(not tested !!)
UPDATE a_table AS a SET a.geom = b.cgeom from (select name,
ST_ConcaveHull(ST_Collect(geom), 0.99) as cgeom from b_table group by
name having count(*) >= 3) AS b WHERE a.name = b.name
the "count(*) >= 3" removes point collections which will result in
degenerative concave hulls
Den 27-04-2020 kl. 12:29 skrev Shaozhong SHI:
I added a new column.
alter table a_table add column geom geometry(Polygon, 27700);
Then,
update a_table set geom = (select ST_ConcaveHull(ST_Collect(geom),
0.99) from b_table where name = _name) where name = _name;
It kept throwing up an error message saying: "geometry type point does
not match polygon".
I thought that a concavehyll is a polygon. That is why I created a
polygon column for it.
Can anyone help?
Regards,
Shao
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Med venlig hilsen / Kind regards
Bo Victor Thomsen
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