-## Reverse Geocoding
+# Reverse Geocoding
-Reverse geocoding generates an address from a latitude and longitude. The optional `zoom` parameter specifies the level of detail required in terms of something suitable for a Leaflet.js/OpenLayers/etc. zoom level.
+Reverse geocoding generates an address from a coordinate given as
+latitude and longitude.
+
+## How it works
+
+The reverse geocoding API does not exactly compute the address for the
+coordinate it receives. It works by finding the closest suitable OSM object
+and returning its address information. This may occasionally lead to
+unexpected results.
+
+First of all, Nominatim only includes OSM objects in
+its index that are suitable for searching. Small, unnamed paths for example
+are missing from the database and can therefore not be used for reverse
+geocoding either.
+
+The other issue to be aware of is that the closest OSM object may not always
+have a similar enough address to the coordinate you were requesting. For
+example, in dense city areas it may belong to a completely different street.
+
+## Endpoint
+
+The main format of the reverse API is
-### Parameters
```
-https://nominatim.openstreetmap.org/reverse?<query>
+https://nominatim.openstreetmap.org/reverse?lat=<value>&lon=<value>&<params>
```
-* `format=[xml|json|jsonv2|geojson|geocodejson]`
+where `lat` and `lon` are latitude and longitude of a coordinate in WGS84
+projection. The API returns exactly one result or an error when the coordinate
+is in an area with no OSM data coverage.
+
+
+!!! tip
+ The reverse API allows a lookup of object by coordinate. If you want
+ to look up an object by ID, use the [Address Lookup API](Lookup.md) instead.
+
+!!! danger "Deprecation warning"
+ The API can also be used with the URL
+ `https://nominatim.openstreetmap.org/reverse.php`. This is now deprecated
+ and will be removed in future versions.
+
+
+## Parameters
+
+This section lists additional parameters to further influence the output.
+
+### Output format
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| format | one of: `xml`, `json`, `jsonv2`, `geojson`, `geocodejson` | `xml` |
+
+See [Place Output Formats](Output.md) for details on each format.
+
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| json_callback | function name | _unset_ |
+
+When given, then JSON output will be wrapped in a callback function with
+the given name. See [JSONP](https://en.wikipedia.org/wiki/JSONP) for more
+information.
+
+Only has an effect for JSON output formats.
+
+
+### Output details
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| addressdetails | 0 or 1 | 1 |
+
+When set to 1, include a breakdown of the address into elements.
+The exact content of the address breakdown depends on the output format.
+
+!!! tip
+ If you are interested in a stable classification of address categories
+ (suburb, city, state, etc), have a look at the `geocodejson` format.
+ All other formats return classifications according to OSM tagging.
+ There is a much larger set of categories and they are not always consistent,
+ which makes them very hard to work with.
+
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| extratags | 0 or 1 | 0 |
+
+When set to 1, the response include any additional information in the result
+that is available in the database, e.g. wikipedia link, opening hours.
+
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| namedetails | 0 or 1 | 0 |
+
+When set to 1, include a full list of names for the result. These may include
+language variants, older names, references and brand.
+
+
+### Language of results
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| accept-language | browser language string | content of "Accept-Language" HTTP header |
+
+Preferred language order for showing search results. This may either be
+a simple comma-separated list of language codes or have the same format
+as the ["Accept-Language" HTTP header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Language).
+
+!!! tip
+ First-time users of Nominatim tend to be confused that they get different
+ results when using Nominatim in the browser versus in a command-line tool
+ like wget or curl. The command-line tools
+ usually don't send any Accept-Language header, prompting Nominatim
+ to show results in the local language. Browsers on the contrary always
+ send the currently chosen browser language.
+
+
+### Result restriction
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| zoom | 0-18 | 18 |
+
+Level of detail required for the address. This is a number that
+corresponds roughly to the zoom level used in XYZ tile sources in frameworks
+like Leaflet.js, Openlayers etc.
+In terms of address details the zoom levels are as follows:
+
+ zoom | address detail
+ -----|---------------
+ 3 | country
+ 5 | state
+ 8 | county
+ 10 | city
+ 12 | town / borough
+ 13 | village / suburb
+ 14 | neighbourhood
+ 15 | any settlement
+ 16 | major streets
+ 17 | major and minor streets
+ 18 | building
+
+
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| layer | comma-separated list of: `address`, `poi`, `railway`, `natural`, `manmade` | _unset_ (no restriction) |
+
+The layer filter allows to select places by themes.
- * Output format
- * defaults to `xml`
- * `jsonv2` adds the next fields to response:
- * `place_rank`
- * `category`
- * `type`
- * `importance`
- * `addresstype`
+The `address` layer contains all places that make up an address:
+address points with house numbers, streets, inhabited places (suburbs, villages,
+cities, states etc.) and administrative boundaries.
