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I would like to use OpenStreetMap vector data for land cover analysis in my city. Here is my goal:

  1. I set up a PostGIS database with the city area extent (around 20x20 km) on my server.
  2. I will download the polygon data from OpenStreetMap. Maybe I could use a command-line tool like osm2pgsql
  3. The local copy will be "read-only".
  4. On a daily basis or more often, I want to "synchronize" my local PostGIS copy of the OpenStreetMap data of my city with the latest online edits to ensure that my data is up-to-date.

Is this possible without re-downloading all of the OpenStreetMap data from my region every time? (I would like to download the 'latest changes' only and somehow merge them with my local PostGIS OpenStreetMap copy)

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1 Answer 1

up vote 3 down vote accepted

You can use osm2pgsql for a local read-only Postgis.

Osmosis can feed daily diffs, but these are globally. If only way or relation information is changed, there is no way to determine whether this is inside your bbox or not. In OSM, coordinates are only attached to nodes.

For smaller regions, a complete re-import is much easier and faster.

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To explain about my question: My local copy of the osm database for my city will be read-only. So, I don't want to have any local editors. All the edits should be done on the global OSM dataset using the openstreetmap.org web editor. And I want to have a "synchronize" command on my local server that will check the global OSM for changes and move the changes from the global OSM to my local copy. –  jirikadlec2 May 2 at 11:57
    
That makes it a lot easier. But completely importing 20x20km is still much faster than applying the worldwide daily diffs. These are 70MB compressed, every day. Compare that to your complete dataset. –  Andre Joost May 2 at 12:18

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