Creating Project Curves

This task explains how to project a curve on a surface.
Open the ProjectCurves.CATPart document.

  1. Click the Curve Projection icon .
    The 'Curve Projection' dialog box opens.
 

  1. Select the curve as 'Element'.

  2. F8 to move to the next selection field.

  3. Select the surface as 'Support'.
 

  1. Set the 'Proj. Direction' to 'Direction'.

  2. Use the context menu of the 'Direction' field to set the option 'Z Axis'.
 

  1. Select 'Apply'. The curve is projected on the surface.
 

  1. Select the option 'G1' for 'Start' in the 'Extrapolation' field.

  2. Select 'Apply'. The start position of the projected curve is tangentially extrapolated.

  
 

  1. Select the option 'G1' for 'End' in the 'Extrapolation' field.

  2. Select 'Apply'. The end position of the projected curve is now also tangentially extrapolated.

  
 

  1. Select the option 'G2' for 'Start' and 'End' in the 'Extrapolation' field.

  2. Select 'Apply'. The start and end position of the projected surface is extrapolated depending on curvature.

You can define the following options:
  • Element: Selection of the curves to be projected.
  • Points: Selection of projection points.
  • Support: Selection of the projection support (surfaces).
  'Options' tab
 
  • Proj. Direction: The projection can be executed in one of the following directions:
    • Normal: The projection is in the direction of the surface normal.
    • View: The projection is in the current view direction.
      Note: In central perspective, the projection is carried out along the view direction of the screen centre. Thus, original curve and projection curve are not congruent outside the screen centre..
    • Direction: The direction can be defined via the field Direction.
  • Extrapolation: These options are only available for the projection on surfaces.
    Start and/or end of the projected curve is automatically extrapolated to the nearest surface edge and trimmed. The curve is extrapolated by the amount of its length at maximum .
    The extrapolation types G1' or 'G2' can be defined separately for the curve start and end (see figures above).
  • Parameter: Parameterization of the projection curve
    • Domain: The following options are available:
      • Off: The parameterization of the curves to be projected is calculated across the entire curves independent of the selected support surfaces.
      • Separate: The curves can either be projected onto the support as a whole, or separately onto each selected surface.
      • Divide: The parameterization of the curves is calculated across the entire curve, but the result is divided at each of the support surface boundaries.
      • 2D Curve: The 2D curve is a parameterized NURBS curve.
    • Standard: The control point distribution of the original curve will be preserved.


      Note: This setting is suitable if the curve can be projected clearly on the support, and if original and projected curve are looking largely similar.
    • Adapt: The parameterization of the projection curve is adapted to that of the support to realize a better control point distribution. When using this option, the projection curve should lie nearly isoparametrically on the support.

    • Max Dist: When projecting a curve on a surface, only those points having a distance from the original curve that is smaller than the value specified here are taken for the computation.
    • Basic Surface: The curves can be projected onto the underlying surface of the face selected as support.
      Note: This option is recommendable when the curve to be projected is larger than the face being used as the support.
  See 'Approximation' tab
  See 'Output' tab
  Click onto the 'More Info' button to display deviations and output results.
 
  • Display: The graphical display of the deviation values can be globally switched on and off.
  • Deviation
    • Max: Display of the maximum deviation between projection curve and support.
  • Output Result: See Output Result