CityGML and IFC: Going further than LOD

Modeling a built environment for any construction project or asset management is usually limited to a simple 3D visualization. Data and metadata related to modeled objects are not included sufficiently in the modeling, especially for infrastructures. In addition, the needs of the construction industry are constantly changing: we mainly retain in a lot of projects, concurrent engineering, life cycle analysis and the implementation of the European Directive INSPIRE. These changes in the design and building practices require large flows of information that cannot be left to self-organization. Furthermore, the information flow from the project to the built heritage is sequenced. Following these findings, we examined the existing data models for the construction trades such as CityGML and IFC. Both of these standards provide in principle to manage design, construction and operation of a project. Firstly, this paper shows the reason for which we believe that the approach by these two standards is not sufficient to structure information in urban and infrastructure projects, considering design but also long-term operation of built structures. In addition, we discuss the fact that IFC and CityGML data models respectively integrate Level Of Development and Level Of Detail which differ in their name and also in their content. We will explain our interpretation of these two kinds of levels. Finally, we discuss about adding other levels types which are needed to make the data model more structured and consistent to the various demands and needs that must respond, from the beginning of the project to the asset management.