IFC to CityGML Transformation Framework for Geo-Analysis: A Water Utility Network Case

The development of semantic 3D city models has allowed for new approaches to town planning and urban management (Benner et al. 2005) such as emergency and catastrophe planning, checking building developments, and utility networks. Utility networks inside buildings are composed of pipes and cables located between ceilings and walls (examples of these systems include sewerage, electrical, gas, water). The traditional representations of these networks are in 2D, and are associated with different drawbacks, such as the overlapping of lines representing different networks, and different vertical elements (which can be represented only as points) can be missing (Du and Zlatanova 2006). Moreover, topological analyses are not possible by using this 2D geometric representation. Therefore, interest in 3D representation of such infrastructures is rapidly increasing. The purpose of incorporating utility networks into GIS is for modelling them topologically rather than geometrically. Geospatial analysis of such utility network systems requires the path and point connections of the elements, instead of their geometry. On the other hand, the CAD/BIM systems offer a rich 3D geometrical representation. Developing a system that supports both CAD/BIM and GIS capabilities is still not feasible, and thus the best approach to concentrate on is CAD/BIM-GIS interoperability at the data level (Wu and Hsieh 2008). Detailed geometric information about utilities infrastructure can be obtained from design and real-world 3D CAD/BIM models, which could be automatically exchanged if a formal framework, would be made available. In this paper, we investigate the possibility of integrating the 3D BIM utilities network data into a GIS based on user cases defined for water utilities maintenance operations and management. CityGML has been employed in this study as a base model to provide an integrated ontology covering the BIM and GIS model concept within one framework. The work includes developing a software component for automatic conversion from IFC into CityGML, and analysing network elements in an already developed system that supports utilities analysis functions