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handling of complex opening shapes (reveals, vertical extrusions)
based on
extended coordination view
24. Feb 2006
ISG meeting in Berlin
summary handling of complex opening shapes (reveals, vertical extrusions)



It is allowed to export openings that extrude perpendicular to the main element extrusion dimension (horizontally for walls), and along the main element extrusion direction (vertically for walls). Both are of the same type, i.e. 'opening'

In addition, an opening body may be described by one, two or more extruded solids (independed of extrusion directions).

[modified 05-May-06] The opening extruded bodies shall not overlap (only by some epsilon value), but join at one face.

  • this is possible for openings in straight walls
  • open issue for openings in round walls (due to necessary overlap)

[added 05-May-06] If many extrusion bodies are used for an IfcOpeningElement SweptSolid geometric representation, these bodies may overlap. This is unavoidable for openings in round walls and may therefore be allowed also in all cases.

Note: It should be clear that by this agreement the opening volumes can not be directly used as a subtraction measure for quantity take-off, as the opening body volume may be bigger than the cut-out volume caused in the wall.


Figure: showing the potential and legal overlapping of volume by two or more opening bodies of the same instance of IfcOpeningElement

see also agreement #CV-2x3-108