Raster to vector conversion

The most useful function there for raster values to Vector is ST_DumpAsPolygons(). As a result we get geomval (set-of-records).

SELECT rid, (foo).* 
   FROM (SELECT rid, (ST_DumpAsPolygons(ST_Reclass((ST_SLOPE(rast::raster,'1'::int,'32BF'::text,'DEGREES'::text,'111120'::double precision))::raster, '1'::int,'0-5):1, 5-15]:2, [10-15:3, [15-25):4, 25-90]:5'::text,'32BF'::text))) FROM eudem.clip) AS foo; 

Another way to get some information is to query for values of raster cell at point of interest. As an example, let's check the value of DEM height for Istebna commune center:

mastering_postgis=# SELECT ST_Value(c.rast,(SELECT geom FROM raster_ops.places WHERE name='Istebna')) FROM eudem.clip c; 
     st_value      
------------------ 
 661.260009765625 
(1 row)