Imbricate two calls to ST_MapAlgebraExpr() Pierre
> -----Original Message----- > From: postgis-users-boun...@postgis.refractions.net [mailto:postgis-users- > boun...@postgis.refractions.net] On Behalf Of JamesH > Sent: Wednesday, April 25, 2012 2:53 PM > To: postgis-users@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 > -- > View this message in context: http://postgis.17.n6.nabble.com/MapAlgebra-on- > three-Rasters-tp4917643p4917643.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 _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
