Converting Mesh to Surface (.dwg file from Autocad to Rhino)

I am having a problem in importing a 3D surface (not poly-surface) from Autocad to Rhino. The surface turns to a mesh and is only convertible to poly-surface after it has been imported from Autocad. How do I solve this? Attached are the files. Thanks.
Try3.3dm (626.1 KB)
Try3.dwg (1.5 MB)

Hello - in this case it is relatively easy to get what might be an acceptable surface from the mesh.

  1. ExplodeBlock the objects.
  2. ExtractMeshPart the top ‘surfaces’ (four mesh parts) of each and hide the rest.
  3. Join the two parts on each half.
  4. Patch each mesh
  5. Trim the surfaces with a centerline
  6. DupBorder the two meshes
  7. ProjectToCPlane the border curves. (actually, just trimming the initial patces with the border curves should work fine - probably no need for the project and Boolean steps.)
  8. CurveBoolean to get the outer loop.
  9. Trim or Split the patch surfaces with this curve.

  10. OffsetSrf Solid=Yes, as needed

Note in all of this the outer trim will be with a polyline - to make a smooth trim, you’ll need to remake that outer curve with a clean Nurbs curve.



Pascal’s option here is the simpliest. But, I did want to point out another option is to use the Quadremesher and the SubD tools in the Rhino 7 WIP. This leads to a lot of ways to edit these forms.

You can find out more about the SubD here: Rhino 7 Feature: Subdivision Geometry

Here is how Meshes to SubD can be converted:

And the here is a new draft of a tutorial on getting these shapes with SubD:


Thank you for the reply!