One particular Rhino surface will not import into Revit.

[jverser]

This particular Rhino surface will not import into Revit 2018.

I've exported as an SAT file and DWG file -- both produce the error below.  I've tried to Make Uniform, Shrink, Trim, Rebuild, Flip direction, and maniuplate UV directions in Rhino. I've tried to bring this into a mass family first -- same error (i.e. "Revit cannot import some of the geometry. This Result can be caused by various issues with the source file. Adjust the geometry in the file and try the import process again"). Only after significantly splitting or deleting control points down to a small portion can I get this object to import. I've sucessfully imported similar, but more complex surfaces from the same Rhino file into Revit. I've tried exporting and importing from/to new Rhino and Revit files. How should I proceed to trouble shoot this surface to clean, purge, audit, or check it? Am I missing something critical? Rhino and Autocad don't seem to identify any geometry problems with this object.

.  

object details:

     Surface.
     NURBS Surface (rational)
     "U": degree =3 CV count = 6 (0" <= U <= 19'-4 5/8")
     "V": degree =3 CV count = 30 (0" <= V <= 5'-11 7/8")
     Edge Tally:
     4 boundary edges
     Edge Tolerances: all 0"
     Vertex Tolerances: all 0"
     Render mesh: 1 fast mesh 1801 vertices 2128 polygons
     Analysis mesh: none present

. 

[Anonymous]

Hi Jverser,

You probably sorted this thing out. I faced the same problem and tried all the workarounds you mentioned below. The 3dm file wouldn't load in the first place in an in-place mass in Revit. Exporting the Rhino Surfaces to ACIS solved part of the problem where the file could load in Revit but the "roof pick by face" tool wouldn't work for all surfaces. I then tried all the tricks you mentioned and none worked stating that "Revit cannot create roof. The problem turned out to be that the surfaces were just too wrinkly for the roof to adapt on (you wouldn't see it unless you really zoom in). The reason of that is that the curves used to create the surfaces had a big number of control points. The only workaround that worked was going back to Rhino and duplicating the edge of the surfaces, rebuilding them with a smaller number of control points in a way were they meet the difference tolerance, and recreating the surfaces. After reimporting the geometry as ACIS in a mass in Revit it worked.