Collaboration: Revit Support

[Matthew Johnson]

More than just having to share model content with other consultants, our practice is multi-platform because of client mandates and so we are working between both Archicad and Revit every day. There is a limit to how much I can complain about how bad Revit's implementation on IFC importing is but I'd like to get some discussions going on how the IFC export from Archicad can be tweaked to better enable importing to Revit. 

RFA/RVT addon

1. No support for Storeys / Reference Levels in the exported geometry. The resultant Revit model may be geometrically correct but it cannot be used to view the building cut into floors.
2. No support for grids.

IFC Model Exchange with Revit Add-on

1. The add-on currently uses the "Open IFC" workflow which I understand Autodesk has stopped development on many years ago. They now focus on the Link IFC workflow which opens/translates IFC data much faster but uses an entirely different engine. On some of our projects this difference can equate to a hour versus a day to open a 30 storey IFC model. This means if we want a fast translation to Revit we have to forego the benefits of the Add-on and do the steps manually.
2. On of the issues we are curerently wrestling with is the visability of 2D information for doors and windows. https://github.com/Autodesk/revit-ifc/issues/358. ifcOpenShell has a patch to attempt to fix the issue (when it works) but it would be great to have the fix built into the Achicad IFC export in the first place. According to the programmers at ifcOpenShell:

   ArchiCAD has the ability to store 2D data with objects like doors for door swings. ArchiCAD's implementation is not 100% correct (using
   footprint instead of annotation contexts), but otherwise not too shabby.
   
   Revit, however, is incapable of understanding this 2D representation. Revit users linking in IFCs produced by ArchiCAD may experience the
   following symptoms:
   
   A. Invisible doors, and difficulty selecting doors
   B. Invisible door swings, or only visible at particular view ranges
   C. Weird arc shapes around doors
   D. Extra lines around doors and walls
   E. Cannot easily change visibility graphics of 2D vs 3D elements
   F. Cannot view 2D data in a 3D view

3. Grid elements trasferred to Revit via IFC have a behaviour of being generated first so their 2D extent is correct but their height is limited to 0-1m so they have to be manually stretched to match the height of models and reference levels before they can be seen in plan views.

I'm sure there will be more items to dicsuss, but I thought I'd get a topic going so that we have somewhere to discuss them. 

[Erik Bjornhage]

Yes!

This is interesting - we are about to become multi-platform (not by choice) and this would be crucial for our collaborations wihtin project teams.

If we can't change our clients then we have to try the second best...