Standard Options

The Standard Options tab of the Curve and Surface Fitting dialog box allows you to set how breakpoints are positioned, and the tangency for surface boundaries. It is divided into two areas.

In the Curve Parameterisation area, you can select the following options to set how the breakpoints used to create surface internals are positioned:

• Manual Breakpoint Insertion – If you select this option you must enter manually the breakpoints you require for the curve. To do this hold down the Ctrl key and click to insert a guide point (red asterisk), then Ctrl-click again on the point to make it a breakpoint (yellow asterisk).
  
  
• Breakpoint Insertion to Tolerance – If you select this option, CopyCAD automatically inserts breakpoints (magenta asterisks) to ensure that the curve follows the underlying model to tolerance whilst still maintaining continuity in tangency. You enter the tolerance you want in the Curve Fitting Tolerance box on the Advanced Curve Fitting Options tab.

If you select this option, you can insert additional breakpoints manually if you require them.

• Even Breakpoint Insertion in 3D – If you select this option, CopyCAD automatically inserts breakpoints (magenta asterisks) evenly over the curve in 3D. This means that the breakpoints are evenly distributed over the true length of the curve.

  You must also enter the number of breakpoints you want CopyCAD to insert on each of the surface boundaries using the Number of breakpoints boxes below:

  • Type the number of breakpoints you want CopyCAD to insert on the first and third surface boundaries in the Number of T breakpoints (sides 1 and 3) box.
    
    
  • Type the number of breakpoints you want CopyCAD to insert on the second and fourth surface boundaries in the Number of U breakpoints (sides 2 and 4) box.

• Even Breakpoint Insertion in 2D – If you select this option, CopyCAD automatically inserts breakpoints (magenta asterisks) evenly over the curve in the current 2D view. This means that the breakpoints are evenly distributed over the length of the curve as you are currently seeing it on screen, not over the curve itself.

  You must also enter the number of breakpoints you want CopyCAD to insert on each of the surface boundaries using the Number of breakpoints boxes below. See the explanation above for Even Breakpoint Insertion in 3D.

Note: If you have Simple Curve Fitting selected in the Curve Fitting area on the Advanced Curve Fitting tab, you cannot select an even breakpoint insertion option. You must change the curve fitting option first.

	Note: If you manually insert breakpoints when one of Even Breakpoint Insertion options is selected, CopyCAD ignores your breakpoints and inserts them according to the option selected.
	Note: This area is available as the Curve Parameterisation area in the Curve Fitting Options dialog box.

In the Tangency Options area, you can set the following options, which apply for each side of a surface:

• Tangency Off - the surfaces are created to provide best fit to the underlying triangles, without regard for tangent continuity.
  
  
• Tangency to Surfaces - new surfaces are created tangent to any neighbouring surfaces along their common boundary. This ensures that the transition between surfaces is smooth.
  
  
• Tangency to Model - new surfaces are created tangent to the digitised model. At open boundaries, tangency is maintained with the points by approaching perpendicular to the point normals.
  
  
• Tangency to Curves, Surfaces and Model - new surfaces are created tangent to the neighbouring surface, its boundaries and its internals, and the digitised model.
  
  
• Tangency to Curves - the boundaries of new surfaces are created tangent to those of the neighbouring surface. There is no tangency however between the neighbouring surface's internals.

• Tangency to Curves and Surfaces - the boundaries and internals of new surfaces are created tangent to those of the neighbouring surface.

You can also specify the maximum angular difference at which tangency must still be maintained, in the Max Tangency Angle (degrees) box. This is applied when one of the Tangency options above is selected.

Note: The Max Tangency Angle (degrees) and the Curve Fitting Tolerance option on the Advanced Curve Fitting tab strongly affect tangency.

More:

Using the Curve and Surface Fitting Options