[OSM-talk] Multi Polygon problem - could someone take a look?

[Dave F]

Hi

 >Hence while the shape my have been drastically altered, the polygon 
way is still the "same" it has been since you touched it 2 weeks ago. 
You can see that in the history of the individual nodes.
 >Potlatch uses a slightly different data model where a way's nodes are 
integrated with the way, hence Potlatch "sees" a changed way.

I'm struggling to see how this isn't a fundamentally incorrect way for 
OSM/JOSM etc to interpret the data. If nodes are moved then ways are 
amended & should be listed as such to avoid confusion & "reverting good 
edits made by the mapper".

> Hi,
> Reverting the *correct* changeset (that contained the node edits)
> would have solved the issue

Unfortunately not. In JOSM I tried two operations:
I downloaded all the data in the 
https://www.openstreetmap.org/changeset/47243857 into JOSM
Also a boundary box of the area.
In each case I attempted to revert just the affected polygon with the 
revert plugin. Neither case worked.

In P1 I selected the polygon & a similar attempted revert of the way failed.


>   but probably also reverted good edits made
> by the mapper. The scripts I used are on github
> (woodpeck/osm-revert-scripts) however they require some Perl/Unix foo to
> use correctly (or else you run the danger of creating more damage). In
> this case what I did was
>
> * create new changeset (using changeset.pl)
> * download the polygon (using wget)
> * extract from it a list of nodes it's using (using "grep" and "cut"
> unix utilitiess)
> * revert every node to whatever state it was in before touched by the
> user ndm (using a "for" loop and undo.pl)

This long-winded procedure + the failed reverts clearly indicates an 
improvement in data storage/interpretation is required: Ways with moved 
nodes need to be tagged as being amended.

DaveF.

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