Performs local modification on a curve. Local means that the modification to the selected point will be localized and not distributed along the entire curve. You can modify the position, tangency and radius of curvature for any point on the curve.

 

A triad is displayed at the selected point and at the end points of the curve. The triad is used to modify, lock or unlock the constraints at the selected point. The visual indicators on the triad are used for this purpose. When you are dome modifying the curve, middle-click again to exit the command.

 

See Indicators for Modify Curve Locally command in the Notes section below.

 

 

 

Required Inputs

 

• Curve - Select a curve to modify.

• Point on Curve - Select a point on the curve to modify or middle-click to exit the command. As you move the cursor over the curve, a triad will appear. This triad is used to modify the position, tangency and radius of curvature at the selected point.

• Parameter - Select a parameter to modify or middle-click to select another point on the curve. The visual indicators listed in the Notes section below are displayed on the triad. Select an indicator to modify the parameter.

 

Optional Inputs

 

• Control points - Select this option to modify one or more of the curve's control points. Select the controls points and then select one of the options below.

• Add - Select a point on the curve. A control point for that point will be added. Middle-click to return to the control point options.

• Modify Position - Select the control points to move. As you drag the cursor around, the preview echo will dynamically display the new curve.  Next, select the destination point.  middle-click to return to the control point options.

• Delete - Select one or more control points to delete and then middle-click to return to the control point options.

• Reduce - Select this option to reduce the total number of control points.

• Refit - Select this option to refit the curve. This option can remove unwanted abnormalities that currently exist in the curve. Note that this option will change the path of the curve.

• OK - Return to the Modify Curve options.

• Display - Modify the display of the curve during editing.

• Display curvature comb - Check this box to display the curvature plot of the curve during editing. This is similar to the Draw Curvature Plot of Curve command. Use the slider to control the density of the plot (i.e., the total number of teeth).

• Show hints for modifications - Check this box to toggle the display of the indicator hints during editing.

• Local - Use this option to specify how the modification should affect the curve. Select one of these options:
  
  Local - Keep changes local to the affected point of the curve. This only relates to "point on curve" editing, not control point editing.
  Global - Distribute the changes along the entire length of the curve.

 

 

 

 

Use this command to remove many curve imperfections by reducing the total number of knots (i.e., control points) and thus eliminating offending knots. This command is ideal for simplifying problematic curves imported from other CAD systems.

 

Required Inputs

 

• Curve - Select the curves to reduce.

• Tolerance - Enter the allowable deviation from the original curve.

 

 

 

Use this command to remove unwanted imperfections in a curve. It involves the redeployment of control points. Some points are allowed to move freely while others are constrained. The types of imperfections that this command will remove include:
 

• Ogee - Inflection point (sudden 180 degree change in curvature).

• Flat spot - A local minimum of curvature.

• Buckle/bump - A local maximum of curvature.

• Bulge/knob - A discontinuous curvature.

• Crease - A discontinuous tangent plane.

 

 

Required Inputs

 

• Curves - Select the curves to smooth.

 

 

Optional Inputs

 

• Fairing - Select the smoothing technique to apply:
  
  None - No fairing is applied.
  Energy - The curve is created for minimum energy. This produces a less stressful and a more gradual smoothing of the curve.
  Variation - The curve is created with less curvature variation such as with lines and circular arcs.
  Jerk - The derivative of the curvature is minimized. A curve with less total fluctuation is created.
  Bending - An approximated form of the Energy method that requires less calculation time is used.
  Tension - Uses the same techniques as the Energy method and couples it with the desire to produce the shortest total curve length.
   

• Tolerance - Enter the allowable deviation from the original curve.

 

 

 

Use this command to insert a knot (i.e., control point) at a specified parameter vale (t) along a selected curve. Optionally, you can pick a point on the curve to insert a knot. The parameter space partition of the curve is displayed as a reference. This command is similar to the Control points/Add option of the Modify Curve command.

