Research On Building Semantic Model Transformation Based On Integration Of BIM And GIS

The realization of indoor and outdoor integrated technology for modern urban models of buildings has always been the core of promoting smart city construction.Conventional mapping methods can only obtain the geometric contour of the building,ignoring the semantic and topological relationship of the model,and can only be used for 3D visualization,which cannot meet the requirements of deep application technologies such as spatial data mining and topic query In addition,these models do not have access to indoor information about buildings,especially indoor components such as furniture.However,with the development of digital cities,the construction and management of modern cities are gradually becoming more precise and refined,and the demand for space informationization of 3D models of buildings is more urgent.The Building Information Model(BIM)refines the three-dimensional model with rich semantic information and describes the information inside the building very finely.The digital three-dimensional model built by the Three-Dimensional Geographic Information System(3DGIS)technology is extremely scarce compared to outdoor information,and cannot be applied to urban disaster emergency response and indoor navigation applications.Therefore,the BIM model's accurate information can be used as an important data source for GIS.This paper analyzes the general data standards of the BIM field,the Industry Foundation Classes(IFC)and the general data standard in the field of GIS.City Geography Markup Language(CityGML)The geometric and semantic differences,as well as the characteristics of the indoor information model,design and implement a method to transform from the IFC model to the semantically rich CityGML LOD4 model.Since the IFC model is richer in semantics than the CityGML model,there is a problem of semantic information asymmetry between the two,and the problem of semantic information loss exists directly from the IFC model to the standard CityGML model.Therefore,this paper combines the complex features of building components of IFC model,and uses the ADE mechanism of CityGML to extend the three-dimensional semantic model of buildings to form an information model of multi-scale semantic expression of buildings based on CityGML extension.Extract the rich semantic information in the IFC model into the extended CityGML model.The building model based on IFC standard is integrated into the GIS system for unified management.Firstly,To establish the semantic mapping relationship between IFC and CityGML,the IFC model is semantically filtered based on the semantic mapping relationship.Secondly,focus on the geometric expression difference between the IFC standard and the CityGML standard,a geometric reconstruction algorithm is proposed.The geometric information of the IFC model is reconstructed into the geometric information conforming to the CityGML standard,and finally the CityGML model with correct geometry and semantics is obtained.Based on the proposed method,we design a custom CityGML extension model that meets the requirements of this paper.This extended CityGML model can integrate the rich semantics of the IFC model into CityGML.Finally,through the design experiment and test analysis,the results show that the transformation method of this paper can automatically convert the IFC model into a geometrically correct and semantically rich CityGML model.And by comparing with the commonly used conversion methods,the effectiveness of the conversion method is obtained.Therefore,the method of this paper can provide strong support for the integration of BIM and GIS.