Editing Media Properties: Tutorial # 2: Simple Tutorial # 2: Simple

Creating and Editing a Simple Grid:

1. Under the File  menu item, select New Model. In the widget that appears, change the number of vertices from a 2x2x2 model to an initial one with 5x4x2 vertices (i.e., 12 cells).
2. Under the Draw  menu item, select Objects and click the Lattice selection box to toggle it on. In short, toggle on the  Draw Objects Lattice, in order to draw the edges of the interior cells.
3. `Tear off' the Edit  Menu. The Undo button is used to correct or `undo' editing mistakes. Select the  Edit Grid widget (see Figure 4) to edit and refine the grid. Also, `tear off' the Draw  menu, so that the Redraw button is available for use to view the resulting changes in the Main Window.



Figure 4: Edit Grid Widget

4. Select the Edit Slice button on the Grid Edit widget to bring up an initial slice editing window (see Figure 5(a)) which contains the currently selected slice (X-slice 1). The default editing mode (i.e., 2D radio button=`on') is to edit within this slice, holding the x-index constant and altering the y-z coordinates of the grid. (If one sets this to `off', one may edit out-of-slice as described in Step 5 below when we edit z-slices).



Figure 5.a: Initial Edit Slice Widget with x-index = 1.

Adjust vertices in the x=1 slice by selecting the Pick radio-button to pick vertices. Click various vertices (respectively, lines or planes) and drag to change their position . Notice that the Vertex and Coords text fields below the Draw Area change accordingly. In fact, precise coordinate positions may be entered in the Coords text fields and vertices of large, dense data sets may be precisely selected by using the Vertex text fields.

Note that changing the text field of Vertex-x changes to the corresponding x-slice in this edit window, since this window resulted from selecting EditSlice with Axis: x chosen in the Grid Edit widget. Also, note that the View controls for in-slice editing only permit rotations about the x-axis, and the drawing is a projected view of the main window in this mode.

You may `Dismiss' these edit-windows when done.

5. Using the EditGrid widget (Figure 4), choose Axis: z and select the Edit Slice button to choose a z-slice to edit. We will move some of these vertices out-of-plane to illustrate adding `topography' to the model. In the EditSlice Window toggle the 2d option to `off' and select the View buttons to Pan, Zoom and Rotate the object so that the azimuth is at aproximately a angle with the screen (i.e., the rendering projection plane). 2-button and 3-button mice behave in View mode in the exactly the same manner as described in the Main Window section.
6. Choose the Pick radio-button, and select a vertex. To change the z-coordinate of the vertex, select and drag. By editing the z-Coords text field, you may precisely adjust the z-components of the vertices in that logically-rectangular z-slice as well. Redraw-ing the Main Window (Figure 1) shows the resulting changes. Undo's also update and re-render both the Main Window and the EditSlice Window as corrections are made. Again, when done, you may `Dismiss' this EditSlice Window.
7. Refine the current basic grid using the Insert Slices button of the EditGrid widget (Figure 4) to interpolate two additional slices between the top and bottom of our vertex model. Select  Axis: z  and choose the z=1 slice by entering 1 into the text field at the top of the widget. Just below the Insert Slices button, change the text field of the widget from the default value of 1 to 2. Select Insert Slices button to uniformly interpolate 2 slices from the currently selected slice (in this case, z slice = 1) to is successor.
   Additional x- and y- slices may be inserted by choosing the corresponding  Axis: -, the number of slices to insert, and selecting the Insert Slices button.
8. Select Edit Attributes and change the Z-Scale View text field from 50.00 to 8.00 and select Redraw.

A sample grid constructed in this way (see Figure 6) has corresponding x slice=1 as shown in Figure 5(b).

Figure 5.b: Edit Slice Widget with x-index = 1.

Figure 6: Resulting simple grid of Tutorial #2.

Now that the grid is constructed, the other parameters may be set in arbitrary order. We first set the coefficients of the Partial Differential Equations (i.e. Material Properties), followed by Initial and Boundary Conditions. The grid may be altered, however, during or after any of the operations on the other parameters. Since each of these tools uses `patches' determined by ranges of vertex indices, an insertion of additional slices may require an appropriate adjustment of the patch ranges for properly specifying the medium's properties.

Editing Media Properties: Tutorial # 2: Simple Tutorial # 2: Simple