Menu | Edit > Lines > Smooth and Filter |
Filter and/or smooth lines with tightly curved or angular line segments.
Filtering is applied based on a selected algorithm. When using this option, vertices are removed from the lines if they are not necessary. A number of filtering algorithms are available, one of which is the Douglas-Peucker algorithm. For more information on this algorithm, see Douglas-Peucker Algorithm.
Smoothing is performed using the bSpline algorithm. When using this option, the distance between vertices is shortened by adding additional vertices. By having shorter edges, smoother curves are achieved.
If using both options, the lines are first filtered and the resulting features are then smoothed.
Interface
The Smooth and Filter command uses the following dialog box.
Option | Description |
Filter | This option is used to apply filtering to the vertices in the selected contours. You can choose the algorithm by which to apply filtering, and whether to filter by metres on the ground or by millimetres (mm) at map scale, which requires you to enter a scale. |
Method | The filtering algorithm to be applied. The algorithms available are: • Douglas-Peucker • Reumann-Witkam • Lang • Radius • Opheim |
Tolerance | The number of units by which to perform filtering. Enter a value in the field. |
Edge length | The maximum edge length when filtering using the Opheim method. This field is only enabled when the Opheim filter method is selected. |
Distances are | The distance type to use for filtering. 1. Select either metres on the ground or mm at map scale. If you choose mm at map scale, a value must be entered in the map scale field. |
Look ahead | The number of vertices to be considered when filtering using the Lang method. |
Smooth | This option is used to apply smoothing to the selected contours. A bSpline Order value must be specified if using this option. |
bSpline Order | The bSpline Order defines the degree of smoothing you wish to apply. |
Procedure
1. Select a feature layer with line features available.
2. Select one or more lines.
3. Select the Smooth and Filter command.
4. Select Filter and/or Smooth.
5. Set any necessary options.
6. Click OK.
The selected line is smoothed/filtered according to the settings defined.
Example
Below is a group of contours that have been smoothed using a bSpline Order of 3.
