Alisson, Can you provide a sample dataset that didn't work?
On Fri, Mar 15, 2013 at 6:20 PM, Alisson Barbosa <alisson.u...@gmail.com>wrote: > Thank you Chaitanya, > > I had read the explanation of Peter Halls. But that was *raster > polygonization*. I am currently working with another type: *polygonization > of OGRLineStrings*. > > My question was because i was not able to polygonize using the mentioned > method. I created an OGRMultiLineString or an OGRGeometryCollection and > added geometries (many OGRLineStrings) by addGeometry or > addGeometryDirectly methods. But the polygonization always returned null. > > I solved using this: > > OGRMultiLineString *mls = new OGRMultiLineString(); > OGRMultiLineString* pTemp = NULL; > while(...) //iteration of lines > { > //creation of line > pTemp = static_cast<OGRMultiLineString*>(mls->Union(line)); > if (pTemp != NULL) > { > if( mls != NULL) > { > if( mls->getNumGeometries() > 0) > delete mls; > } > mls = pTemp; > } > } > > Thanks, > > > 2013/3/14 Chaitanya kumar CH <chaitanya...@gmail.com> > >> Alisson, >> >> You can refer to the method's documentation here: >> http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec >> >> The mechanism of this operation was already explained Peter Halls in this >> mailing list[1]. GEOS does a good job identifying line strings touching at >> end points and then combining them to make rings and then polygons. >> >> However, it's your job to ensure that all the line strings passed to the >> method are part of a single polygon. >> >> [1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html >> >> >> On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa <alisson.u...@gmail.com >> > wrote: >> >>> Can you explain a bit better? >>> >>> >>> 2013/3/14 Chaitanya kumar CH <chaitanya...@gmail.com> >>> >>>> Allison, >>>> >>>> Check out OGRGeometry::Polygonize() >>>> >>>> The result depends on the type of intersections in your lines. >>>> >>>> -- >>>> Best regards, >>>> Chaitanya Kumar CH >>>> On 14 Mar 2013 21:53, "Alisson Barbosa" <alisson.u...@gmail.com> wrote: >>>> >>>>> Hi friends, >>>>> >>>>> I have a set of OGRLineStrings and an OGRLinearRing with many >>>>> intersections. I would like to polygonize this set of lines. Can anybody >>>>> help me? >>>>> >>>>> Best regards, >>>>> -- >>>>> Alisson Barbosa >>>>> Systems Analyst - FUNCEME >>>>> M.Sc. in Computer Science - MACC >>>>> Graduate in Computer Science - UECE >>>>> >>>>> >>>>> _______________________________________________ >>>>> gdal-dev mailing list >>>>> gdal-dev@lists.osgeo.org >>>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev >>>>> >>>> >>> >>> >>> -- >>> Alisson Barbosa >>> Systems Analyst - FUNCEME >>> M.Sc. in Computer Science - MACC >>> Graduate in Computer Science - UECE >>> >>> >> >> >> -- >> Best regards, >> Chaitanya kumar CH. >> >> +91-9494447584 >> 17.2416N 80.1426E >> > > > > -- > Alisson Barbosa > Systems Analyst - FUNCEME > M.Sc. in Computer Science - MACC > Graduate in Computer Science - UECE > > -- Best regards, Chaitanya kumar CH. +91-9494447584 17.2416N 80.1426E
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