New Concepts for Structuring 3D City Models – An Extended Level of Detail Concept for CityGML Buildings

We propose a new Level of Detail (LoD) concept for CityGML buildings that differentiates a Geometrical Level of Detail (GLoD) and a Semantical Level of Detail (SLoD). These two LoD concepts are separately defined for the interior characteristics and the outer shell of a building, respectively. The City Geography Markup Language (CityGML) is an open and application independent information model for the representation, storage, and exchange of virtual 3D city models. It covers geometric representations of 3D objects as well as their semantics and their interrelation. The CityGML Level of Detail concept in general offers the possibility to generalize CityGML features from very detailed to a less detailed description. The current LoD concept suffers from strictly coupling geometry and semantics. In addition it provides only one LoD (LoD4) for the description of the interior of a building. The benefits of our new LoD concept are first, a substantially higher informative value for the Level of Detail, second, a better description of the interior Level of Detail, third, a broadening of the opportunities for indoor modelling, and last, a better assignability to all other modules represented in CityGML. Due to more combinations of GLoD and SLoD, the Level of Detail definition for every module in CityGML can be defined according to the nature of modelled real world phenomenon.