Hi, That could translate into something like this in PostGIS:
WITH floodareas AS ( SELECT ST_MapAlgebra(rast, ‘1BB’, ‘CASE WHEN [rast] < 10 THEN 1 ELSE NULL END’) rast FROM elevation ) SELECT d.* FROM districts d, floodareas f WHERE ST_Intersects(g.geom, f.rast) NULL becomes nodata values. You could also use ST_Reclass() instead of ST_Mapalgebra(). Pierre De : postgis-users <[email protected]> De la part de Joao Cordeiro Envoyé : 15 juillet 2019 10:19 À : 'PostGIS Users Discussion' <[email protected]> Objet : [postgis-users] raster regions Hi there, I am not actually a POSTGIS user, or developer, although I am doing some research of integration of vector -raster in a dbms context. My main question s about identifying regions represented in a domain like the "hybrid raster" so that they can be referred to in a query. For example, I would like to write something like "select d from districts where d.geometry touches flooding", where "flooding" indicates an expression intended to decide on the pertinence of locations to a flooding risk area described, for instance through map algebra. Thanks for any hints or suggestions. Att.
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