Transformation of Underground Space Models Based on IFC and CityGML—A Case Study of Utility Tunnel

The similarities and differences between industry foundation classes (IFC) and city geography markup Language (CityGML) are analyzed in terms of geometric expression and semantic information. A transformation method between IFC and CityGML for utility tunnel is established including semantic extraction, geometry and coordinate system transformation. Then the transformation experiment of utility tunnel in Liupanshui city is carried out and the results show that the mapping rules of the IFC utility tunnel model and the CityGML utility tunnel model can realize the transformation of the IFC utility tunnel model to the CityGML model, at the same time, the converted CityGML utility tunnel model contains the property information extracted by the IFC model, which can be used for the integration of three dimension geographical information system (3DGIS) and building information modeling (BIM), it helps to promote the life cycle management of urban underground utility tunnels.