Check out the last example (Multi-band versions) of ST_AddBand(). http://postgis.refractions.net/documentation/manual-svn/RT_ST_AddBand.html
-bborie On Sun, Jul 7, 2013 at 8:43 PM, Mark Wynter <[email protected]>wrote: > I'm hoping someone can suggest a way of efficiently combining 3 individual > (but concordant) single band rasters into single raster having 3 bands? > We're working with PostgreSQL9.1, PostGIS2.1Beta. > > The starting point is a single tiled raster with 3 bands representing RGB > values. > > Let's say we perform some color smoothing on each of the RGB bands using > mapalgebra. > > CREATE TABLE resample_myrastertable_b1 AS > SELECT rid, st_mapalgebrafctngb(rast, 1, '8BUI', 5, 5, > 'st_mean4ma(float[][],text,text[])'::regprocedure, 'ignore', NULL) as rast > FROM original_rastertable; > > CREATE TABLE resample_myrastertable_b2 AS > SELECT rid, st_mapalgebrafctngb(rast, 2, '8BUI', 5, 5, > 'st_mean4ma(float[][],text,text[])'::regprocedure, 'ignore', NULL) as rast > FROM original_rastertable; > > CREATE TABLE resample_myrastertable_b3 AS > SELECT rid, st_mapalgebrafctngb(rast, 3, '8BUI', 5, 5, > 'st_mean4ma(float[][],text,text[])'::regprocedure, 'ignore', NULL) as rast > FROM original_rastertable; > > This gives us 3 single-band results rasters. > > How do we now join the individual smoothed RGB "results" rasters into a > single multiband "results" raster? We'd also like to add a 4th band to > the "results" raster based on say a calculation which references the > smoothed values in bands 1-3. > > I'm getting reasonably comfortable writing MapAlgebra callback > expressions. Its more a case of how do we efficiently handle table > operations (e.g. appending single band raster outputs) each time we perform > some MapAlgebra? > > Any suggestions and or a simple worked example would be most appreciated. > > Many thanks > > Mark > > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >
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