Hey Miguel, If you're on PostGIS 2.0, there aren't faster alternatives for ST_SetValue() and ST_Value(). PostGIS 2.1 (hopefully released in the next several weeks) brings ST_SetValues() and ST_DumpValues().
As for your specific implementation, You could consider the use of ST_MapAlgebraFct() where the callback function counts the points included in the cell. -bborie On Fri, Jun 28, 2013 at 2:02 AM, Miguel-Angel Manso-Callejo (UPM) <[email protected]> wrote: > Good morning, > > It's my first comment to the email-list. > > I'm developing a PLSQL-procedure that generate a raster band counting points > of a geometry table/layer that are included in a cell. This can be seen as a > simple clustering algorithm. > > To do it, i'm using a cursor and determining the row and column of the pixel > do an increment operation over pixel value. This is a ST_Value + ST_SetValue > operation foreach point. > This is very slow. > > In Oracle, this is slow too, but i can take an alternative way. Using a > Array with binary index simulate the image, and latter when all the point > has been "mapped" over the matrix transform this to a cellblob and later > insert it on table that store image. > > Have any one in the list any similar experience? > Can any give me a new orientation? > > > Best regards, > Miguel A. Manso > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
