| 22 | | A two rasters version of the ST_MapAlgebra SQL function already exist. It allows a PostGIS user to create a new raster coverage as a function of two existing one with a simple SQL query. e.g.: SELECT ST_MapAlgebra(rast1, rast2, "(rast1 + rast2) / 2") FROM coverage1, coverage2 WHERE ST_Intersects(rast1, rast2). The extent of the resulting raster can be equivalent to the extent of the FIRST, the SECOND, the INTERSECTION or the UNION of both raster. |
| | 22 | A [http://postgis.refractions.net/documentation/manual-svn/RT_ST_MapAlgebraExpr2.html two rasters version of the ST_MapAlgebra SQL function already exist]. It allows a PostGIS user to create a new raster coverage as a function of two existing one with a simple SQL query. e.g.: SELECT ST_MapAlgebra(rast1, rast2, "(rast1 + rast2) / 2") FROM coverage1, coverage2 WHERE ST_Intersects(rast1, rast2). The extent of the resulting raster can be equivalent to the extent of the FIRST, the SECOND, the INTERSECTION or the UNION of both raster. |
