Design And Implementation Of BIM Lightweight Management Platform Based On Cesium Framework

With the continuous improvement of China’s informatization and industrialization system,the construction industry informatization has reached a new stage of development.BIM technology has produced great benefits in the actual engineering field because of its visualization,parameterization,coordination,simulation and other characteristics.However,as BIM data types become richer and richer,the model volume becomes larger and larger,resulting in the IFC file which was applied in the field of BIM data exchange in the past is difficult to meet the actual needs of today’s engineering due to its huge data system.There are many professions involved in the whole life cycle of a project,and the traditional single BIM software cannot effectively integrate the engineering data information of various professions,classes and departments.The resulting "data silos" problem is becoming more and more prominent,which becomes a shackle for the in-depth and coordinated development of BIM technology and other interdisciplinary disciplines.How to make full use of BIM data information,break the barrier of data sharing between different BIM software,find the way of information transfer between different professions,and effectively integrate with external data information has become an urgent problem to be solved.The rise of WebGL technology,Web-based mobile applications,and Internet of Things technology has created conditions for solving the above problems and provided a new way of thinking.This paper explores the application of Cesium visualization technology and WebGL graphics engine to the field of BIM technology,by developing a BIM lightweight management platform based on Cesium framework,realizing fast loading of large volume BIM models on the Web side,and integrating external engineering data and sensor data into the platform for information sharing.For this purpose,this paper specifically investigates the following work:(1)Based on the data structure of IFC files,the relationship between IFC and glTF and3 D Tiles data formats with lightweight characteristics is studied.Through secondary development of Revit in C# language and a series of open source tools,the conversion of Revit models to glTF and 3D Tiles data formats is completed.(2)Analyze the performance of glTF and 3D Tiles files when loaded under the Cesium graphics engine,and further improve the performance of loading BIM models on the Web based on the octree algorithm.Using model structure trees to optimize spatial loading strategies to achieve manual hierarchical scheduling,reducing the dependency of BIM visualization on hardware device configurations to meet the use of different devices and scenarios.(3)The transformation relationship between different coordinate systems in different formats of BIM models is studied,and the position and attitude of the model are kept consistent through matrix transformation.(4)Analyze the shortcomings of the C/S architecture system,and develop a B/S architecture BIM lightweight management platform based on the above research.Discuss the key points of BIM data integration and platform design solutions,and integrate BIM model geometric information,semantic data,externally imported engineering data,and sensor data through the platform.On this basis,complete the design and development of functional modules.Finally,a project case model is applied to a complete set of technical frameworks and research results formed in this article,and the visualization performance and functional modules of the BIM platform are tested.The results show that the platform has good smoothness and stability when loading the model.The platform designed and developed has certain scalability and foresight on the premise of meeting the scientific and practical requirements.It can continue to enrich the platform’s functions in the future and provide theoretical support for future smart city research.