Creating Planar Sections

You can cut a cloud of points or a terrain mesh with cutting planes to create discrete polylines or curves.

This task shows you how to:

See Also
About Planar Sections

Create Planar Sections

You can create planar sections of a cloud by cutting it with planes.

  1. From the Create section of the action bar, click Planar Sections .
  2. Select the Element to cut.

    • Multiselection is available.
    • Right-click elements to clear the selection or display the list.

    1. Click Elements list to display the list of elements selected.
    2. Click an element in the work area to add it to the selection list.
    3. Select an element in the list, and click Remove to modify the selection list, or Replace to replace it.
    4. Click Close to end the selection and revert to the main dialog box.
    The name or the number of elements selected is displayed under Element.

    A cutting plane is displayed.

    The cutting planes proposed are parallel to either YZ, XZ or XY planes depending on which is perpendicular to the largest edge of the working box of the first element selected.

  3. Select a second element.

    If some elements selected are a volume or a surface, they are tessellated.

    The Sag value becomes editable.
    Note: Whenever you modify the Sag value, the tessellation is restarted.
  4. Define the cutting planes.
    • parallel
    • perpendicular to a guide
    • independent.
  5. For parallel or perpendicular planes, drag the reference plane to position it, or right-click it and select Edit.
  6. Select Keep this point to create the point at the center of the plane.
  7. Specify the orientation, then drag the center of the green handle in the required direction to move the reference plane along its normal or along the section guide.
  8. If the cutting planes are created on the wrong side of the reference plane, click Swap to create them on the right side.
  9. Except for the independent planes option, freeze either the Number of cutting planes, the Step between each cutting plane.
    • Type the requested values under Step and Number.
    • Or drag the handle available on the last cutting plane proposed to modify either the Step between cutting planes (when Number is selected), or the Number of planes (when Step is selected).
  10. Right-click the handle to:
    • Edit the position of the plane.
    • Keep the point created at the center of the plane.
    • Fix the number of planes. Selecting or clearing Fixed number of planes is the same as selecting Number or Step in the dialog box.

    An alternative is to select the Infinite check box.

  11. Select Keep this point to create the point at the center of the plane.
  12. Clear the Preview check box to improve performance while you are adjusting the parameters.

    • It displays the computed planar sections dynamically on the selection.
    • It is available for meshes, surfaces, and volumes, not for clouds of points.

  13. Define the Influence area according to your needs.

    For clouds of points, the Influence Area parameter defines a computation area around the cutting planes: When the points are not dense, a cutting plane (black line) may be unable to intersect the points. The Influence area(shown in yellow ) contains the points considered to intersect the cutting plane.

  14. If required, select one or two limiting curves for any of the plane options:
    1. Place the cursor under First limiting curve and select the curve. Its name is displayed in the dialog box.
    2. If required, repeat this under Second limiting curve.
    3. Right-click a curve to clear the selection.

    Notes:
    • The limiting curves should lay on the element selected.
    • The limiting curves must be continuous.
    • User selection filter capabilities are available to select a whole entity or one of its components as a limiting curve.
    • When using a limiting curve, the discrete polylines may be created on the wrong side of the curve. In fact, this side is determined by the origin of the reference plane. Right-click the reference plane and select Edit to create the discrete polylines on the right side, or use the Robot.

    • Result without a limiting curve:

    • Result with a limiting curve:

  15. Define the type of output.

    In addition, you can choose to create discrete polylines or curves.

    is not pressed and you create scans and only scans.

    • Click OK to create them and exit the dialog box.
    • Click to create curves, and click Apply in the Planar Sections dialog box. A temporary scan is displayed in the tree and in the work area. Click OK in the Planar Sections dialog box to create the curves and exit the dialog box.
      Notes:
      • Curves and only curves are created.
      • The Curve from Scan dialog box is displayed. The operating mode is the same as for Creating Curve from Scans except that only the curvature comb (no curvature analysis dialog box) is displayed.
      • If you need a complete curvature analysis of the curves you create, you have to create the scans first, and then create the curves from those scans.
      • When you modify a parameter, click Apply in the corresponding dialog box to take it into account.

Define Parallel Cutting Planes

You can use cutting planes parallel to a reference plane.

The reference plane can be:

  • One of the standard planes , , or
  • A plane defined by the Robot
  • An existing plane
  • A plane that you define inside Planar Sections.

  1. Click .
  2. Pick anywhere in the work area to define a first point.
    A line appears as you move the cursor.
  3. Pick anywhere in the work area to define a second point.
    The Planar Section dialog box is redisplayed and a reference cutting plane is displayed. Its origin is the first point defined, its first direction the vector defined by the two points, the second direction is the vector normal to the screen plane.

Define Planes Perpendicular to a Guide

You can use cutting planes perpendicular to a guide.

Select a curve.

  • The degree of the guide must be greater than 2.
  • A join (in the Generative Shape Design sense) is not allowed as a guide.

  • Its name is displayed in the dialog box.
  • The cutting planes are perpendicular to this curve.
  • Right-click the curve to clear the selection.

Define Independent Planes

You can use independent cutting planes.

Select a plane.

  • You can select as many independent planes as required using multiselection . Their number is displayed in the dialog box.
  • Right-click Plane to create them.
  • The parameters Number and Step are not available with this option.
  • For a quicker selection, use the Selection Sets capabilities.

The name of the plane is displayed in the dialog box.