2 Dynamic Markers

Tutorial 2: Basic Dynamically Changing Markers

This tutorial aims to show you the basics of creating, and animating, a static layer to use with the Animation Workbench. There are three pre-made layers to allow the main focus of the tutorial to be on the Animation Workbench and not on QGIS as a whole.

1. Download and extract the Required Tutorial Zip Folder  

2. Open the tutorial_2.qgz project file that is in the folder.  

3. Set the CRS of your project to WGS84/UTM zone 35S (EPSG: 32735).

 

4. In the Browser, expand the tutorial_2.gpkg and add the three pre-made layers (VaalDam, SouthAfrica, and route) (A) to your project.

 

5. In the Layers Panel, arrange the layers in the following order: route, VaalDam, SouthAfrica. Then right-click on the VaalDam layer and Zoom to Layer(s) (B)

Style the three layers to your preferred style.  

6. Now create a new layer in the tutorial_2.gpkg by clicking Layer➔Create Layer➔ New GeoPackage Layer... (C).

 

Click on the Ellipsis (D), navigate to and select the tutorial_2.gpkg, and click Save. Change the Table name to fish (E), set the Geometry type as Point (F), and change the CRS to match the Project CRS (G).

Click on OK and then click Add New Layer on the window that pops up.  

7. Select the fish layer and then click on Toggle Editing➔Add Point Feature (H).

Add a few points wherever you feel they should go (Hint: This is a fish layer so adding them above the dam layer would be best). Don't worry about naming the points, just add them.

Save your changes by clicking on Save Layer Edits just next to the Toggle Editing button. Then stop editing the layer.  

8. Repeat steps 6. and 7. but change the Table name to bird and add the points over the land areas.

 

9. Select the fish layer and then in the Layer styling toolbar (I) change the Symbol layer type to Raster Image Marker (J).

Select the marker image by clicking the Dropdown menu➔Select File... (K) and then choosing fish➔fish_0000.png.

Click Open  

10. Change the marker's Size Unit to Meters at Scale (L)

and set the Width and Height to 1000.  

11. Repeat Steps 9. and 10. with the bird layer but instead choosing bird➔bird_0000.png and setting the Width and Height to 3000.

 

In QGIS 3.26, or later, the Symbol layer type can simply be selected as Animated Marker and Step 12. can be skipped.

12. To animate the fish and bird layers using the QGIS Expressions system click the Dropdown Menu➔Edit... (M).

For the fish layer use the following expression:

    @project_home
    || 
    '/fish/fish_00'
    ||
    lpad(to_string( @frame_number % 32), 2, '0')
    ||
    '.png'

And for the bird layer use:

    @project_home
    ||
    '/bird/bird_00'
    || 
    lpad(to_string(@frame_number % 9), 2, '0')
    || 
    '.png'

Refer to the What is the Workbench doing? section for an explanation about what the above code snippet is doing.

13. Open the Animation Workbench (refer to the Using the Animation Workbench section if you are unsure how to open the Workbench).

In the Animation Plan tab set:

• the Render Mode to Planar (N),
• the Animation Layer to route (O) using the dropdown menu,
• the Zoom Range (P) to 1:270000 for the Minimum and 1:135000 for the Maximum,
• the Frame rate per second to 9 fps (Q),
• the Travel duration to 4,00 s (R),
• and the Feature hover duration to 2,00 s (S)

Enable both the Pan and Zoom easings and set them to linear.

14. Skip past the Intro, Outro, and Soundtrack tabs to the Output tab. Set the Output Format as Animated Gif (T) and the Output Resolution to 720p (1280x720) (U). The Output Resolution can be set as any of the three choices but was set at 720 for this tutorial for the sake of speed. Set the output location to one you can find easily (V)

 

15. Click Run and watch what the Workbench is doing in the Progress tab. Once the Workbench is finished running, you should end up with an output similar to this:

After this tutorial you should have a better understanding of how to create a point layer in your project and then to change the Single Symbol markers into stationary animated markers. A key focus is the idea that you can tell versions of QGIS before 3.26 to dynamically change markers using short code snippets. Versions of QGIS post 3.26 allow a user to simply use the Animated Marker feature without editing an expression.