IFC Import Not Aligning to Survey Point

[scottjm]

Hi,

I'm looking for some help with import IFC files from Archicad, and aligning with the Survey Point and Local Base Point.

In Archicad I configure the Survey Point to align with 0,0 of the surveyors DWG file.  In this simplified instance is 20m West and 10m South of the Project Base Point in Archicad.

I then setup a new Revit file and in Manage>Corordinates> Specificy Co-ordinates at Point, I click the Project Base Point (and Internal Origin) and enter Easting: 20,000mm Northing: 10,000mm N.  Giving me the following, which matches with Archicad.

I then go Insert>Link IFC and select the IFC exported out of Archicad.

After it finishes processing, I am left with the below, which aligns the Archicad Survey point with the Revit Project Base Point, which is not correct.

Interestingly.  If I open the .IFC.RVT file created as part of the IFC linking, the Survey Point, Project Base Point and Internal Origin are all sitting at the same spot at 0,0.

However, if go File>Open>IFC and open the IFC file directly, it shows the Survey Point in the correct location relative tot he Local Base Point and Internal Origin.

What I am I doing wrong when I link the IFC into Revit?

Sample IFC File attached for reference.

Thanks,

Scott

[TripleM-Dev.net]

Hi @scottjm,

I don't think you are doing anything wrong.

A IFC format knows nothing about a "Archicad Survey point", I believe a IFC can contain a second origin point.

So depending the export settings in Archicad (don't know what settings are possible in Archicad) it will use model origin or the surveypoint as origin point in the IFC.

In Revit when importing the IFC origin will be placed in the Model orgin (normally the project base point)

So a couple of options:

1. Export the IFC from Archicad with the model origin.

2. Move the IFC to the survey point in Revit (if Survey changes so should the position of the IFC), when the IFC link is updated with a new version of the IFC it will retain it's place as long as the IFC is always exported with the same settings.

Now for the thing with Revit; When exporting a IFC from revit while there's a Survey point set, re-linking that IFC back into Revit, it sees the Survey point and displaces it from the Model origin. A so-called round-trip Revit>IFC>Revit often goes wrong with shared coordinates etc. But this does mean a secondary origin (coordination system) can be saved in the IFC.

I Think in the roadmap of Revit (future version) it could include a placement option when linking IFC's, like with linking Rvt models.

- Michel

[scottjm]

Hi @TripleM-Dev.net ,

Thanks for your comprehensive response.

My understanding was that when using the Archicad Survey Point, it will add this a 'second origin point' (for lack of a better term) in the IFC file so that so you can report Global and Local Co-ordinates within the IFC file.

Managed to get a round trip working in the end with my consultant team by manually repositioning the linked IFCs in Revit as suggested.  So it's at least functional now.

The ability to determine what the placement option for the linked IFC file in Revit (similar to the options Link CAD currently has) is what is needed I think. Fingers crossed it is not far away on the roadmap.

Cheers,

Scott