on December 24, 2022

How to identify feature from multiple layers in QGIS?

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Digging Deep: Identifying Features Across Layers in QGIS

QGIS, that trusty open-source Geographic Information System, is packed with tools. And one of the handiest? The ability to identify features even when they’re stacked on top of each other in multiple layers. Think of it like this: you’ve got a map showing roads, buildings, and underground utilities. How do you quickly see what’s under that road without digging a virtual hole? That’s where this feature comes in. Whether you’re knee-deep in urban planning, wrestling with environmental data, or just plain curious, knowing how to pinpoint and grab info from overlapping features is pure gold. So, let’s dive into how to effectively identify features from multiple layers in QGIS.

Meet the Identify Tool: Your Data Detective

The Identify tool in QGIS is your go-to for accessing feature attributes right from the map. Forget sifting through endless spreadsheets! This tool lets you view the juicy details of individual features from the layers you’ve loaded. Instead of drowning in attribute tables, you get a neat little form showing the attributes of just the feature you clicked on. Pretty slick, huh?

Finding Your Detective Badge (Accessing the Identify Tool):

  • Hunt Down the Attributes Toolbar: The Identify tool hangs out on the Attributes toolbar. Don’t see it? No sweat! Right-click in an empty spot on the toolbar area, go to “Toolbars,” and make sure “Attributes Toolbar” is checked. Alternatively, you can find it under “View” -> “Toolbars” -> “Attributes Toolbar.”
  • Grab the Magnifying Glass (Select the Identify Tool): The Identify tool icon is usually the first one on the Attributes toolbar. Hover over the icons; the tooltip will tell you it’s the “Identify Features” tool. Click it, and you’re ready to roll.

    • Tweaking Your Detective Skills (Configuring the Identify Tool)

    QGIS lets you fine-tune the Identify tool’s behavior. Think of it as adjusting the sensitivity of your metal detector.

  • Head to the Lab (Accessing Options): Go to “Settings” -> “Options” in the QGIS menu bar. In the Options window, click the “Map Tools” tab. You’ll find the “Identify” section there, where you can tweak the search radius and highlight color.
  • Adjust the Search Radius: This is how far around your click QGIS will look for features. The default is 2 millimeters (on your screen). Crank it up for a wider search (good if you’re a bit clumsy with the mouse) or dial it down for pinpoint accuracy.
  • Pick a Highlight Color: This determines how selected features light up on the map. Click the dropdown to open a color picker and choose something that pops. You can also adjust the “buffer,” which is the thickness of the highlight outline.

    • Cracking the Case: Identifying Features, Step-by-Step

  • Arm Yourself (Activate the Identify Tool): Click the Identify Features icon on the Attributes toolbar. You’re now in “detective mode.”
  • Click the Suspect (Click on the Map Canvas): Click the feature you’re interested in on the map. If multiple features from different layers are piled up there, QGIS will pop up a window listing them all, along with their attributes.
  • Read the Evidence (Navigating the Results): The Identify Results window shows the feature number, layer name, and all the attribute fields with their values. You can even customize this window to show specific fields.
  • Use Your Tools (Exploring Options): At the bottom of the Identify Results window, you’ll see some handy icons:
    • Expand/Collapse Tree: Opens or closes the tree view of the results.
    • Default Behavior: Resets the tree view to its original state.
    • Copy Attributes: Copies the attributes of the selected feature to your clipboard.
    • Print: Prints the selected feature information.
  • Right-Click for More Options: Right-clicking in the Identify Results window opens up a whole new menu:
    • View Feature Form: Opens a form for editing the feature’s attributes (if you have editing permissions).
    • Zoom to Feature: Zooms the map right to the selected feature.
    • Copy Feature: Copies the feature’s geometry and attributes.
    • Copy Attribute Value: Copies just the value of the attribute you clicked on.
    • Copy Feature Attributes: Copies all the attributes of the feature.
    • Clear Result: Clears the results from the window.
    • Clear Highlights: Removes the highlighting from the selected features on the map.
    • Highlight All: Highlights all the identified features on the map.

    • Pro Tips and Things to Keep in Mind

  • Right-Click to Choose: Here’s a neat trick: instead of a regular click, right-click while using the Identify Tool. A menu pops up, letting you pick which layer’s attributes you want to see, or view all layers at once.
  • Control Who Gets Identified: You can decide which layers the Identify tool can “see” in the Project Properties. Go to “Project” -> “Properties” -> “Identify Layers” and check or uncheck the boxes next to each layer.
  • Layer Order Matters: The order of your layers in the Layers panel affects how the Identify tool works. QGIS usually identifies features from the top-most layer first. So, make sure your layers are stacked in the right order to easily grab the info you need.
  • Plugin: There was a plugin called Multiple Layer Selection which allowed you to select stacked features . It added a new icon to the toolbar .

    • Mastering the Identify tool is like unlocking a secret level in QGIS. You’ll be able to efficiently pull valuable information from multiple layers, making your spatial analysis work a whole lot easier – and maybe even a little fun!

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