InsertKnot

The InsertKnot command adds knots in curves or surfaces.

Steps

Select the object.

Pick a location for the knot.

Note:

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Inserting a knot in a surface also displays an isoparametric curves at the knot location if isoparametric curves are being displayed.

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The status bar distance pane displays the parameter value when inserting a knot to a curve. You can also type a parameter value to add a new knot.

Command-line options

Automatic

Adds a knot/knot line halfway between existing knots to maintain as uniform a structure as possible.

Increases the knot density of a curve or surface to add more control points while maintaining an even knot distribution for better point pulling behavior.

Midpoints

Places markers half-way between the existing knots/knot lines that can act as guides for inserting knots midway between existing knots.

Symmetrical

Adds knots on both sides of the center of the curve or surface.

Undo

The Undo option reverses the last action.

Direction (Surfaces only)

Specify the u, v, or both directions.

Toggle (Surfaces only)

Toggles the direction between u and v.

RemoveKnot

The RemoveKnot command deletes a knot from a curve or surface.

Steps

Select a curve or surface.

Click the knot to remove and press Enter.

Note: Remove knot can be used to remove the connecting joint between two joined curves. The resulting curve will not Explode into separate parts.

Command-line options

Direction (Surfaces only)

Specify the u, v, or both directions.

Toggle (Surfaces only)

Toggles the direction between u and v.

Undo

The Undo option reverses the last action.

RemoveMultiKnot

The RemoveMultiKnot command removes multiple but not fully-multiple knots from curves and surfaces.

Notes

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Multiple knots means more than one knot at a location. Fully-multiple knots means as many as possible at a location, which is equal to the degree.

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There may be a kink at that point that is desired. Surfaces created with the Sweep2, BlendSrf, and OffSetSrf commands can be built with multiple knots.

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The Simple Sweep option in the Sweep2 dialog box makes surfaces that do not have multiple knots, but this option is only available in restricted cases where all the curves are perfectly matched and correctly placed. The usual behavior of the Sweep2 command allows accurate sweeps to be made from diverse input.

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The RemoveMultiKnot command removes these stacked knots if they are not fully multiple. Removing the multiple knots can cause some loss in the surface precision, but in practice, this is usually not a problem.

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The advantage to removing these knots is that the surface point count is reduced.