Jump to content
Sign in to follow this  

Optimising IFC Project Export

Recommended Posts

I'm currently creating an IFC project to send to a Revit user and was wondering if anyone had any tips to make the export quicker?

The .vwx file is a furniture layout consisting of loads of symbols for chairs, tables, storage etc. File size 37mb. I've remodelled all the symbols so they are relatively simple whilst keeping their basic form, but on export, the IFC is coming out at 900mb and takes 30mins to export.

Are there ways to optimise the vwx file before exporting to reduce the IFC file size and to speed up the export?

Edited by willcfg

Share this post

Link to post

digitalmechanics - Yet to try this due to time constraints, but that is a good suggestion!

Jeffrey - I set it to low but it didn't seem to make any difference in file size.

Share this post

Link to post

Incase anyone is interested, I did some experimenting with exporting different complexity models to both IFC and DWG with a view of comparing the file sizes and identifying what was causing the large output. I found that when I filleted (rounded) the edges of objects, the exported IFC file size was increased dramatically.

(It is worth noting that I had attached 35 pieces of IFC data to the original symbol which will of course have been stripped out of the DWG.)

IFC export test results:

Cube: 10 KB

Cube with filleted edges: 1.4 MB

DWG export test results:

Cube: 276 KB

Cube with filleted edges: 493 KB

Vectorworks original file:

Cube: 126 KB

Cube with filleted edges: 193 KB

I also found that an exported IFC file of a model with solid subtracts was larger than if you drew a 2D shape with a hole in the middle then extruded it, however no where near the same increase in size as the filleted edges caused.

IFC export test results:

Cube with hole (extruded from 2D shape): 13 KB

Cube with hole (solid subtracted): 97 KB

So in future, when exporting an IFC project I will remove all of the fillets I can (whilst retaining the critical dimensions) in an effort to minimise the final IFC export size.

Share this post

Link to post

That's no secret.

And a problem for any Export from VW.

IFC concentrates on data, not so much on geometry.

What you will see there is the least way to describe geometry.

All gets converted down to meshes, or even worse, just single faces.

Like VW, ACAD knows Solids.

If you export with Solids option on, the DWG export data will be similar

small like in VW. It is saved as a cube with rounded edges.

But if you deactivate to export solids, which you have to for many Apps

that can read (only simple) DWG or DXF, everything will be converted to


No problem for things like a normal cube. A Mesh from a cube is best

"a group" of 6 Faces. Worse, 12 Faces if you have to use triangulate for

better export results.

The problem with exports start when geometry gets rounded.

Their data saved as Solids is f.e. a Cube with its 3 dimensions plus

the radius for the rounded corner, pretty small data.

If you export (or convert) this geometry to a Mesh, the rounded corner

has to be divided to a certain amount of planar faces, that it will still look


So an export option, to control that mesh resolution those Cylinders, Pipes

or even more complex geometry is mandatory.

Of course there are small parts where you won't see and need all that resolution,

while thick columns will need more resolution to reach a certain quality.

Also there may be less important parts that need simply to look a bit rounded

or more important parts that you will have a certain quality.

Normally an App has at least a simple setting, into many corners a circle

will be divided. That may force you to export parts of your geometry with different

resolution settings.

Better is advanced software that gives an option to set the min/max size of the

faces, or combined with the circle division.

Back to VW, there is missing a resolution setting for mesh export in any export


But there is a setting that controls that meshing resolution for internal operations.

It is hidden as a global VW setting in VW preferences > 3D > "3D conversion resolution"

(Which should be at least a file wide setting),

which influences meshing for exports Too.

Well, it does most of the time, at least it works for DWG/DXF, but it gets ignored for

C4D save/export, where always the highest resolution is used.

(Which makes it very useless, if you get 30 mb for your Architecture, but 2,5 GB (!!!)

because of the unimportant duct pipes, that just have to be there in a very reduced

manner, because a client want to see these through the gaps of the ceiling panels)

So as a conclusion for the IFC,

try to set the VW > 3D > conversion resolution to "low",

(better reopen the file or VW complete after)

An try if IFC export will not ignore that setting like C4D, and if the file size gets smaller.

If the resolution is not sufficient, set this setting back a bit higher, step by step.

Share this post

Link to post

Hi Zoomer, thanks for the detailed response. Every day is a school day! It is useful to understand what is actually going on behind the scenes when an export is done.

I'll experiment with altering the resolution setting again and see what the outputs are like.

Share this post

Link to post


1. as for me, a good point with the '3d conversion resolution' settings, thanks a lot. here are the results:

- a setting 'low' - 84 mb

- a setting 'medium' - 150 mb

- a setting 'high' - 957 mb

i preferred to not to try with 'very high' :P

2. is it normal that the grid axes appear on each storey in the ifc (screenshot)? i have them on one separate layer in the project file.

3. but there's still a point missing: the storeys case with offset foundation layer (screenshot). i've tried above and below ground, to no avail. eventually i'd probably be forced to remove the storey dependancies. and the strange thing is: it worked well in the v2014....

4. is the promised ifc export manual ready yet?


Share this post

Link to post

more to point 3:

deleting of the storeys resulted in such situation (screenshot 3). what the f*#%k is wrong with the ifc export? in the project file everything looks ok.

i'm helpless. thx in advance for any clue...


Share this post

Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  


7150 Riverwood Drive, Columbia, Maryland 21046, USA   |   Contact Us:   410-290-5114


© 2018 Vectorworks, Inc. All Rights Reserved. Vectorworks, Inc. is part of the Nemetschek Group.

  • Create New...