public static string CreatePolygonFromLines() { // arrange const string firstline = "LINESTRING (122804.613000002 485610.0381, 122794.59 485612.74013569974)"; var line1 = (ILineString) new WKTReader().Read(firstline); const string secondline = "LINESTRING (122794.039999999 485635.864100002, 122794.58999999998 485635.7686024924)"; var line2 = (ILineString) new WKTReader().Read(secondline); var poly = new GeometryFactory().CreatePolygon(new Coordinate[] { new Coordinate(line1.Coordinates[0].X, line1.Coordinates[0].Y), new Coordinate(line1.Coordinates[1].X, line1.Coordinates[1].Y), new Coordinate(line2.Coordinates[0].X, line2.Coordinates[0].Y), new Coordinate(line2.Coordinates[0].X, line2.Coordinates[0].Y), new Coordinate(line1.Coordinates[0].X, line1.Coordinates[0].Y) }); return(poly.AsText()); }