Creating 3D Primitives

You can recognize basic shapes in clouds of points or meshes.

Before you begin: If you have imported a large digitization file, extract a subset of this file to work with.
  1. From the Surface Reconstruction section of the action bar, click 3D Primitive Recognition .
  2. Select the mesh or cloud of points that represents the part to reconstruct.
  3. Specify the type of primitives to recognize (Plane, cylinder, sphere, or cone).
  4. Specify a deviation.
    • Angular deviation in degrees for planes.
    • Maximum deviation in mm for the other types.
  5. Optional: Select the Hide primitive points check box.
    The points or triangles already use to recognize a primitive are hidden and de-activated.
  6. Optional: Specify constraints compatible with the type of primitive to recognize.

    Constraint Defined by Available for
    Parallelism Direction (DX, DY, DZ) Plane, cylinder, cone
    Perpendicularity Plane Plane, cylinder, cone
    Imposed radius Value Cylinder, sphere

    1. Select the relevant type of constraint.
    2. Enter required values.
    Constraints are listed.
    Note: To avoid errors, the list is reset when you specify another type of primitive to recognize.
  7. To create a primitive:
    • Either pick a point or a triangle. The primitive is recognized by propagation to the neighbors points or triangles.
      Note: You cannot recognize a cone from a point picked in a cloud of points.
      Tip: To recognize a primitive from several separate areas, pick a triangle on the first area. With Ctrl key pressed, pick a second triangle on the second area, then a third triangle on the third area, and so on.

      Not available for clouds of points.

    • Or select a subset of points or triangles. 3D Primitive Recognition creates a primitive of the expected type, that respect the constraints.
    • The primitive is displayed.
    • The generated primitive for cylinder and cone is a closed surface (including the basis), if you have selected Volume as the Reconstruction Approach in the Preferences..
    • The geometric properties of the primitive are displayed.
  8. Use the handles to adjust the dimensions of the primitive.
  9. To confirm the quality of the primitive, activate the display of the deviation between the cloud of points or mesh and the primitive.