AutoCAD in Revit – A Bizarre Linked File Approach

Sam Swegle and I recently worked through a problem he was having with linking an AutoCAD file into his Revit Project.  He specifically wanted to link the file rather than import it since the file was still being updated by the mechanical engineer.

The problem he was having was that the HVAC components needed to be located so that they appeared to be partially concealed by a lower ceiling as viewed in his (RCP-reflected ceiling plan) with a portion of the HVAC system being exposed and fully visible where there was no ceiling.

Our initial solution was to link the AutoCAD file into a separate Revit file that would then be linked into his active project.  We opened both the active project and the empty Revit file that would receive the AutoCAD file in the same instance of Revit and copied the ceiling and then pasted it into the empty file to get a registration component to which the AutoCAD file could be aligned to.  Once the AutoCAD file was linked in and registered we applied a masked region where the ceiling was and deleted the ceiling.

The hope was that the masked region would block out that portion of the ACAD file we didn’t want to see, leaving only the visible portion of the HVAC and the ceiling that was present in our active project file.

The results were that the masked region effectively covered our ceiling in the active project.  Not what we wanted.

Now I’ve done some counterintuitive things in Revit before with mixed results and thought I would test an off the wall approach.  I had Sam override the visibility setting for the masked region and make it transparent, in the linked file, and then update the link.  For some baffling reason the ceiling could now be seen and the ACAD file was properly masked where the ceiling was.

The only thing I can figure is that the override to transparency was carried through to the active project revealing the ceiling but the masked region was still seen as a masking element as it related to the ACAD file.

Go Figure.
Still Scratching my Head on This One
Carl