OSG Real-time Rendering Large-scale Architectural Models

With the development of the Internet and the popularity of computers,building information is more and more important in the construction industry’s future projects.Building information contains many information,such as design data,construction data,building data.Building Information Modeling(BIM)is an engineering data model which integrates all the relevant information in the construction lifecycle.In most of the current system,the effect of large-scale BIM model rendering is often unsatisfied,so real-time rendering large-scale BIM model on the computer is very significant.According to the characteristics of BIM building model,the content of the paper mainly focuses on two parts: the first part is the data processing and the second part is the model rendering.In the data processing stage,the geometric data and attribute data are extracted from IFC data,then the geometric data are preprocessed to remove the redundant data and reorganize the geometric data.And then the model is divided and regenerated by using the octree algorithm.In the model rendering stage,our system uses the project model hierarchical tree structure to manage the loading state of multi-model files,and the model file can dynamically loaded and unloaded in conjunction with paging loading technology.By this way,our system realize real-time rendering of large-scale building model.This paper develops and implements a system for rendering large-scale building models based on the OpenSceneGraph open source graphics rendering engine.Our system mainly consists of two main parts,the first part is the data conversion part which has three modules,namely the Parser module,Transformer module and Serializer module.This part is mainly to convert the IFC file to a custom model file.The second is the rendering part which has four modules,namely the Project Level Tree module,Deserializer module,Renderer module and Business Function module.This part is mainly responsible for rendering the BIM model and provides various functions to solve practical problems,such as model operation,scene roaming,distance measurement and so on.Finally,the paper uses the BIM model which is provided by professional BIM Design Company to demonstrate the effect and performance of this system,and compare it with other system.