Is there any way to make QGIS layout to activate/deactivate certain layers?

Making QGIS Layouts Dance to Your Tune: Taming Layer Visibility

QGIS, that trusty open-source Geographic Information System, is a powerhouse for crafting maps that not only inform but also look darn good. Ever wished you could make certain layers pop in your layout while others take a backseat? Maybe you’re dreaming of a map series, or just want to declutter a complex map for different audiences. The question then becomes: can you actually tell QGIS layouts which layers to show and hide? Absolutely! And let me tell you, there are several cool ways to pull this off.

Map Themes: The Quick and Dirty Solution

For a straightforward approach, Map Themes are your best friend. Think of them as saved outfits for your map. You simply decide which layers should be visible, like picking your favorite shirt and jeans, and then save that combo as a theme. Want a different look? Create another theme with a different set of layers showing. Easy peasy.

Inside your QGIS layout, you can then assign a specific map theme to a map element. This ensures that element only displays the layers you’ve chosen for that theme. I’ve used this countless times to create different map versions highlighting, say, population density versus land use. It’s a lifesaver.

Atlas: Data-Driven Layer Magic

Now, if you’re feeling a bit more adventurous – perhaps you’re diving into creating a map series with the Atlas tool – you can crank things up a notch with data-defined overrides. This is where you let the data itself dictate which layers are visible in each map of the series. Sounds complicated? It’s not as bad as it seems.

Here’s the gist:

Let’s say you have a field called “VisibleLayers” in your coverage layer. If it contains “Roads|Buildings” for a particular feature, the expression will ensure only the “Roads” and “Buildings” layers are visible when Atlas creates the map for that feature. I’ve used this to generate hundreds of maps showing different infrastructure projects based on location. Trust me, it’s powerful stuff.

Layer Visibility Presets

Don’t overlook “visibility presets”! QGIS allows you to save and load preset layer and group visibility settings. This feature allows you to save different layer arrangements and visibility and apply them as needed.

Pro Tips and Tricks

Here are a few extra nuggets of wisdom I’ve picked up over the years:

• Expressions are your friends: QGIS expressions can manipulate almost anything in your layout, including layer visibility (indirectly, of course). You could, for example, set a layer’s opacity to zero based on an expression, effectively making it disappear.
• Scale matters: Use scale-based visibility to declutter your maps at different zoom levels. This is especially handy for showing detailed features only when you’re zoomed in close.

Final Thoughts

QGIS hands you a versatile toolkit for dynamically controlling layer visibility in your layouts. Whether you’re after simple thematic tweaks or complex, data-driven map series, QGIS has your back. By mastering Map Themes, Atlas overrides, and visibility presets, you can create maps that are not only informative but also truly engaging and tailored to your audience. So go ahead, experiment, and make your QGIS layouts sing!