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Whats the state of navigation for linux in car systems? It'd be fun to homebrew one, but without decent navigation it's not a whole lot of use.

I'm sure i should have some BSOD joke in here too, but i haven't had my coffee yet

Navigation is a hard problem, primarily due to a lack of data. There are free sources (as in public domain) of street line data for many countries, however you need topological network data to accurately route a car -- street intersections, one-way streets, weighting of streets according to real-world local conditions, etc.

The US Census releases the TIGER data, and OpenStreetMaps builds on that (and other) data with a public domain wiki-style site, but neither sources have sufficient topological data to route autos.

There are two primary providers of topological map data -- you'll see their logos at the bottom of most maps, including Google Maps: NavTeq and TeleAtlas. For a brief introduction to the scale of the problem, I'd actually recommend watching TeleAtlas's marketing video on their production process

I'd love to see furtherance of open topographical data -- data about the communities around us is useful for more than just routing automobiles. One very interesting development is Google StreetView. In taking these photographs, Google has removed the need to actually drive the routes to gather, correct, or refine data -- they can collect the photographs en-masse, allowing more specialized analysis to be done offline -- anyone, anywhere, can determine whether a street is one-way, where the freeway on-ramp is, etc.

I should also mention that OpenStreetMaps uses a share-alike creative-commons license. The definition of an "aggregate work" of data is very fluid -- I can not use OSM data, since I can't combine it with data available under different licensing -- even publicly available municipal data that simply can't be re-licensed CC Share-Alike.

Please forgive the slightly off-topic post...

Two of the biggest map data providers are Navteq and TeleAtlas. Each company has a section on their website where you can report errors in their maps.

Since they will need to review your submission and mapping sites like Google Maps and Mapquest only update their map data a couple times a year, it will be a while before your correction goes public (if ever).

It might have something to do with Navteq competitor Tele Atlas being acquired by TomTom back in July.

Here's the official press release. There's additional articles on Bloomberg and TradingMarkets.

This news was predicted after TomTom bought Tele Atlas last July, NAVTEQ's main competitor.

• NavTeq Driver feedback
• Tele Atlas feedback form

gps companies like gtk and teleatlas and many others all have giant workcenters for data pluggers -- they just sit there with lists of nodes to verify. they have to use multiple souces to update an error. it's no surprise with the amount of red tape involved with getting a correction done that the updates are delayed.

And don't forget Tele Atlas.
Their data is in lots of in-car Navigation CDs/DVDs, and various online map services, such as Maporama.

They do more or less the same as NavTech to obtain the data.