ToNURBS

Toolbar Menu

Geometry Fix

SubD Tools

Not on menus.

The ToNURBS command converts mesh objects and SubD objects/edges to NURBS surfaces or curves. It can also convert simple objects to NURBS for programs that only read NURBS. For example, Extrusion object is one of the simple object types. It is defined only by a profile curve and a length.

To create NURBS surfaces

  • Select a mesh or SubD object.

To create NURBS curves

  • Hold down Shift+Command and click mesh or SubD edges. Double-click to select an edge loop.

Command-line options

DeleteInputObjects
Yes

The NURBS object will replace the non-NURBS object.

No

The NURBS object will simply be added on the current layer. Both the old and new objects will be in the same location.

MeshOptions (Mesh input only)

Click to set the options only used for mesh to NURBS conversion.

TrimTriangularFaces
Yes

Mesh triangles will be replaced by trimmed NURBS surfaces.

No

Mesh triangles will be replaced by untrimmed NURBS surfaces.

SubDOptions (SubD input only)

Click to set the options only used for SubD to NURBS conversion.

Faces

Specifies if quad face grids will be merged when converting a SubD into a polysurface.

Packed

Merges a quad face grid into a larger NURBS surface.

ShowFacePacks

Shows different colors on SubD faces based on the divisions of rectangular quad grids.

ForceUpdateFacePacks

Resets the rectangular quad grids after creases are added or faces are deleted on the SubD. It is equivalent to the PackSubDFaces command.

Unpacked

Creates a NURBS surface from each quad SubD face.
Unpacked
SubD
Packed
ExtraordinaryVertex

Continuity on a SubD at extraordinary vertices is G2. When converting a SubD to a polysurface, extraordinary vertices can only be approximated. This option controls the continuity of the polysurface at extraordinary vertices. Away from extraordinary vertices, the polysurface is always G2 in smooth SubD regions.

Zebra analysis shows G2 near an extraordinary vertex on a SubD.
G0

Makes the polysurface G0 at the extraordinary vertices. The shape of the polysurface will be as close as possible to the SubD.

G1

Makes the polysurface G1 at the extraordinary vertices. The polysurface deviates from the SubD a little bit more than G0.

G1x

Similar to the G1 option, but tries to make the edge normal deviation around extraordinary vertices 1 degree or less.

G1xx

Makes the polysurface G1 at the extraordinary vertices and uses double knots on the isocurves near the edges. More control points will be added to improve the smoothness of Zebra stripes.

G2

Makes the polysurface G2 at the extraordinary vertices.

Forcing G2 adds bulges or dents around extraordinary vertices.