Research On 3D Modeling Method Of Buildings Based On CAD Data

In recent years,with the continuous breakthroughs of technologies of Computer,Virtual Simulation,Big Data,Cloud Storage and Internet,the constructions of Smart Cities in China and abroad have shown a spurt of growth.As the core organizational unit of cities,expressing architecture in a two-dimensional plane,which is the traditional way,has already can't meet the need of the integration management and analysis of the interior and exterior of a building.Scholars have studied the standard of the three-dimensional model of buildings in the field of BIM and GIS,and put forward the integrated expression of the interior and exterior of buildings based on BIM + GIS.In this paper,the building spatial information model of BIM + GIS is studied and constructing the geometric,semantic,topology and attribute information of the building spatial information model from graphic CAD data of the building is explored,from the BIM Industry open standard IFC(the Industry Foundation Classes)and geographic information Industry open standard City GML.Finally,through an example of the intelligent management system of a park,the application of the building spatial information model is verified.There are three parts that this paper can be divided into.First,the theoretical research part of building model.According to the expression of 3D models of buildings,this paper starts from the IFC of BIM industry and the City GML of geographic information industry,and contrasts the four levels of architecture from geometry,semantics,topology and attributes.The spatial information model of the building is designed from both concept and logic.The detailed building semantics and attribute information in BIM are introduced into the design of spatial information model,and used to describe the spatial composition of buildings.Meanwhile the spatial topological connectivity of geographic information is introduced into the building space information model to offset the lack of spatial topological relations,in order to achieve the description of the space and information of the building in all aspects.Second,the construction of model.According to traditional plane CAD data,this article firstly research the simplified algorithm of CAD data.Then models of the special parts of the building are constructed,and finally the construction of indoor and outdoor model of buildings is achieved by using Revit,aiming at the design of spatial information model.Third,the application of the building model.According to the 3D model of building spatial information which has been constructed,the application scene of the model is designed from BIM+GIS.By using Unity3 D engine,an intelligent management system of the park is developed,which is based on the constructed model.Through the functions virtual roaming,environment simulation,asset management,measurement analysis,construction simulation and contingency plans,the integration of indoor and outdoor building model browsing is achieved,also the space measurement of objects,query of building component,calling of monitoring information,construction schedule simulation and emergency plan display.The design of the model is verified from the application layer.