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  • Hy, testing your software and have a problem with the export of walls and slabs. The windows and doors are exported ok. Attached my ifc file. I changed the ending from ifc to txt. I am using your template ifc-lod4city.fmw kind regards, Jaka
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Hy, testing your software and have a problem with the export of walls and slabs. The windows and doors are exported ok. Attached my ifc file. I changed the ending from ifc to txt. I am using your template ifc-lod4city.fmw kind regards, Jaka

  • 20 October 2021
  • 2 replies
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8

Attached my ifc file. I changed the ending from ifc to txt.

 

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2 replies

jovitaatsafe
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Hi @89jaka​,

Thanks for reaching out! It looks like we're not reading in the walls correctly on your provided file so I'm also missing walls when I gave it a try in the ifc-lod4city.fmw workspace from the BIM to GIS (Intermediate) tutorial. I've filed an issue with our development team to investigate what might be going wrong on the read, tracked internally as (FMEENGINE-71058), and I'll let you know as soon as it has been addressed.

 

In the meantime, is your file created in Revit 2021? I noticed that the walls didn't seem to have a Family and Type set, and when I set it and re-exported it to IFC, FME was able to read the walls in again. If you're seeing a similar situation where the walls are missing when you inspect it in FME, it might be helpful to go back and make sure a Family and Type are set before exporting to IFC.

 

On my side, I was able to get the slabs written out correctly by replacing the existing IfcSlab feature type with your file's IfcSlab, and disabling the IfcRoof feature type because your file didn't have one. In the AttributeFilter, I changed the connection on the <Empty> port to AttributeRename_6 instead of the FeatureMerger and that was enough to write out both slabs to Floor Surface (though you could change it up so the top slab becomes a roof by routing the feature to the IfcRoof feature type instead using a Tester for example. Similarly for the Walls bookmark, I just ignored the IfcMember stream because your file didn't have that feature type either.

 

Hopefully these changes get the workspace working for you! I'll let you know when the read issue has been resolved.

jovitaatsafe
Rank
Userlevel 1
Badge +11

Hi @89jaka​,

Our development team had a look at your file and unfortunately it doesn't look like there's too much we can do in this case to read the walls in correctly with the openings. The problem seems to be that the opening objects are overly complex and the reader isn't able to resolve it.

 

One thing that you can change in the reader parameters for some partial success is to change 'Subtract Opening Geometries' to No.

subtract-opening-geometriesSince this seems to be a test file for you, I would suggest trying to read a more common IFC file that you might work with and see if you still have a problem with missing walls due to the openings. If it's a common problem for you, here's a possible workaround:

 

I've attached a workspace that recreates the openings in the wall by:

  1. Making the door and wall geometries solids
  2. isolating the wall with the opening
  3. Using the CSGBuilder's Difference port to subtract the door solid from the wall solid

 

You could then do the same with subtracting the windows and plug that back into the tutorial workspace. It's a bit of a more intermediate workaround, but should work to get your walls into CityGML with proper openings. Below is a screenshot of the result from the attached workaround to recreate the opening for the door:

 

workaround-resultHope this helps!

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