SubD objects

Rhino SubD objects are high-precision Catmull Clark subdivision surfaces designed to quickly model and edit complex organic shapes.

• SubD objects in Rhino are measurable and manufacturable. They can be converted to either high-quality NURBS or mesh (quads or triangles) objects, and exported to file formats (e.g., IGES, STEP, OBJ, STL...) that support either meshes or NURBS.

• Most SubD creation and editing commands can be found on the SubD menu and SubD Tools toolbar.

• The Rhino SubD Rules document provides the gold standard technical description of the mathematical definition used by Rhino SubD objects.

• Press the Tab key or use the SubDDisplayToggle command to switch SubD objects between flat and smooth modes.

SubD edges and vertices

Rhino SubD objects have two types of edges (crease and smooth), and four types of vertices (smooth, crease, corner, and dart).

	Smooth edge An edge that smoothly connects two faces.
	Crease edge A hard edge that connects two faces. Edges on the boundary are also crease edges.
	Smooth vertex A vertex that is attached to only smooth edges.
	Crease vertex Any vertex that is between exactly two creased edges that form a smooth crease.
	Corner vertex A vertex at a sharp corner between two crease edges and any vertex attached to three or more crease edges.
	Dart vertex A vertex attached to exactly one crease edge.