I am writing an importer using c++. I am successfully creating meshes from vertexes and face indexes, but I would like improve/smooth the completed meshes.
The underlying SDK function, to the RhinoCommon function you reference, is ON_BrepFromMesh. See opennurbs_brep.h for details.
That said, this isn’t a very useful function, in most cases, as it creates a faceted polysurface with a degree-1 NURBS surface for each mesh polygon/face which really isn’t anymore useful than a mesh. You might have more “smoothing” success converting the Mesh to SubD.