Storage And Display Of BIM In Ancient Building

It is an important form of cultural relic protection to store the ancient buildings in the form of digital scanning,which has important guiding significance for the research of ancient buildings.The construction of BIM of ancient buildings effectively promotes the realization of ancient building digitization,and is conducive to the visualization analysis,dynamic simulation and collaborative decision-making of ancient building protection.But no matter in which terminal,it is a time-consuming and memory-consuming operation to display a massive original BIM,and the amount of data captured by the digital scanner is huge,with various models of ancient building,more than the model itself,the amount of data of the related documents of the model such as text,video,etc.will also continue to increase,so it's important to preprocess the original BIM,and to effectively store the huge amount of different types of data.Based on an ancient building as an example,this paper analysis the subdivision method of BIM and build different LOD levels,to preprocess the BIM,and use MongoDB to storage the preprocessed data of BIM,the tilt photography 3D model data of the ancient building obtained by tilt photography and other text,video data,and display different models under different camera distance and model text,video data on the desktop.The main contents of this paper:(1)By preprocess operations of the BIM,that is grouped the eleven kinds of components that make up the entire BIM,after octree subdivision of the members in each group,use different compression methods to storage mode,saving the storage space,and encodes the sub-block after subdivision,facilitate derived the model section level and son node's position in the parent node according to the coding,improve the retrieval speed of model,and for the subdivision model,use QEM 3D grid simplification algorithm to generate LOD level models,and analyze the file structure after pretreatment;(2)Analyze the MongoDB storage mode and the way to express the relationship between different sets and documents.Combine with the file structure after preprocessing the BIM,store the BIM of ancient buildings,oblique photography 3D model,descriptive files of ancient buildings and video files,and complete the conceptual design,logical design and physical design of MongoDB;(3)Design data access interfaces for the built MongoDB,including the database access interface,two kinds of model data access interface,ancient building's text and video data access interface,in order to obtain the model and the related data from the database,and through the data display interface in combination with OpenGL interface display different models,text and video information about ancient architecture model on the desktop.