landscape is often carried out in two-dimensional plane,through three-dimensional vertical perspective.There is little discussion on the measurement of 3D urban landscape development and its relationship with urban vitality,which is embodied in:First,the previous landscape index measurements based on two-dimensional planes lacked rigor.Since the traditional two-dimensional space is used as the projection of the topography of the three-dimensional terrain surface,the landscape pattern obtained based on the two-dimensional plane measurement and calculation is the plane information after the compression of the three-dimensional urban landscape,so it is impossible to truly describe the continuous fluctuation characteristics of the threedimensional urban landscape form in space.Most studies did not quantitatively measure the landscape index from the perspective of the vertical dimension,resulting in the lack of landscape information in the vertical dimension,and it was impossible to analyze the spatial characteristics of urban landscape in three-dimensional urban space.Second,previous landscape indices based on subjective data lacked reliability.Due to individual perceptions of urban landscapes,the previous subjective questionnaire survey methods based on perceptions of urban landscapes lacked the ability to specifically describe the visual perception quality and spatial perception level of landscapes.At the same time,the weights obtained by previous researchers based on subjective judgments of two-dimensional planes further weakened the spatial heterogeneity of feature sets under different terrain gradients in the vertical dimension,resulting in the lack of reliability of previous landscape indices based on subjective questionnaire interview data.Third,the previous analysis methods based on influencing factors and linear causality lack universality.The analysis methods used in most studies are limited to the coefficient value and significance analysis based on linear regression,and the discussion of nonlinear and non-causal relationships in real urban problems is lacking,and the interaction between features and features is insufficient.This leads to a gap in the research on the interaction between topographic features and landscape indices and their relationship with urban vitality.Case studies based on linear causal inference have different conclusions on the impact of different topographic features on urban vitality,and the research results are universal.Weak and limited comparability.In view of this,this paper applies multi-source urban data to the field of 3D urban landscape research,conducts in-depth research on 3D urban landscape and its relationship with urban vitality from the perspective of multi-spatial scale measurement and multi-dimensional evaluation,and provides a system for the field of 3D urban construction and management.Sexual theoretical research framework and targeted decision support.First of all,based on the existing research results,this paper defines the relevant concepts,combines the theory of compact city,landscape urbanism,landscape perception theory,reductionism and hierarchy,vitality and holism to carry out theoretical analysis,and analyzes The research results of scholars at home and abroad will be critically summarized and discussed,so as to construct a theoretical analysis framework that meets the needs of this research,and provide theoretical support for the study of 3D urban landscape measurement and its relationship with urban vitality.Then,through the typical analysis of the research area,the built-up area of Chongqing is determined as the research area of this paper,and the urban multi-source data fusion method is scientifically used to extract the urban built-up area.After selecting the research scale,a 3D urban landscape index measurement system is constructed.Secondly,this paper measures and evaluates the spatial form of 3D urban landscape through the landscape index analysis method,analyzes the difference between the three-dimensional index and the two-dimensional index from the scale of urban landscape plots,and analyzes the spatial form of 3D urban landscape from different topographic gradient perspectives.Through the analysis,the spatial differentiation characteristics of the 3D urban landscape spatial form in the study area in the vertical dimension are clarified,and the spatial differentiation characteristics of the3 D urban landscape spatial form are discussed.Thirdly,this paper proposes and applies two new 3D urban landscape perception algorithms: 3D urban landscape accessibility algorithm and 3D urban landscape visibility algorithm.The 3D urban landscape perception is measured and applied from the urban landscape architectural scale and different terrain gradients.The evaluation clarifies the spatial distribution characteristics of the 3D urban landscape perception plane dimension and the spatial differentiation characteristics of the vertical dimension in the study area.Then,by constructing a 3D urban landscape-urban vitality correlation model based on multi-source data fusion,XGBoost machine learning algorithm and SHAP value interpretation method,the nonlinear relationship between 3D urban topographic landscape and different urban vitality components is revealed through the interaction between 3D urban landscape index and topographic features.Finally,through the research on the influence of 3D city on urban vitality from multiple perspectives,this paper summarizes the characteristics of 3D urban landscape that are beneficial to the improvement of urban comprehensive vitality from different perspectives,and puts forward relevant policy suggestions for the 3D urban space governance under the guidance of urban vitality improvement.Combining the multidisciplinary theoretical foundation,this paper constructs a 3D landscape index system that fits the three-dimensional urban development,and proposes a research framework based on "3D urban landscape spatial form-3D urban landscape perception-3D urban vitality impact",which not only optimizes and enriches 3D cities Theoretical research in the field of landscape,and to a certain extent,it has also corrected and optimized the previous urban landscape research data,indices,measurement methods and models based on two-dimensional planes.It reveals the complex relationship between 3D cities,topographic features,urban landscapes and urban vitality,improves the accuracy of measurement results,expands the ideas of related urban research,and provides theoretical and decision-making support for the government to carry out 3D urban planning and construction work according to local conditions.