Cutting Through a Model (3D Cut)

This task deals with the 3D Cut functionality:

About the 3D Cut FunctionalityTop

3D Cut functionality cuts through a model computing the intersection (or the difference as defined by the user) between a CATPart, a CATProduct, a multi-selection of CATParts and a 3D box. The result is a truncated polygonal mesh, lighter than the original selection which can be saved as an independent geometry.

Note that the resulting geometry keeps color attributes as well as faces and edges.The resulting 3D Cut can be automatically treated as an alternate shape as in any other DMU Optimizer functionality.

Step-by-Step ScenarioTop

This task will show you how to create 3D cut

Open Mobile_Phone.CATProduct document.

Use Fit All In I_ReframeP2.gif (216 bytes)  to position the model geometry on the screen.

Alternate Shape ManagementTop

  1. (Optional) 
    You can manage automatically your result as alternate shape of the initial component. For this:

    • Select Tools > Options from the menu bar.
      The Options dialog box is displayed.
    • Expand the Digital Mockup category from the left-hand tree.
    • Select  DMU Optimizer item to display the corresponding tab. The Alternate Shapes Management is available
    • Select the 3D Cut option: it is automatically activated as an alternate shape. When activated the 3D cut representation is the one visualized in session.
  2. Right-click Battery(Battery.1) in the specification tree and select Representations-> manage Representations... from the contextual menu displayed

    The Manage representations dialog box is displayed
  3. Select Battery.1_SWEPTVOLUME.cgr and click Activate button in the Manage Representations dialog box displayed.

  4. Click Close

  5. Click 3D Cut in the DMU Optimizer toolbar.
    The 3D Cut dialog box is displayed:

    This dialog box contains a variety of tools letting you positioning the section box and selecting the cutting type
  6. Select Battery.1 either in the specification tree or the geometry area

    Product (s) selected are highlighted in the specification tree and geometry area
    The section box is not yet correctly positioned (not snapped onto the battery)
    Note: if you select the product(s) of interest for your selection before entering the 3D Cut command, the section box will be automatically positioned on the selected product(s).
  7. Click the Positioning tab and click the Reset Position icon

    The section box is positioned with respect to the selection:
  8. Select the automatic Reset check box.

    This new capability lets you reset the section box on a selected product with correct dimensions.

    For example, if you change your selection:

    • select Front shell either in the geometry area or in the specification tree, this is what you obtain:
    • select again Battery.1, the section box is positioned and resized accordingly
    see picture in step 7
  9. Adjust the thickness of the section box:

    • Clicking the Edit Position and Dimensions icon and entering the desired values in the Edit Position and Dimensions dialog box displayed:

    • Notes:
      • For more information about the Edit Position and Dimensions dialog box, read refer to Sectioning section in DMU Space Analysis User's Guide
      • Units are current units set using Tools > Options (Units tab under General > Parameters and Measure).

      The Undo and Redo icons in the Edit Position and Dimensions dialog box let you cancel the last action or recover the last action undone respectively.
      Only the section box position is recovered, the dimensions are not.

    • positioning the cursor over one of the slave box plane edges, clicking then dragging to translate the plane in the desired direction


    • As you move the cursor over box edges, the cursor changes appearance and arrows identifying the directions along which box thickness is defined appear.
    • You can also re-size the box by clicking and dragging one of the box sides. Arrows likewise appear to help you.
  10. Click the Definition tab to select the desired cutting types.

    By default, the new Boolean cutting behavior is selected (On the Border area)

    Select the cutting type using the arrow:
    :cuts away the material from the product, inside the box to expose the cavity within the product
    : cuts away the material from the product, outside the box
    Note: you can swap from one cutting type to the other directly in the geometry area, all you need to do is click the section box edges (the arrows are reversed)
    Select the On the Border behavior using the arrow:

    : cuts the triangles  on the selection border within the cutting box.

    : keeps only the triangles included within the cutting box.

    : keeps the triangles included within the box or partially included.


  11. Still in the Definition tab page, click Volume Cut in the Visual Feedback area to obtain a section cut.

    This capability gives you an automatic visual feedback of what you can get, for instance if you resized the section box as following:

    The material is cut away exposing the cavity of the product. Click Volume Cut again to go back to the initial state.
    Note: the volume cut is purely visual and therefore cannot take into account the cutting type (in/out)
  12. Click Preview when satisfied

  13. Click Save. The Save As dialog box automatically appears:

    • Set the Type to .cgr. You can also save your resulting shape in .wrl, .model .stl formats
    • Identify the folder in which you want to save the file
    • Enter a file name
    Note: clicking Save keeps the command active and lets you therefore launch the calculation again if needed. When satisfied click Save in the Save As dialog box. Click Close to exit the dialog box.
  14. Click Close

  15. In our scenario, we managed the result as an alternate shape, therefore the 3d cut replaces the original representation:


If a surface body intersects the border of the 3D box, then its edges are lost. Edges are kept only for surface bodies entirely inside or outside the 3D box.

When the Cuts the triangles option is not selected

The 3D Cut functionality does not relimit the triangles of the initial mesh intersecting the boundaries of the 3D box.
Result: triangles are integrated entirely (or rejected entirely, as defined by the user.)
Note that triangles whose vertices are outside the 3D box are considered totally outside.

When the Cuts the triangles option is selected

Note that the computation time is increased (it can be increased up to two times that of the previously measured computation time)

Results - Examples