Recover deleted OSM data, for import into OHM - Pyongyang Folk Park

I’d like to import data that has very recently been deleted from OSM, into OHM.

Indeed, a contributor has deleted data for good reason because the site has been destroyed, but I spent a lot of time mapping this area accurately (I created it by Changeset: 126417242 | OpenStreetMap and Changeset: 126424143 | OpenStreetMap).
See the changeset which removed obsolete data from OSM Changeset: 141007282 | OpenStreetMap, and also Changeset: 139974568 | OpenStreetMap

This concerns the area of the Pyongyang Folk Park (Relation: ‪평양민속공원‬ (‪5474315‬) | OpenStreetMap) created in 2012 but destroyed in 2016.

Here is the image of the area on OSM before the data was deleted but not switched to OpenHistoricalMap File:Map of Pyongyang Folklore Park.png - Wikimedia Commons and see after OpenStreetMap

I don’t know how to import thoses datas into OHM.
How do I go about it? Is this possible? Do you have any tips?

Finally, I managed to find a solution, thanks to the community on Discord !

1/ I used JOSM’s reverter plugin (JOSM/Plugins/Reverter - OpenStreetMap Wiki) to recover the deleted data, put everything in a new layer and copied the still-correct data to the new layer.
2/ I saved this layer in a geojson file, and imported this geojson file with JOSM for OHM.
3/ I made a few modifications, in particular to the start_date, end_date, the multipolygon and few landuse/highway thanks to old Esri imagery

And here’s the result : OpenHistoricalMap !

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Glad you found a solution! It looks quite detailed, and the modifications you’ve made will be important for keeping the map historically accurate.

Remember to respect OSM’s license by tagging each feature with:

attribution=© OpenStreetMap contributors

You don’t have to do this for any feature that only you have edited, since you retain full rights to your contributions. In the future, this would be a good reason to reach out to the mapper who originally mapped this park, politely asking them to agree to the default OHM license of CC0 (public domain) or to transfer it themselves.

By the way, there’s an outstanding request to make transfers like this easier:


Yes, it’s me who map all the area, so I made an agreement with myself, and I approved :sweat_smile:


@Koreller - this is fantastic - thank you so much for recovering and importing this data. Such a good preservation of data & history!!

That is an novel solution to collect deleted objects. I was thinking it might require regular overpass queries or other intensive searches to find them. My interest in creating a service that automates the process.

It would allow a user collecting those objects from OSM and prepare them for OHM inclusion. Doing everything from basic validation of the object and associated tags. Including making sure it is ready to be added to OHM. That would include the less glamorous tasks of object licencing. Such as sending out requests for permissions and the tracking responses. I was thinking about calling it the “Dust Bin”.

This would be a great tool, especially when you see that OSM contributors regularly say: “this belongs on OHM”, so that they can delete it from OSM, but never transfer it to OHM…

I like the idea of a facilitated transfer a lot. Rights management would be a very compelling feature. Without it, transferring others’ OSM contributions to OHM becomes painful in lasting ways. If someone transfers a structurally important feature from OSM, this either undermines OHM’s claim to being in the public domain “unless otherwise noted” to the point of fiction, or it forces us to accommodate two copies of an object that overlap both spatially and temporally and differ only in their licenses.

For example, if someone imports a high-voltage transmission tower under ODbL, then later someone wants to map the high-voltage power line as a public domain feature in OHM, they could connect it to the transmission tower. But a public domain–only extract of OHM’s power infrastructure would have an inaccurate power line, possibly missing important connections.

There are several possible ways to approach rights management. It could be a ticket queue similar to the OTRS system that OSM’s Data Working Group uses. Alternatively, the OSM user could add a standardized declaration to their profile that gives blanket approval to use their deleted contributions in the public domain, or a similar declaration as a comment on a changeset. Either way, getting a full chain of custody over an area in OSM is challenging due to the data model. The DWG’s license redaction bot broke a lot of the map and still missed quite a few features whose authors didn’t agree to the ODbL.

I was thinking that any object would be to have any rights released before it could be transferred to OHM. This would be easy with single user created objects. It should be checking a box next to a simple disclaimer saying “by transferring this object, you agree to have allow any object you have created or edited to be re-licensed so that it can be included as part of the OHM”. At that point they can continue the process of transferring an object they created. Their agreement will be treated as a blanket release for anyone else trying to transfer objects they have edited.

Additional blanket releases would be needed for any objects with multiple user edits. I was thinking it may be simpler to use the existing OSM messaging system to send out the automated requests. Although not the most visible system, it follows a similar process of notice of delivery to a place that only the target user has access to. This should provide a reasonable chain of custody so the process is considered legally binding.

The rights system itself would be in charge of verifying whether an object has had all user releases. Sending out the individual release requests for those users not in the system. Processing the “signed” responses and then informing the original user when an object has been fully released.