IFC Syntax : Geometry Tessellation

Tessellation is faceted geometry : a mesh of flat triangles or polygons. It was introduced in IFC4 and is the geometric backbone of the Reference View MVD, because a consuming application can render a mesh with almost no implementation effort. IFC2x3 has no tessellation entities : its faceted equivalent is IfcFacetedBrep.

The design is index-based : one shared point pool holds every vertex once, and every face is a short list of integer indices into that pool. This makes a tessellated model far more compact than thousands of repeated point instances.

This skill covers IFC4 and IFC4.3. The differences between those two versions are small and listed in the Version Differences section.

Quick Reference

The indexed model