Research On BIM Model Similarity Calculation Method And Application

In recent years,with the in-depth application of informatization in the construction industry,the application of BIM technology in the construction industry has become more and more extensive,and the number of BIM models has also increased.There is an increasing demand for rapid acquisition of similar models.Whether it is an online website or platform in the BIM field that provides downloading models or a practitioner’s own model library,people can only obtain the models that best meet the needs of the business through manual search methods,preliminary screening through the names,time of establishment and other information.Open one by one for manual reading,this method requires a lot of time and manpower.As an important information carrier,the BIM model can include all the data of the entire life cycle of the building from planning and design to construction operation and maintenance,and this information can be extracted and used to provide a basis for the similarity calculation of the BIM model.This paper combines building information model,graph theory and Internet three-dimensional display technology.Based on the structure of the model,a similarity calculation method of BIM model based on components and the connection relationship between components is studied and its application method is shown.The following research results have been achieved:(1)Construct the BIM model as a graph model.The BIM model contains a lot of information,and it is difficult to directly calculate the similarity,so it is constructed as a graph model,and the similarity of the BIM model is calculated by calculating the graph model similarity.By analyzing the information description and association mechanism of Industry Foundation Class(IFC),the semantic information and geometric information of the components are extracted,and then used as a data source to establish OBB bounding box / OBB bounding box hierarchy tree for each component,use the improved collision detection algorithm to obtain connected components,and then use the component as the vertex of the graph model,and the connection relationship between the components as the edge of the graph model,the BIM model is constructed as a graph model.(2)A heuristic graph similarity calculation method.In order to consider the influence of the labels on the adjacency graph on the similarity,the graph editing distance algorithm is used in this paper to calculate the graph similarity,but this is an NP-hard problem and has higher requirements on the computer.In order to reduce the time complexity and space complexity in the calculation process,a heuristic search algorithm(beam-stack search algorithm)is selected to establish the mapping,the depth-first traversal is used to determine the vertex sequence,and the beam width B is specified.Estimating total editing cost,cutting out nodes with higher total editing cost,limiting the number of mapping nodes in each layer,greatly reduce the time complexity and space complexity.(3)Based on the research of HTML5 / WebGL three-dimensional display technology,the application of BIM model similarity calculation method is studied,and a "one-click" system for obtaining similar models is established.Similar models can be quickly obtained and the models can be quickly viewed in this system.The system shows that the component-based BIM model similarity calculation method has certain reference and application value to meet the needs of practitioners to obtain similar models.