I need to extract and polygonize only those pixels of a raster that have a value (e.g.) greather than 2000.0
The reason is that I wish to do an operation like the following one (which is done only on polygons), but including also rasters and selecting only those areas that satisfy a particular condition. As a result I wish to get a polygonal area.
select st_intersection( ( select st_multi(st_union(geom)) from import.geology where geo_ita='Sedimenti permo-giurassici' ), ( select st_multi(st_union(geom)) from import.reaka where landuse_i='Aree prative' ) ); The query above produces the intersection between the layers 'geology' and 'land use' and returns only those areas that have a particular geology AND a particular land use. I wish to do the same thing introducing a raster (e.g. dtm) and selecting only those areas which are higher than 2000 meters.
أكثر...
The reason is that I wish to do an operation like the following one (which is done only on polygons), but including also rasters and selecting only those areas that satisfy a particular condition. As a result I wish to get a polygonal area.
select st_intersection( ( select st_multi(st_union(geom)) from import.geology where geo_ita='Sedimenti permo-giurassici' ), ( select st_multi(st_union(geom)) from import.reaka where landuse_i='Aree prative' ) ); The query above produces the intersection between the layers 'geology' and 'land use' and returns only those areas that have a particular geology AND a particular land use. I wish to do the same thing introducing a raster (e.g. dtm) and selecting only those areas which are higher than 2000 meters.
أكثر...