OOF2: The Manual

3.7. Skeleton
	Chapter 3. Task Pages

3.7. Skeleton

An OOF2 Skeleton is a bare-bones object containing geometric information about a Mesh. It is composed of Elements, Nodes, and Segments. It also includes boundaries (PointBoundary and EdgeBoundary) where Mesh boundary conditions will be applied.

A Skeleton is in essence a discretized geometric representation of Microstructure. A Mesh is created by adding muscles (material properties) and internal organs (mathematical properties) onto a Skeleton. Thus, the validity of a Mesh is critically dependent on how faithfully its Skeleton has been adapted to the Material (pixel) boundaries present in its Microstructure.

This Skeleton Page contains all the tools that are used in creating, managing, and modifying Skeletons so that they conform to material boundaries.

The layout of the Skeleton Page follows that of the Image and Pixel Selection pages. At the top of the page is a Skeleton Chooser, which selects the Skeleton to which the operations on the page apply. Like the Image Chooser on the Image Page, the Skeleton Chooser is in two parts. The first part chooses a Microstructure, and the second part chooses one of the Skeletons within it.

Figure 3.13. The Skeleton Page

Buttons

Below the Skeleton Chooser is a row of buttons for performing common Skeleton operations. The first three buttons create Skeletons, and set the Skeleton Chooser to the newly created Skeleton:

The New button creates a new Skeleton with a given number of Elements. The Skeleton will be created in the Microstructure specified by the first part of the Skeleton Chooser. The Skeleton will have a uniform rectangular array of Elements, and the Elements will not have any relationship to the Material boundaries in the Microstructure. It will almost certainly be necessary to modify the Skeleton for it to be a good representation of the Microstructure.
The Simple button creates a new Skeleton in which each pixel of the Microstructure is divided into one quadrilateral or two triangular Elements. The Skeleton will be created in the Microstructure specified by the first part of the Skeleton Chooser. A Skeleton created in this way already matches the Material boundaries in the Microstructure, so it doesn't need any modification. However, it probably creates far more elements than are necessary to represent the Microstructure and also includes unphysical jagged edges.
The Auto button creates a new Skeleton and automatically refines it to fit the Microstructure, using a predefined set of operations. This set may not be suitable for all Microstructures, but it often does a very good job.

The remaining buttons act on the Skeleton currently selected in the Skeleton Chooser:

The Rename button renames the current Skeleton and leaves it selected in the Skeleton Chooser.
The Copy button makes a copy of the current Skeleton. The copy becomes the new current Skeleton.
The Delete button deletes the current Skeleton and all Meshes associated with it. It does not otherwise affect the Skeleton's Microstructure.
The Save button saves the current Skeleton in a file. (The Save button is exactly the same as the Save/Skeleton command in the File menu, except that the Save button operates on the Skeleton named in the Skeleton Chooser, and the File command can save any Skeleton.)

The Skeleton Modification Pane

The Skeleton Modification Pane contains tools for modifying a Skeleton so that it follows the Material and pixel group boundaries in its Microstructure. See the discussions of the OOF.Skeleton.Modify command and the SkeletonModifier subclasses to learn about the specific tools.

At the top of the pane (see Figure 3.13) is a Chooser (marked method) for picking a modification method. The parameters of the method appear below it. Below that are five buttons:

The OK button applies the selected modifier to the current Skeleton by invoking the OOF.Skeleton.Modify command.
The Undo and Redo buttons undo and redo the latest Skeleton modifications.
The Prev and Next buttons cycle the method chooser through the recently applied methods. They have no direct effect on the Skeleton.


3.6. Materials		3.8. Pin Nodes