[postgis-users] ST_MapAlgebraExpr 2 rasters problem with resultant raster

[g.singh at utwente.nl]

Hi,

I am using ST_MapAlgepraExpr for the intersection of two rasters.
The first raster has minimum and maximum values as 5.112e-020 and 0.000125 respectively.
The second raster has minimum and maximum value as 0.000 and 0.000400 respectively.

I carry the raster intersection using expression
ST_MapAlgebraExpr(a.rast1,b.rast2, '[rast1.val] * [rast2.val]', '32BF', 'INTERSECTION', 'NULL', 'NULL')
And got a resultant raster whose value ranges from 0.000 to 1.862e-008.

When I query the resultant raster for sum(ST_Summarystats(rast)) or max(ST_Summarystats(rast)) I get the blank cell with double precision datatype.

I can visualize the raster and can see the sum of all cell values, max and min cellvalues in ILWIS software but can not calculate the same using postgis queries.

Is there something wrong in my above map algebra expression or there is a problem with map algebra function?

Can someone please provide any solution to this problem.

Thanks in Advance.
Gaurav
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