I develop IFC Importer and would like to ask for the legitimate algorithm in terms of IFC standards for handling
IfcPolygonalBoundedHalfSpace. Is it allowed to extrude
PolygonalBoundary into directions of positive and negative Z axis defined by the
Currently my software does extrusion only into direction of positive Z. So the resulting geometry depends on placement of
Position coordinate system. More over the result can be changed if I edit IFC file and move coordinate system along its Z axis. I have example of IFC file with incorrect (this is my guess) Z component of coordinate system’s placement which makes my importer produce wrong geometry.
Other viewers produce desired shape of geometry. Also some of them do not react on changing Z component of ‘Position’ coordinate system no matter which values I set to the IFC file. That is why I think they do extrusion into both directions. If my importer does extrusion into negative Z direction I also get correct results. But it is not allowed by specification.
I have pictures which describe use case very well, but I cannot attach them because my account is limited.
So I am wondering if my IFC file contains correct coordinates? If it does and my Importer handles it incorrectly then please suggest the right algorithm for evaluating the resulting IfcPolygonalBoundedHalfSpace’s solid.