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#1 2020-06-06 08:46:59

kucai
Moderator
Registered: 2011-11-08
Posts: 283

Split ways and history

When a way is split, does the history stays with both segments? I always thought so, but  a few past interactions with other mappers doesn't seem to indicate so.

This leads to confusions since suddenly there is an edit by out of state mapper drawing seemingly new highways (history shows version 1) with highway names on them (unlikely to be obtainable without ground survey or mapillary/openstreetcam). The history of the highway's properties are not available unless contacting the mapper directly.

A  x-> B + C
B gets A's history?
C gets new slate?

regards.

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#2 2020-06-06 09:33:17

Jillis E
Member
From: Amersfoort
Registered: 2019-06-08
Posts: 290
Website

Re: Split ways and history

Short answer: no.
And yes, it works exactly as you suppose: one of the segments has all the tags of the original and version 1.

OpenStreetMap is not the only versioned geodatabase working like this, by the way.

Last edited by Jillis E (2020-06-06 09:36:42)

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#3 2020-06-12 08:02:33

kucai
Moderator
Registered: 2011-11-08
Posts: 283

Re: Split ways and history

It's kinda dissapointing though. A major interstate highway that I traced way back when currently only has history dated back to Dec 2019, credited to an out of state Indonesian mapper, which still has the source as GPS.

There are many more of course. A cursory look might have the viewer assuming that a major portion of highways in Malaysia were traced by the mighty Apple mappers and Indian Grabbers.

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#4 2020-06-12 08:57:20

Tordanik
Moderator
From: Germany
Registered: 2008-06-17
Posts: 2,580
Website

Re: Split ways and history

I agree it's misleading and makes it harder to understand what was going on with those edits.

Perhaps instead of altering the versioning concept entirely, a feasible solution would be to have some place to store meta-data for the changeset where the editor could add the information "way X was split off from way Y". Actually, we could use the changeset tags for that purpose – somewhat hacky, but it has the advantage that a few editor and changeset viewer authors could start building this feature without the massive coordination task involved in getting the API (and all the software interacting with it) changed first. If it catches on, we could always migrate it to a proper data model in a future API version.

When implementing that, there will be a lot of questions to answer, of course – such as what to do when the split way is then later merged with a different way, etc. There won't be an easy way to summarize more complex editing operations in a machine-readable fashion. But in principle, it seems possible – you would just need to convince the devs of one of the major editors to start adding this kind of meta-data. Once it's there, it's likely that the changeset viewers will start making use of it.


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