30DayMapChallenge 2026

Adam Roberts · 3D, cloud-native Earth observation and analytics in the browser. Code on GitHub.
Three maps of central Paris comparing what GeoParquet, shuffled GeoParquet and PMTiles had to download for the same query box
Day 1 · Points · 1 November
103 million places, one box over Paris: what three formats had to download
 Dark 3D relief of the Rhône basin with every river that drains to the Rhône mouth glowing teal, thickening toward the sea
Day 2 · Lines · 2 November
26,297 km of lines that all end in one place: the Rhône, traced upstream from the sea
 The buildings of Paris's 4e arrondissement packed into rows by use, residential in amber, commercial and public in blue, largest first
Day 3 · Polygons · 3 November
The 2,696 buildings of Paris's 4e, lifted off the map and sorted by use and size
 Building footprints in Nørrebro, Copenhagen, on a dark basemap, each coloured by its 10 m cluster
Day 4 · Clusters · 4 November
Every building in Denmark grouped into settlements at 10 m: 4.16 million footprints in 5.3 minutes, inside Snowflake
 Dark relief map of the Belledonne range with the GR 738 from Aiguebelle to Vizille and, in amber, all the ground visible from the trail
Day 5 · Senses: Sight · 5 November
What you can see from every point of the GR 738 across Belledonne
 Map and Sankey chart of France's wine trade in 1962, dominated by a thick gold flow of 1.45 billion litres from Algeria
Day 6 · Vintage · 6 November
In 1962, Algeria sold more than half the wine traded across borders, almost all of it to France
 Dark map of Florida with hexagons shaded red to pale yellow counting wildland-urban interface homes more than a ten-minute drive from the nearest fire station
Day 7 · 10 minute map · 7 November
177,614 Florida homes are in the wildland-urban interface and more than ten minutes from a fire station
 Dark map of the UK with hexagons coloured by places named Utopia per 100,000 people
Day 8 · Utopia · 8 November
283 places in the UK have "Utopia" in the name. Adjusted for population, the Highlands beat London