Am 18.01.2021 12:48, schrieb Tomas Straupis:
Hi again
Here is a working forest aggregation routine.
I'm feeling really dumb, but I can't get your example working...
Here my code:
CREATE SEQUENCE city_boundaries_seq START 1;
ALTER SEQUENCE city_boundaries_seq OWNER TO _renderd;
CREATE TABLE city_boundaries AS
SELECT NEXTVAL('city_boundaries_seq') AS id
,0::bigint AS way_area
,10 AS res
,ST_CollectionExtract(unnest(ST_ClusterWithin(way, 500)),
3)::geometry(MultiPolygon, 3857) as way
FROM planet_osm_polygon
WHERE landuse IN ('residential', 'retail', 'retail;residential',
'commercial', 'school', 'university');
ALTER TABLE city_boundaries OWNER TO _renderd;
DELETE FROM city_boundaries WHERE ST_Area(ST_Buffer(way, -10)) < 10 and
res = 10;
UPDATE city_boundaries SET way =
ST_Makevalid(ST_Multi(ST_SimplifyPreserveTopology(ST_Buffer(ST_Buffer(way,
10, 'quad_segs=1'), -10, 'quad_segs=1'), 10))) WHERE res = 10;
UPDATE city_boundaries SET way_area = st_area(way) WHERE res = 10;
So, if I undestand correctly I create a new table city_boundaries with
all buildings of the given types in a radius of 10 meters, is if
correct?
Then I try to display it on the map. Same result as previous: many
little areas...
Maybe should I enhance the distance between the buildings? I'd like to
have a radius maybe about 500 meter or one kilometer...
But I don't understand what "res" means...
Could you help me again?
Really many thanks!!
Luca Bertoncello
(lucab...@lucabert.de)
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