Sort of off topic: Where do commercial map data come from?

I just ran across OSM when I discovered MaemoMapper uses it as a primary data source. I think the effort is cool and I want to contribute some data from my area. Thinking about open and closed map data has led me to a question I haven’t been able to answer on my own. It’s specifically to do with US jurisdictions but I imagine the answer is general.

I understand that companies like TeleAtlas license the map data to companies like Google, but I don’t understand where TeleAtlas gets it and why it isn’t free. Is there some huge team of guys at Rand Mcnally or whatever running around the US with GPS units? If not, are they getting this data from federal/state/county/local GIS offices? Whatever they’re doing to get their map data, why can’t OSM do the same thing?

My county (government organizational unit smaller than American state and bigger than city/town) has a GIS desk where they sell all sorts of map data including aerial photos, tax boundaries, geocoding data, etc. My state has similar data. The data aren’t cheap (USD 2300 for the county data for example), and the license agreement the data come with reads like a combination of a government secrecy order and a Microsoft EULA. How is it possible that governments funded by tax payers can use tax dollars to pay for surveyors/GIS infrastructure/etc then charge the very same taxpayers for the information so gathered, and on top of that claim copyright on the information such that it cannot be shared? The TIGER data are public domain; why aren’t other similar data?

I know that’s a legal/political question, and I’m not looking to start a debate, I’m just trying to understand why things are the way they are and if there’s any legal way to improve OSM data that doesn’t involve legions of volunteers with GPS receivers and bicycles (not that there’s anything wrong with that).

I think asking how it’s possible that governments funded by tax payers can use tax dollars to pay for making maps/data and then charge the very same people for that is a very frequent question, and a lot of people oppose it, and that leads people onto just getting down to making there own. In the UK the data is far less free or available that in a lot of places, and until recently OS (the main mapping body) was completely funded by the tax payer.

In the end, the reason none of the examples are free is because if they can earn money from it, they will, regardless of what the public want. If there is a free competing source of data then maybe they would have to respond, but so long as there isn’t and the data therefore has value they will profit from it.

For Teleatlas I imagine that they do a lot of tracing of areal imagery, a lot of extracting data from old maps. I’m not sure if they actually have surveyors of there own for street names. Personally I think teleatlas data is pretty poor, with multiple big errors in the small area I have looked at around me alone. (unconnecting junctions/ roads going well off the correct line/marking private estate drives as through roads, as well as make believe roads across nowhere) I think the ambition of OSM is now really to map to a better quality than that, which in UK terms is OS, and if you can persuade them to free there data then you will have people kissing your feet in swarms.

I have sent my fair share of emails to OS bitching at them anyway, and there just not interested, and the answers are repetitive. I realised we can probably map this place quicker than getting them to understand what is fair play.

**Ben:**Exactly what are you bitching to the OS about? The Landsurveying agency in Sweden (Lantmäteriet) has very nice maps of Sweden, especially for the vast countrysides. In Sweden we will never have better maps than they have for all areas.

Going back to the original question, yes those mapping companies have surveyors but they are using satellite images a lot more these days. Teleatlas has about 30 patents on their methods so I guess you could get some info out of them, and there are many articles around the web about their surveyors.

I’m not sure but I think the TIGER data set was made by the government with GPS:es for the US Census.

Since I’m Swedish the concept is very foreign to me, but I’ve heard that people have successfully been able sue their state (or federal government) for open access to these kinds of data. I’m guessing it’s a greater problem to get access now, with all the paranoia in the US.

emj: I never complained about the quality of OS maps, quite the opposite. Just that data paid for by the tax payers should be free for the tax payers (at least), but instead it’s sold back in a restricted form so doubly-unfair with catches.