The way I see it, for any kind of polygon: - Convert a polygon to a set of points proportional to the area by ST_GeneratePoints (the more points, the more beautiful it will be, guess 1000 is ok); - Decide how many parts you'd like to split into, (ST_Area(geom)/max_area), let it be K; - Take KMeans of the point cloud with K clusters; - For each cluster, take a ST_Centroid(ST_Collect(point)); - Feed these centroids into ST_VoronoiPolygons, that will get you a mask for each part of polygon; - ST_Intersection of original polygon and each cell of Voronoi polygons will get you a good split of your polygon into K parts.
Will it work for you? вс, 17 июн. 2018 г. в 13:11, Jibran Khan <jib...@envs.au.dk>: > Hello everyone, > > > > I need some help in terms of splitting polygons based on the polygon area. > I am using PostgreSQL 9.5.12/PostGIS 2.3 on Windows 10 (x64). I have two > tables i.e. polygon (poly) and points (pts) in my Postgres db. Some of the > polygons contain points inside them while, some do not (sample scenario > below): > > > > > > The following query: > > > > /*Start of query*/ > > Select > > a.gid poly_id, count(b.geom) pt_cnt, > > st_area(a.geom)::int poly_area > > FROM > > poly a > > LEFT JOIN > > pts b > > ON st_contains(a.geom, b.geom) > > GROUP BY a.gid > > Order by a.gid; > > /*End of query*/ > > > > Returns the area of polygons (from left to right) as 1079, 744, 340 > square-meter, respectively. I need to split these polygons' geometry based > on the area i.e. if area is above 100 meter-square, then each polygon needs > to be divided/split into “approximate equal” parts (assuming that majority > of the polygons are *straightforward* like above). The division does not > have to be “strictly” equal. Does anyone know or have any idea how this can > be achieved? > > > > *Side Notes:* > > > > · I earlier posted this question here at GIS SE > <https://gis.stackexchange.com/questions/286184/postgis-how-do-i-split-polygon-in-equal-parts-based-on-polygon-area> > > · Also, came across this > <https://gis.stackexchange.com/questions/239801/how-can-i-split-a-polygon-into-two-equal-parts-along-a-n-s-axis> > relevant question but I guess my problem is different > > > > Any help or idea(s) would be highly appreciated. > > > > Best, > > /Jibran > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/postgis-users
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