> -----Original Message----- > From: Dmitry Terentiev [mailto:djterent...@yandex.ru] > Sent: Sunday, April 08, 2012 12:16 PM > To: talk@openstreetmap.org > Subject: Re: [OSM-talk] Detecting unwanted edits and vandalism > > Adam, > Very often newbie to OSM start their contribution with moving object > according misaligned imagery.They just don't know imagery can be offset. > It's can be detected automatically. Plus overleaping or unconnected > ways, ways without tags, intersections without shared nodes. > > It will be grate If we can have such a tool to analyze changesets.
Some technical thoughts on detecting these: If you compute the displacement of each point moved a mass move should show up as a low standard deviation/1st moment of area. Alternately, if you normalize the moments of area right a move of many nodes all in the same way should all be equal. The problem with this is that determining the distance moved requires a /history API call and full history dumps are difficult to work with. Ways without tags should be easy to detect - every untagged way created should be added to a relation in the same changeset. Tags being removed from a way with no relation membership added in the changeset is not necessarily an error, it could already be a member of one. Intersections without shared nodes is difficult. If working on current changesets it doesn't require any history calls but it requires issuing a map call for each node you want to check. Or you could run it with direct access to a database and use a database query. Either way, the problem is that every node created needs checking. _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk