Cover Image Credit: buildingSMART Deutschland
Štefan taught a three-hour online tutorial on IFC 4.3 georeferencing for buildingSMART Deutschland (bSD) on October 14, 2024. The session covered coordinate reference systems at the schema level, transformation math, and how IfcProjectedCRS, IfcMapConversion, and IfcRigidOperation behave on real infrastructure projects.
What the session covered
The session covered coordinate reference systems (projected, topocentric, and geocentric) and why all three come up in BIM work. Building models typically use a local coordinate system; surveys and infrastructure data use a projected CRS. IFC 4.3 has to bridge both, and that bridge is where most georeferencing errors start.
Next came transformations. Moving between reference systems introduces distortions in scale, rotation, and translation that compound until models from different disciplines fail to align.
The IFC 4.3 part went through IfcProjectedCRS, IfcMapConversion, and IfcRigidOperation: what each entity does, how they relate, and how to populate them so any compliant tool can place the model correctly. Last were failure modes: the coordinate mismatches that come up in multidisciplinary projects and how to catch them early.