[mapserver-users] Raster parameter PROCESSING "BANDS=..." and ECW files

[Frank Warmerdam]

On 11-09-04 09:33 AM, Armin Burger wrote:
> Hi all
>
> I noticed a strange behaviour of MapServer (5.6.7 and 6.0.1) when defining for
> a raster layer based on an ECW file a processing parameter for the bands order
> like
>
> PROCESSING "BANDS=3,2,1"
>
> The order of the bands does not have any effect. The image is always displayed
> in the original band order 1,2,3, whatever I define for the BANDS value. If I
> just define a single band, like
> "BANDS=3" or "BANDS=1"
> then it's displaying it correctly using the right band.
>
> This problem seems just to appear for ECW files, not e.g. for Tiff files. If I
> wrap a VRT image around the ECW and use this VRT in the DATA tag of the map
> file then the BANDS order is taken into account, just not when defining the
> DATA using the pure ECW file.
>
> Any ideas what's going wrong?

Armin,

I suspect that the special interleaved read method in the GDAL ECW driver
is not properly honouring the list of bands passed in to it.  If this is
the problem then it might not have come up with earlier mapserver versions
that didn't do such reads in one interleaved request.

If this is the issue then please test with GDAL "trunk" and if the problem
persists file a ticket against GDAL.

Best regards,
-- 
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