Your expression is not using the correct placeholders. It should look something like:
... ST_MapAlgebraExpr(a.maxrast,b.minrast,'[rast1.val] * [rast2.val]', 'INTERSECTION', 'NULL', 'NULL', 'NULL') as rast from max_rast a, min_rast b On Tue, Sep 10, 2013 at 12:36 PM, <[email protected]> wrote: > > Dear Postgis Community, > > > > I have two rasters and I want to create new raster using intersection through ST_MapALgepraExpre() function. The new raster should have pixel values as max pixel values from either of the two rasters. I guess that I want to use product of these two rasters for what I want in new raster. I use following query and encounter the problem. I am sure there is something wrong in my query with expression. Can someone please guide me how to correct it. My Postgis version is of data "2012-03-29 09:07:33" and raster lib build data "2012-03-29 09:07:33" > > > > With env as( > > select rid, gaztext_id, st_area(ST_Envelope(rast)) as area, rast from text_rast_intersection ), > > max_rast as(select e.rid, e.gaztext_id, e.rast as maxrast from env e, env b where e.area > b.area ) > > ,min_rast as (select e.rid, e.gaztext_id, e.rast as minrast from env e, env b where e.area < b.area ) > > select '222' as rid, 964 as gaztext_id, > > st_MapAlgebraExpr(a.maxrast,b.minrast,'minrast'*'mnaxrast', 'INTERSECTION', 'NULL', 'NULL', 'NULL') as rast from max_rast a, min_rast b > > > > ERROR: > > ERROR: operator is not unique: unknown * unknown > > LINE 14: st_MapAlgebraExpr(a.maxrast,b.minrast,'minrast'*'mnaxrast', ... > > ^ > > HINT: Could not choose a best candidate operator. You might need to add explicit type casts. > > > > ********** Error ********** > > > > ERROR: operator is not unique: unknown * unknown > > SQL state: 42725 > > Hint: Could not choose a best candidate operator. You might need to add explicit type casts. > > Character: 468 > > > > > > Thanks, > > Gaurav > > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
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