Creating NURBS curves

NURBS (Non-Uniform Rational B-Splines) are used to create curves in 3D space. They can also be used as defining objects for extrusions along a path.

NURBS curves can be created using the NURBS Curve tool and one of two modes. Specify the NURBS curve degree prior to clicking a mode.

NurbsCurve_modes.png 

NURBS curves can also be created from planar objects by converting them to NURBS; see Converting to NURBS.

Setting the NURBS curve degree

Mode

Tool

Tool set

Shortcut

NURBS Curve Degree Setting

NurbsCurve_NurbsCurveDegreeSetting_mode.png 

NURBS Curve

nurbscurve_tool.png 

3D Modeling

Shift+7

The curve degree affects the number of vertices created; the higher the degree value, the greater the number of vertices.

To specify the NURBS curve degree:

1.      Click the tool and mode.

Alternatively, double-click the NURBS Curve tool to open the Curve Degree dialog box.

2.      The Curve Degree dialog box opens. Specify the curve degree for the tool to use.

Set the degree value to 1 to create a NURBS curve with linear segments (similar to a 3D polygon). A linear NURBS curve can be used to measure an object from point to point in a 3D view.

NURBS curve by interpolation point

Mode

Tool

Tool set

Shortcut

Interpolation Point

NurbsCurve_InterpolationPoint_mode.png 

NURBS Curve

nurbscurve_tool00167.png 

3D Modeling

Shift+7

 

To create a NURBS curve by interpolation point:

1.      Click the tool and mode.

2.      Click to set the first point on the curve.

3.      Click to set the point through which the curve passes.

Continue clicking to add more interpolation points, extending the curve.

NurbsCurve_interpol.png 

4.      Double-click to set the end point of the curve.

NURBS curve by control point

Mode

Tool

Tool set

Shortcut

Control Point

NurbsCurve_ControlPoint_mode.png 

NURBS Curve

nurbscurve_tool00170.png 

3D Modeling

Shift+7

To create a NURBS curve by control point:

1.      Click the tool and mode.

2.      Click to set the first point on the curve.

3.      Click to set the point that the curve pulls toward but does not touch.

Continue clicking to add more control points, extending the curve.

NurbsCurve_control.png 

4.      Double-click to set the end point of the curve.

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Reshaping NURBS curves

Concept: NURBS curves and surfaces

 

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