Extracting Geometry from an IFC File

An IFC element keeps its shape and its position apart. The geometry items sit in a LOCAL coordinate system; the element's place in the world is carried separately by ObjectPlacement. Extracting usable geometry means doing two things ALWAYS together: decoding the shape items, and resolving the placement chain to a world transformation matrix.

Verified against the buildingSMART IFC4.3 specification, with IFC4 ADD2 TC1 and IFC2x3 TC1 deltas noted. See references/methods.md for full entity signatures, references/examples.md for worked STEP snippets and matrix computation, and references/anti-patterns.md for the extraction mistakes that produce wrong or empty geometry.

Quick Reference

The resolution path