multi-polygon #1 is valid ... multi-polygon #2 is valid ... expected diff: MULTIPOLYGON(((2218 2189,1920 1660,1920 1462,3720 1462,3720 3262,1920 3262,1920 2157,2562 2799,2818 3253,3043 2829,3718 2154,3718 1957,3718 1561,3360 2233,3718 1957,3360 2234,3360 2233,2818 2653,2218 2189))) computed diff: MULTIPOLYGON(((2218 2189,1920 1660,1920 1462,3720 1462,3720 3262,1920 3262,1920 2157,2562 2799,2818 3253,3043 2829,3718 2154,3718 1957,3718 1561,3360 2233,3718 1957,3360 2234,3360 2233,2818 2653,2218 2189))) ((((2218, 2189), (1920, 1660), (1920, 1462), (3720, 1462), (3720, 3262), (1920, 3262), (1920, 2157), (2562, 2799), (2818, 3253), (3043, 2829), (3718, 2154), (3718, 1957), (3718, 1561), (3360, 2233), (3718, 1957), (3360, 2234), (3360, 2233), (2818, 2653)))) # of points: 18