OPENBIM collaboration and the use of IFC2x3 (format currently supported by ARCHICAD 19) files requires a reasonable amount of skill to get right. There are a number of issues that users are likely to face when taking advantage of OPENBIM collaboration processes via IFC. Not all users have been trained in such processes and many are not sure what to expect from an IFC based workflow. Rob Jackson has a great post over on the Bond Bryan BIM Blog for REVIT Users collaborating with ARCHICAD Users so make sure you read this in conjunction with this post. Read it here...

An area worth discussing initially is symbology - the way that objects / elements in display in plan when an IFC2x3 is opened in the authoring software of choice. This is one of the biggest issues most commonly raised by anyone that we collaborate with, be it in REVIT or ARCHICAD.

The thing to be mindful of here is that IFC2x3 consists of the following:

3D Geometry representing elements … and Data attached to these elements.

It does not include data relating to 2D symbolic display. This explains why IFC files with complex geometry will display linework similarly to how an element will display if it were in 3D plan projection mode in ARCHICAD. Many collaborators we work with get frustrated that the elements are not as clean and don’t match the appearance of native elements in their own authoring software – "this looks different, so I don’t want to play anymore".

There is a solution to this problem and a reasonably simple one. The collaboration process is really split into two parts. The first one is the reference model > 3D mode, which is the BIM side of things and the reason we should embrace IFC in the first place. Turn it off / filter it when you produce your plan drawings.

The second part is drawings > 2D mode, where you use a DWG / PDF file as the reference background where required for drawing production. This will give you the clean symbolic output that you desire and as long as the DWG / PDF file is coming directly from the model in the native software then there will not be any conflicts / clashes.

When you export your IFC file periodically it should include with it, DWG files for use as backgrounds and PDF files of your current layout sheets. Publishing these when set up correctly is all done by only a few clicks and if linked to a cloud service like Dropbox these files can be instantly obtained by your collaboration partners.

At the recieving end by using Xref / linking methods, the backgrounds will update more quickly than it would take to clean the received IFC file to prevent Attribute pollution.

We will likely see future developments in this area that will allow for data to be attached within the IFC schema for symbolic display which will remove the need for this current workaround which is a method that a number of leading users are employing around the world.