Export from dwg to IFC in civil 3D help

[Anonymous]

Hi!

I am having trouble exporting a dwg in Civil 3D to IFC. It can export, I get the IFC-file, but the IFC-file isn't correct.

This is the background story:

• I have a dwg with 3D objects (polyface mesh). It is a dwg that is exported from Novapoint. This dwg is in world coordinates and done in the units meter. 
• The project that I am working in, they use internal coordinates and the unit millimeter. 
• To get my dwg to fit theirs I have changed the UCS to the internal coordinates and I have scaled up my objects to fit the unit millimeter so that it is in the same scale.
• I have double checked that the coordinates in my dwg corresponds to the other dwg:s in the project.

Now, when I export the dwg to an IFC in Civil 3D, it works and all, but apparently it doesn't end up correctly in the world. The coordinates compared to the other files are with a huge offset. See printscreen.

Does anyone know why this happens?

Best regards, Linda
Pipe network designer, Sweco, Sweden

[samir_rezk]

Hi @Anonymous 

Civil 3D Drawings can only be in Meters or Feet! Civil 3D Objects like Surfaces and Alignments, simply can not be in Millimeters! Double Check the Project Civil 3D Drawing Settings

With that being said, your AutoCAD units is perhaps set to millimeters, but your Civil 3D Units is set to meters which is conflicting each other and you end up with a "meters" IFC Export 

If you are determined to create a millimetres IFC Export; you need to have 3 Dialog boxes to be in Sync!

1. AutoCAD Units Command = Millimeters

2. Type AECDWGSetup / Units Tab, and select Millimeters

3. Confirm the Civil 3D Drawing Settings indicate Millimieters. (very important disclaimer: The drawing absolutely can not contain any Civil 3D Objects, only AutoCAD object like Blocks and Solids can be scaled to be in mm!)

Although it is doable, It is generally very bad practice to set a Civil 3D drawing in anything but Meter or Feet! it will cause many headaches when working with Civil 3D Objects!

Hope this helps,

[Anonymous]

Thank you for your response!

I have no civil 3D objects in this dwg, just autocad, so it should work. 

I have used the command DWGUNITS to scale from meters to millimeters. I got asked if I wanted to scale up the objects. Should I have done that?

Otherwise I already had the correct settings to millimeters as you described.

/Linda

[samir_rezk]

Hi @Anonymous 

I am not 100% certain! but I believe the IFCExport exports the data located relative to WCS. I would test using the Move command and locating the geometry correctly while being in WCS rather than creating a new UCS

[Anonymous · Accepted solution]

I think you are right! Apparently if you are converting to IFC you don't need to change the unit, when you import the IFC in a BIM-program e.g. Solibri, the program will recognize the unit and convert it from there. 

Thank you for the help.

/Linda

[jaiswal_manish]

This solved my problem. Thanks, Samir.