ToNURBS

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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.

The ToNURBS command replaces: 

To create NURBS surfaces

To create NURBS curves

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.

Unpacked

Creates a NURBS surface from each quad SubD face.

Unpacked
SubD
Packed
ExtraordinaryVertex (G0/G1/G2)

Continuity on a SubD at extraordinary vertices is G2. When the ToNURBS command converts a SubD into a polysurface, extraordinary vertices can only be approximated. This option controls the continuity of the polysurface near extraordinary vertices. Away from extraordinary vertices, the polysurface is always G2 on smooth SubD regions.

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

Makes position continuity near extraordinary vertices. The polysurface is as close as possible to the SubD.

Zebra analysis shows G0 near the extraordinary vertex on a polysurface.
G1 (Default)

Makes tangent continuity near extraordinary vertices. The polysurface deviates from the SubD a bit more than G0.

Zebra analysis shows G1 near the extraordinary vertex on a polysurface.
G2

Makes curvature continuity near extraordinary vertices. The polysurface deviates from the SubD a bit more than G1.

Zebra analysis shows G2 near the extraordinary vertex on a polysurface.

Forcing G2 may add bulges or dents to the polysurface around extraordinary vertices.

See also

For more information, see Rhino SubD Project.

 

 

 

Rhinoceros 7 © 2010-2021 Robert McNeel & Associates. 23-Jul-2021