Existing meshes, 2D polygons, 3D polygons, and solid objects with planar faces can be converted into subdivision objects for modeling.
To convert an existing object to a subdivision object:
Select the object to be converted.
Select Modify > Convert > Convert to Subdivision.
The object is converted to a subdivision object. This action cannot be reversed. By default, all edges and vertices in a subdivision object are smooth. To sharpen an edge or vertex, use the Edit Subdivision tool (see Smoothing or Sharpening a Subdivision Model).
To create a subdivision object based on a solid with non-planar faces, such as a cylinder or sphere, first convert the object to a mesh, then convert the mesh to a subdivision object.
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