Posts Tagged ‘scale ranks’

Natural Earth Vector Preview: Cities (Part 2)

Thursday, November 12th, 2009

Announced at NACIS in Sacramento, California in October, we’re closing in on final release of Natural Earth vector and raster map data.

Bill Buckingham wrapped up processing the Natural Earth Vector cities (populated places point locations) this week. I’ve been honing our admin-1 and admin-1 rankings and feature names (only 4,000 states and provinces around the world, wew!).

Bill’s added population estimates for each city based on LandScan. The technique allows the user to know both the relative “regional” importance of a town, regardless of it’s population, based on which map scales the feature should be visible (thanks to Dick Furno) at AND to know how many people live there.

By taking a composite of both, you can still show small population cities that are regionally important at a small type point size along with larger populated places at the smaller map scales.

We have about 6,500 cities in Natural Earth Vector. Over 90% of those have population estimates (the ones that don’t are usually out in the boondocks). Together, our cities capture over 3 billion people or half of humanity.

For comparison, most other populated place GIS files have only 2,000 some cities and they focus on country and first order administrative capitals with a bare smattering of other towns. For instance: Lagos, Nigeria or San Francisco, California.  This makes smaller countries with lots of administrative divisions (like Slovenia, Vietnam, or Jamaica) seems way more populated than larger countries with larger administrative divisions (like the United States). See the North America screenshot below for an example and look at the Caribbean versus United States.

They also don’t estimate populations, and if they do they use official census number that hide the true “metro”-style counting of people that should inform a thematic map regardless of formal administrative boundaries at the smaller map scales that Natural Earth excels at.

Now for some screenshots:

(Scale ranks, followed by population view color coded like the scale ranks with nodata green dots, then cyan dot version is ESRI cities overlayed)









More continents o’ dots after the jump.