On Thu, 29 Aug 2019 at 03:42, Martin Davis <mtncl...@gmail.com> wrote: >> >> >> >> > About the union question, probably no good news there, unless your data >> > has some very unlikely characteristics. The GEOS Cascaded Union approach >> > is remarkably efficient at unioning sets of overlapping polygons - which >> > it sounds like you have. The other alternative hack is to run buffer(0), >> > but it is unlikely to be faster. >> >> Ok, thanks for the confirmation. Is there any benefit in "batching" >> sets of geometries to cascaded union (e.g. unioning 100 geometries in >> sets of 10, and then doing a final union of the result)? Or best to >> throw EVERYTHING at GEOS and let it sort it out? > > > Best to let GEOS handle it. It uses a spatial index to choose sets of > polygons to union. It's unlikely you could do this better (unless there is > some characteristic of the data you can take advantage of)
Perfect, thanks Martin! > It looks like GEOSCoverageUnion is able to detect non-fully-noded inputs [1] > and overlaps [2], and throws an exception in this case. And this is ideal too, great. Nyall > > I would think holes and non-contiguous parts are fine as input. > > [1] > https://github.com/libgeos/geos/pull/158/files#diff-7cd9f5f9244e77677b80591da3d99207R94 > [2] > https://github.com/libgeos/geos/pull/158/files#diff-7cd9f5f9244e77677b80591da3d99207R123 > _______________________________________________ > geos-devel mailing list > geos-devel@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/geos-devel _______________________________________________ geos-devel mailing list geos-devel@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/geos-devel
