EXTRACTION AND TRANSFORMATION OF IFC DATA TO CITYGML FORMAT
The integration of Geographic Information System (GIS) and the Building Information Modeling (BIM) referred to as the merging of the two systems for the purpose of data interoperability. The need to share information between the two systems is what motivated the integration process purposely for geospatial analysis. This can be achieved through their data exchange formats such as; City Markup Language (CityGML) and Industry Foundation Classes (IFC). The formats are the two most prominent key schemas of GIS and BIM systems respectively. The integration is a step towards information exchange or sharing (data interoperability) between the two systems. The selection of the two most prominent data exchange formats is as a result of their widespread applications in the GIS and BIM domains. However, the differences in geometric and the semantics information hinders data interoperability (information sharing) between GIS and BIM. Also, coupled with the difference in schema structure and the level of information richness between IFC and CityGML. This paper, propose a geometry transformation process that can be used to extract and transform IFC building objects to that of CityGML building objects to enable 3D model design and constructed using BIM tool to be easily reused in 3D GIS applications which will be able to support the CityGML model format. Where the geometric information will be extracted using the IFC tree-structure (hierarchy) and transformed to destination CityGML.