[gdal-dev] How do we know the number of raster bands of a WKT Raster object?

[Mateusz Loskot]

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)

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org