Using Dynamic Cutting Planes

This task shows how to analyze a surface using parallel cutting planes. The intersection of the planes with the surface is represented by curves on the surface. From these curves, you can visualize the porcupine analysis. This analysis is dynamic, meaning that you can interactively modify a number of parameters to fine-tune the analysis.

There are two commands for an analysis using cutting planes:
  • The Cutting Pane Analysis command analyzes selected elements. The output is a feature which is added to the tree. The analysis will be updated automatically whenever you modify any of the elements in the analysis (for example when you deform an element using control points).
  • The Global Cutting Plane Analysis command performs a single cutting plane analysis for all elements inside a part. It updates itself on creation of new elements, deletion, or modification of existing elements inside the part. The feature is not added to the tree.

The command functionalities of both analyses are identical.

Open the CuttingPlane1.CATPart document.

  1. Select the surfaces to be analyzed.

  2. Click Cutting Plane Analysis in the Shape Analysis toolbar.
    A reference plane is displayed along with the default number of cutting planes, and the corresponding projected lines onto the selected surface.
    The Cutting Plane Analysis dialog box appears.
      If you click Global cutting Plane Analysis in the Generic Tools toolbar, the Global Cutting Plane Analysis dialog box appears. You can clear or select Activate/Deactivate global cutting plane analysis and Activate or deactivate Auto-Apply options in the Global Options area if required.
       
     

    You can define analysis parameters from this dialog box:

    • Activate/Deactivate global cutting plane analysis: If this button is selected (default), the analysis is created and displayed in the work area. If it is cleared, global analysis is deleted, and no global analysis will be created afterwards, even if you add, modify, or delete elements.
    • Activate or deactivate Auto-Apply : If this button is selected (default), the analysis updates itself immediately on changing any option. If it is cleared, you can select all inputs and then press Apply button to compute the analysis.
    • Elements: You can add surfaces to be analyzed. This option is only available in Cutting Plane Analysis dialog box.
      The icon lets you edit the list of surfaces selected for analysis. Click the icon to display the Input Elements List dialog box that allows you to remove or replace an surface.
      • The Geometric Set or valid elements (surfaces) under it can be selected as input elements. The entire geometric set is not added as input on selection; only the surfaces under it are added. Press Ctrl key for multiple selection of geometric sets.
      • Scan or tessellation surfaces can be selected as input elements.
    • The plane in which the analysis is to be performed, using the three icons (Parallel planes , Planes perpendicular to curves , Independent planes ).
    • You can select the reference element in the Sections Type area. The field changes depending on the type of analysis:
      • In case of Parallel planes option, the field name is Reference and allows you to select the direction of reference plane. You can select the default planes (xy, yz, zx planes) or compass direction as reference element. These selection options are available in the contextual menu or can be selected from geometry or specification tree. The default direction is given by compass.
      • In case of Planes perpendicular to curves option, the field name is Curves, allows you to select a curve or a surface edge as reference element. If On curve option is selected, multiple selection of curves is not possible and thus the option is not selectable.
        In this case, if Geometric Set is selected, all the curves under it are added in the reference field.
      • In case of Independent planes option, the field name is Planes, and allows you to select the reference plane. You can select default planes (xy, yz, zx planes) or create a plane. These selection options are available in the contextual menu or can be selected from geometry or specification tree.
        In this case, if Geometric Set is selected, all the planes under it are added in the reference field.
    • Number/Step
      • Number, Step: Choose whether you have a set number of planes or a distance (step) between two planes. In the latter case, the number of planes depends on the size of the analyzed area. This option is only available in Parallel panes and Planes perpendicular to curves mode.
      • On curve: Allows you to create perpendicular planes. This option is only available in Planes perpendicular to curves mode. If this option is selected, only one curve could be selected at a time.
      • On Point: Allows you to a create plane passing through a point. You can select an existing point or create a new point. To create a new point, right-click in the point field and select Create Point.
        This option is available in:
        • Parallel planes: The plane is created passing through the selected point and parallel to the reference plane defined by the compass. This reference point from which the plane position is defined is the origin of global axis system.
        • Planes perpendicular to curves: The plane is created passing through the selected point and perpendicular to the curve. This reference point from which the plane position is defined is the extremity of the curve which is closest to the origin of global axis system.
      • On Value: Allows you to a create plane at the specified value from the global axis system. To enter values click . The Value List dialog box appears that allows you to enter new values and further edit them. Multiple planes can be created by entering required values. Every new value creates a new plane.
        This option is available in:
        • Parallel planes:

          The plane is created at the specified value with respect to the reference point.

