IFC Export Georeference Doesn't Match Model Georeference.

[Jack2022]

Hi All,

 

Our model is georeferenced to shared project coordinates. The internal origin is set to match the lead consultant project coordinate and the user origin is set to British National Grid 0,0. We use Nothing and Easting coords.

 

The Architect on the project told us our IFC export isn't arriving in their model in the correct location - our DWGs do and design layer coords match in our main model.

 

When I import my own exported IFC file into a correctly georeferenced empty file and select 'use IFC file coordinate system' in the import menu it is indeed wrong. When I use a N/E coord stake on the internal origin of the design layer with the IFC it shows as a South / West coordinate that does not match the X/Y coord. 

 

N/E coord matches the X/Y coord in the georeferenced import file before import: 

 

 

Import settings: 

 

 

 

On investigation the only thing I can find to affect the IFC coords is something called 'Reference Latitude' and 'Reference Longitude' under Site Data in export settings. 

 

 

Is this where the problem lies? and how can I fix it (no way to input accurate N/E coords)? 

 

Other consultants use Revit so I can t ask them to just import using their document coords. The IFC needs have the correct coords.

 

Kind regards,

 

Jack

 

 

 

[Poot]

19 hours ago, Jack2022 said:

Hi All,

 

Our model is georeferenced to shared project coordinates. The internal origin is set to match the lead consultant project coordinate and the user origin is set to British National Grid 0,0. We use Nothing and Easting coords.

If I am not mistaken, you should be setting your User Origin to set the project coordinates/origin, and not adjusting the Internal Origin numbers. If you are using a specified coordinate system, the internal origin coordinates should be created automatically for the drawing.

You're images show there might also be an issue with the unit precision for the document/coordinates....(there are 3 digit differences indicating some issue between metres and millimetres). Not sure why you'd get different values though.

I have exported several IFC models using the 'project coordinates' as the User Origin, with the expected results. I have never done the opposite, and adjusted the internal origin.

Edited February 27 by Poot

[Mihail Rizov]

Hi @Jack2022,

 

Prior to Vectorworks 2024 Update 4, IFC model origin is always the User Origin.

(Site Data, like Ref. Longitude/Latitude are for informational purposes only in the receiving applications)

 

Best Regards,

Mihail Rizov

[Jack2022]

Thank you both. Will look at how 2024 Update 4 has changed.

 

I believe I have solved the problem - our Internal Origin coords were not aligned with the Architect's (school boy error). Not sure why the IFC imports as a different coord system when I try it but it is now correct on our project.

 

@Poot - the unit precision didn't help unfortunately. 

 

To Answer your question about origins - Revit only recognises the Internal Origin so we change ours to match the Revit user's Internal Origin which should also be the agreed Project Base Point. Otherwise our models won't arrive in the correct space when they import them. It's fine for other software like Autocad and various BIM clash softwares as these all use the User Origin (which should be 0,0 British National Grid to arrive in the correct place (if British project). Unfortunately I'm yet to come across an Architect who isn't a Revit user in a BIM situation. 

 

Secondly I understand it is good practice to keep the Internal Origin close to the model otherwise you get bugs.