[mapserver-users] accessing different band values in the same layer

[Smith, Michael ERDC-RDE-CRREL-NH]

Helen,

It does not appear that you can. Based on the docs

Raster classifications always take place on only one raster band. It
defaults to the first band in the referenced file, but this can be altered
with the BANDS PROCESSING directive. In particular this means that
including even a single CLASS declaration in a raster layer will result in
the raster layer being rendered using the one band classification rules
instead of other rules that might have applied (such as 3 band RGB
rendering).

http://mapserver.org/input/raster.html



You could have multiple layers and do classification on each band by
changing the first value in the PROCESSING BANDS directive.

Mike




On 6/14/12  8:27 AM, "Helen San Segundo Navazo" <hsansegundo at meteo.cat>
wrote:

>Hi,
>I have a raster file with different bands inside it.
>when I create my mapfile inside the layer tag I can define the bands I
>want to access with  PROCESSING "BANDS=4,2,1"
>When I select 1 band I can access to its data using the EXPRESSION tag:
>     CLASS
>         NAME "0 - 5"
>         EXPRESSION ([pixel] >= 0 AND [pixel] < 5)
>         STYLE
>         COLOR 80 0 0
>         END
>     END
>But if I select more than one band, how can I do to acces to the
>different band values inside the same EXPRESSION tag? is it possible?
>
>The problem is that I have wind information in different bands, in one
>band I have speed and in other band I have direction, and I have to draw
>the wind symbol depending on both values.
>Is possible to acces to the different pixel band values inside the same
>EXPRESSION tag?
>Thanks,
>Helen
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