Extrapolating Curves and Surfaces

This task explains how to extrapolate a curve/surface.
Curves and surfaces can be extrapolated or trimmed. In case of surfaces, topological contiguous edges can be extrapolated as one edge.

The 'Extrapolation' command is available in two variants:

  • Extrapolation (Feature): After having carried out the extrapolation, a Feature element 'Extrapolation.X' is inserted in the specification tree and the original elements are set to Hide mode.
  • Extrapolation (Datum): With this command, the extrapolated elements remain datum elements.
  Open the Extrapolation.CATPart document.

  1. Click the Extrapolation (Feature) icon or Extrapolation (Datum) icon.
    The Extrapolation (Feature) or Extrapolation (Datum) dialog box opens.


You can define the following options:
  • Type:
    • Standard: Dynamic extrapolation at one surface side along two opposite edges.
    • Unequal: Dynamic extrapolation of a single edge.
    • Factor: The geometry is extrapolated by a factor. For this extrapolation mode, the popup-menu Stretch Type and the text fields Factor and Range are used.
 
  • Elements: Specifies the elements to be extrapolated.
    (Extrapolation Feature: Specifies only one element, Extrapolation Datum: Specifies several elements and boundaries.)
 
  • Boundaries: Only available for the Extrapolation Feature.
    Specification of the boundaries (surface) and the end points (curve) to be extrapolated.
 
  • Stretch Type: Only available for the extrapolation type Factor.
    • Factor: The modification is done via the definition of a value in the text field Factor and each time applied via clicking the Apply button.
    • Range: The modification is done dynamically via the slider Range.
  • Options:
    • Both Sides: Only available for the extrapolation type Standard.
      The opposite end is extrapolated simultaneously.