Alexandre,
Overlap has a very particular meaning. See
http://postgis.refractions.net/documentation/manual-1.5/ST_Overlaps.html
Your 2 polygons intersects well, but they do not "overlap" because the
intersection is equal to geometry 1...
Best regards,
Even
Le Friday 23 April 2010 21:29:02 Sorokine, Alexandre, vous avez écrit :
> Hi!
>
> I noticed that Geometry.Overlaps in ogr sometimes returns "no overlap"
> while intersection is not empty. For example:
>
> Geometry 1:POLYGON ((-1 -1,-1 1,1 1,1 -1,-1 -1))
> boundaryLINESTRING (-1 -1,-1 1,1 1,1 -1,-1 -1)
> Geometry 2:POLYGON ((-2 -2,-2 2,2 2,2 -2,-2 -2))
> boundaryLINESTRING (-2 -2,-2 2,2 2,2 -2,-2 -2)
> Overlaps? NO
> Intrsects? YES
> Intersection: POLYGON ((-1 -1,-1 1,1 1,1 -1,-1 -1))
>
> This contradicts description of the overlap method in geos or am I doing
> something wrong?
>
> The Java code to reproduce the condition attached.
> --
> Alex Sorokine
> sorok...@ornl.gov
>
> ==== cut here ====
>
> import org.gdal.ogr.Geometry;
> import org.gdal.ogr.ogr;
>
> public class OverlapTest {
>
> public static void main(String[] args) {
>
> Geometry lr1 = new Geometry(ogr.wkbLinearRing);
> lr1.AddPoint_2D(-1.0, -1.0);
> lr1.AddPoint_2D(-1.0, 1.0);
> lr1.AddPoint_2D( 1.0, 1.0);
> lr1.AddPoint_2D( 1.0, -1.0);
> lr1.AddPoint_2D(-1.0, -1.0);
> Geometry geom1 = new Geometry(ogr.wkbPolygon);
> geom1.AddGeometry(lr1);
> System.out.println("Geometry 1:" + geom1.ExportToWkt());
> System.out.println(" boundary" +
> geom1.GetBoundary().ExportToWkt());
>
> Geometry lr2 = new Geometry(ogr.wkbLinearRing);
> lr2.AddPoint_2D(-2.0, -2.0);
> lr2.AddPoint_2D(-2.0, 2.0);
> lr2.AddPoint_2D( 2.0, 2.0);
> lr2.AddPoint_2D( 2.0, -2.0);
> lr2.AddPoint_2D(-2.0, -2.0);
> Geometry geom2 = new Geometry(ogr.wkbPolygon);
> geom2.AddGeometry(lr2);
> System.out.println("Geometry 2:" + geom2.ExportToWkt());
> System.out.println(" boundary" +
> geom2.GetBoundary().ExportToWkt());
>
> System.out.print("Overlaps? ");
> if (geom1.Overlaps(geom2)) System.out.println("YES");
> else System.out.println("NO");
>
> System.out.print("Intrsects? ");
> if (geom1.Intersect(geom2)) System.out.println("YES");
> else System.out.println("NO");
>
> System.out.println("Intersection: " +
> geom1.Intersection(geom2).ExportToWkt()); }
>
> }
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev@lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
_______________________________________________
gdal-dev mailing list
gdal-dev@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/gdal-dev
