Hi,

I'm seeking some clarification of Nominatim's behaviour. I have a TOWN, down the road is a SUBURB, and down the road is a VILLAGE. The three places are separate entities.

If I search for X street in TOWN, Nominatim returns: "X street, SUBURB, TOWN, Country" - where SUBURB is a smaller locality outside of the town which should not be any part of the search result.

Likewise, if I search for Y Street in SUBURB, Nominatim returns Y street, VILLAGE, SUBURB, Country - and again, VILLAGE is a separate and smaller locality outside of suburb, and it should not be part of the result.

I understand it can be helpful for a nearby (larger) population centre to be mentioned as part of the results when searching a smaller locality, but it seems to make no sense to mention a smaller completely-unrelated locality when searching in a larger town. Perhaps there's something I'm missing?

The specific examples use Forster (Town), Forster Keys (Suburb), and Green Point (Village). http://www.openstreetmap.org/?lat=-32.2061&lon=152.5205&zoom=13&layers=M

Thanks!

asked 22 Sep '12, 22:31

wolftracker's gravatar image

wolftracker
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accept rate: 33%


See the place and suburb wiki pages. A suburb is defined as an area inside a town or city. So there is not a clear hierarchy as long as suburbs are tagged as nodes. Every address search engine has to know the exact boundary of a suburb to be able to decide which other map feature belongs to this suburb. If there is just a node Nominatim tries to estimates the outline of the suburb.

From your explanations I chose this example search (next time clearly tell us a search example or even better a link!). As you can see, Nominatim thinks Wallis Street belongs to the suburb Forster Keys which is only tagged as a node and therefore has no clear outline. If you think this is wrong then try to replace the Forster Keys suburb node with an area. It doesn't have to be exact and can be improved later either by you or by others.

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answered 23 Sep '12, 09:05

scai's gravatar image

scai ♦
31.1k18281434
accept rate: 23%

I think it's simply because the Green Point dot happens to be (at a glance, although it's a bit hard to judge) slightly closer than the Forster one, and place=village ranks higher than place=suburb. If Green Point were a place=hamlet or Piper Points and Foster Keys had is_in tags (which nominatim apparently takes into account), the problem would solve itself.

In theory, the most surefire way, though (as Scai points out) would be to make sure there is a boundary relation but I'm not sure that would alter the Forster Keys -> Green Point ->Forster hierarchy as it looks like all would fall within the same boundary and put it back to square one.

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answered 23 Sep '12, 06:58

Circeus's gravatar image

Circeus
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accept rate: 7%

edited 23 Sep '12, 19:36

Thanks. Our community is undergoing discussion about importing suburb boundaries, so I think I'm going to leave any arbitrary boundary work out for now, but that's a great reminder about the is_in tag which might be a suitable work-around, I'll try it and see how it goes, otherwise will wait for a decision about our boundaries. Cheers, and i appreciate both good answers on this one.

(09 Oct '12, 17:05) wolftracker
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question asked: 22 Sep '12, 22:31

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last updated: 09 Oct '12, 17:05

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