On Tue, Jun 23, 2009 at 6:45 PM, Frederik Ramm<[email protected]> wrote: > Hi, > > Andy Allan wrote: >> >> Anyone fancy a challenge? It looks to me like an entire county has >> been duplicated in Pennsylvania - Huntingdon, PA. Looks like Milenko >> and DaveHansen both uploaded copies a day apart from one another. > > How could this have gone unnoticed for so long?
I've made some more investigations, and it looks like some fairly extensive problems in Pennsylvania. The list that I've come up with (using some postgis jiggery pokery and checking each on the data layer) is that there are 16 counties duplicated. See http://wiki.openstreetmap.org/wiki/TIGER_fixup#Duplicate_Counties for the list. Unfortunately none of them are exactly duplicated, i.e. I suspect some areas have been fixed up a bit, but only partially. That makes it impossible to 'trivially' remove one copy of the road network without destroying topology. Something more advanced may be needed. I was thinking along the lines of identifying (somehow) identical-twin roads, then pick one to remove and stitch all the attached roads onto the remaining roads. Then repeat until no twin roads remain. Aaargh. I wish someone had noticed much earlier - before everything was "partially" repaired! For those interested I reckon there's approx. 86,600 ways across those counties that need de-twinning. If anyone can find previous discussions on this problem please let me know. Cheers, Andy _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
