[postgis-users] ST_MapAlgebraExpr() Function
Deepak R aj Awasthi
deepakrajawasthi at yahoo.com
Sun Jan 22 09:13:29 PST 2012
I am a M.Sc. student and currently working with postgreSQL/PostGIS to handle raster. I have installed PostgreSQl 9.0 and PostGIS 2.0 in windows 7 home premium OS. I had no problem on handling raster so far but now I got problem while accessing ST_MapAlgebraExpr () function which takes two rasters as function arguments. I have followed the example provided in the link below as follows.
First, I create the table as given,
CREATE TABLE fun_shapes(rid serial PRIMARY KEY, fun_name text, rast raster);Then, the second syntax to insert raster and finally the use of the function ST_MapAlgebraExpr() as.
SELECT ST_MapAlgebraExpr( area.rast, bub.rast, 'rast2', '8BUI', 'INTERSECTION', 'rast2', 'rast1') As interrast, ST_MapAlgebraExpr( area.rast, bub.rast, 'rast2', '8BUI', 'UNION', 'rast2', 'rast1') As unionrast
FROM (SELECT rast FROM fun_shapes WHERE fun_name = 'area') As area
CROSS JOIN (SELECT rast
FROM fun_shapes WHERE fun_name = 'rand bubbles') As bub
But I got error on using this syntax as:
ERROR: function st_mapalgebraexpr(raster, raster, unknown, unknown, unknown, unknown, unknown) does not exist
LINE 58: SELECT ST_MapAlgebraExpr()
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
Although I am new to this database, I think that there is problem with PostGIS 2.0 to support the function. If this the case which version I have to install to use this function. Can anyone provide me solution for it.
With Best Regards,
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