[Gdal-dev] Re: MapServer WCS

[Frank Warmerdam]

Martin Daly wrote:
> Frank,
> 
> No freaky corrupt files this time.  Instead the 24-bit TIFF that
> MapServer produces has TIFFTAG_PLANARCONFIG=PLANARCONFIG_SEPARATE (=2).
> According to the TIFF spec:
> 
> PlanarConfiguration=2 is not currently in widespread use and it is not
> recommended
> for general interchange. It is used as an extension and Baseline TIFF
> readers are not required to support it.
> 
> Any reason for using this?  SIS's internal TIFF (via libtiff) doesn't
> support it, but TIFF via GDAL via libtiff does.  We plan to use GDAL in
> our WCS client anyway, so this is not a big issue.  More curiosity
> really.

Martin,

I have used PLANARCONFIG_SEPERATE within GDAL (and PCI's GDB before that)
by default because it is more efficient for access given the band-by-band
approach of GDAL.  This makes some sense when GDAL is used to produce TIFFs
for consumption in GDAL, but it is true when aiming for maximum interoperability
it would be better to use PLANARCONFIG_CONTIG.

Steve ... I would suggest you add the FORMATOPTION "INTERLEAVE=BAND" line in the
OUTPUTFORMAT declaration in your mapfile to improve interoperability of the
TIFF files.

Martin ... I would encourage you to support planarconfig_seperate files in
your built-in TIFF reader if possible.  They aren't too hard ... just yet
another case.

I am taking the liberty of cc:ing the gdal-dev mailing list so that others
using GDAL to generate TIFF files can keep this issue in mind.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent