Using surface reference creating pipe network

[Ingrid91]

Hi, 

I think I'm missing something incredibly obvious but can't for the life of me figure out the answer (my English is probably also going to be a bit unintelligible with the state of my mind right now).

The heart of the matter is this: is it possible to create a pipe network if you only have the surface referenced as a CAD-file? As far as I can tell, when creating either pipes or feature lines a reference is not enough as it doesn't show up as an alternative in the creation window.

The background is this: The surface models are available as both LandXML (about 100 MB), as DWG (about 50 MB) and as DGN. I've previously used "Import LandXML" when I've needed it, but for this particular model I'm going to need to reference many more in the same model and when I've tried it it becomes very heavy to open and mms-files are created because of the size.

I know that surfaces should be available as Data shortcuts (not in this project anyway) - are they automatically smaller if used like that?

[Joe-Bouza · Accepted solution]

The xref surf cannot be picked up directly.

Drefs do help and you can consider a cropped surface or data clip for the area of interest.

I like cropped 

[chriscowgill7373 · Accepted solution]

I agree with Joe, even if you dref the surface, it wont reduce or make your file run smoother unless you do some clipping/cropping, but an xref surface wont work for what you are wanting to do.   With surfaces, you can change them so that they are only referenced, instead of adding the geometry to the file, that may help with what you are trying to accomplish.  Not sure what version of C3D you are using, but if you use 2024 and newer I believe, they increased the threshold for when an MMS file is used, and in 2025 they made even more improvements when working with surfaces.  So it may not feel as heavy if you utilize newer software.