I have tried it and it works. Thank you Pierre. On 22 November 2011 15:33, Pierre Racine <[email protected]>wrote:
> > I have used ST_MapAlgebraExpr but I get the error below. > > > > > > select * from (select ST_MapAlgebraExpr(kb.rast, kb1.rast, > 'kb1.rast+kb.rast') as > > rast from kb_dsm_clip kb, kb_dsm_clip100 kb1) as r1 limit 5; > > ERROR: missing FROM-clause entry for table "kb1" > > LINE 1: SELECT (KB1.RAST+KB.RAST)::double precision ^ > > QUERY: SELECT (KB1.RAST+KB.RAST)::double precision > > Try this instead: > > SELECT ST_MapAlgebraExpr(kb.rast, kb1.rast, 'rast1 + rast2') as rast > FROM kb_dsm_clip kb, kb_dsm_clip100 kb1 > WHERE st_intersects(kb.rast, kb1.rast) > > 1) There is no need for a subquery > > 2) You must refer to the raster using 'rast1' and 'rast2', not their real > names > > 3) I don't know if your rasters are tiled but it is always a good idea to > restrict the process to intersecting footprints. > > Pierre > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users >
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