Hi - I want to use Nominatim's reverse geocoder to get a lat/lon for this node: 269908858 (Mérida, Yucatán, Mexico)

Here's the node on OSM:

https://www.openstreetmap.org/node/269908858

The node has lat/lon data according the XML provided by OSM API:

https://www.openstreetmap.org/api/0.6/node/269908858

However, when I pass it to Nominatim it returns an error:

https://nominatim.openstreetmap.org/reverse?osm_type=N&osm_id=269908858&format=json

(the code format tag on this board is subbing "&" for "&" so correct this manually before opening)

Error message:

Output:{"error":"Unable to geocode"}

What's missing from this node that causes this error, and what can I do about it?

Thanks loads for the help!

asked 21 Feb '18, 10:37

case_the_joint's gravatar image

case_the_joint
11112
accept rate: 0%


I think you want to use the /lookup method since you're not supplying a lat,lon in the search. https://nominatim.openstreetmap.org/lookup?osm_ids=R6265959&format=json

When you do a forward search https://nominatim.openstreetmap.org/search?q=M%C3%A9rida&countrycodes=mx you'll note that Nominatim uses the city relation (https://www.openstreetmap.org/relation/5961522), not the city node (https://www.openstreetmap.org/node/269908858).

What's missing from this node

Nothing. The relation has a Node Mérida (269908858) as admin_centre set. For Nominatim that means both describe the same place. Nominatim chooses to ignore the node in this case.

permanent link

answered 21 Feb '18, 11:06

mtmail's gravatar image

mtmail
2.3k540
accept rate: 25%

edited 21 Feb '18, 13:27

1

Hi @mtmail thanks so much for the quick response and advice. I forget why I used the reverse and not the lookup. For completeness' sake, the lookup has a slightly different syntax than you suggest:

https://nominatim.openstreetmap.org/lookup?osm_ids=R6265959&format=json

So if I wanted to get a set of coordinates for the Merida node itself, and Nominatim won't return that, then is the best substitute I can get from OSM the centre point of the Merida relation (5961522)?

(21 Feb '18, 11:28) case_the_joint
1

You're right, thanks, I updated the URL in my answer. For a relation result Nominatim tries to use the linked admin_center or admin_label roles (nodes) to set the center. So it knows about those nodes just merges the information. For example for "Hamburg" (the state, https://www.openstreetmap.org/relation/62782) which is split into two parts it returns the center point of the admin_center not the geographic center https://nominatim.openstreetmap.org/lookup.php?osm_ids=R62782 because that wouldn't even be inside the relation/multi-polygon.

(21 Feb '18, 13:37) mtmail

Thanks for the clarification! You've been very helpful, thank you.

(21 Feb '18, 15:58) case_the_joint
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question asked: 21 Feb '18, 10:37

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last updated: 21 Feb '18, 15:58

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