Mapping Population in 3D

UK developers Parallel have released an interactive map which visualizes UK population density in 3D. Their ONS Population Estimates map shows the population density in each UK Lower Super Output Area (LSOA) and the age breakdown of the population in each LSOA.

The population density view on the map uses Mapbox GL's extrusion property to create 3D towers on the map. The height of the towers