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I was wondering if anyone knows how often OpenStreetMap updates their building footprint data.

I can pull the building data from the Nominatim API but it does not indicate when that footprint was identified. Further, I checked the OSM buildings wiki, but did not see any info on an update schedule or frequency.

It would be nice to know how long a gap there is between footprint extractions, so that we can understand how those footprints change over time.

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    I would ask the maintainers directly. See if you can find the history for your region of interest and who might be the final editor pushing changes to the database. You might also want to consider asking this question on the Open Data Se. May 15 '19 at 20:19
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    Note that OpenStreetMap has a Q&A site of its own (similar to StackExchange, but based on different software)
    – das-g
    May 16 '19 at 0:10
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    @Mapperz I was actually interested in Tanzania, in particular the area around Dar Es Salaam.
    – krishnab
    May 16 '19 at 1:25
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    click on the query features will give you the history example openstreetmap.org/way/463853072/history
    – Mapperz
    May 16 '19 at 1:45
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    @scai I actually posted to the Q&A site based upon a suggestion from another commenter das-g. And I also explained that I would post any response from that post to this site, since other users might be interested. So could you explain what issue you are raising?
    – krishnab
    May 18 '19 at 7:32
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Despite its name, OpenStreetMap is a collaborative geodatabase (or geodata collection) first, and a map only second (if at all). Anyone with an OpenStreetMap account can edit the data. Live. That is, changes made that way are reflected in the database right away, without having to go though any review or approval process first. Kinda like edits on Wikipedia, but without protected articles.

I was wondering if anyone knows how often OpenStreetMap updates their building footprint data.

Whenever you (or any other OpenStreetMap mapper) edits them.

I'm unsure whether Nominatim works directly on the OpenStreetMap database or whether it (like many other OpenStreetMap-internal secondary services) consumes the minutely diffs of the OpenStreetMap dataset as they become available and processes them to update its indices. In either case, while there might be a slight delay (i.e. lag), there should be almost no perceivable "update cycle". Changes should become visible shortly after having been made in the main OpenStreetMap database.

If your question is how often and when buildings are being edited OpenStreetMap: Well, that depends.

  • Most of the changes in OpenStreetMap are made manually, by actual humans (mostly volunteers). They do that whenever they feel like it, for the areas (or even individual buildings) they choose.
  • Automated imports (especially mass imports) of external sources are frowned upon in OpenStreetMap for various reasons and thus seldom.
  • Manual imports (and for building outlines, you could say that tracing them from provided orthophoto imagery is a manual way of importing) are also done by volunteers and thus mostly whenever they feel like it. (Sometimes "mapathons" are organized, e.g. by HOT, to coordinate some larger-scale efforts.)
    • New external sources or new versions of external sources (like orthophotos of an area) may become available (or be made eligible by compatible licensing or permission) at irregular intervals. Each time, that may or may not trigger someone to update OpenStreetMap manually or automatically.
  • External sources (like high-resolution orthophoto imagery or cadastral surveying) often only cover specific areas (e.g. one country) not the whole globe. Thus even if everything available was integrated right away, this would still lead to differing update cycles for different regions of the world.
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  • thanks for the info. Perhaps I could have been a bit more detailed in my assumptions. So I was imagining that something like the building footprints were probably provided by a company like Microsoft or such that collect imagery for the entire globe and then occasionally release it to the public through OSM. So I was assuming that only a large company could do this kind of large scale task, and hence there might be a release cycle. Is it rather that different volunteers are probably generating building footprints for different regions independently and on their own schedule?
    – krishnab
    May 16 '19 at 0:10
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    Yes, or more accurately: On no set schedule at all, most of the time. Just like there is no pre-defined general schedule for updating Wikipedia articles.
    – das-g
    May 16 '19 at 0:11
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    Re "only a large company could do this kind of large scale task" no - many building footprints in OSM have been traced by individuals. May 23 '19 at 12:44

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