OpenStreetMap displaying very different data depending on zoom level following edits

Question

Yesterday (19 hours ago) I made an edit to OpenStreetMap to reflect walkways around a new local train station. Some informal walkways have been blocked by a wall and some new walkways have been constructed around the station, bus stop and car park.

These edits are showing up on the map at openstreetmap.org at the zoom level map=18 and higher, but at map=17 and lower the old walkways are visible and my edits are not showing up. The images below illustrate:

I made the edits in JOSM for Windows. I did not notice any way of making different maps based on the zoom level. The OSM help suggests that the main Mapnik map should be updated every few minutes or in some cases a few hours, which leads me to think I may have done something wrong in my edits and would like to confirm this as I would like to be a good custodian of OpenStreetMap in my future contributions.

• Have I done something wrong here?
• How long does it take for Mapnik to update all the zoom level tiles?

Answer 1

Edits are to the Openstreetmap database of geographical information, not to a 'map' in the conventional sense of the word.

When these changes show up on a map depends on lots of factors.

On many mapping services on the internet the system is that maps are occasionally re-drawn ('rendered'). This takes place separately for each zoom level - obviously creating different maps (in that they look different) at different zoom levels - the 'tiles' (square images) which make up the map may be rendered for one zoom level but not others.

On this specific occasion that's what you are seeing.

There are multiple variations on this - for instance you may be using an app on a mobile device on which maps are rendered from data stored on the device (I say this to distinguish from situations where your device saves pre-drawn map tiles)... with that data being occasionally downloaded through a service provided by the app developer. The data they provide in turn might be occasionally extracted from the Openstreetmap database. The change to the database is immediate, but it won't show up on your device until the new data is extracted from the database by the developer, processed, and provided to you (and downloaded to your device).