Basemaps and styling

Add a basemap

QGIS lists web basemaps under XYZ Tiles in the Browser panel.

1. Show the panel if needed: View → Panels → Browser.
2. Expand XYZ Tiles and double-click OpenStreetMap.
3. In the Layers panel, drag the basemap to the bottom so your Databricks layers draw on top.

If OpenStreetMap isn't listed, or you want another basemap, right-click XYZ Tiles → New Connection… and add one of these:

Name	URL	Max zoom
OpenStreetMap	https://tile.openstreetmap.org/{z}/{x}/{y}.png	19
Esri Light Gray Canvas (subtle, good under data)	https://server.arcgisonline.com/ArcGIS/rest/services/Canvas/World_Light_Gray_Base/MapServer/tile/{z}/{y}/{x}	16
Esri World Imagery (satellite)	https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}	19

• Esri URLs end {z}/{y}/{x} and OSM ends {z}/{x}/{y}. Swapping them puts tiles in the wrong place.
• CARTO basemaps now need an API key; without one they show "API KEY REQUIRED" watermarks.
• Check each provider's terms of use and attribution for published maps.

Style a layer

Right-click a layer → Properties… → Symbology.

Heat map of counts (e.g. the H3 hotspot query in Custom SQL queries): 1. Change Single Symbol to Graduated. 2. Value: crashes. Color ramp: Reds. Mode: Quantile. Classes: 6. 3. Click Classify, then OK. Set Opacity to about 75% on the Layer Rendering section so the basemap shows through.

Colour by category (e.g. SEVERITY): choose Categorized, Value: the column, Classify.

Styles are saved with the project, including for layers saved in the project, so they look the same when reopened.