Selon Hermann Peifer <[email protected]>: I've finally added a new switch to ogr2ogr : -wrapdateline. See http://trac.osgeo.org/gdal/ticket/3158
> Even, > > Thanks for the possible algorithm.... but to be honest: some sort of > command line switch would be /somewhat more handy/, for non-programmers > like me. > > Hermann > > Even Rouault wrote: > > Selon Hermann Peifer <[email protected]>: > > > > I think this should be prefectly doable with some code/script just using > OGR > > API. > > > > Here's a possible algorithm : > > > > 1) Create a new empty WGS84 shapefile > > 1) Loop over features in the source shapefile (the one after reprojection > to > > WGS84) > > 2a) If the polygon has points with longitudes both near 180° and near > -180°, > > create a duplicate temporary polygon and add 360° to the negative > longitudes. > > Compute the interescection with Geometry.Intersect (you need GEOS support) > of > > that polygon with POLYGON((0 90,180 90,180 -90,0 -90,0 90)) and with > > POLYGON((180 90,360 90,360 -90,180 -90,180 90)). For the second > intersection, > > substract 360° to the longitudes in order to get again longitudes in the > > [-180,180] range. Finally, write 2 new features into the output shapefile, > or > > better, just one with the geometry being a multipolygon with the 2 parts. > > 2b) Otherwise, just copy the original feature into the output shapefile > > > > Best regards, > > Even > > > > > >> Eric, > >> > >> I can't help much apart from confirming that the same happened to me > >> when trying to reproject Russia from LAEA to WGS84. > >> > >> My "solution" was to ask a colleague, who is using ESRI products to do > >> me a favour... :-( > >> > >> Hermann > >> > >> > >> Eric Muller wrote: > >> > >>> I am trying to reproject shapefiles that represent Russia (from > >>> > http://wagda.lib.washington.edu/DATA/geography/world/russia/download.html) > >>> from the original: > >>> > >>> The map is Albers equal-area projection Clarke spheroid of1866 with > >>> the first standard parallel 46 00 0.000, the second standard > >>> parallel 73 00 0.000, the central meridian 84 00 0.000. The latitude > >>> of the projection's origin is 60 00 0.000. Units -- meters. > >>> > >>> to lat/long WGS84. I use the following command: > >>> > >>> ogr2ogr \ > >>> -s_srs '+proj=aea +ellps=clrk66 +lat_1=46.0 +lat_2=73.0 +lat_0=60.0 > >>> +lon_0=84.0 +units=m +no_defs' \ > >>> -t_srs '+proj=latlong +ellps=WGS84 +datum=WGS84 +no_defs' \ > >>> rs_polbnda_${f}.shp rus${f}.shp > >>> > >>> I would like polygons that cross the 180 degree longitude to be split. > >>> It there a way to ask ogr2ogr to do that? What is the recommended way to > >>> do it, if not? > >>> > >>> Thanks, > >>> Eric. > >>> > >>> > >>> ------------------------------------------------------------------------ > >>> > >>> _______________________________________________ > >>> gdal-dev mailing list > >>> [email protected] > >>> http://lists.osgeo.org/mailman/listinfo/gdal-dev > >>> > >> _______________________________________________ > >> gdal-dev mailing list > >> [email protected] > >> http://lists.osgeo.org/mailman/listinfo/gdal-dev > >> > >> > > > > > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
