Why is convert to lines or polygon so hit and miss when converting a section viewport and yet so wonderful when exported as DWG?

[shorter]

We have a received an IFC.  It's a monster once imported.  It's a 1:1 model.  Nuts, Washers, Bolts... even window gaskets.  Someone clearly hasn't heard of LOD.

 

We need some sections through the model for detailing purposes.

 

Because the model is huge, there is no way we can federate it with our model take sections through it and use it live.

 

So, we have asked for 2D DWG sections from the author, all nicely coordinated with our 2D detail sections (that are NOT drawn in viewport annotation because we like to coordinate our details...) which in turn are coordinated (i.e, they drop in WITHOUT MOVING THEM), with our model and the design team models.

 

However, because they (and my client) do not understand concepts like 'validation' they refuse to issue DWG and expect us to take the sections outselves.

 

Now the issue here is two-fold.

 

1 We have to assume that VW is importing the IFC correctly.  It seems to but who would know?

 

2 We have to generate the DWG section and again who knows if it is what the issuer intended.

 

So, with gay abandon, we extract the section as a viewport on a design layer, and 'convert [the viewport] to lines'.  Stuff goes missing.  We try 'convert to polygons'.  Weird things start to happen where triangulation in the model rears it's ugly head.  And don't get me started on what happens when you 'Convert to Group'...

 

So we export the design layer as a DWG, and re-import the DWG, and it's... perfect!  It's a really lightweight file, and we save loads of time not having to wait for the viewport to update!

 

The question is 'Why?'.

 

Why must we go through this rigmarole to get a clean or complete 2D section from a section viewport of an albeit overly complicated IFC model?  Because

 

You 'should' be able to convert to lines or convert to polygons and bang!

 

[mjm]

I'm just surprised and happy to hear the round trip thru VWX as the converter actually produced a more usable file! Have you found that to be repeatable?

[shorter]

Repeatable in what sense?

[mjm]

46 minutes ago, shorter said:

Repeatable in what sense?

In the sense that every time you have an unwieldy AutoCad file, passing it through Vectorworks reliably creates a smaller, nimbler file.

[shorter]

I wouldn't have thought so.  This exercise was merely to get a useable 2D output from a VW model or imported IFC where no 2D data was forthcoming from the author of the model.

 

Importing an unstructured, chaotic autocad file (you know the sort of thing you usually get from an autocad user...) is a huge problem.

 

Importing a DWG from Revit can be a huge problem.

 

In most cases the 'problem' is created by the issuer not checking or caring what they send you.