Have resolved this MapAlgebra issue, the issue was with the slope surface, I was trying to produce as a 32BF but it needed to be 32BSI to be visible.
Calculation and resample ran effectively using: CREATE TABLE Metro_location2 AS( SELECT ST_MapAlgebraExpr(ST_Resample(a.rast, b.rast), 1, b.rast, 1, '([rast1] * 0.2) + [rast2]', '32BF') as rast, 1 as rid FROM Slope a, DensDist b ); To produce this final Raster: http://postgis.17.n6.nabble.com/file/n4931130/Metro.png This is the product of three standardises/Normalised Rasters: a Slope surface, Point Density and Euclidean Distance. Each was then weighted and combined together into one Raster showing the most suitable locations in Newcastle for a proposed new Metro Station (in red). Kind Regards, James ----- GIS Undergraduate -- View this message in context: http://postgis.17.n6.nabble.com/MapAlgebra-on-three-Rasters-tp4917643p4931130.html Sent from the PostGIS - User mailing list archive at Nabble.com. _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users