on December 31, 2022

Adding lon/lat grid on map in QGIS 3.0?

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Adding a Lon/Lat Grid to Your Map in QGIS 3.0 – The Human Way

So, you’re diving into QGIS 3.0 and want to add those handy longitude/latitude grids to your maps, huh? Smart move! A good grid, also known as a graticule, can really make your map pop and, more importantly, help people understand the spatial relationships you’re showing. Think of it as adding those helpful lines of reference that instantly give context. Let’s walk through how to do it, step by step.

First Things First: Coordinate Reference Systems (CRS) – Don’t Sweat It!

Now, before we jump in, a quick word on Coordinate Reference Systems, or CRS. It sounds complicated, but it’s really just about how your map “connects” to the real world. Longitude and latitude are those angular measurements we all learned about in school, and a geographic CRS like WGS 84 (EPSG:4326) is what you’ll typically use for displaying your grid lines in good old degrees. Basically, it ensures your grid shows lat/lon and not some other unit like meters. Trust me, you want lat/lon!

Let’s Get Gridding: A Step-by-Step Guide

Alright, ready to add that grid? Here’s the lowdown:

  • Fire Up Print Layout: First, get your print layout open in QGIS. This is where you’ll actually design the final, exportable version of your map. Go to Project -> New Print Layout. Easy peasy.

  • Make That Map Item Active: Click on the map itself within your layout. You’ll know it’s active when it’s highlighted. This tells QGIS, “Hey, I’m working on this map right here.”

  • Add a Grid – The Green Plus is Your Friend: In the “Item Properties” tab (usually on the right), scroll down until you see “Grids.” Hit that green “+” sign to add a new grid. Boom!

  • Tweak It! Select the grid you just added and click “Modify Grid…” This is where the magic happens.

  • CRS Time: WGS 84 is Your Pal: In the “Grid Properties” window, find the “CRS” option. Select “WGS 84” or “EPSG:4326.” This is key for displaying your grid in latitude and longitude, like we talked about.

  • Spacing is Everything: Set the Interval: Now, decide how far apart you want your grid lines. This is the “X” (longitude) and “Y” (latitude) interval. What you choose here depends on your map’s scale. Mapping the whole world? You might use intervals of 10, 20, or even 30 degrees. Zoomed in on a city? Try 1 degree or even less. Play around and see what looks good.

  • Make It Pretty: Customize the Look: This is where you can really put your stamp on things:

    • Line Style: Change the color, thickness, and style of the grid lines. You want them visible, but not overwhelming. Think subtle, not screaming.
    • Frame Style: Add a frame around the map and customize it to your liking. A simple black line often works well.

  • Show Me the Numbers: Draw Coordinates: Scroll down to “Draw Coordinates” and check that box. This adds the actual latitude and longitude numbers to your grid.

  • Coordinate Formatting – Get Fancy: Now, let’s make those numbers look good:

    • Format: Choose how you want the coordinates displayed – Decimal, Decimal with suffix, or Degrees, Minutes, and Seconds.
    • Font: Pick a font that’s easy to read. Size and color matter too!
    • Placement: Decide where you want the labels – all sides, just the top and bottom, etc.
    • Orientation: How should the labels be oriented? Horizontal? Vertical? “On tick” can look pretty cool.

  • Tweak, Tweak, Tweak: Seriously, experiment! There’s no one-size-fits-all. What looks good depends on your map and what you’re trying to show.

    • Pro Tips for the Grid-Obsessed

    • Project CRS vs. Grid CRS: A Quick Note: Your project CRS is the overall coordinate system for your project. The grid CRS is specifically for the grid. Usually, you’ll want WGS 84 for the grid, but your project CRS might be something different.
    • Grids Gone Wild? Densify! If your grid lines look jagged, especially with certain projections, use the “densify” tool in the processing toolbox. This smooths things out by adding more points to the lines.
    • Get Creative: Custom Grids: Feeling adventurous? You can create custom grid layers with specific intervals and labeling schemes. This is for the true power users!

    And there you have it! Adding a longitude/latitude grid in QGIS 3.0 isn’t rocket science, but it can really elevate your maps. Play around with the settings, find what works best for you, and happy mapping!

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