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Segment operator attributes menu item

This item pops up a window which allows you to set operator attributes for segment operators. If you select a plot that has a segment operator applied from the Active plots list in the MeshTV Main window, then anything you change and apply will affect selected plots. Plots not highlighted will not be changed, unless Apply operators to all plots toggle button is on, in which case all plots will be changed. If you select this item without selecting a plot first, and you try to apply changes, a Query window will pop up asking if you want to add a segment operator so you can apply the changes you have made. Note that if you make changes in this window and then select a plot that has a segment operator applied, your changes will be lost.

You can modify the default settings for attributes for future operators by pulling up this window, making your changes, and pressing the Make default button. This affects only operators applied in the future, not already applied ones, and stays in effect only for the remainder of the current MeshTV session unless you also select Save settings from the File menu.

Currently the segment operator only works for 3D UCD datasets.

Segment attributes window

The Segment attributes window looks like Segment attributes , if you are using MeshTV's defaults. If you aren't, the values might be different.

This window allows you to specify a starting zone from which to "grow" layers. For example, if you want to see all the neighboring zones to zone 20 in your problem, you specify zone 20 as your zone number, and set the layer slider to 1, indicated you want the search to go out one layer. Because of this layering capability, the operator is also called Onion Peel.

If you don't see a description for an item in this window, check in the Shared items section near the front of the chapter.

Initial zone area

The controls in the area allow you to set the "seed" zone for the segment operator. The seed, or starting, zone sets the initial location to which layers can be added. When the segment operator is first applied, it displays only the initial starting zone, unless the user has modified the default settings for the operator. Note that if the mesh contains a large number of zones, the single zone MeshTV displays might take up only one pixel on the display, so you might think nothing has been displayed.

Zone text field

This text field allows you to set the seed zone for the segment operator. If you know the number of the zone you want to see, type it here. Note that if the mesh contains a large number of zones, the single zone MeshTV displays might take up only one pixel on the display, so you might think nothing has been displayed.

Block text field

If your data file contains blocks, you can set the toggle to indicate that you want to specify a block number. The Block text field allows you to type in that block number. The value in the Zone text field is then understood to be a zone in the supplied block.

Use picked zone toggle

You can set the seed zone for the segment operator by picking a zone in 3D pick. Once you have picked this zone, return the visualization window to Navigate mode, and then apply the segment operator. Once you select this toggle, your picked zone will be the one displayed. Note that if the mesh contains a large number of zones, the single zone MeshTV displays might take up only one pixel on the display, so you might think nothing has been displayed.

Layers slider and text field

Use the Layers controls to display the zones that neighbor the starting zone. Each time you add a number to the number of layers, the segment operator will find and display all zones that are neighbors of the current set of zones displayed. A neighbor is any zone that shares a vertex. For example, if we're only displaying the seed zone, and we apply a layer of 1, the segment operator will find all zones that share a vertex with the seed zone. If we now increment the layer to 2, the segment operator will find all zones that share a vertex with any zone in layer 1.

Each collection of neighbors constitutes a new "layer" of zones. The number in the slider or text field indicates how many layers are displayed. If you decrease the number of layers, MeshTV "peels away" the outermost layer of zones.