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Hey folks, this is my first post so let me know if I am doing anything wrong. I was wondering how often the OSM building footprints get updated--specifically for Dar Es Salaam, Tanzania. I don't expect anyone to know that locations specifically. I was not sure if the building footprints are updated in bulk for the world at one time, or all of Africa at one time, etc. Or are these updates done by individuals on no particular schedule? Also, is there a way to find out the date that the building footprints for a location were updated from the metadata or from the API for download. I checked the OSM PBF file and did not see a date column or something similar. Thanks. |
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Just to make it clear, there is no worldwide freely available data set of buildings that can be imported. For many countries, there is even no data set of buildings at all. Although in some countries buildings are imported from government data sets, in many others the buildings in OSM are manually traced from aerial imagery. In many countries, people are still adding buildings for the first time, rather than updating existing building footprints. Tracing buildings from aerial imagery alone (without local knowledge), has the drawback that one is mapping the past. Aerial imagery is almost never up-to-date. The edit dates you will find on the buildings on OSM, does not necessarily mean the building was updated in the real world. It could also mean that someone refined or improved a previous trace. Furthermore, edit dates on building ways do not include changes to individual node positions of the building. |
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There's no particular schedule, though there are often groups doing organized mapping using OpenStreetMap as a platform: https://www.hotosm.org/where-we-work/tanzania/ The date of the most recent update should be retrievable, for instance, you can see that the OSM data view shows the edit date for individual buildings: https://www.openstreetmap.org/way/594295733 The particulars of retrieving the data will depend on how you are accessing the data. |
