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How can I retrieve IFC Relations?

  • January 16, 2020
  • 2 replies
  • 35 views

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Hi

I found that FME converts IFC Relations to some attributes such as ifc_is_containd_in and ifc_decomposed_by but for me these attributes don't have any value. I've selected these attributes in Format Attributes but still there is no value. Also, I tried GeometryPropertyExtractor and AttributeExposer but nothing changed. Is there any way to extract IFC Relations in FME?

Thank you in advance.

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2 replies

daveatsafe
Safer
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  • Safer
  • January 16, 2020

Hi @mbarzegar,

The IFC reader uses the relations to build the add the property sets to the features, so the info is there, but not explicitly. You could decompose the property sets from the geometry to rebuild the relationships. The relationships between the features (ie. Window -> Opening -> Wall) are stored using the ifc_parent_unique_id, which corresponds to the parent feature's ifc_unique_id.

Alternatively, you could try using deprecated reader, which is available as an option in the IFC reader parameters. This older version of the reader outputs the relationships explicitly, but has not been kept current, and may not read all IFC files correctly.


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  • Author
  • January 17, 2020

Hi @mbarzegar,

The IFC reader uses the relations to build the add the property sets to the features, so the info is there, but not explicitly. You could decompose the property sets from the geometry to rebuild the relationships. The relationships between the features (ie. Window -> Opening -> Wall) are stored using the ifc_parent_unique_id, which corresponds to the parent feature's ifc_unique_id.

Alternatively, you could try using deprecated reader, which is available as an option in the IFC reader parameters. This older version of the reader outputs the relationships explicitly, but has not been kept current, and may not read all IFC files correctly.

Thank you so much for your answer. The deprecated reader worked for me and solved my problem.