Types in Freecad

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  • edited April 2023

    [ EDIT -
    Remark : The discussion split below is based on the ifc file in the OP of the original thread
    BlenderBim Tutorial - Floorplan Update - in 20mins - BlenderBim 23.04.17.
    (Thanks for splitting, my fault making the discussion derailed from original theme )]

    Seems the structure is loaded but BIM objects are not imported correctly.

    @yorik ? Care to have a look ? Thanks :)


  • @paullee that library contains an IfcProjectLibrary with associated types. If it doesn't load this probably means FreeCAD doesn't have support yet for types. Types are pretty fundamental to BIM so maybe it'll come soon (think door type sheets, window type schedules, wall type details, lists of structural member cross sections in structural models, luminaire types for light installations, etc).

    paulleeAce
  • I just used Acad before FreeCad/Blender.

    So the types in 'external' file are something similar to XRef right? Like a Block with Attrib (forget if this is the correct name in Acad, too many years ago). Thanks for the time.

  • Indeed no support for types yet... I understand a type is like a class, it does not have a "visible" instance, right? How does it work in BBIM?

  • @brunopostle 's ifc is about 4MB but it is a village, wondering if it have used 'types'?
    It was imported in FreeCAD with NativeIFC.


  • @paullee I think it uses types, though I may have done something horrible with mapped representations

    paullee
  • This was all done before I realised that all the information you actually need in the IFC specification is hidden behind invisible links - I just assumed the documentation was deliberately incomplete

    paulleetheoryshaw
  • So it was imported 'without problem' though 'Types' is not supported by NativeIFC import / FreeCAD Arch yet.

    Can you slightly elaborate what does it means by 'mapped representation' and how may it be different from the demo file in the OP ?

    Thanks again :)

  • @paullee looking at the file, there are no window or door types. All the windows just have a representation that points to the same brep geometry.

    Attached a more recent file created with the Homemaker add-on that uses a lot of types (including profileset, layerset and 3d geometry types)

    paullee
  • @brunopostle said:
    This was all done before I realised that all the information you actually need in the IFC specification is hidden behind invisible links - I just assumed the documentation was deliberately incomplete

    Haha.. design matters.

    brunopostleMoult
  • Always remember that IFC concepts always begin with normal industry concepts. So from a regular industry professional, a "Type" is exactly what you'd expect if you asked the question "What Type is that X?" For example, if I asked "what wall type is that?" typically I'd expect an answer describing the wall layer buildup (thus a thickness, but not a length), and typical properties like acoustic and fire ratings. If I asked "what type of beam is that?" instead I might expect an answer describing the cross sectional profile with its structural properties and material. If I asked "what type of furniture / pump / light fixture is that?" I'd expect an exact model number I could procure from a manufacturer and I know exactly what it looks like (i.e. you know the complete geometry, as opposed to just a thickness or cross sectional profile). If I asked "what type of space is that?", I might expect an answer not describing any geometry at all, but instead describing this like leglislative occupational class, or fire compartment, or purpose like circulation / office / F&B, etc. A "Type" in IFC is exactly that: the answer to the question "What Type is that X?"

    From a computer perspective, a Type has a 1:N relationship with occurrences. That is, one light fixture type may have many individual light fixture occurrences (or "instances" in programming classes speak). An instance inherits geometry, materials, classifications, and properties from its type. So if a light fixture has a complete geometric representation, all occurrences have the same representation. If a wall has a particular material layer set, all occurrences must use that same parametric material layer set. If a space type has a classification code as part of a classification system (e.g. legal occupancy class), the space inherits it. And of course, if a door type has a fire rating property, all door occurrences inherit that fire rating property.

    Occurrences not only inherit, they are allowed to override, but in my opinion this should be used sparingly. For example you might say all doors have black paint ... EXCEPT that one!

    The reason why types are so critical is that it describes the contents of a project from a high level view of its product types that professionals use all the time. Like "there are 30 light fixture types we've got to procure and install" or "we've got 19 wall types, let's divide them into masonry, partition, and other to start organising trade packages".

    paulleebrunopostleGorgiousAcecvillagrasaberndbaswein
  • edited April 2023

    @brunopostle said:
    @paullee looking at the file, there are no window or door types. All the windows just have a representation that points to the same brep geometry.

    Attached a more recent file created with the Homemaker add-on that uses a lot of types (including profileset, layerset and 3d geometry types)

    The file in opening post was opened (with FreeCAD NativeIFC Import) without error, just nothing.

    But Brunopostle latest file return errors upon opening with FreeCAD NativeIFC Import, for @yorik's attention please.





  • @paulee @yorik this IFC file has some mesh objects that consist of a single point (for stashing the topologic Cell) - I can see why this would be a problem in freecad, probably my bad.

    paullee
  • edited April 2023

    Hmm there is a bug in my code there.. Will fix ASAP! https://github.com/yorikvanhavre/FreeCAD-NativeIFC/issues/40

    paullee
  • I fail to see how this discussion is relevant to the BlenderBim tutorial. Can it be moved elsewhere?

  • I split it out into a new thread, here.

  • Cross-posting Discussion at FreeCAD Arch/BIM Forum

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