Is it possible to get cities polygonal boundaries like in Google Maps?

Question

I would like to have the possibility to tell if a GPS location is in an inhabited or uninhabited zone.

Answer 1

If you will not find a public service then it gets interesting, and expensive in terms of developping effort.

Public data (world wide) is only available from OpenStreetMap, i think they have such a layer (could be named Land_use (rural, etc.)) This layer is usually used to color a map, look at openstreet map Web page if you find a suitable coloring, that coresponds to your task. (E.g look at green, or gray).

These data are stored in polygons, you would have top extract these polygons (i asume millions of them). Ten you need a fast searching spatial index, like a region Quadtree.

Then you do a "point(lat, lon) in polygon" call, and get the polygon related to your position.

Probaly not all that polygons will fit into main memory, so you must load them on demand (e.g by country).

A variant of this approach is to use a geo spatial database like postgres to store that polygons, and do a DB query.

With that approach most work will be extracting the polygons from OpenStreetMap DB file.

More acurate is data from TomTom, but these can be really expensive.