How do I add tiles in QGIS?

You can add tiles in QGIS using the XYZ Tiles functionality. Here's how:

1. Open the Add XYZ Layer dialog: Navigate to the "Layer" menu in QGIS, select "Add Layer," and then click "Add XYZ Layer."

2. Create a new connection (if necessary): If you haven't already set up the tile service you want to use, click the "New" button in the "Add XYZ Tile Layer" dialog.

3. Configure the new connection: A new window will appear where you need to enter the following information:

   • Name: Give your tile service a descriptive name (e.g., "Iowa Historical Imagery").
   • URL: Enter the URL of the tile service. This is the most crucial part. The URL typically follows this pattern: http://your-tile-server.com/tiles/{z}/{x}/{y}.png (or .jpg). {z} represents the zoom level, {x} the column, and {y} the row of the tile. A working example URL is: http://cawm.lib.uiowa.edu/tiles/{z}/{x}/{y}.png. This provides access to historical imagery from the University of Iowa.
   • Optionally, you can also set Min. Zoom Level, Max. Zoom Level, CRS, and other advanced options.
   • Click "OK" to save the connection settings.

4. Select the tile service and add it to your project: In the "Add XYZ Tile Layer" dialog, you should now see the name you gave to your tile service in the dropdown menu. Select it. Click "Add" to add the tile layer to your QGIS project.

5. View the tiles: The XYZ tiles will now be displayed in the QGIS map canvas. You might need to zoom in to see them clearly.

Example Scenario:

Let's say you want to add the historical imagery tiles from the University of Iowa to your QGIS project. Here's how you would do it:

1. Follow steps 1-2 above.
2. In the "Create a New XYZ Connection" dialog:
   • Name: "Iowa Historical Imagery"
   • URL: http://cawm.lib.uiowa.edu/tiles/{z}/{x}/{y}.png
   • Click "OK".
3. Back in the "Add XYZ Tile Layer" dialog, select "Iowa Historical Imagery" from the dropdown and click "Add."

Important Considerations:

• Valid URL: Ensure that the URL you enter is correct and that the tile server is accessible. A common mistake is a typo in the URL.
• Terms of Use: Be aware of the terms of use and licensing associated with the tile service.
• Performance: Using online tile services depends on your internet connection. Slow connections can lead to slow tile loading.
• Projection/CRS: Ensure that the tile service's coordinate reference system (CRS) is compatible with your QGIS project's CRS. While QGIS often handles reprojection automatically, conflicts can sometimes arise.