Inverting Surfaces and Curves

This task explains how to invert and align the normals and directions of selected curves and surfaces.
In the graphics area, the following vector symbols are used to display the UV and normal directions:
  • green: UV direction
  • black: surface normal depending from the UV vectors
  • red: shell normal (basis for the basic direction of the commands applied in the following on the surface)
   

With this command, the following invert operations can be carried out:

Invert (Feature)
  After having carried out the inversion, a Feature element 'Invert.X' is inserted in the specification tree and the original elements are set to Hide mode.
The input geometry will not be modified.
For certain modes (Align Normals to Surface Normal, Align UV, Align Directions), the input geometry must be topologically contiguous (see Gap Distance).

Invert (Datum)
  With this command, the inverted elements remain datum elements.
If the command is carried out on a datum element, the result will be applied directly on the input element.
The selected elements need not to be topologically contiguous, however, in case of carrying out the command with a selected Reference, only the region containing the reference element will be considered.

Open the InvertCurve.CATPart document.

  1. Click the Invert (Feature) icon .
    The Invert dialog box is displayed.
 

  1. Select Invert Direction in the Mode list.

  2. Select Curves 1 to 3.
    The curve direction is displayed by vectors if Display Vectors is selected.

  3. Click Apply.
    The direction of all selected curves is inverted.
    A Multi-Output feature result is displayed in the tree.

  4. Select Align Directions in the Mode list.

  5. Select Curve 1 as Reference.

  6. Click Apply to align the direction of all selected curves to the direction of Curve 1.

Open the InvertSurface.CATPart document.
 

  1. Select Change Orientation in the Mode list.

  2. Select Surfaces 1 to 9.
    Normals and UV directions are displayed if Display Vectors is selected.

  3. Select Invert Shell Normal.
    The normals of all selected surfaces are inverted.
    A Multi-Output feature result is displayed in the tree.

  4. Select Align Normals to Surface Normal in the Mode list.

  5. Select Surface 1 as Reference.

  6. Click Apply to align all selected surfaces in direction of the normal of surface 1.

  7. Select Align UV in the Mode list.
    Surface 1 is still selected as Reference.

  8. Click Apply to align the U and V direction to the U and V direction of surface 1.
You can define the following options::
  Mode
For inverting surfaces and curves, you can select the following modes:
  • Change orientation:
    Changes the orientation of surfaces. In this mode, the following options are available:
    • Reverse U/V: Inverts the U or V direction of all selected surface elements.

      Attention:
      Inverting U or V direction also inverts the surface normal!



    • Swap UV: Inverts the U and V directions of all selected surface elements.

      Attention:
      Inverting UV direction will also invert the surface normal!



    • Invert shell normal: Inverts the shell normal direction of the selected surface elements.



      Note: In case of constructions on top, this option is not available for subsequent edition, as updates cannot be guaranteed to be free of errors.
  • Align normals to surface normal: Aligns all normals, i. e. shell and surface normals of all selected surfaces lying within one topologically contiguous region (see Gap Distance) according to the surface normal direction of the surface selected as Reference.



    Note:
    In order to be able to select a reference, it may be necessary in certain constellations to use the selection filter 'Geometrical Element Filter' (see Selecting Using a Filter). In some special cases, e. g. a federated join (see Using the Federation Capability) as input element, the selection of a reference may not be possible.
  • Align UV: Aligns U and V direction of all selected surface elements lying within one region (see gap distance) according to the U and V direction of the surface chosen as a Reference.
    The surface normal direction remains unchanged.

  • Invert direction: Inverts the direction of the selected curve elements.



    Note: In case of constructions on top, this option is not available for subsequent edition, as updates cannot be guaranteed to be free of errors.
  • Align directions: Aligns the direction of all selected curve elements lying within one region (see gap distance) according to the direction of the curve chosen as a reference.
 
  • Surface: Selects the surfaces to be inverted.
  • Curve: Selects of the curves to be inverted.
  • Reference: Only available for the options Align direction, Align normals and Align UV.
    Selects from the selected surface or curve element the reference element specifying the normal direction, UV alignment, and curve direction.
  • Gap distance: Only available for the options Align direction, Align normals and Align UV.
    If the distance between selected surfaces is larger than the specified tolerance value, they are assigned to different regions.
    Curves and surfaces cannot be mixed.
    To preserve all surfaces, the minimum from the specified gap tolerance and the smallest edge of the surfaces concerned is used.
  • Display vectors: Displays the normal vectors,
    the U and V direction arrows on a surface, and
    the direction vectors of a curve.
    To distinguish the different vectors the following colors is used:
    • UV directions: green
    • Shell normals: yellow
    • Surface normals: white
  • Display face normals: This display option is enabled if the Display vectors option is selected.
    The face normal is displayed for each input face. To distinguish the different normals the following colors is used:
    • Shell normals: red
    • Surface normals: white
    • Face normals: light blue

  • Results: Displays the number of selected and adjusted elements as well as the number of regions after a multi-selection.