When working with line networks in QGIS, sometimes it is necessary to make sure of the digitized line directions for modeling linear network purposes. It is simple in QGIS to display the directions of the digitized line segments; and reverse the direction if required. Basically, to show the line directions in QGIS, simply add a directional arrow marker style to the line segments as described below:
- In QGIS, ensure the linear feature of interest, e.g. segments are displayed in the map view.
- Press the mouse right button on the segment legend entry, and choose the Properties in the pop up menu.
The Layer Properties dialog box appears.
- Click Symbology on the left, if necessary. Ensure it is Single Symbol symbology and then click the + icon,
A Simple Line is appended to the Line.
- In the Symbol layer type drop down list, choose Arrow.
The Simple Line type is changed to Arrow.
- Optional. Toggle off Curved arrows, and toggle on Repeat arrow on each segment for better visualization.
- Click OK.
The segment linear features are styled with directional arrows.
Reversing the digitized linear features
- In QGIS, click the Toggle Editing icon to enter editing mode for the selected feature e.g. segments.
- Then click the Reverse Line icon to activate the command. Click on one or more linear feature to reverse the line directions.
