Multi-scale geometric-semantic modeling of linear infrastructure facilities for GIS and BIM applications

The planning of large infrastructure facilities such as inner-city subway tracks requires the consideration of widely differing scales, ranging from the kilometer scale for the general routing of the track down to the centimeter scale for detailed design of connection points. On the one hand this implies the utilization of both, Geographic Information Systems (GIS) as well as Building Information Modeling (BIM) tools, for performing the required analysis, modeling, and visualization tasks. On the other hand, a sound foundation of handling multi-scale representations is required. While multi-scale modeling is already well established in the GIS field, there are no corresponding approaches in Infrastructure BIM so far. However, multi-scale concepts are also much needed in the BIM context, as the planning process typically provides only rough information in the early stages and increasingly detailed and finegrained information in later stages. To meet this demand, this paper presents a comprehensive concept for incorporating multi-scale representations with building information models, with a particular focus on the geometric-semantic modeling of shield tunnels. Based on a detailed analysis of the data modeling methods used in CityGML and the requirements present in the context of infrastructure planning projects, we discuss potential extensions to the BIM data model Industry Foundation Classes (IFC) for incorporating multi-scale representations of shield tunnels. Particular emphasis is put on providing means for preserving the consistency of the representation across the different Levels-ofDetail (LoD), while taking into account both, semantics and geometry. For realizing consistency preservation mechanisms, we propose to apply a procedural geometry description which makes it possible to define explicit dependencies between geometric entities on different LoDs. The modification of an object on a coarse level consequently results in an automated update of all dependent objects on the finer levels. Finally, we discuss the transformation of the IFC-based multi-scale tunnel model into a CityGML compliant tunnel