on January 2, 2023

Setting Atlas scale and scale bar for each map to round number using QGIS

Hiking & Activities

Taming the Atlas: Getting Nice, Round Numbers on Your QGIS Maps

QGIS is fantastic, especially its Atlas feature. Think of Atlas as your personal map-making machine, churning out a whole series of maps from a single template. Perfect for creating map books, showing different areas, or just iterating through a region. But let’s be honest, sometimes the scales it spits out are just…weird.

We’ve all been there, right? You’re trying to create a professional-looking map, and the Atlas gives you a scale of 1:27,322. Or a scale bar with segments measured in fractions of millimeters. It’s functional, sure, but it’s not exactly easy on the eyes, and it definitely doesn’t help anyone quickly understand the map. The challenge is that QGIS dynamically adjusts the map view for each feature in your coverage layer, which can lead to these odd numbers. So, how do we wrangle those numbers into something clean and understandable?

Rounding the Map Scale: No More Weird Numbers!

The secret sauce is using expressions within the map item properties. It sounds complicated, but trust me, it’s not. Here’s the breakdown:

  • Fire up the Print Layout: First things first, open your QGIS project and head to the Print Layout where your Atlas magic happens.
  • Grab the Map Item: Select the map that the Atlas controls. You know, the one that’s changing with each feature.
  • Dive into Item Properties: Look for the “Scale” property in the “Item Properties” panel.
  • Data Defined Override – Your New Best Friend: Click that little button next to the scale input box – the one that looks like a cylinder. Choose “Edit.” This is where the fun begins.
  • Whip Out the Expression: Now, paste in one of these expressions, depending on how you want to round things off:

    • qgis

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