simple ifc created with FreeCAD does not work with BlenderBIM 0.0.200722

Hi Dion,
we had problems with a simple model exported from FreeCAD to import in BlederBIM. I am curious where the problem is.

https://forum.freecadweb.org/viewtopic.php?f=23&t=49030&p=420130#p420116
and
https://forum.freecadweb.org/viewtopic.php?f=23&t=49030&p=420130#p420130

cheers bernd

Comments

  • @bernd thanks for the head's up!

    For the file opensource_house_struct-engin_01.ifc, it seems as though the IFC produced by FreeCAD is not quite valid. The issue is that the IfcBuilding is not properly aggregated back into the IfcProject. If you add the following line to the bottom of the IFC file, that will fix it:

    #150=IFCRELAGGREGATES('1kXbZYnPj569eu6dkG9Zan',#5,'ProjectLink','',#23,(#24));
    

    The result:

    For the file opensource_house_struct-engin_02.ifc, it seems to only contain 2D sketches. You have to enable "Import Curves" prior to import, but after you do that, it'll import successfully:

  • thanks for the fast answer. Got it.

    The problem is in FreeCAD is a long existing colored viewing bug. Thus I do not make a IfcProject an IfcSite in FreeCAD. Thus the connection seams missing. Seams some regression, this has been working, exporting a building without a site and project. I will have a look.

    cheers bernd

  • It's not a but it's a feature. One needs to activate a setting in FreeCAD for adding a default site if there is no.

    BTW: most viewer import geometry anyway even if they is not in any container. They call it unreferenced items. Might be good to have this in BlenderBIM too?

    cheers bernd

  • BTW offtopic: is there a possibelity in Bleder to get a empty document on new document. I need to delete these camera and light any time I open a IFC.

  • ahh and another one. Where do I see the material name from an object in BlenderBIM?

  • another offtopic one. There was a disscussion about some generic methods in IfcOpenShell for example to get properties or materials from an object. I can not find the topc ATM. Do you have the linkt to it?

  • Just forced myself today to open any IFC I open in BlenderBIM too ... Thus some more posts as usual ... One more ... How about spaces. They do not show up in BlenderBIM. What do I need to trigger to make them show.

  • It's not a but it's a feature. One needs to activate a setting in FreeCAD for adding a default site if there is no.

    @bernd - a missing aggregation back to the IfcProject is a bug I believe, as therefore it is not referenced in the spatial tree, and so the correct behaviour of an IFC viewer is to show nothing. Or, I guess, in BlenderBIM's case, show an error :)

    Changing the default startup: https://blender.stackexchange.com/questions/186/how-to-change-blenders-default-startup-settings

    Material data can be seen in the materials tab:

    Generic methods are available in the (small, but growing) util library: https://github.com/IfcOpenShell/IfcOpenShell/issues/829 - but I think you're also referring to the comment I made here: https://github.com/FreeCAD/FreeCAD/commit/ebaac63777ea58b85e504d3e25aafb82cc4b05fc

    Spaces can be enabled as so:

    carlopav
  • @bernd said:
    BTW offtopic: is there a possibelity in Bleder to get a empty document on new document. I need to delete these camera and light any time I open a IFC.

    Erase all, then File->Defaults->Save startup file

  • edited July 29

    @Moult said:

    It's not a but it's a feature. One needs to activate a setting in FreeCAD for adding a default site if there is no.

    means we should add a site in any case without asking the user for it to add, because without it would be non standard ifc?

  • edited July 29

    @Moult said:
    Generic methods are available in the (small, but growing) util library: https://github.com/IfcOpenShell/IfcOpenShell/issues/829 - but I think you're also referring to the comment I made here: https://github.com/FreeCAD/FreeCAD/commit/ebaac63777ea58b85e504d3e25aafb82cc4b05fc

    I missed this comment. But yes exactly. We had the disscussion a few weeks month ago. Lately I needed this, but it had to be fast. Thus I used what I know the FreeCAD way. But I will have a look at the ifcos utils. I may even add it to FreeCAD.

    I will have some more remarks questions in this regard. We had a topic already. Do you know the link or should I just open a new topic?

    cheers bernd, from 30 degree hot zurich

  • thanks for all the other answers.

  • @bernd maybe start a new topic :)

    I don't think an IfcSite is required from an IFC point of view... but what is required is that somehow, the objects are related back to the IfcProject.

  • @Moult said:
    @bernd maybe start a new topic :)

    I don't think an IfcSite is required from an IFC point of view... but what is required is that somehow, the objects are related back to the IfcProject.

    got the point

  • How about IfcGrid? What button do I need to trigger in BlenderBIM to see or import the IFC Axis system?

  • The setting to put everything under the default bldg structure is on by default, you must have turned it off at some point @bernd ... imho it makes sense to allow objects in a file that are not part of a project. What each app does with that is another question of course.. but it seems wrong to be mandatory (ex. temporary objects, alternative design options, etc). So this option is there basically so people can experiment with it and decide for themselves

  • In IFC, at the moment, the IfcProject is considered to be akin to the "root" node. Therefore all parsing starts there, and anything which the application should display must be linked to the IfcProject, either directly or indirectly. So I think most, if not all IFC apps use that behaviour. There are some advantages to this method - such as easier parsing - e.g. XML has a root node, JSON has a root object, and so on.

    However, as you say @yorik there are quite a few shortcomings to this method, or shortcomings to the IFC spec, which doesn't allow design options. Another big issue is that it makes it difficult for IFC data sets to include multiple projects aggregated into one, or to link from one IFC file to another.

    For now, I think the BlenderBIM Add-on will follow the prescribed behaviour, but in the future, we should definitely explore options!

    @bernd grids should come in without issue. If it doesn't, let me know which file and I can help debug?

  • @bernd grids should come in without issue. If it doesn't, let me know which file and I can help debug?

    https://forum.freecadweb.org/viewtopic.php?f=23&t=49030&start=70#p420482

  • Once again in the regard of IfcSite. I still think there is a bug in FreeCAD. We should let the user decide if he would like to add a site or not, but in any case we should link the objects to the IfcProject See https://forum.freecadweb.org/viewtopic.php?f=39&t=49108

  • I also agree that it is a bug. An IfcSite is optional, but it is currently mandatory to link back to the IfcProject.

  • I have been thinking again. We should make it possible what Yorik said, but not the way it is ATM in FreeCAD. I will coninue on FreeCAD forum.
    https://forum.freecadweb.org/viewtopic.php?f=39&t=49108

  • I just changed thes lines in BlenderBIM manually, The grid is imported but not displayed. Do I miss something more?

    Bernd

  • everything allright ... my fault. A restart of Blender is needed to make sure the changed module is loaded ...

    Moult
Sign In or Register to comment.