[postgis-users] MapAlgebra on three Rasters

[Pierre Racine]

Imbricate two calls to ST_MapAlgebraExpr()

Pierre

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> bounces at postgis.refractions.net] On Behalf Of JamesH
> Sent: Wednesday, April 25, 2012 2:53 PM
> To: postgis-users at postgis.refractions.net
> Subject: [postgis-users] MapAlgebra on three Rasters
> 
> Hi all,
> 
> I have three Raster's stored in seperate tables which I am looking to
> perform a weighted calculation on all three to produce a single Raster as an
> output (or a visualisation through OpenJump or Quantum).
> 
> The calculation I am attempting is basically:
> (raster1 * 0.2) + (raster2 * 0.5) + (raster3 * 0.3)
> 
> I know MapAlgebra has a two Raster version, but is it possible to do this
> with three rasters?
> All three rasters are single band.
> 
> An alternative I've considered is to perform the calculation on the first
> two rasters and then a second on the new and the third raster but to be able
> to do it one query would be ideal.
> 
> Kind Regards,
> James
> 
> -----
> GIS Undergraduate
> --
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> three-Rasters-tp4917643p4917643.html
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