IFC Syntax : Georeferencing

IFC geometry is authored in a flat, metre-scale local engineering coordinate system. Georeferencing is the separate, additive layer that tells a consumer where that local origin sits on Earth and how it is rotated onto a map grid. This skill covers the three generations of georeferencing mechanism, the entities they use, the transformation order, and the version availability.

Legacy site coordinates exist in IFC2x3, IFC4, and IFC4.3. Precise georeferencing (IfcMapConversion, IfcProjectedCRS) is IFC4 and later. Linear placement is IFC4.3 only. The Version Differences section is load-bearing.

Quick Reference

The three mechanisms