Reverse geocoding less accurate compared to Nominatim

[avshabavsha]

Hello,

I noticed in some of the reverse geocoding queries I do, the returned feature (e.g. street name) is not always accurate.

Searching the same lat/lon gave different result between Photon and Nominatim (the street in Nominatim was correct).

Taking into account Photon's data is migrated from Nominatim, I would expect that the accuracy would be consistent - both would either be wrong or be right.

I both checked photon result with the public https://photon.komoot.io, and ran locally using latest data (specifically in this case of Greece). In both I got the wrong address as the top result.

I am trying to understand the gap, and see if there's some change in query that can be done to make the photon result more accurate.
The only thought I had is that maybe during migration to photon, the street geometry is stored as a the a point which is the center of each street and not as a LineString?

Visual Explanation

To understand better what is returned from Photon, I made the call with limit of 20 to see the features found in the wanted area (pasted in geojson.io).
I've marked the coordinates location I looked at, which features returned and the feature which is considered the closest.

Comparison between Photon and Nominatim calls (notice the returned name):

Photon
https://photon.komoot.io/reverse?lon=23.90427952592436&lat=38.032463599743316&lang=default
{
"features": [{
"geometry": {
"coordinates": [23.903924, 38.0336909],
"type": "Point"
},
"type": "Feature",
"properties": {
"osm_id": 63853942,
"extent": [23.9021816, 38.034418, 23.9064719, 38.0329742],
"country": "Ελλάς",
"city": "Δημοτική Ενότητα Πικερμίου",
"countrycode": "GR",
"postcode": "153 51",
"county": "Περιφερειακή Ενότητα Ανατολικής Αττικής",
"type": "street",
"osm_type": "W",
"osm_key": "highway",
"district": "Ντράφι",
"osm_value": "residential",
"name": "Πυθαγορα",
"state": "Αποκεντρωμένη Διοίκηση Αττικής"
}
}
],
"type": "FeatureCollection"
}

Nominatim
https://nominatim.openstreetmap.org/reverse?lon=23.90427952592436&lat=38.032463599743316&accept-language=default&format=geojson
{
"type": "FeatureCollection",
"licence": "Data © OpenStreetMap contributors, ODbL 1.0. https://osm.org/copyright",
"features": [{
"type": "Feature",
"properties": {
"place_id": 117494205,
"osm_type": "way",
"osm_id": 62092990,
"place_rank": 26,
"category": "highway",
"type": "tertiary",
"importance": 0.09999999999999998,
"addresstype": "road",
"name": "Αιολέων",
"display_name": "Αιολέων, Ντράφι, Κοινότητα Πικερμίου, Δημοτική Ενότητα Πικερμίου, Δήμος Ραφήνας - Πικερμίου, Περιφερειακή Ενότητα Ανατολικής Αττικής, Περιφέρεια Αττικής, Αποκεντρωμένη Διοίκηση Αττικής, 153 51, Ελλάς",
"address": {
"road": "Αιολέων",
"suburb": "Ντράφι",
"city_district": "Κοινότητα Πικερμίου",
"city": "Δημοτική Ενότητα Πικερμίου",
"municipality": "Δήμος Ραφήνας - Πικερμίου",
"county": "Περιφερειακή Ενότητα Ανατολικής Αττικής",
"state_district": "Περιφέρεια Αττικής",
"state": "Αποκεντρωμένη Διοίκηση Αττικής",
"postcode": "153 51",
"country": "Ελλάς",
"country_code": "gr"
}
},
"bbox": [23.8949478, 38.0324145, 23.9055246, 38.0344383],
"geometry": {
"type": "Point",
"coordinates": [23.904281013355874, 38.03248857205444]
}
}
]
}

Used versions:

photon version: 0.3.5
downloaded data (28-Dec-2021): https://download1.graphhopper.com/public/extracts/by-country-code/gr/photon-db-gr-latest.tar.bz2

Thank you,
Avshalom

[lonvia]

Photon does not store complete geometries for its features but just the bounding boxes. The accuracy of reverse geocoding is limited by that. See also #357 for more discussion on that.

[lonvia]

Closing as duplicate of #357.