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buildingSMART / IFC4.3.x-development

Repository to collect updates to the IFC4.3 Specification
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RepresentationIdentifier: Row #628

Open TZwielehner opened 1 year ago

TZwielehner commented 1 year ago

The element component (https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3_0_0/lexical/IfcElementComponent.htm) mentions a "row" identifier that is not listed in the shape representation (https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3_0_0/lexical/IfcShapeRepresentation.htm).

aothms commented 1 year ago

This is a valid comment.

[This is specifically about] Symbolic Representation [where] ... rows or arrays may contain possibly large numbers of individual pieces ... [and] curves represent where reference points of the pieces are located.

I have seen this also in the steel fabrication mvds, they do not care about the opening geometry per se, but they want reference lines indicating where to mill in the steel.

For general usage I find this highly speculative and for typical rebar elements you just get a swept disk solid (possibly positioned several times as mapped items).

My recommendation would be to remove this section.

Edit: because the approach of using 'Row' for rep identifier I find unsuitable also. Repeated positioning of elements should not be expressed at this level. We have similar issues for e.g rail way sleepers and I really don't see a single element with many representation items a viable way to represent that. My general view is that decomposition and repetition should be expressed as object level relationships.