Research On Instantiation And Hierarchical Clustering Methods For Efficient Rendering Of Complex BIM Components

Model of a building pipe network(Hereinafter referred to as the "pipe network model")is an important data support for the visualisation of information inside buildings in the "smart city".A hierarchical clustering method for pipe network component instance models is proposed to address key visualisation issues such as inefficient organisation and scheduling of pipe network model data and poor visual consistency.The method firstly incorporates the model organisation and geometric similarity of the building components to generate example groupings,secondly performs spatial division and hierarchical clustering based on the spatial structural characteristics of the component example models,and finally combines instantiation techniques to batch render the pipe network models.The main points of this article include:(1)The research background and significance of this paper are introduced,and the relevant research and development trend of BIM and GIS integration application,3D city model visualization and spatial object extraction are summarized.At the same time,the current 3D city models and their drawing acceleration techniques are compared.By analysing the characteristics of BIM models and the shortcomings of traditional drawing acceleration techniques in the real-time drawing of pipe network component models,a hierarchical clustering method for pipe network component instance models is proposed.(2)The BIM model organisation method based on the hierarchy of building elements lacks the consideration of geometric similarity.This paper groups a large number of component models into instances based on model three-view similarity and BIM model organisation by removing the influence of rigid body transformations from the pipe network component models.(3)Traditional spatial indexing is used to reduce the number of rendered scene models through spatial subdivision.In the face of highly clustered and complex spatial structure of BIM models,it is difficult to meet the drawing requirements through traditional spatial indexing alone.Therefore,this paper adopts a spatial segmentation management organization method for the spatial distribution of instance models,classifying them into different clusters and managing them hierarchically.In order to verify the effectiveness of the hierarchical clustering method for component instance models,a 12-storey BIM pipe network model(including the underground layer)is selected for visualisation experiments.The experimental results show that the hierarchical clustering of instance-oriented models can effectively improve the visualisation effect of the pipe network component models,and the average frame rate of the optimised BIM pipe network model rendering is about 50 fps,with the lowest frame rate stable at about 30 fps,which can better ensure the visualisation effect of the massive pipe network models.