Permanent ID
Aus Geoinformation HSR
Version vom 4. April 2019, 20:30 Uhr von Stefan (Diskussion | Beiträge) (Die Seite wurde neu angelegt: «This is an '''unofficial proposal for a "permanent ID"'''. See https://wiki.openstreetmap.org/wiki/Permanent_ID for a more official state of discussions. The…»)
This is an unofficial proposal for a "permanent ID".
See https://wiki.openstreetmap.org/wiki/Permanent_ID for a more official state of discussions.
The goal is to get an opaque fixed length ASCII string. And that are the design considerations:
- The OSM id alone is not stable enough (as probably most agree; see (*)); and it can represent many concepts (and that's by design in OSM).
- The version no. of the object is needed which makes clear which tags are (or have been) referred to.
- Coordinates are needed, because a change of the geometry does not increment the version number.
So a stable Permanent-ID could have the following form (which leads to a fixed length string of 34 chars):
[N|W|R]<osm_id>#<version>[+|-]<lon>[+|-]<lat>
where:
- osm_id is left-padded with zeros to get 10 chars ("digits"),
- version is 4 zero-padded digits
- coordinates have 5 fixed decimal places (lat is 2 and lon is 3 decimal places, both signed and left-padded with zeros).
Example: "Schloss Kyburg" (Castle Kyburg) has relation 1169711, version #5 at coordinates 47.4584, 8.74343 which becomes following Permanent-ID:
R0001169711#0005+47.45840+008.74343
