Hi, Peter Körner wrote: >> Is there a way to process the diff files in a way that the diff only >> contains changes in my area of interest?
> If you're fetching the diffs with "osmosis --rrii --wxc", can't you plug > a --bb task afzter that? Or does this task not work with > changeset-streams? The latter. > If so, this would be the place to implement this > functionality, wouldn't it? No. Imagine a relation with 500 members and someone changes a tag. The relation itself will be contained in the osmChange file, but none of the members will because they are unchanged. Any task handling the osmChange file will not know anything about the spatial extent of the relation. This would only work if the geometry of ways and relations was included in the osmChange file, significantly increasing their size - or if the process which wants to cut a section out of the osmChange file has access to the underlying data. With osmosis you can do a --rrii --rx --ac --bb --wx to read your xml, apply the change, cut out the area of interest (again) and save it. But that is impractical for something like minutely diff application. It would have to be done in osm2pgsql - when applying a change, it would have to do the following: * if change type = modify or delete: apply change as long as object to be modified or deleted is present in local data base (I think it does this already) * if change type = create and object type = node: apply change only if node is within bbox * if change type = create and object type != node: apply change only if referenced members are present in local data base A problem arises (as always) if you have objects that are half in and half out; they will need special treatment. There will be difficult scenarios (nodes A, B created outside bounding box; way C created to connect A and B; all these changes are ignored; later node A is moved inside the bounding box in a different osmChange file; how will you now get hold of way C which suddenly has entered your area of interest?). Bye Frederik -- Frederik Ramm ## eMail [email protected] ## N49°00'09" E008°23'33" _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
