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Source Editor
Menu | Tools > Coverages > TIN > Long Edges |
Tool |
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This command is only available if the Bathymetry Compilation module is enabled. See Modules for further information |
The initial TIN creation produces a convex outer hull. This means that long edges are typically added along the outside of the TIN, over areas where no express data has been collected. It may be desirable to limit the TIN to only the areas where there is true data by removing long edges. This is particularly important if the TIN is to be cut to a geometry. Removing these long edges is an iterative process that can be run on the data as many times as needed until no hull edges extend beyond the true data coverage.
The Long Edges command can be used to remove long edges on the exterior of the dataset, remove long edges from the interior of the dataset, or to restore any long edges removed from the exterior of the dataset. Long edges removed from the interior are actually removed through the automatic use of coverage hole features, and they can be restored by selecting the hole feature on the TIN Editor layer and deleting the feature.
Related commands:
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Interface
Option | Description |
|---|---|
Edge length histogram | The edge length histogram provides important statistical data on the lengths of the edges in the TIN you selected. TIN edge length values are grouped according to edge lengths. Each group is displayed as a vertical bar in the histogram at the appropriate position along the horizontal axis. The shortest edges are in the rightmost on along the horizontal axis and the longest edges are in the leftmost group. The frequency or count of the edge lengths in each group is displayed along the vertical axis. There are two scale visualization methods for vertical axis data: • Logarithmic: displays the number of edges in a group over progressively exaggerated vertical intervals (for example, 10, 100, 1000, and so on.). The intervals are based on the natural logarithm of the frequency. • Linear: displays the number of edges in a group over constant vertical intervals (10, 20, 30, and so one). When the data contains many edges of similar length, it is recommended that you use the logarithmic scale. |
Cursor position | The length of the edge group at the current cursor position when moving the cursor over the histogram. |
Shortest edge | The shortest edge length in the TIN. |
Longest edge | The longest edge length in the TIN. |
Mean length | The mean length of the edges in the TIN. |
Standard deviation | The standard deviation of all the line lengths. |
Remove long edges | Enable this option if the tool is being run to remove long edges. The Type and Threshold options become available. |
Type | The type of edges to remove Select outer, inner or both. |
Threshold | Edges are removed based on the threshold value. The threshold value is the longest edge length you want to keep in the TIN. There are three ways to define the threshold: • Mean + 2 x standard deviation, which identifies edges to be removed using this formula Mean length + (2 X Standard deviation length) • Mean + 3 x standard deviation, which identifies edges to be removed using this formula: Mean length + (3 X Standard deviation length) • User specified, where you define the longest edge length allowed, causing all edges longer than this value to be removed. This option is defined by by typing a value in the field or by clicking the histogram to select a value. All edges that will be affected by the threshold value will be highlighted in red in the histogram. If entering a specific value, it must be longer than the shortest edge length in the TIN. |
Restore outer long edges | Enable this option if the tool is being run to restore long edges. The Type and Threshold fields are disabled. |
Preview | Preview the changes that would be made to the TIN if the process was run with the current settings. The dialog box is disabled while in Preview mode. The lines that fall outside the selected range of standard deviation values are highlighted in black in the Display window. |
Undo Preview | Turn off preview mode and return the TIN to the original view. The dialog box is enabled. |
Apply | Apply the current settings to the TIN. The dialog box will remain open, allowing further editing of the TIN if necessary. |
Close | Close the dialog box when all edits are complete. |
Procedure
1. Make he TIN Editor layer active.
2. Select the Long Edges command.
The Long Edges dialog box is displayed.
3. Choose the type of long edges to remove.
4. Define any other necessary options.
5. [Optional] Click Preview to preview the changes to the TIN.
6. Click Apply to apply the changes to the TIN.
7. [Optional] Repeat to remove additional long edges.
8. Click Close to exit the dialog box.
The TIN is updated with the selected changes.
This image shows the TIN after two iterations of edge removal.
