See Subdivision Surfaces for more information on subdivision surfaces.
Poorly tessellated (non-subdivision) surfaces may show artifacts when rendering like dark edges and outlines. It's recommended to render smooth subdivisions to avoid this artifact. You may also use polygons with no normals defined and then subdivide, RenderMan will compute the normals for you.
To render a polygon as a subdivision surface, add the RenderMan tab to the OBJ node. Toggle the "Render Polygons As Subdivision" parameter found in the Geometry > SubdivisionMesh rollout. You will also need to set the Style parameter to Catmull-Clark, Bilinear, or Loop.
To match geometry from Maya (a common request and our default) you will see:
- Interpolation: Sharp Creases and Corners
- Facevarying Boundary: New Style, internal only
Details on these settings along with illustrations can be found on the RenderMan page for Subdivision Surfaces
The images below were rendered using the PxrVisualizer integrator in Houdini.