Multi-scale Geometric-semantic Modeling And Visualization Of Drainage Network

Urban drainage network has dual functions of protecting environment and reducing disaster in cities.Whether its management is perfect or not will affect urban production,life and ecological environment.With the proposal of “digital twin” and “new infrastructure”,the construction and management of "digital city" have higher requirements.The multi-dimensional visual management and construction of underground space facilities,including drainage network,have been put on the agenda.Like other real world entities closely related to human life,people need to observe and recognize drainage network from multiple scales and different perspectives in many aspects such as planning,construction and management.According to the different business needs of the drainage network,how to construct the multi-scale model of the drainage network and realize the multi-scale visual management and planning and construction of the drainage network has become an urgent problem to be solved.Therefore,according to the different business requirements of the drainage network,this paper researches the multi-scale geometric-semantic coherent representation method of the drainage network,and puts forward the multi-scale geometric-semantic model of the drainage network containing “source-network-plant-sink”.The model realizes the multi-scale visual representation of the drainage network,and can meet the needs of users at different levels,so it has certain research significance.The research work on multi-scale geometric semantic modeling and visualization of drainage network in this paper mainly includes the following aspects:(1)The components of the drainage network including the whole drainage process of“source-network-plant-sink” and their relationship are systematically analyzed,and the semantic description of the components of the drainage network and their relationship is carried out in detail by using UML class diagram.(2)Based on the multi-scale representation of CityGML(City Geography Markup Language)and the different business requirements of the drainage network,the Levels of Detail(LODs)model of the drainage network is designed,and the semantic information and geometric information of the models of the drainage networks at different LODs are defined.(3)According to the contents represented by the models of the drainage networks at different LODs and the characteristics of different components of the drainage network,a set of methods of multi-scale modeling of the complete components of the drainage network involving “source-network-plant-sink” are established.Implicit representation is carried out for a large number of the drainage network components with similar fixed structures,and the model symbol libraries of these components at different LODs are established by multi-scale symbolic modeling method.The large and complex components of the drainage network that are difficult to be represented by model symbols are explicitly represented,and the three-dimensional models of these components at different LODs are constructed by using multi-software hybrid modeling methods such as two-dimensional vector stretching,3ds Max modeling and Revit BIM modeling.(4)In view of the discrete models with different data formats of the components of the drainage network,the method of the integrated visualization is discussed.Taking the drainage network data of a certain region as an example,the models of the components of drainage network at different LODs are integrated to construct the drainage network scenes involving the whole drainage process of “source-network-plant-sink” at different LODs.Aiming at the discrete scenes of the drainage networks at different LODs,a coherent visualization method of the multi-scale scene based on range of visibility is proposed to realize the coherent visual representation of the discrete scenes of the drainage networks at different LODs.At the same time,some application analyses are carried out on the scenes of drainage networks at different LODs to verify the effectiveness of the proposed method and the practicability of the established model in this paper.