[Geotiff] data types in bands

[Frank Warmerdam]

Kyle Shannon wrote:
> Thanks Frank,
> We are changing our input file type from a proprietary type to a well 
> supported/maintained data type.  GeoTiffs seemed the obvious choice.  
> Our files can have 3, 5, 6, or 8 bands.  Is there a way to specify a 
> band is empty? We would like to keep the number of bands constant to 
> allow user defined bands (bands 9 - n).  We were going to user a 
> GDT_Byte for those bands to identify them as 'NoData'.  Is there a way 
> to identify 'empty' bands in a geotiff, or is it even worth it to try?

Kyle,

There is no standard way to indicate that a band is considered to be all
nodata.  Were you planning to store blank data for all the unused bands
on disk?

Further to my last message, I should add that libtiff and GDAL do not
support mixed data types in GeoTIFF.

If you were to store the data with PLANARCONFIG_SEPARATE, all zeros
for unused bands and a run length encoding compression like LZW the
unused bands would take very little space but would otherwise continue
to exist.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent