Enhancing the ifcOWL ontology with an alternative representation for geometric data

Over the past few years, several suggestions have been made of how to convert an EXPRESS schema into an OWL ontology. The conversion from EXPRESS to OWL is of particular use to the architectural design and construction industry, because one of the key data models in this domain, namely the Industry Foundation Classes (IFC), is represented using the EXPRESS information modelling language. These conversion efforts have by now resulted in a recommended ifcOWL ontology that stays semantically close to the EXPRESS schema. Two major improvements could be made in addition to this ifcOWL basis. First, the ontology could be split into diverse modules, making it easier to use subsets of the entire ontology. Second, geometric aggregated data (e.g. lists of coordinates) could be serialised into alternative, less complex semantic structures. The purpose of both improvements is to make ifcOWL data smaller in size and complexity. In this article, we focus entirely on the second topic, namely the optimization of geometric data in the semantic representation. We outline and discuss the diverse available options in optimizing the data representations used. We quantify the impact of these measures on the ifcOWL ontology and instance model size. We conclude with an explicit recommendation and give an indication of how this recommendation might be implemented in combination with the already available ifcOWL ontology.