Documentation on ifcdiff

on the wiki there is some great documentation about ifc quality gates made by bimtester ...

But I could not found any documentation about ifcdiff? Is there anything around?

cheers bernd


  • Not much to document, really. ifcdiff -h will provide a standard help statement:

    usage: [-h] [-o OUTPUT] [-r RELATIONSHIPS] old new
    Show the difference between two IFC files
    positional arguments:
      old                   The old IFC file
      new                   The new IFC file
    optional arguments:
      -h, --help            show this help message and exit
      -o OUTPUT, --output OUTPUT
                            The JSON diff file to output. Defaults to diff.json
      -r RELATIONSHIPS, --relationships RELATIONSHIPS
                            A list of IFC classes to check in inverse
                            relationships, like "IfcRelDefinesByProperties", or

    So in its simplest form: ifcdiff old.ifc new.ifc

  • No I do not mean how to run it. You mentioned the results can be opened and shown in BlenderBIM. How does this works? Does Blender reads the json file? I do not think so.


  • @bernd at the moment, there is no way to "visualise" the JSON file in the BlenderBIM Add-on. It's been on my todo list for a while :)

    However, one way it can be used is during import. Prior to import, point to a JSON data with Diff data inside. Then, when you import an IFC file, the diff will be applied, so it will only import what's changed / new, and will delete existing deleted elements:

  • edited July 31

    Is it possible to visualize the diff off two ifc somehow like the picture attaced? There the black lines and red volumes are the geometry which has changed from one ifc to the other. Exaclty it shows the volumes (concrete) which where added from one IFC to the other

  • @bernd not yet. It is a feature I plan to add. There are some manual ways to do it, but a feature is needed to make it easy.

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