[Talk-us] MassGIS Building Import - process

andrzej zaborowski balrogg at gmail.com
Sat Dec 15 21:27:01 GMT 2012


On 15 December 2012 20:09, Jeff Meyer <jeff at gwhat.org> wrote:
> Paul - I've added a few comments and questions about changeset size and
> revert policies on the Import Guidelines & Plan Outline wiki pages.
>
> Are there any recommended changeset size limits and/or revert plan
> practices?

One good practice is not to revert data that is not known to be wrong.
 If a big changeset fails halfway through it's possible to fix the
remaining part to use the nodes that have been uploaded and continue,
rather than delete the 1000s of nodes just to create new ones in the
same places.

You can probably now do that in JOSM by downloading the changeset
containing the orphaned nodes, opening in JOSM together with the data
being uploaded and telling the validator to "fix all" duplicate nodes.
 Myself I've been using the python scripts at
http://wiki.openstreetmap.org/wiki/Upload.py in such situations,
although the api is much more stable now than it was a couple years
ago.

The other good practice, but possibly not usable with JOSM alone, is
not to let the program upload the "naked" nodes in bulk and then the
buildings in bulk.  You can sort the elements in such a way that every
50k element changeset contains say 45k nodes and 5k ways.  The scripts
let you limit the number of elements in a chunk which the next chunk
depends on to the minimum (optimally 0), this way there's no risk of a
passer by spotting orphan nodes and deleting some causing you
conflicts in your next chunk.

Cheers



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