          You can also create a plane passing through a pointed position on the geometry. Select a point (on the fly) on the geometry. The pointed position is projected on the axis defined by the compass and the computed value is shown in the value field.

          In both the cases, the cutting plane is created parallel to the reference plane defined by the compass. The reference point from which the plane position is defined is the origin of global axis system.

        • Planes perpendicular to curves:

          The plane is created at the specified value with respect to the reference point.

          You can also create a plane passing through a pointed position on the geometry. Select a point (on the fly) on the geometry. The pointed position is projected on the curve and the computed value is shown in the value field.

          In both the cases, the cutting plane is created perpendicular to the curve. The reference point from which the plane position will be defined is the extremity of the curve which is closest to the origin of global axis system.
    • The boundaries of the set of planes (available in Parallel planes mode only):
      • Automatic: The analysis is performed based on all selected surfaces bounding boxes. The cutting planes are evenly distributed within this area, one being necessarily located on the reference plane if the Step option is active.
      • Manual: The analyzed area is defined by the Start and End values.
      • Start/End: The Manual mode defines the distance at which the first (start) and last (end) cutting planes are located on the reference plane axis.
    • Display options facilitating the analysis reading:
      • Planes: Activates/hides the representation of the cutting planes.
      •   Arc Length: Displays the length of each section cut created.
      • Curvature: Activates the display of the curvature comb.
      • Interpolation: When activated it computes interpolated NURBS curves when cloud/mesh surfaces are sectioned. If deactivated, polyline section curves are computed.
         
        • In case of datum surfaces, cutting plane analysis computes the intersection curves independent of the Interpolation option selected.
        • The selection of Curvature Analysis and Interpolation option buttons are independent to each other.
        • The curvature snalysis can be performed on the interpolated NURBS curves and intersection curves, however not on polyline section curves.
    If you click the Settings button, the Porcupine Curvature dialog box appears.
    Clicking the Display diagram window opens the 2D Diagram. This curvature analysis command is only available with the Freestyle Optimizer license.
    See Performing a Curvature Analysis.

  3. Click Parallel planes .
    The compass moves to the reference plane center, and then you can manipulate the reference plane.
    If you want to perform an analysis in planes perpendicular to curves, select a curve and click the Planes perpendicular to curves .
    Using the Planes perpendicular to curves type, you can select the On curve option in the Number/Step area to create perpendicular planes:
    • Select a reference curve.
    • Select the On curve option.
    You can create several planes: right-click the reference plane and select Keep this plane from the contextual menu.
    Planes are added to the specification tree.
    The Keep this point option is also available from the contextual menu. For more information see FreeStyle Shaper, Optimizer & Profiler: Generic Tools: Editing and Keeping a Point.
    This option is only available with the Planes perpendicular to curves type.
    If you want to perform an analysis in independent planes, click Independent planes .
    You can use the contextual menu in Planes field to create the a plane.
    Each created plane is added to the current list of planes used for the analysis. See Stacking Commands for further information.

  4. Select the Manual mode, set the Step value to 30, and the Start value to -150 and End value to 150.
    The planes are automatically relocated.

  5. Click Arc Length . The arc lengths are displayed.

  6. Click OK in the Cutting Plane Analysis dialog box, when you have finished the analysis.
    The analysis (identified as Cutting Plane Analysis.x) is added to the specification tree.
    • Click OK to interrupt the function while keeping the analysis on the surface, so that it is dynamically updated when deforming the surface.
    • Click Cancel to interrupt the function and remove the analysis.
    • Right-click the intersection curves to actually create the curve on the analyzed surface. You can choose to create only the curve over which the pointer is (Keep this intersection curve option) or to drop all curves onto the element (Keep all intersection curves option). You can choose to keep the curve as NURBS or parameterized curve depending on the option selected in the settings. For more information about the setting see, CATIA Infrastructure User's Guide: Customizing: Shape, General, Curve Analysis Results.
    • You can select any type of solid as an input for the cutting plane analysis. The result displays an outline of cross section for the selected solid. This outline is applicable for the curvature analysis.