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| − | This is an '''unofficial proposal for a "permanent ID" (osm_pid) for OpenStreetMap ([[OSM]])'''.
| + | #REDIRECT [[Permanent_ID_for_OSM]] |
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| − | See https://wiki.openstreetmap.org/wiki/Permanent_ID for a more official state of discussions.
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| − | The goal is to get an opaque fixed length ASCII string. And that are the design considerations:
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| − | * The OSM id alone is not stable enough (as probably most agree); and it can represent many concepts (and that's by design in OSM).
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| − | * The version no. of the object is needed which makes clear which tags are (or have been) referred to.
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| − | * Coordinates are needed, because a change of the way and area geometries does not increment the version number.
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| − | So a stable Permanent ID could have the following form (variable length to a maximum of currently 35 chars):
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| − | [N|W|R]<osm_id>#<version>[+|-]<lon>[+|-]<lat>
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| − | where:
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| − | * N,W,R stands for Node, Way, or Relation.
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| − | * osm_id an unsigned big integer ("digits").
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| − | * version is an unsigned integer with a hash in front.
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| − | * coordinates (lat/lon) are signed floats (always showing the +/- sign), with a maximum of 6 digits. In case of a line (linestring) or an area/relation (polygon) geometries the coordinates taken into account are the lat/lon minimum of the geometry.
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| − | Example: "Schloss Kyburg" (Castle Kyburg) has relation 1169711, version #5 at coordinates 47.4584, 8.74343 which becomes following Permanent ID:
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| − | osm_pid = R1169711#5+47.4584+8.74343
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| − | Service: In order to be really useful, a service should be implemented, which returns most recent Permanent ID even if an object has been changed (thus having another Permanent ID).
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| − | NOTE: Encoding OSM id with type (Node, Way, Relation) as integer (64 bit): osm_id = <node id> × 10 (eg. 123 → 1230), osm_id = (<way id> × 10) + 1 (eg. 123 → 1231), osm_id (<relation id> × 10) + 4 (eg. 123 → 1234). (Source: Mapbox, see [https://docs.mapbox.com/vector-tiles/reference/mapbox-streets-v8/#openstreetmap-ids]). Example: "Schloss Kyburg" is a relation with id 1169711, so it becomes 11697114.
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