Splitting Geometry

You can split a surface or wireframe element by means of a cutting element.

This task shows you how to:

Before you begin: Create a 3D shape containing geometric elements.

Split Two Elements

You can split elements by selecting a cutting element.

  1. From the Surfaces Reconstruction section of the action bar, click Split .
  2. In the Element to cut box, select the element to be split.
    Make your selection by clicking the portion that you want to keep after the split.

    You can select several elements to cut. In that case, click Element to cut again or click . The Elements to cut dialog box appears. Select as many elements as required. Click Close to return to the Split Definition dialog box. The number of selected elements is displayed in the Element to cut box

    Click Remove or Replace to modify the elements list. When several elements to cut are selected, the selected portions are not taken into account as parts to keep. The parts to be kept depend on the type of the cutting element (such as point, curve, surface) and the orientation of the cutting elements and the elements to cut. Click Other side to reverse the portion to be kept, element by element.

  3. In the Cutting elements area, select the cutting element.
    A preview of the split appears. You can change the portion to be kept by selecting that portion.

    You can also select the portion to be kept by clicking Other side. This option applies on all selected elements to cut.

    Note: You can select several cutting elements. In that case, the selection order is important. The area to be split is defined according to the side to be kept in relation to the current splitting element.

    Right-click in the Cutting elements area and select Create Join to create a join as the splitting element. If you split a surface and you keep both sides by joining the resulting splits, you cannot access the internal sub-elements of the join. The splits result from the same surface and the cutting elements are common.

  4. Optional: Select the Keep both sides check box to retain the other side of the split element after the operation. In that case, it appears as aggregated under the first element and both split elements can only be edited together and the aggregated element alone cannot be deleted.
    Important:
    • If you use the Datum mode, the second split element is not aggregated under the first one, but two datum surfaces are created.
    • If there are several elements to cut, the Keep both sides check box is available only for the first selected element.
  5. Optional: Click Show Parameters>> to view more options.
  6. Optional: In the Options tab, select the Ignore no intersecting elements check box to split many elements (curves, surfaces, volumes) when the cutting element does not intersect all the elements.
    Important: When this check box is selected, the Intersections computation check box is cleared and become unavailable.
  7. Optional: You can select the Keep elements in half space check box to keep all the elements that are on one side of the cutting infinite plane. The cutting element defines this half space.
    Important:
    • This check box applies only when the cutting element is an infinite plane.
    • If the split side is not toward the element to cut, an error message is issued. Note that this behavior differs from the behavior in the Part Design apps, that is, no error message is issued.
    • If the element to be cut is a volume, no error message is issued in case the cutting element is not an infinite plane.

    Elements to cut: dark blue and light blue surfaces; Cutting elements: yellow and purple planes

    Result with the Ignore no intersecting elements check box selected

    Element to cut: non connected light blue surface; Cutting element: yellow plane

    Result with Keep elements in half space check box selected

    Warning: Avoid splitting geometry when the intersection between the element to cut and the cutting element is merged with an edge of the element to cut. We advise you to use the Elements to remove and Elements to keep boxes to remove the positioning ambiguity.
  8. Optional: You can select the Approximation tab to control the quality of the result of the split through several parameters and modes.
  9. Click OK to split the element.
    If several elements to cut were used, the created elements are aggregated under a Multi-Output.xxx feature.

    Here, the top-left line is the first splitting element. In the left illustration, it defines an area that intersects with the other three splitting curves, and in the illustration to the right, these three elements are useless to split the area defined by the first splitting element.

    To remove or replace one of these cutting elements, select it from the list and click Remove or Replace.

Split a Surface by a Curve or a Surface by a Surface

You can split a surface by selecting a curve or another surface as a cutting element.

Split a surface by a curve

You can extrapolate the cutting curve, surface, or volume. The cutting element (the curve) is laid down on the surface.

  1. Select the Extrapolation type.
    OptionDescription
    None No extrapolation. The cutting element has to cut entirely the element to cut.
    Tangent Extrapolates the cutting element in tangency.
    Curvature Extrapolates the cutting element in curvature.
  2. Extrapolate the curve in tangency.


    Warning: When this extrapolation leads to the intersection of the cutting element with itself before fully splitting the initial element, an error message is issued as there is an ambiguity about the area to be split.
  3. Split the surface by the curve.


Warning: If the cutting element does not reach the free edges of the element to cut, an extrapolation in tangency is performed using the part of the cutting element that lays down the surface.

Split a surface by a surface

You can extrapolate a surface to split another surface.

  1. Create an intersection (the green wire) between the two surface elements.


  2. Extrapolate the result of the intersection in tangency up to the closest free edges of the element to cut.
  3. Use the result of the extrapolation as the cutting element to perform the split operation.


    Important: It is not the cutting element, which is extrapolated but the result of the intersection.
    Tip: If the result of the split is not what was expected, it is also possible to manually extrapolate the cutting element with the extrapolate feature before creating the split.
  4. Extrapolate the cutting element (the red surface) to fully intersect the element to cut.


  5. Use the extrapolated surface as the cutting element to split the surface.


Important: Avoid using input elements, which are tangent to each other since this may result in geometric instabilities in the tangency zone.

Split Volumes

You can split volumes by means of a cutting element.

Important:
  • This capability is only available with Generative Shape Morphing.
  • It only concerns volumes since the transformation of a surface can only be a surface.

If the element to be cut is a volume and the cutting element is a volume or a surface, you can select whether you want the result of the split to be a surface or a volume.

Select either the Surface or Volume option.

Notes:

  • Replacing an input element does not change the result type.
  • The switch between surface and volume is grayed out when editing the feature. If the result of the split is a volume, the split is a modification feature. If the result of the split is a surface, the split is a creation feature. For more information about volumes, see Creating Volumes.

  • You can also split a solid using a plane, a volume, or a surface as a cutting element. The result of the split is a volume or a surface. You can choose whether you want the result of the split to be a surface or a volume. To do so, switch to either Surface or Volume option.

Approximate the Split Result

You can control the quality of the result of the split through several parameters and modes.

  1. Double-click the split result in the tree to edit it.
    The Split Definition dialog box appears.
  2. Select the Approximation tab.
    The dialog box appears as follows:
  3. In the Approximation mode list, select any one of the below options:

    • None: the resulting split surface is not approximated.

      By default, this option is selected.

    • Deviation: the resulting split surface is deviated according to the given length.

      Notes:
      • The Deviation box is available when you select this option.
      • The deviation between the resulting surface and the original Split result is not more than the given value.

    • Parameters: the resulting surface is computed according to the given parameter limits.

      You can control the following parameters:

      • Max Order: On each scale (U, V), the polynomial approximation order is lower than the input value.
      • Max Segment: On each scale (U, V), the surface is divided into segments that define approximated areas. The number of segments is lower than the input value.

  4. Click OK.
    The split result is approximated.

Important: The approximation is only available for rectangle type surfaces, that is, for the surfaces, which have only four side edges.