on December 31, 2022

How to add point features from longitude and latitude coordinates on QGIS

Hiking & Activities

Plotting Points Like a Pro: Adding Coordinates in QGIS

Okay, so you’ve got some data with longitude and latitude coordinates, and you want to see it come alive on a map in QGIS. Awesome! QGIS is a fantastic, free tool that lets you do all sorts of cool things with spatial data. And trust me, plotting points from coordinates is one of the most basic, yet powerful, things you can do. Let’s walk through it, step by step.

First things first: your data. The best way to get your coordinates into QGIS is with a simple CSV file. Think of it like a digital spreadsheet. Now, a few things to keep in mind here. You’ll want columns for longitude (that’s your X coordinate) and latitude (your Y). I usually throw in an extra column for a name or description, just to keep things organized.

  • CSV is Key: Make sure you save your spreadsheet as a CSV. QGIS can be picky and doesn’t play nice with those fancy XLSX files directly.
  • Headers Matter: Give your columns clear names, like “Longitude,” “Latitude,” or even just “X” and “Y.” QGIS is pretty smart and can usually figure it out, but it helps to be clear.
  • Dot’s the Spot: This is a big one! Make sure your numbers use a dot (.) as the decimal separator. If you’re used to using commas (,), QGIS might get confused. There’s a workaround in QGIS, but using dots from the get-go saves you a headache.
  • X Before Y: Remember, it’s longitude first, then latitude. X comes before Y, just like in the alphabet.

Alright, data prepped? Let’s get it into QGIS!

  • Fire Up QGIS: Open QGIS Desktop. You probably already knew that, right?
  • Add Delimited Text Layer: Go to Layer > Add Layer > Add Delimited Text Layer. This is where the magic starts.
  • Point QGIS to Your File: In the window that pops up, click the little button with the dots (…) next to “File name.” Find your CSV file and select it. You should see a preview of your data in the “Sample Data” box.
  • File Format and Delimiters: QGIS should automatically recognize that it’s a CSV file. If it doesn’t, just tell it that it is. Also, double-check that it knows what’s separating your data (usually a comma). If you used tabs, you might need to tell it specifically.
  • Geometry Definition: This is where you tell QGIS what your data is. Choose “Point coordinates.”
  • X and Y Fields: Now, tell QGIS which columns have your longitude and latitude. It might guess correctly, but always double-check!
  • Coordinate Reference System (CRS): This is super important. It tells QGIS where on Earth your coordinates are located. For standard latitude and longitude, you’ll almost always want to use WGS 84 (EPSG: 4326). Think of it like telling QGIS what language your coordinates are speaking. Click the globe icon and search for “WGS 84” or “4326.”
  • Add the Layer: Click “Add” and then “Close.” Boom! Your points should now be showing up on the map.

    • Now, sometimes things don’t go quite as planned. Don’t worry, it happens to the best of us! Here are a few common hiccups and how to fix them:

    • Points in the Wrong Place?
      • CRS is Wrong: This is the most common culprit. Go back and double-check that you selected WGS 84. You can fix it by right-clicking the layer, going to Layer CRS > Set Layer CRS, and picking the right one.
      • Coordinates Swapped: Yep, it happens. Make sure X is longitude and Y is latitude.
      • Missing Minus Signs: If your points are showing up in the wrong hemisphere, you might be missing a negative sign on your longitude or latitude.
    • “Add” Button Greyed Out? You probably forgot to set the CRS. Go back and do that!
    • Data Not Showing Up as Numbers? This almost always means QGIS is misinterpreting your decimal separator. Make sure you’re using dots (.) in your CSV file.

    Okay, so you’ve got your points on the map. Awesome! But right now, they’re just living in QGIS’s memory. If you want to save them for later, you need to save them as a shapefile.

  • Right-Click: Right-click on your imported layer in the Layers panel.
  • Export: Go to Export > Save Features As….
  • Format: Choose “ESRI Shapefile.” This is a common and widely compatible format.
  • Name and Location: Give your shapefile a name and pick a place to save it.
  • CRS: Double-check that the CRS is still correct!
  • Click “OK”: You’re done!

    • Bonus Tip: Adding Coordinates to Existing Layers

    What if you already have a point layer and just want to add the latitude and longitude as attributes? Easy peasy!

  • Open Attribute Table: Right-click the layer and select “Open Attribute Table.” This is where all the data associated with your points lives.
  • Toggle Editing: Click the little pencil icon to start editing.
  • Open Field Calculator: Click the abacus icon. This is where you can do calculations and add new data to your table.
  • Create New Fields:
    • Check “Create a new field.”
    • Give your latitude field a name (like “Latitude”) and choose “Decimal number (real)” as the type.
    • In the expression box, type $y. This tells QGIS to grab the Y coordinate (latitude) for each point.
    • Do the same for longitude, naming the field “Longitude” and using the expression $x.
  • Click “OK”: QGIS will calculate the latitude and longitude for each point and add them to your table.
  • Save Edits: Click the pencil icon again to save your changes.

    • And that’s it! You’re now a point-plotting pro in QGIS. Go forth and map!

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