9 replies to this topic

[Hans van der Maarel]

Hi everybody,

I'm looking for a global, low-detail dataset of cities. There is some free data floating around the internet, but that's a file of airports and airbases, rather than cities. Can anybody help me out? It's intended for a roughly 6-feet wide wall map.

[Nick Springer]

What about the DCW? Doesn't that have cities?

[Hans van der Maarel]

Yes, but iirc the DCW was the predecessor to VMAP. Given that in VMAP the cities are not 100% reliable, I sort of assumed this would also be the case with DCW. I'll give it a closer look though.

[Rob]

esri has a pretty complete world cities layer, although I think at least part of it might be sourced to DCW, available on the media cd if you have a license, or perhaps on their website. if interested and can't find, contact me off the board and I can email it to you.

rob

[Hans van der Maarel]

Rob,

The ESRI data, as well as the data that came with Manifold, is indeed sourced from the DCW. Also, the interface on the ESRI website won't let you download data for the entire world in one go... It looks like they made some improvements, but still it often shows airport locations rather than cities.

I guess one of the key aspects of free data is the fact that you have to be aware of things like this. The data might be old, it may not be 100% reliable etc...

"You only get what you pay for, in the end" -- John Entwistle

[Rob]

what scale are you designing at?

Another free idea is to project the CIA data via MicroCAM, export to dxf, and then rescale in AI. Hmmm, I think that data contains cities, but now that I'm thinking about I'm not too sure. Would have to check it out. No ideas about accuracy.

rob

[Hans van der Maarel]

Roughly 1:23M along the equator. That's small enough to only show very general data, but so large that the stuff you do show has to be accurate.

[Rob]

That's pretty small scale. I'd think that whatever symbol you use for your cities would cover the airports and probably far beyond at 1:32M. Accuracy for DCW was 2km or 2mm at 1:1,000,000. I think at your working scale you need not sweat the quality of 1:1M data.

cheers, rob

[Hans van der Maarel]

It's not just that...

- Not every city has an airport
- Not every city has the correct name attribute, in some derived datasets those 'UNK' (unknowns) are simply removed. This would, for example, be the case with the 4th biggest city in The Netherlands.
- Sometimes military airbases are included as well. These usually don't correspond with major cities.

[Hans van der Maarel]

Found some usable data on TravelGIS.

I'm not sure about the population numbers and some of the locations are off, but at least it's a pretty decent start.

There's also the
Worldwide Gazetteer, it's not free but I assume the quality is much higher.