We ran into this issue for an Air Force project I worked on. We ended up splitting the polygons into multiple polygons E and W of the dateline.
Joe Bussell On Mon, Jan 4, 2010 at 10:34 AM, Nelson Correia <nelson-corr...@telecom.pt> wrote: > Here is the simplified shapefile, along with a mapfile that uses it: > http://www.2shared.com/file/10449234/a18d6a03/countries.html > > Nelson > > -----Original Message----- > From: Lime, Steve D (DNR) [mailto:steve.l...@state.mn.us] > Sent: segunda-feira, 4 de Janeiro de 2010 17:28 > To: Nelson Correia; Barend Köbben; Andy Colson > Cc: mapserver-users@lists.osgeo.org > Subject: RE: [mapserver-users] Problem with Russia polygon > > Would be interesting to get a copy of the data in shapefile format, plus the > mapfile that generates the error... > > Steve > > -----Original Message----- > From: mapserver-users-boun...@lists.osgeo.org > [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of Nelson Correia > Sent: Monday, January 04, 2010 7:32 AM > To: Barend Köbben; Andy Colson > Cc: mapserver-users@lists.osgeo.org > Subject: RE: [mapserver-users] Problem with Russia polygon > > Hello, > > All the russian polygons are valid (st_valid) and closed (st_closed). The > problem seems to be in the vertical lines at 180º and -180º that divide > certain areas of the country. It seems like when mapserver tries to draw > these lines, there's some kind of unknown behavior that make it draw > horizontal lines instead, resulting in very strange polygons. > > However, I have not solved the problem yet. > > Nelson > > -----Original Message----- > From: Barend Köbben [mailto:kob...@itc.nl] > Sent: sábado, 2 de Janeiro de 2010 15:33 > To: Andy Colson; Nelson Correia > Cc: mapserver-users@lists.osgeo.org > Subject: Re: [mapserver-users] Problem with Russia polygon > > Hi, > >> I guess to make a long story short, do you have any editors (like qgis) that >> you can use to see/edit the layer and make sure each record is valid? > You can use PostGIS's ST_IsValid() for that. > > The problem of Nelson seems to me to be a 'dateline' problem: you have > coordinates in latlon and some polygons are crossing the dateline (and/or > the poles), therefore the coordinates' sign jumps from - to + (or from E to > W). If you then draw that in a Plate Carree 'projection (where latitudes and > longitudes are treated as if they were Cartesian coordinates , which they > surely aren't: they are angles from the middle of the Earth!), then the > polygon jumps from the extreme right to the extreme left of the picture... > > > -- > Barend Köbben > Senior Lecturer > University of Twente, Faculty of Geo-Information Science and > Earth Observation (ITC) > PO Box 6, 7500AA Enschede, The Netherlands > +31 (0)53 4874253 > > > > On 02-01-10 15:50, "Andy Colson" <a...@squeakycode.net> wrote: > >> On 12/30/2009 11:14 AM, Nelson Correia wrote: >>> Hello, >>> >>> I¹m using shapefile world data from gadm.org (I¹ve had this same problem >>> with other data sources too) and I¹m having a problem with the Russian >>> polygon: mapserver draws some strange lines parallel to the equator, >>> near the north pole (like you can see in the attached image). >>> >>> Anyone had the same problem and knows how to solve it? >>> >>> Thanks, >>> >>> Nelson >> >> I have no idea if this is the same problem, but I have run into weird drawing >> problems before. I import shape files into PostGIS and then use mapserver on >> that. I got a polygon layer that had an unclosed line (I guess that is a >> good >> way to describe it). It pissed off mapserver. I could run sql like: >> >> select gid from layer where not ST_IsClosed(the_geom) >> >> and it would pull it up. The people that sent me the layer swore there was >> nothing wrong with it (they didn't see any error). >> >> I guess to make a long story short, do you have any editors (like qgis) that >> you can use to see/edit the layer and make sure each record is valid? >> >> -Andy >> _______________________________________________ >> mapserver-users mailing list >> mapserver-users@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/mapserver-users > > International Institute for Geo-Information Science and Earth Observation > (ITC) > Chamber of Commerce: 410 27 560 > > E-mail disclaimer > The information in this e-mail, including any attachments, is intended for > the addressee only. 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