On Wed, Dec 07, 2022 at 11:13:08AM +0100, Douglas Fan wrote: > I am trying to build topology on PostGIS with 4000+ polygons. The input are > not clean, with overlaps and gaps. I have created a procedure to commit > each update statement for each polygon so that I can catch the exception > and continue the process. The result still contain gaps and overlaps that > are smaller than the tolerance and expected to be snapped.
Expectance is wrong. It's expected for the resulting dataset to contain gaps and overlaps. Having them in a topological model makes it easier for you to spot them and fix them. > I have also tried to run toTopoGeom in the order of the number of vertices > of each polygon, with the idea that creating polygons with more vertices > may help the snapping process. It doesn't solve the problem and the number > of slivers is almost the same. However I have noticed that sequence of the > polygon to run toTopoGeom changes the result. Yes, order changes result because incoming geoms are snapped to already-loaded ones. But snapping is only done against vertices, not segments, so if you want to increas snapping you should densify your geometries. Check out ST_Segmentize. My suggestion though is to complete the data load process and AFTERWARDS look for gaps/overlaps/slivers and process them. --strk; Libre GIS consultant/developer https://strk.kbt.io/services.html _______________________________________________ postgis-users mailing list postgis-users@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/postgis-users
