well vh are you colorblind?
the numbers above are pretty arbitrary. i suggest a log scale going from 10^-2 to 10^7 by powers of 10
10^-2 is probably achievable with large farm areas or mountains.
10^7 is achievable with a 100m skyline and 10m^3 per person
They're somewhat arbitrary yes, I suggested using a rougly power of 2 scale (where it skips some numbers).
I don't think the power of 10 scale is very good. 10 million people per square meter? The 100m skyline example is really just an apartment block, 1 square km in size with 10 cubic meters for everyone, and all the apartments border each other, with no walls, no celings and floors, no ventilation, no streets, no corridors, no parks, no shops, offices, hospitals.... etc., and even then, if your apartment is 2m tall, having 2.24m long walls is hardly a realistic size for people to live in, just a bed would alone take up almost half the room. In reality, not even the densest city districts come anything near that. Manhattan for example has 27,221 people per km
2.
http://en.wikipedia.org/wiki/List_of_city_districts_by_population_densityhttp://en.wikipedia.org/wiki/ManhattanI think the area that will actually come above around 20,000 people/km
2 is so small that it's simply not interesting to have different colors for anything above definitely 10
5.
If we want to use a power of x system, I'd say power of 2-4 would be much more sensible, even if the numbers don't look very nice... But then again, if our planet was going to use a base 8 or 16 number system it would make plenty of sense from their point of view.
