Yes, that technique only applies to polygonal coverages. Your use case is not clear to me. An example dataset might make that more clear.
On Mon, May 2, 2022 at 11:40 AM Shaozhong SHI <[email protected]> wrote: > > > On Mon, 2 May 2022 at 19:05, Martin Davis <[email protected]> wrote: > >> That blog post does provide useful queries for finding polygon overlaps >> and gaps. >> >> Overlaps are found via testing if polygon interiors intersect, using the >> DE-9IM relate mask 2********. >> >> Gaps are found by identifying holes in the union of the set of polygons. >> One issue with this is that computing the union of large datasets can be >> slow. Lars' solution provides some ideas for dealing with this. >> >> >> I think that matters are rather more complex than this. > > For instance, I found 2 lines meet with each other at both ends. In this > case, 2 intersections are both a point. One will find two lines form an > enclosed area. > > When 2 lines intersect or meet/touch more than 2 times, intersection will > return more than 2 points. For instance, when two lines meet at 3 points, > one would get 2 gap polygons. > > Given 2 zigzagging lines, how to write a function to return overlaps and > gaps is an interesting matter. > > Regards, > > David > > _______________________________________________ > postgis-users mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/postgis-users >
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