Coverage Boundary

Like surfaces, TIN layers have boundary objects to define the extents of the TIN. For a TIN, the boundary is a coverage boundary object. The New Coverage Boundary command can be used to create a new coverage boundary for your TIN. You can then apply the new boundary to change the extents of the TIN. This may be done if the default boundary is too detailed for the task at hand, or if you only need to TIN a small section of a surface.

By default, the boundary object is digitized using the Point‑to‑Point method. You are not limited to this method. There are several digitizing methods available, in particular, the Grab function, which allows you to use the existing geometry of another feature to create the boundary. You can switch digitizing methods at any time without damaging the polygon.

The changes from new the boundary are not applied automatically. If you are satisfied with the boundary, you must update the TIN with the new boundary to save the changes to the TIN Editor layer. These changes will be remembered the next time a TIN is created for the layer. If you do not update the TIN, the changes will be lost when the layer or surface is closed.

Procedure

1. Select the TIN Editor layer in the Layers window.

2. Click the check box to turn on the TIN Editor layer.

3. Select the Coverage Boundary command.

4. Click in the Display window to place the first vertex for the new coverage boundary.

5. Continue adding vertices until the object surrounds the area for which you wish to have a TIN.

6. Once all vertices are added, use one of the following methods to turn off Digitizing mode and complete the coverage boundary:

• Press the <Home> or <End> key.

• Right-click and select Close Area.

The newly digitized coverage boundary is added to the display.

7. Select the Update TIN command to apply the new boundary to the TIN.

8. Refresh the Display window.

The TIN is updated using the new coverage boundary.