Georeferencing in the context of building information modelling

An important element of metadata for any building information modelling (BIM) model is its location and orientation on the Earth. In most cases, engineering design is based on Cartesian coordinate systems. However, as facilities are placed in a geospatial context, discrepancies result from the transformation from the Earth's curved surface to the orthogonal coordinate system and engineers and developers must take this into account. With this in mind, the dimensions of a model may not correspond to those in the real world, but are rather distorted according to the used coordinate reference system (CRS). We provide a thorough background of geospatial and BIM models to define and illustrate the problem at hand. We introduce three possibilities for spatial interpretation of the geometries and their locations within a BIM model. Option A sees the model as a true-to-scale representation of the asset, option B interprets the model distorted in the same manner as the underlying CRS, and option C is a combination of the former. We explore each option with a case study and visual clues. We show that, while Option A is the most prevalent interpretation in the literature, experts from the infrastructure field prefer Option C, whose underlying rationale is explained in detail. We find that introducing infrastructural concepts to BIM methods requires the systematic resolution of georeferencing. We propose a workflow for the correct handling of any BIM geometries for construction projects. Additionally, we provide a decision diagram to help project stakeholders determine when the distortions of a CRS can be knowingly neglected.