Approximating and Segmenting Procedural Curves

You can convert curves and modify the segments of any curve.

Note: This approximation automatically performs when you edit a curve using control points.
  • When an exact conversion can be performed, it is done automatically, and the Converter Wizard dialog box does not open. This is often the case with splines and lines.
  • When an exact conversion cannot be performed, as for ellipses, hyperbolas, parabolas, for example, the Converter Wizard dialog box opens allowing you to define the approximation tolerance.

Before you begin: Open an existing 3D shape containing a curve approximate.
  1. Select the curve.

    Notes:
    • You can multiselect curves.
    • To convert a multi-cell curve, select it from the tree to avoid that you select only one cell instead of the whole curve.
    • You can mix the approximation of curves and surfaces.
    • Use the Exact conversion mode (no parameter to define) on a NUPBS element to display the number of control points, curve order, and number of segments in the curve. Note that in this case, the initial element duplicates.

  2. From the section of the action bar, click Converter Wizard .
    Depending on the type of the initial element, a text displays indicating what approximation needs to be performed:
    • CV: The curve is not a NUPBS and needs to be approximated using the Converter Wizard parameters.
    • EXACT: The curve can be converted in exact mode (no parameter to define).
    • Seg: The curve already is a NUPBS.
  3. Set the deviation Tolerance from the initial curve. On the geometry, a red text appears if the tolerance is not respected. This text changes to green when the new element is within the specified tolerance.
  4. Set the maximum allowed Orders along the U direction for each curve segment. This value must be greater than or equal to 2 if the segmentation options are grayed (one segment only). When there are several segments, it must be larger than 4.

    The maximum value allowed per segment is defined in the Order option in Me > Preferences > App Preferences > 3D Modeling > Styling > FreeStyle Shape Design, General tab, Geometry section, and must be less than or equal to 16.

  5. Set the Segmentation, that is the maximum allowed segments along the U direction. If Single is selected, a mono-segment curve is created.
  6. Click Priority for Order or Segmentation to define which parameter takes precedence over the other one.
  7. Optional: Select one of these options:
    • 3D conversion to convert a curve on a surface into a 3D curve.
    • 2D conversion to retain the 2D representation of a curve on a surface.
  8. Optional: Click Continuity in the App Options panel.
    If at least one conversion option is selected (Tolerance, Orders, or Segmentation, that is, you are not in exact conversion mode), a continuity constraint can be imposed identically on both curve end points. Two continuity types are available: Tangent or Curvature. You can change it either by using the context menu or by clicking the text in the work area.
  9. Optional: Click More to display additional options.
  10. Optional: Select Information to display further information on the element.
    • Max: Maximum deviation in relation to the initial element.
    • N: Number of control points.
    • o: Curve order.
    • s: Number of segments in the curve.
  11. Optional: Select Control Points to display the curve's control points.
  12. Optional: Select Auto Apply to dynamically update the resulting curve.
  13. Click OK.