Analyzing a Curve by Porcupine Analysis

You can create a visual representation of the point, tangent, and curvature continuity of curves. You can conduct porcupine analysis on curves.

This task shows you how to:

Before you begin: Create 2D sketches.
  • Ensure the sketch is curved and not linear.
  • You can also use use-edges resulting from projecting 3D elements.

View the Porcupine Analysis of a Curve

You can select various options to view the analysis of a curve in the active view.

  1. Open the dialog box for analysis:
    1. From the Sketch section of the action bar, click Curvature Analysis .
      The Porcupine Curvature dialog box appears.
    2. Click More.
      The dialog box expands to reveal all its options.
  2. Select a curve in the active view of the work area.
    The curve is highlighted. A porcupine comb appears along the curve. The default type of this curve is Curvature.
    Tips: You can:
    • Select multiple curves by sequentially selecting them in the work area
    • Select multiple curves at a time by trap selection
    • Select an already selected curve to clear its selection
    • Click in the empty space of the work area to clear every selection
  3. View the analysis on a curve:
    1. In the Type area, select the type of analysis as Radius.
      The porcupine comb shows the radius of the curve.
    2. In the Type area, select the type of analysis as Curvature.
      The porcupine comb shows the curvature of the curve.
      Radius analysis

      Curvature analysis

  4. In the dialog box:
    1. Select Plane curves check box.

      This option projects the porcupine analysis on a mean plane, if it exists within the given tolerance. The minimum tolerance is 0.001mm.

      The Tolerance box is available for edition.
    2. Enter the required tolerance.
  5. Define the amplitude characteristics of porcupine comb.
    1. In the Amplitude area, clear the Automatic option.

      When the Automatic amplitude check box is selected, the length of the spikes is optimized. So, even when zooming in or out, the spikes are always visible.

      The Amplitude box is available for modification.
    2. Click X 2.
      The amplitude is doubled.
    3. Click / 2.
      The amplitude is halved.
    4. Select the Logarithm option.
      The nature of the comb is changed to logarithmic.
    5. Select the Reverse option.
      The porcupine comb is reversed.
    6. Clear the Comb option.
      The envelope of the porcupine comb is visible, the teeth are not.
    7. Clear the Envelop option.
      The teeth of porcupine comb are visible, the envelop is not.
      Note: At a time, you must select either Comb, or Envelop options.
  6. Define the density characteristics of porcupine comb.
    1. In the Density area, define the density of the teeth in the comb.

      Adjusting the density of the spikes is useful when the geometry is too dense to read but the resulting curve may not be smooth enough for analysis.

    2. Click X 2.
      The density is doubled.
    3. Click / 2.
      The density is halved.
    4. Select the Curvilinear option.

      In the curvature graph, the X axis abscissa is curvilinear when Curvilinear is enabled, otherwise the X axis abscissa is parametric. When X axis abscissa is parametric, its range is not necessarily between zero and one.

    5. Select the Particular option.
      The points of maximum and minimum magnitude are displayed on the curve.
      Note: If you select both Particular and Project on Plane options, the inflection points are displayed over the comb.
    6. Select the Inverse option.
      The inverse values in radius or curvature appear when the Curvature or Radius option are selected, respectively. This option does not recalculate maximum and minimum values. It only displays the inverse values. The maximum and minimum location for the selected type are still displayed.
  7. Right click on any tooth of the comb and select Keep this point.
    Point.x is listed in the tree.
    Note: If you select the Particular option, then following contextual commands are available:
    • Keep this point
    • Keep local minimum
    • Keep local maximum
    • Keep global minimum
    • Keep global maximum
    • Keep all minimum
    • Keep all maximum
  8. View the curvature diagram:
    1. In the Diagram area, select Display diagram window .

      The curvature amplitude and parameter of the analyzed curve are represented in this diagram.

      The 2D Diagram dialog box appears. The color of the curves in the 2D Diagram dialog box match the ones on the geometry.
    2. Move the cursor over the porcupine comb in the work area.
      The local amplitude is displayed in the work area and the current location is displayed in the 2D Diagram dialog box.
    3. Right-click a curve in the 2D Diagram and choose one of the following options:

      • Drop marker: adds Points.x in the tree.
      • Inverse X-coord
      • Inverse Y-coord

    4. You can use the following options in 2D Diagram dialog box:

      • All curves with the same vertical length
      • All curves with the same origin
      • Use a logarithmic scale on vertical axis
      • More Options >>: The Diagram Options dialog box appears. With these options you can customize the 2D diagram viewing area.

The porcupine comb analysis of the selected curves is displayed.

Note: The analysis is only visible for the geometrical elements in the current view. Changing the active view hides the analysis and shows it when the view is activated again. Similarly, the analysis is visible for geometrical elements in main view of the sheet. Changing the main view to background view hides the analysis.
Important:
  • The following types of elements are unavailable for selection, analysis, or propagation:
    • Construction elements
    • Axis elements
    • H and V elements
    • Output features
  • If you select a linear element like a straight line, no analysis is displayed.
  • Curvature analysis is not possible for curved edges in 2D layout view background.

Auto-propagate the Curve Analysis

You can use auto-propagation of the porcupine comb during curve analysis.

  1. From the Analysis section of the action bar, click Curvature Analysis .
    The Porcupine Curvature dialog box appears.
  2. Select a curve in the work area.
    • The curve is a single element: The porcupine comb appears over this element only.
      Single element

    • The curve is in a connected profile: The porcupine comb propagates over all the elements within the profile which are in continuation with the selected curve. If the elements connected to the selected curve are deleted, the comb appears only on the selected curve.
      Propagation in a connected profile

    • The curve is in a connected profile posing ambiguity for propagation: The porcupine comb appears only over the selected curve and propagates till it encounters any ambiguity.
      Propagation of the comb stops at an ambiguity

      Propagation continues after removal of ambiguous element

    • The curve is in an unambiguous connected profile, and is removed: The porcupine comb extends to the connected elements but cannot propagate further if new elements are added to the profile.
      Curve is in a connected profile

      Selected curve is deleted: Comb still propagates over the connected elements

      Comb cannot propagate further on to new elements