Points

Firefly cartography

April 2022

Firefly cartography - population of major World cities.

Points glowing against a dark background.

Data

• Cities data from Natural Earth Data. (Which dataset?)

Tools used

• QGIS

What did I learn?

• The effectiveness of draw effects in QGIS.
• Firefly cartography! How to create firefly cartography with QGIS

Process

Data

• Natural Earth data
  • 1:10m Populated places
  • 1:10m Countries

Preparing data

• Set project background to black - Project > Properties > General > Background color.
• Countries = dark grey fill with black outlines.
• Populated places - Select by expression where POP_MAX > 700000

Firefly effect for points

• Set points to Graduated styling with 4 classes.
• Set values as required.
• Double-click on first symbol and click on Simple Marker. Set size, Fill colour = White; Stroke = no pen.
• At bottom, tick Draw Effects and click on Star button.
• Click on Source and set Opacity, e.g. to 70
• Tick Outer glow
  • Spread = 1
  • Blur radius = 1
  • Set colour for the glow, e.g. bright turquoise!
• Experiment with settings, e.g spread and blur of outer glow
• would a bit of Inner glow help too?

Repeat for each class, choosing graduated sizes, and different bright colours.