Represent the frustum of a rectangular pyramid

[Supporting]

Hi,

is it possible to represent the frustum of a rectangular pyramid as a IfcExtrudedAreaSolid + IfcRectangleProfileDef. I found IfcDerivedProfileDef to transform the base profile. However, this entity transforms the base profile. Is there anyway to transform the profile along the extrusion?

Using IfcRectangularPyramid + IfcHalfSpaceSolid is not an option, because the apex of the pyramid is not necessarily directly above the centre point of the base.

Any other ideas?

[theoryshaw]

I'm no IFC expert, but could you use IfcExtrudedAreaSolidTapered?

Attribute	Type
1 SweptArea	IfcProfileDef
2 Position	IfcAxis2Placement3D
3 ExtrudedDirection	IfcDirection
4 Depth	IfcPositiveLengthMeasure
5 EndSweptArea	IfcProfileDef

see the following data excerpt from the air terminal example. It uses the IFCDERIVEDPROFILEDEF entity.

/* The air terminal type (imported from referenced library) */
#270= IFCCARTESIANPOINT((0.,0.,0.));
#271= IFCAXIS2PLACEMENT3D(#270,$,$);
#275= IFCRECTANGLEHOLLOWPROFILEDEF(.AREA.,$,$,24.,24.,2.,10.,0.);
#276= IFCCARTESIANPOINT((12.,12.,0.));
#277= IFCAXIS2PLACEMENT3D(#276,$,$);
#278= IFCDIRECTION((0.,0.,1.));
#280= IFCCARTESIANPOINT((0.,0.));
#281= IFCCARTESIANTRANSFORMATIONOPERATOR2D($,$,#280,0.5);
#282= IFCDERIVEDPROFILEDEF(.AREA.,$,#275,#281,$);
#283= IFCEXTRUDEDAREASOLIDTAPERED(#275,#277,#278,4.,#282);
#284= IFCSHAPEREPRESENTATION(#212,'Body','AdvancedSweptSolid',(#283));
#285= IFCREPRESENTATIONMAP(#271,#284);
#286= IFCAIRTERMINALTYPE('1FESQ2M9vC7xYWZpI_LlCh',#209,'Acme Diffuser 1234','Ceiling diffuser',$,(#260,#269),(#285),$,$,.DIFFUSER.);

And in hierarchy...

[Supporting]

Thanks, this is exactly what I was looking for.

Unfortunately, the support in tools seems to be quite limited. Any idea which tool can render an IfcExtrudedAreaSolidTapered?

[jmirtsch]

Hi Supporting, If you're a revit user, then my revit plugin should create a swept blend, http://www.geometrygym.com/downloads You can also download the evaluation version of Rhino3d and install ggRhinoIFC from the above link as an alternative. Get in touch if there are problems.

[martin1cerny]

Hi @Supporting, development branch of xBIM supports full IFC4 including all kinds of geometry. Development branch of XbimXplorer can visualize all these including IfcExtrudedAreaSolidTapered.