[postgis-users] MapAlgebra on three Rasters

JamesH james.holmes at newcastle.ac.uk
Thu Apr 26 09:05:20 PDT 2012

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(
	ST_MapAlgebraExpr(ST_Resample(a.rast, b.rast), 1, b.rast, 1, '([rast1] *
0.2) + [rast2]', '32BF') as rast, 1 as rid
	Slope a, DensDist b

To produce this final Raster:

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

Kind Regards,

GIS Undergraduate
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