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This article or section may contain out-of-date information: An experimental conflation plugin is now available in JOSM, and some of the content here has been moved there. See JOSM/Plugins/Conflation for more information
If you know about the current state of affairs, please help keep everyone informed by updating this information. (Discussion)

This page will outline possible designs for a conflation tool that works with nodes. This page will not discuss the value of or challenges associated with imports, other than to say that any contributor is expected to be aware of issues surrounding mass imports, and will exercise caution in using this tool.


This will present a user-centric workflow of syncing OSM data with external data.

  1. Convert Shapefile/Geodatabase/etc to an OSM XML file, using an appropriate field mapping.
  2. Load XML into JOSM and download OSM data for the same region in a separate layer.
  3. Start conflation plugin.
  4. Conflation dialog will ask user to specify:
    1. Selection to use for "My" and "Their" data (aka "Target" and "Source")
    2. Key(s) to match against (e.g. ref=* or name=*)
    3. Distance threshold (i.e. do not attempt to match nodes more than 10 meters apart)
  5. After analysis, user is presented with a dialog showing:
    1. Possible matches
    2. Nodes in Mine not found in Theirs
    3. Nodes in Theirs not found in Mine
  6. For matches, the user will be presented with another dialog that shows a table with:
    1. Each pair of nodes along with their respective attributes (presented in a table format with columns for A and B, and rows for each key)
    2. The distance between the nodes
    3. The cost associated with the match, perhaps color coded (green or 0 being a perfect match)
    4. A dialog to merge tags and location/geometry, perhaps reutilizing some of the conflict dialogs
  7. The user can then run the plugin again, perhaps with an increased distance threshhold, and repeat the above steps
  8. For the remaining nodes manual analysis is required (list of nodes ONLY in A and ONLY in B can be stored, and selected by clicking a button on the docked dialog)