Surface continuity vs. geometry types

  • Properly designed NURBS surfaces can guarantee C2 continuity, but it can be difficult/time consuming to make complex C2 parts
  • The limit surface of the Catmull-Clark algorithm (SubD) can guarantee C2 continuity in areas with no extraordinary points. In areas with extraordinary points - C1 can be guaranteed. For complex parts, designing surfaces with SubD can be much easier/faster than using NURBS

An extraordinary point in a regular 4 edge mesh is a vertices with more or less than 4 edges connected, see example in (fig. bottom)

1:13 - RobinGen