[Talk-ca] Large amount of nodes displaced across Montreal region

Jean-Sébastien Moreau Jean-Sebastien.Moreau at USherbrooke.ca
Thu Jul 9 14:18:28 BST 2009


I know a way to revert the modify nodes to their original position. Starting
from the changeset # 1765828

http://www.openstreetmap.org/browse/changeset/1765828

you get all the nodes that have been modified. From there, what you can do is
for every modify node in the changeset:

MODIFY NODE (id=215239834):
<modify>
<node id="215239834" lat="45.4750677" lon="-73.4883204" changeset="1765828"
user="sjacques" uid="143128" visible="true" timestamp="2009-07-07T20:20:51Z"
version="2">
<tag k="created_by" v="JOSM"/>
</node>
</modify>

Extract the earlier version of that node with the following command:

URL: http://api.openstreetmap.org/api/0.6/node/215239834/1

RESULT:

<node id="215239834" lat="45.5284925" lon="-73.6409625" changeset="592772"
user="moyogo" uid="246" visible="true" timestamp="2008-01-10T12:59:20Z"
version="1">
<tag k="created_by" v="JOSM"/>
</node>

Then extract the lat and long coordinates and use it to build a new modify in a
new changeset.

NEW MODIFY:
<modify>
<node id="215239834" lat="45.5284925" lon="-73.6409625" changeset="??????"
user="??????" uid="??????" visible="true" timestamp="?????????" version="2">
<tag k="created_by" v="JOSM"/>
</node>
</modify>

That should work but it obviously mean some programming to be able to do it in
an automated manner. If you feel that you are unable to apply these steps
yourself, I can try to do it tomorrow afternoon.

I will wait for your answer.

Jean-Sebastien

Quoting Nicolas Marchildon <nicolas at marchildon.net>:

> George B. a écrit :
> > This afternoon, I took a look at the Mapnik render of the Montreal
> > region map only to notice that tiles were being rendered with many of
> > the ways erroneously leading from the island towards the South Shore.
> > ( http://osm.org/go/cIrPUhi ) After double-checking with the
> > Osmarender version and the actual data, this isn't a rendering error
> > but actually, it seems that someone has moved a very large amount of
> > nodes, which resulted in the ways (streets, Metro lines, etc..) being
> > transposed.
> >
> > It seems that the changeset # 1765828 (
> > http://www.openstreetmap.org/browse/changeset/1765828 ) is responsible
> > for this.  This happens to be the user's (sjacques) very first edit so
> > it may be just him/her testing the functionality of OSM, a bug with
> > their editor or a case of vandalism.  Either way, I have contacted the
> > user and am waiting for a response.  In the meantime, I was wondering
> > if anyone knows if it is possible to revert this entire changeset.  If
> > so, who can do this and how is it done?
>
> I also saw this after I uploaded a GPS trace. Out of curiosity, how did
> you come to the conclusion that is is this changeset? I'm seeing I'm the
> last editor of many ways that were messed up. For example:
> http://is.gd/1qGb4
>
> As for reverting, I googled a bit and didn't find lots of encouraging
> results. However, there's this Revert.pm Perl script that might be a
> good starting point:
>
> http://svn.openstreetmap.org/applications/utils/revert/
>
> Nicolas
>
>
>
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