-* `json_callback=<string>`
+The `poi` layer selects all point of interest. This includes classic points
+of interest like restaurants, shops, hotels but also less obvious features
+like recycling bins, guideposts or benches.
- * Wrap json output in a callback function (JSONP) i.e. `<string>(<json>)`
+The `railway` layer includes railway infrastructure like tracks.
+Note that in Nominatim's standard configuration, only very few railway
+features are imported into the database.
-* `accept-language=<browser language string>`
+The `natural` layer collects features like rivers, lakes and mountains while
+the `manmade` layer functions as a catch-all for features not covered by the
+other layers.
- * Preferred language order for showing search results, overrides the value specified in the "Accept-Language" HTTP header.
- * Either uses standard rfc2616 accept-language string or a simple comma separated list of language codes.
-* `osm_type=[N|W|R]` `osm_id=<value>`
- * A specific osm node / way / relation to return an address for
- * **Please use this in preference to lat/lon where possible**
+### Polygon output
-* `lat=<value>` `lon=<value>`
- * The location to generate an address for
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| polygon_geojson | 0 or 1 | 0 |
+| polygon_kml | 0 or 1 | 0 |
+| polygon_svg | 0 or 1 | 0 |
+| polygon_text | 0 or 1 | 0 |
-* `zoom=[0-18]`
- * Level of detail required where `0` is country and `18` is house/building
+Add the full geometry of the place to the result output. Output formats
+in GeoJSON, KML, SVG or WKT are supported. Only one of these
+options can be used at a time.
-* `addressdetails=[0|1]`
- * defaults to 0
- * Include a breakdown of the address into elements
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| polygon_threshold | floating-point number | 0.0 |
-* `email=<valid email address>`
+When one of the polygon_* outputs is chosen, return a simplified version
+of the output geometry. The parameter describes the
+tolerance in degrees with which the geometry may differ from the original
+geometry. Topology is preserved in the geometry.
- * If you are making large numbers of request please include a valid email address or alternatively include your email address as part of the User-Agent string.
- * This information will be kept confidential and only used to contact you in the event of a problem, see [Usage Policy](https://operations.osmfoundation.org/policies/nominatim/) for more details.
-* `polygon_geojson=1`
- * Output geometry of results in geojson format.
+### Other
-* `polygon_kml=1`
- * Output geometry of results in kml format.
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| email | valid email address | _unset_ |
-* `polygon_svg=1`
- * Output geometry of results in svg format.
+If you are making large numbers of request please include an appropriate email
+address to identify your requests. See Nominatim's
+[Usage Policy](https://operations.osmfoundation.org/policies/nominatim/) for more details.
-* `polygon_text=1`
- * Output geometry of results as a WKT.
-* `polygon_threshold=0.0`
- * defaults to 0.0
- * Simplify the output geometry before returning. The parameter is the
- tolerance in degrees with which the geometry may differ from the original
- geometry. Topology is preserved in the result.
+| Parameter | Value | Default |
+|-----------| ----- | ------- |
+| debug | 0 or 1 | 0 |
-* `extratags=1`
- * Include additional information in the result if available, e.g. wikipedia link, opening hours.
+Output assorted developer debug information. Data on internals of Nominatim's
+"search loop" logic, and SQL queries. The output is HTML format.
+This overrides the specified machine readable format.
-* `namedetails=1`
- * Include a list of alternative names in the results.
- * These may include language variants, references, operator and brand.
-### Example
+## Examples
* [https://nominatim.openstreetmap.org/reverse?format=xml&lat=52.5487429714954&lon=-1.81602098644987&zoom=18&addressdetails=1](https://nominatim.openstreetmap.org/reverse?format=xml&lat=52.5487429714954&lon=-1.81602098644987&zoom=18&addressdetails=1)
<postcode>B72</postcode>
<country>United Kingdom</country>
<country_code>gb</country_code>
- </addressparts>
+ </addressparts>
</reversegeocode>
```
```json
{
"place_id":"134140761",
- "licence":"Data © OpenStreetMap contributors, ODbL 1.0. http:\/\/www.openstreetmap.org\/copyright",
+ "licence":"Data © OpenStreetMap contributors, ODbL 1.0. https:\/\/www.openstreetmap.org\/copyright",
"osm_type":"way",
"osm_id":"280940520",
-"lat":"-34.4391708",
+ "lat":"-34.4391708",
"lon":"-58.7064573",
"place_rank":"26",
"category":"highway",
}
```
-### Hierarchy
-
-* Admin level => XML entity
- * 2 => `<country>`
- * 4 => `<state>`
- * 5 => `<state_district>`
- * 6
- * 7 => `<county>`
- * 8 => `<village>`
- * 9 => `<city_district>`
- * 10 => `<suburb>`
projects / nominatim.git / blobdiff