Reason why some faces of a polysurface transfer cleanly, and others mesh?

All surfaces of a given polysurface are planar and faces are merged, but certain faces looked meshed when they bake into Revit. The other surfaces look like a single boundary of a planar surface. Is there a reason why certain faces are being meshed?

If you use Directshapes, Revit may import them as BREP solids or Meshes. If they are meshes, then the BREP was rejected and the mesh is the backup. The reason BREPs get rejected can be from

  1. bad tolerances
  2. edges that are under 1mm
  3. Surfaces with too many control points.

To see what you are dealing with send us shapes that are not translating in Rhino and we can see what is happening.

QPK Reception Desk to RhinoInside.3dm (7.8 MB) I deleted the faces in question and used cap to remake them (meaning they are planar), but they still came over meshed. In this file I have isolated the two breps with the issue.

More info: I exploded the pre-extruded polysurface and rebuilt the bad surface with a 4-point surface. I then offset that joined polysurface and now it comes into Revit how I expected. For reference, those surfaces were originally created by Boolean differencing with a simple cube.

There are some unusual trims on the faces of the lighter colored solid:

Those little extended edges are super small slits that will drive Revit crazy.

Yeah, I noticed that too. It has to do with how Rhino offsets each face by a different perpendicular normal. I tried an extrusion in the xy plane and a Boolean union which cleaned up some of those weird edges, but that came into Revit as a mesh as well. So in the end, I had to explode the bad face and rebuild it with the 4-point surface tool.

Yes, I would expect that one to come in as a mesh. Revit does not like edges less then a mm. I think those infinitely thin slits would qualify for that.

Thanks for taking a look. I’ll be careful to check corners in the future.