Extrema Detection

Extrema Detection consists in localizing points where a results field is maximum or minimum. You can ask the program to detect either one or both global extrema and an arbitrary number of local extrema for your field.

This task shows how to use the Extrema Detection capability.

You can use the sample26.CATAnalysis document: you created a Stress Von Mises image.

Before You Begin:
Go to View -> Render Style -> Customize View and make sure the Edges points option is not active and the Materials option is active in the Custom View Modes dialog box.
Make the generated image is active.

1. Click the Search Image Extrema icon.
The Extrema Creation dialog box is displayed.

You can ask the program to detect given numbers of global (on the whole part) and/or local (relatively to neighbor mesh elements) extrema at most, by setting the Global and Local switches.

	If you activate the `Global` option, you will launch the detection of the minimum and maximum global extrema. Global means that the system will detect all the entities which have a value equal to the Minimum or Maximum value.
	If you activate the `Local` option, you will launch the detection of the minimum and maximum local extrema. Local means that the system will search all the entities which are related to the Minimum or Maximum value compared to the two-levelled neighboring entities.

3. Click OK to exit the dialog box.
A new image corresponding to the default settings is displayed, with two arrow boxes locating the points of absolute extremum for the current field and containing information about the detected value.

The Extrema object set containing the two Global Extrema appears under the current Image object in the specification tree.

4. Double click the Extrema object set in the specification tree.
The Extrema Edition dialog box appears.
You can modify the objects set by setting the Global and Local switches.

5. Set the Global switch to off and the Local switch to on.
The boxes locating the global extrema disappear, and symbols locating the local extrema are visualized.

The Extrema objects set in the specification tree now contains, in addition to the two Global Extrema objects, as many Local Extremum (Maximum or Minimum) objects as you have required.

6. Double-click one of the Local Extremum objects in the specification tree.
The Image Extremum Editor dialog box is displayed.

7. Set the Show Label option to on and then OK, in the Image Extremum Editor dialog box.

A new arrow box is visualized, locating the position of the corresponding point and containing information about the detected value.

8. Click OK to exit the Image Extremum Editor dialog box.

The extrema detection capability is also available for images obtained under Frequency and Buckling Solutions.