Tutorial: Visualise Flow Direction with Arrows

This tutorial will guide you through the steps of visualising the output of the SAGA flow direction algorithm as a mesh with arrows using the Crayfish plugin.

4. Styling the flow direction mesh layer

The next step is to style the flow direction mesh layer that we have created.

1. Select the flowmesh layer in the Layers panel and open the Layer styling panel

2. Click to toggle off the contours visualisation.

3. Click to toggle on the vector visualisation. The dialogue should now look like this:

4. Click to go to the vector styling tab.

5. Change the Line width to 0.5 and the Color to blue.

6. Change Arrow Length to Fixed with a Length of 2.

7. Zoom in to explore the result.

That already gives a good impression of the flow direction. We're going to further improve the visualisation

8. In the Layer styling panel check the box Display on User Grid and keep the defaults.

The arrows are now fixed to a grid with 10 by 10 pixels spacing.

You can play with the grid settings, the line width and the arrow length until you find the optimal configuration for your zoom level.

In the next section we'll visualise this with the 3D Map View.