Research On Lightweight Display Application Of BIM Model Based On WebGL

With the rapid development of information technology,the construction industry continues to integrate with emerging technologies.BIM(Building Information Modeling)has risen rapidly in recent years,and my country’s "14th Five-Year Plan" requires the promotion of BIM technology in construction.Field development.As an emerging technological concept,BIM’s intrinsic essence is the digital and informatized expression of the physical and functional characteristics of construction projects and their facilities,providing shared information resources throughout the life cycle of the project.BIM technology is based on the digital model of the engineering project and incorporates all the relevant information of the project,which can realize the integration and sharing of information between the various stages of the engineering project and the participants.At present,the collaboration of various construction software in different project phases is becoming more and more close,and the types of data formats generated are also increasing.Different data formats can easily form information islands.Moreover,most of the current BIM servers are C/S architecture,and there are problems with computer hardware.Problems such as high configuration requirements and poor cross-platform performance hinder the popularization and application of BIM technology.WebGL technology is becoming more mature,compatible with multi-terminal browsers such as PCs,Pads,and mobile phones,and has good portability and cross-platform.It provides support for the three-dimensional visualization of BIM models on the Web.This paper takes the lightweight cross-platform display of the BIM model as the goal,combined with the secondary development of Revit and the WebGL 3D visualization technology,and proposes a method of displaying the Revit 3D model on the web side.The main contents are as follows:(1)Revit 3D model lightweight data structure and interface establishment.Use the IFC interface provided by the Revit SDK package to convert the Revit model into an IFC file,study the data structure and information storage method of the model,and determine to store the geometric information and attribute information of the Revit 3D model in an XML format file,and carry out the secondary development of Revit.Realize the export of Revit model data,and establish the Revit-XML data interface to prepare for the reconstruction of the web-side model.(2)Revit 3D model web page reconstruction and lightweight display.Research on the current mainstream WebGL open source framework,determine to use Three.js as the rendering framework of this application,use Java Script language to parse the XML file storing model information,and generate it in the browser by reading the point coordinates and index of the model Triangular facets,combined with WebGL technology and Three.js engine,realize the lightweight display of local 3D models on cross-platforms.(3)Three-dimensional model interaction on the web side.The web-side model cannot directly display attribute information,and requires three-dimensional interactive operations.The three-dimensional interaction of the model is realized by adding mouse click events and button control events on the web side,and adding the ray intersection event to highlight the clicked component model and display the attribute information of the component at the same time to realize the information query function of the web-side model.(4)Rendering optimization of Revit 3D model.Aiming at the problem of slow response speed on the web side of large-scale models,this paper uses WebGL technology and LOD mesh simplification algorithm to model the 3D model hierarchically,and display it on the web side to realize different viewing angles and different fields of view.The function of,to a certain extent,can improve the response speed of web pages,improve rendering effects,and improve user experience.Based on the above theoretical basis,this article uses engineering examples to test various technical indicators of the web page,which verifies that the system has the advantages of crossplatform,lightweight and other advantages,indicating that it has a certain innovative significance and practical value.