The basic building location data is sourced from open street map. This is achieved using the query tool at http://overpass-turbo.eu/, Handy Overpass QL guide / docs here -> http://wiki.openstreetmap.org/wiki/Overpass_API/Language_Guide#All_data_in_a_bounding_box
Using a simple query like this:
/*
This query looks for nodes, ways and relations
with the given key/value combination.
Choose your region and hit the Run button above!
*/
[out:json][timeout:25];
(
way(57.1418796,-2.1119872,57.1491036,-2.0905636) -> .a;
// <;
);
//out;
// print results
out geom;
{{style:
node, way, relation {
/* text: name; */
}
/*node[man_made=surveillance] {
color:black;
fill-color:red;
fill-opacity:1;
symbol-size:3;
}
node[surveillance:type=camera] {
fill-color:black;
}*/
}}