Bill, Either of OGRGeometry::Union() and OGRGeometry::UnionCascaded() should help you.
I would choose the latter if there are more than two polygons. It operates on an OGRMultiPolygon object. On Tue, Apr 5, 2011 at 2:35 AM, Cassanova, Bill <[email protected]>wrote: > Hi All, > > > > I am looking for some direction on if GDAL has the capability has the > ability to build a super-polygon from a series of small polygons…I have > played a bit with the OGR Geometry classes but I can’t > > seem to quite get what I need. > > > > Let’s start with a simply example. > > > > Polygon A has vertices in (X,Y) format of <0, 0>, < 0,1>, <1,0>, <1,1> > > Polygon B has vertices in (x,y) format of < 1,0 >, <1,1>, <2,0>, <2,1> > > > > Since Polygon A and B share a common side with vertices < <1,0> and <1,1> I > want to build super polygon that contains the coordinates of the outer > perimeter of the points. > > When complete the new polygon C will thus have points <0,0>,<0,1>,<2,0>, > <2,1> > > > > I had first looked at OGRPolygon.AddRing wherein A and B above would be > OGRLinearRings and then by making a call to C.getExteriorRing() but this > seem to report the first ring added. > > > > Am I heading in the correct direction or is this something that I will > essentially have to do manually by first creating a OGRLinearRing from the > vertices of polygon A, then creating a OGRPolygon to which I execute > addRing. > > Then interrogating that ring to see which line segments are common between > A and B and removing the ones that are common and adding the line segments > that aren’t common. > > > > Thanks, > > Bill > > ++++ > > > > William Cassanova | Senior GFS Developer | The Weather Channel | > 770.226.2368 | [email protected] > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. /tʃaɪθənjə/ /kʊmɑr/ +91-9494447584 17.2416N 80.1426E
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