OpenStreetMap Forum

rorylila

Member

Registered: 2017-11-21

Posts: 4

Confused result from inner/outer boundary of same name

The two examples below illustrate the issue

Query1:

[out:csv("name";false)]
[bbox:-33.9480172,151.1107534,-33.8594833,151.2207935];
area[name="Sydney"];
way(area)[highway][name];
out;

One result (after obtaining lat-lon and distance) is:

Airport Drive, Sydney, 2000, -33.9272726, 151.1694315, 2.637km

Query 2:

[out:csv("name";false)]
[bbox:-33.9480172,151.1107534,-33.8594833,151.2207935];
area[name="Mascot"];
way(area)[highway][name];
out;

One result (after obtaining lat-lon and distance) is:

Airport Drive, Mascot, 2020, -33.9272726, 151.1694315, 2.637km

The two results are essentially identical (eg lat-lons) except for the name of the suburb. The problem appears to be due to there being an Administrative Area called Sydney which embraces all suburbs. Also, within the all-embracing Sydney, there is a relatively small suburb area also with the name Sydney.

If one is looking for streets in suburbs within a largish BBox well inside the larger Sydney (which includes by design, the smaller Sydney), a large number of 'duplicate' (spurious) streets are generated with a suburb name of Sydney, it would seem, due to the outer Sydney boundary.

How can such a situation be avoided?

rorylila

Member

Registered: 2017-11-21

Posts: 4

Re: Confused result from inner/outer boundary of same name

My bad!

I had checked the admin_level for both the inner and outer Sydneys and thought they were both 10.
However, rechecking, the inner Sydney is admin_level=6, the outer Sydney admin_level=10.
Modifying the definition of 'area' corrected the duplicates problem:
area["boundary"="administrative"]
["admin_level"="10"]
["name"="Sydney"];
way(area)[highway][name];