IFC 4.3.0.1 (IFC4X3_TC1)

8.20.3.10 IfcFaceSurface

8.20.3.10.1 Semantic definition

The IfcFaceSurface defines the underlying geometry of the associated surface to the face.

Informal Propositions:

1. The domain of the face surface is formally defined to be the domain of its face geometry as trimmed by the loops, this domain does not include the bounding loops.
2. A face surface has non zero finite extent.
3. A face surface is a manifold.
4. A face surface is arcwise connected.
5. A face surface has surface genus 0.
6. The loops are not part of the face domain.
7. Loop geometry shall be consistent with face geometry. This implies that any edge - curves or vertex points used in defining the loops bounding the face surface shall lie on the face geometry.
8. The loops of the face shall not intersect.

8.20.3.10.4 Formal representation

ENTITY IfcFaceSurface
SUPERTYPE OF (ONEOF
END_ENTITY;