[postgis-users] Creating a boundary of an aggregate of buildings

[Tomas Straupis]

2021-01-18, pr, 15:05 Luca Bertoncello rašė:
> UPDATE city_boundaries SET way =
> ST_Makevalid(ST_Multi(ST_SimplifyPreserveTopology(ST_Buffer(ST_Buffer(way,
> 10, 'quad_segs=1'), -500, 'quad_segs=1'), 500))) WHERE res = 10;

  This statement has problems.
  You're adding a buffer of 10 then removing a buffer of 500 (so
basically leaving only very large polygons and they are eroded by
500meters). Then you're simplifying the result with a 500m value (a
lot).

  Try this:

UPDATE city_boundaries
SET way = ST_Makevalid(ST_Multi(ST_Buffer(ST_Buffer(way, 400,
'quad_segs=1'), -400, 'quad_segs=1')));