 

Parameter Space Partition of a Curve

 

Required Inputs

 

• Curve - Select the curve to modify.

• Knot value/Point - If Knot value is selected, enter the (t) value here. If Point is selected, pick a point on the curve to locate the knot.

 

 

 

Use this command to perform a cubic refit of one or more curves at the Part, Sketch, and Drawing Sheet Levels. This command replaces the subject curves with non-rational approximations with fewer control points. Both tangent and curvature methods are supported and the refitting may be done separately or in parallel to refit a set of curves with a common knot vector. The parameter space partition of the curves is displayed when selected.

 

Optional Inputs

 

Common parameter space

Check this box to refit multiple curves and try to force them to have a common parameter space (knot vector).

 

Continuity

Specify the continuity method used for refitting.

 

• Tangent - The blend or fillet is tangent to the two subject curves and results in a radial arc. Continuity of curvature is not maintained.

• Curvature - The fillet begins and ends with the tangent radius for the two curves being filleted while attempting to maintain the desired fillet radius in the body of the fillet. Continuity of curvature is maintained along the fillet. The result is a blended curve and not an arc.

 

 

Tolerance

Specify the tolerance used to refit the curves. Curves will be refitted within the specified tolerance of the original curve.

 

 

 

 

 

Use this command to refit a curve by modifying its degrees of freedom. Inputs required for this command include specifying the portion of the curve to refit, the end point continuity, the number of sample points and the degree to refit the curve to (1-6).

 

 

Required Inputs

 

• Curve - Select the curve to refit.

• Portion - Specify the start and the end of the portion of the curve to refit. You can select a control point, a point on the curve, or enter a parameter (t) value in the range of 0.0 - 1.0.

 

 

• Continuity - Select from the pop-up menu to specify which ends of the modified portion of the curve to maintain tangent continuity.
  
  
  None - Do not maintain tangent continuity at either end of the modified portion.
  Start - Maintain tangent continuity at the start of the modified portion (at the first point selected).
  End - Maintain tangent continuity at the end of the modified portion (at the second point selected).
  Both - Maintain tangent continuity at both ends of the modified portion.

 

• Sample - Specify the number of sample points to refit the curve.

• Degree - Specify the degree to refit the curve(1-6).

 

 

Optional Inputs

 

• Tangent - Specify if/where interpolation should occur at end tangents.
  
  None - No interpolation occurs.
  Start - Interpolate the start end tangent (at the first point selected).
  End - Interpolate the end tangent (at the second point selected).
  Both - Interpolate both end tangents.

 

• Knot - Specify the method to determine the knot sequence.
  
  Natural - Use sample parameters as knot values. Sample parameters are parameter values corresponding to the sample points.
  Uniform - Use a uniform knot vector. The knot values are placed at uniform intervals in the parameter space of the curve.

 

• Break at multiple knots - Check the box if you want the curve to be broken at locations where multiple knots occur.

• Sensitivity - Specify the sensitivity of curvature for sampling points. Enter a value within the range 0-200. The default value is 50.

 

 

 

• Curve Editing with Parting Lines (see CAD Tips & Techniques).

• See Command Options Forms for any options not shown here.

• Indicators for Modify Curve Locally command.

 

Indicators for Modify Curve Locally Command
Indicator	Color	Description
	Red	Target point on the curve. This is also the position indicator. Select the indicator and drag it to relocate the position of the target point.
	Red	Tangent indicator at the target point. Select the indicator and drag it to modify the curve tangency at the target point.
	Red	Radius of curvature indicator at the target point. Select the indicator and drag it to modify the radius of curvature at the target point.
	Gray	Tangent indicator for the end point.
	Grey	Radius of curvature indicator at the end point.
	Green	Unlock indicator at the target or end points. Indicates that the position, tangency or radius of curvature (whichever applies) is free to change.
	Red	Lock indicator at the target or end points. Indicates that the position, tangency or radius of curvature (whichever applies) is locked and cannot change.