[Imports] How to merge data to keep object histories when doing small-scale import?

Andrew Guertin andrew.guertin at uvm.edu
Wed May 25 19:38:22 UTC 2011

On 05/25/2011 07:47 AM, Josh Doe wrote:
> On Tue, May 24, 2011 at 5:09 PM, Andrew Guertin <andrew.guertin at uvm.edu> wrote:
>> What is the best way to merge the data I'll be importing with the data
>> that's already there? For example, I have building outlines that are
>> much better than what's already there, but some buildings have tags
>> (amenity=library, tourism=museum) that my imported data doesn't.
>> Further, when changes are made to the university's data source, I'd like
>> to be able to re-import and not lose any changes people have made to OSM.
>> Finally, there's the matter of history, which I'd like to be able to
>> keep if possible.
> I've been working on a JOSM plugin that does exactly what you're
> asking, however it's not quite ready yet. I'd say another couple of
> weeks before it's usable:
> http://wiki.openstreetmap.org/wiki/Conflation/Nodes
>> [...]
> If you don't want to wait for the plugin to be ready, the utilsplugin2
> JOSM plugin does what you're looking for with the Replace Geometry
> command:
> http://wiki.openstreetmap.org/wiki/JOSM/Plugins/utilsplugin2#Replace_Geometry

I'm trying out the replace geometry, and it looks perfect for my initial
import. Thanks for the link!

For updates, it looks like your conflation tool would be a better fit.
My ideal workflow would be this, does it match what you're developing?

Import my data (into one layer)
Download OSM data (into another layer)
Click a button, tool finds matches
Tool discards all matches that are identical
Tool discards all matches where OSM data is strictly a superset of
  imported data. (i.e. geometries match exactly, but OSM can contain
  more tags than imported).
For each remaining match, tool presents a dialog showing the differences
  (in geometry and tags). Dialog gives options to
  * Copy geometry from import to OSM
  * Copy tags (one by one) from import to OSM
  * Find a new match if this one was wrong (present with a list of
  * Copy imported feature straight into OSM layer (if it was new)

How does your tool decide what's a feature that it should try to match
and what's just part of a larger feature?

> Good luck! And if you have any Java experience I'd be glad to have
> help on the plugin. :)

Personally, I'd be happy to. I'll see if I have the time available.


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