P - empty POINT EMPTY POINT EMPTY P - single point POINT(10 10) POINT(10 10) mP - two points MULTIPOINT((10 10), (20 20) ) POINT(15 15) mP - 4 points MULTIPOINT((10 10), (20 20), (10 20), (20 10)) POINT(15 15) mP - repeated points MULTIPOINT((10 10), (10 10), (10 10), (18 18)) POINT(12 12) L - single segment LINESTRING(10 10, 20 20) POINT(15 15) L - zero length line LINESTRING (10 10, 10 10) POINT (10 10) mL - zero length lines MULTILINESTRING ((10 10, 10 10), (20 20, 20 20)) POINT (15 15) L - two segments LINESTRING (60 180, 120 100, 180 180) POINT (120 140) L - elongated horseshoe LINESTRING (80 0, 80 120, 120 120, 120 0)) POINT (100 68.57142857142857) mL - two single-segment lines MULTILINESTRING ((0 0, 0 100), (100 0, 100 100)) POINT (50 50) mL - two concentric rings, offset MULTILINESTRING ((0 0, 0 200, 200 200, 200 0, 0 0), (60 180, 20 180, 20 140, 60 140, 60 180)) POINT (90 110) mL - complicated symmetrical collection of lines MULTILINESTRING ((20 20, 60 60), (20 -20, 60 -60), (-20 -20, -60 -60), (-20 20, -60 60), (-80 0, 0 80, 80 0, 0 -80, -80 0), (-40 20, -40 -20), (-20 40, 20 40), (40 20, 40 -20), (20 -40, -20 -40)) POINT (0 0) A - box POLYGON ((40 160, 160 160, 160 40, 40 40, 40 160)) POINT (100 100) A - box with hole POLYGON ((0 200, 200 200, 200 0, 0 0, 0 200), (20 180, 80 180, 80 20, 20 20, 20 180)) POINT (115.78947368421052 100) A - box with offset hole (showing difference between area and line centroid) POLYGON ((0 0, 0 200, 200 200, 200 0, 0 0), (60 180, 20 180, 20 140, 60 140, 60 180)) POINT (102.5 97.5) A - box with 2 symmetric holes POLYGON ((0 0, 0 200, 200 200, 200 0, 0 0), (60 180, 20 180, 20 140, 60 140, 60 180), (180 60, 140 60, 140 20, 180 20, 180 60)) POINT (100 100) mA - symmetric angles MULTIPOLYGON (((0 40, 0 140, 140 140, 140 120, 20 120, 20 40, 0 40)), ((0 0, 0 20, 120 20, 120 100, 140 100, 140 0, 0 0))) POINT (70 70) GC - two adjacent polygons (showing that centroids are additive) GEOMETRYCOLLECTION (POLYGON ((0 200, 20 180, 20 140, 60 140, 200 0, 0 0, 0 200)), POLYGON ((200 200, 0 200, 20 180, 60 180, 60 140, 200 0, 200 200))) POINT (102.5 97.5) GC - heterogeneous collection of lines, points GEOMETRYCOLLECTION (LINESTRING (80 0, 80 120, 120 120, 120 0), MULTIPOINT ((20 60), (40 80), (60 60))) POINT (100 68.57142857142857) GC - heterogeneous collection of polygons, line GEOMETRYCOLLECTION (POLYGON ((0 40, 40 40, 40 0, 0 0, 0 40)), LINESTRING (80 0, 80 80, 120 40)) POINT (20 20) GC - collection of polygons, lines, points GEOMETRYCOLLECTION (POLYGON ((0 40, 40 40, 40 0, 0 0, 0 40)), LINESTRING (80 0, 80 80, 120 40), MULTIPOINT ((20 60), (40 80), (60 60))) POINT (20 20) GC - collection of zero-area polygons and lines GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), LINESTRING (20 20, 30 30)) POINT (25 25) GC - collection of zero-area polygons and zero-length lines GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), LINESTRING (20 20, 20 20)) POINT (15 15) GC - collection of zero-area polygons, zero-length lines, and points GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), LINESTRING (20 20, 20 20), MULTIPOINT ((20 10), (10 20)) ) POINT (15 15) GC - collection of zero-area polygons, zero-length lines, and points GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), LINESTRING (20 20, 20 20), POINT EMPTY ) POINT (15 15) GC - collection of zero-area polygons, zero-length lines, and points GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), LINESTRING EMPTY, POINT EMPTY ) POINT (10 10) GC - overlapping polygons GEOMETRYCOLLECTION (POLYGON ((20 100, 20 -20, 60 -20, 60 100, 20 100)), POLYGON ((-20 60, 100 60, 100 20, -20 20, -20 60))) POINT (40 40) A - degenerate box POLYGON ((40 160, 160 160, 160 160, 40 160, 40 160)) POINT (100 160) A - degenerate triangle POLYGON ((10 10, 100 100, 100 100, 10 10)) POINT (55 55) A - empty POLYGON EMPTY POINT EMPTY A - almost degenerate triangle POLYGON(( 56.528666666700 25.2101666667, 56.529000000000 25.2105000000, 56.528833333300 25.2103333333, 56.528666666700 25.2101666667)) POINT (56.52883333335 25.21033333335)