Hello, On Sun, Jul 12, 2009 at 11:53 PM, Mateusz Loskot<[email protected]> wrote: > Frank Warmerdam wrote: >> Jorge Arévalo wrote: >>> Hello, >>> >>> I have a doubt: I have a raster loaded in PostgreSQL with >>> gdal2wktraster, and I'm not sure of the best way to know the number of >>> raster bands the raster has. The fields "pixel_types" and >>> "nodata_values" from raster_columns table are arrays with one element >>> per raster band, so, counting the number of elements of one of these >>> arrays, I can get the number of raster bands. But it doesn't seem to >>> be a very "elegant" way. Do we have another way to do this? >> >> Jorge, >> >> I believe taking the count of values in the pixel_types array is the >> correct approach to determining the number of bands. > > Yes, I can confirm this is the way to find number of bands of raster > (raster coverage) registered in RASTER_COLUMNS table. > > Number of bands per single raster BLOB (row) can be retrieved > using SQL function ST_NumBands > (http://trac.osgeo.org/postgis/browser/spike/wktraster/rt_pg/rtpostgis.sql.in.c?rev=4146#L167) >
Thanks Mateusz. And this has remainded me of something always make me to doubt, in the context of GDAL WKTRaster driver. I can get information about raster properties in RASTER_COLUMNS table, but I can get this information from each row too. So, in which information source should I trust? If they both have sync problems (for example, if the number of raster bands in RASTER_COLUMNS table doesn't match the number of bands in the header of each raster), what should I do?. My logic says that the information stored in rasters is the good one, and it may be used to correct the information read from RASTER_COLUMNS table, if needed. AFAIK, there's no automatic update of RASTER_COLUMNS table. Then, this table can easily be out of date. Am I right? Best regards Jorge _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
