There are probably about 600 councils in Australia. I need to work out how to create boundaries for them all within my iPhone application so that when a user is in a certain area the application will know which council the user is in.

I probably can get a lot of this information开发者_C百科 from councils, however what information would I need to ask for? Is boundary information enough? And then how should my developer use that?

Thanks,

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It sounds like what you're asking about is how to define the boundary of a council. Generally the boundary of a council (or country, or any other geographic region) can be defined by an ordered series of latitude, longitude pairs which represent points on the surface of the Earth; the border is the line that connects them.

Such a series might look a bit like the following:

Region 1:
    64.222, 41.135
    64.161, 41.143
    64.114, 41.080
    ...
Region 2:
    64.114, 41.080
    64.008, 41.090
    64.008, 40.902
    ...

Given such a series of border points there are established algorithms for determining whether a given point is within the region (if you're curious you can read about them here). I'm not sure whether there are more efficient algorithms for determining which of several regions a point is in, but that's for your developer to figure out.

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I'll answer your two questions separately:

1. Where do I get council map boundaries for Australia?

The Australian Bureau of Statistics publish this data in ESRI Shapefile and MapInfo format. The areas are known as "Local Government Areas". The 2010 data set is available at http://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/1259.0.30.001July%202010?OpenDocument

2. How do I use geospatial data?

The ESRI Shapefile format can be read by pretty much every spatial data package under the sun. I have some favourites however:

On client side my favourite library is GDAL, a translator library with an X/MIT style Open Source license. It comes with C, C++, Python and C# bindings. Or if this is too heavyweight, you might prefer to directly use Shapelib, an MIT licensed C library used by GDAL.

On the server side you can't go past PostGIS. If you are sending your latitude/longitude pair to a web server, consider installing these spatial extensions for the postgresql server. You can load a shapefile into the database using the bundled shp2pgsql utilty. Then, to find the LGA your lat/lon pair fall into query the database like this:

SELECT * FROM lga2010
  WHERE ST_Intersects(lga2010.the_geom,
                      ST_SetSRID(ST_MakePoint(your_longitude, your_latitude),4326))