ExtractControlPolygon

Creates a polyline through the control points of a curve, or a polygon mesh through the control points of a surface.

Steps:

• Select curves or surfaces.

• This creates polylines and/or meshes that have vertices at the original objects' control points.

Notes

• The ExtractControlPolygon command is useful if you want to extract control polygons as objects.

• It is possible to use the ExtractControlPolygon command to create polygon data that you can export and manipulate in a program that handles mesh smoothing.

ExtractIsocurve

Creates curves that duplicate surface isoparametric curves at specified locations on the surface.

Steps:

1. Select a surface.

   The cursor is constrained to the surface, and isoparametric curve display at cursor.

   The draft angle of the surface displays at the status bar.

2. Pick to create the curve(s).

   Note: Use the Int object snap for snapping to isoparametric curve intersections.

Options

Direction

Specify the u-direction, the v-direction, or both.

Toggle

Toggles the direction between u and v.

Notes

• The ExtractIsocurve command creates the simplest possible curve exactly on the surface in u, v or both directions.

• The ExtractIsocurve command is useful for creating trimming curves on surfaces. You can make surfaces trimmed along isoparametric curves into untrimmed surfaces with ShrinkTrimmedSrf.

• You can use isoparametric curves to recreate an existing surface with different parameterization. To do this, extract several isoparametric curves, and Loft a surface through them.

• If you need to put angled cross sections along a surface, use the Section command instead of the ExtractIsocurve command. If you need curved cross sections, use the Project or Intersect commands.

• The Knot object snap can be used to create isoparametric curves at exact knot locations.

• In contrast to the InsertKnot command, the ExtractIsocurve command creates separate curves that are not attached to the surface.

• If you need to place an object on a surface, use the ExtractIsocurve command to add visual cues or locations that can be snapped to on the surface area and help position the object. Using the ExtractIsocurve command does not change the surface in any way.

ExtractPt

Places point objects at curve control point or edit point locations, surface control point locations, and polygon mesh vertices.

Steps:

• Select curves, surfaces, or polygon mesh objects.

• Rhino creates point objects for every control point in the object.

To extract selected points only

1. Turn on the control points or the edit points on an object.

2. Select the control or edit points to duplicate.

ExtractSrf

Separates or copies a surface or a copy of a surface from a polysurface.

Note: To remove a segment from the selection, press the Ctrl key while clicking.

Stps:

• Select the surfaces.

• The surfaces are separated from the polysurfaces. The remainder of each polysurface will stay joined.

  The extracted surface is also removed from any groups to which the original surface may belong.

Notes

• When you are extracting a surface from the polysurface the ExtractSrf command can save you a lot of time (as opposed to Explode). This is because it lets you extract only the selected surfaces from the polysurface, and so there is not as much joining work to do afterwards.

Options

Copy

ExtractSubCrv

Separates or copies curve segments from a parent polycurve.

Note: To remove a segment from the selection, press the Ctrl key while clicking.

Steps:

1. Select a polycurve.

2. Select curve segments.

Options

Copy

DeleteSubCrv

Removes a portion of a curve that is between two selected locations.

Steps:

1. Select a curve.

2. Pick a start for the deletion.

3. Pick an end for the deletion or enter a length.

ExtractWireframe

Creates curves that duplicate surface or polysurface isoparametric curves displayed in the wireframe view.

Steps:

• Select surfaces or polysurfaces.

CreateUVCrv

Creates curves that duplicate the untrimmed boundary and trim curves of a surface as planar curves onto the world x-y plane.

Steps:

• Select a surface.

Note: The control polygon determines the sizes of the uv curves.