3d population density would be an interesting measure, though. It would provide a better feel for how cramped a populated volume actually is.
It would have to be the displacement volume, to account for cities with only a few really tall buildings, and also somehow adjusted for buildings with high ceilings.
Population density is literally measured over a planar metric: people/km^2
You are suggesting it's measured over a cube volume?
3d population density would be an interesting measure, though. It would provide a better feel for how cramped a populated volume actually is.
It would have to be the displacement volume, to account for cities with only a few really tall buildings, and also somehow adjusted for buildings with high ceilings.
There are some really dense people
Some people are dense... now in three dimensions!