Recovering Basic Surfaces

This task shows you how to recognize the basic shapes of a part
and how to create the corresponding editable surfaces:
  • First identify visually the portions of the part made of the basic surfaces, i.e. planes, cylinders, spheres, cones.
  • Then activate each of those portions in turn and let the application recognize and create the surface.

Open the Canonic1.CATPart from the samples directory. 
  1. Click Basic Surface Recognition .
    The Basic Surface Recognition dialog box is displayed. 

  1. Select the cloud of points or the mesh you want to process. Its name is displayed in the Cloud field and (Activate) becomes available in the dialog box.

  2. Click . The Activate dialog box is displayed. Select the area you want to work on.
    Click OK in the Activate dialog box when you are done.

The Activate dialog box can also be launched by the contextual menu Select Areas of Cloud:
  1. Select the type of surface to detect or click Automatic and Apply to visualize the shape.

  2. For each type of surface, you can choose to let the application compute the surface
    or you can set some data:

    • For a plane: the normal to the plane and its passing point,
    • For a sphere: the center and the radius,
    • For a cylinder: the radius, the axis and the center,
    • For a cone: none,
    • For the automatic check box: the maximum plane error.

    Those data are also displayed in the dialog box when the surfaces are
    computed by the application.

  3. You can activate the corresponding fields by selecting their names and
    edit the values as necessary before creating the surfaces.

  • If you choose a shape type to recognize, you can edit its geometric properties
    (Axis, Center, Radius) by activating the corresponding select boxes and entering new values.
  • If the shape recognized is a plane, you can edit it graphically, using the extension
    (arrows) and rotation (circle) manipulators.
  • If you click Automatic, you cannot modify the geometric properties of the shape directly.
    Once the shape has been recognized, select the corresponding shape type to make
    the corresponding properties editable.
  • Click Apply to take those modifications into account. 
  1. Select the Spikes check box to display the deviation between the canonic surface and the original part.

  2. Click More>> to display the statistics on the action.

  3. Click OK to create the shape.

  4. Double-click the shape to edit it, if required:

The following features are created in the specification tree:
An extrusion element named Plane.x with its components,

The normal to that plane named PlaneNormal.x and its components

An extrusion element named Cylinder.x with its components,

The axis of that cylinder named CylinderAxis.x and its components.


  A feature sphere named Sphere.x and its components
  A rotation element named Cone.x and its components,

The axis of that cone named ConeAxis.x and its components.