[Gdal-dev] Killing nodata images

[Doug_Newcomb at fws.gov]

Hi folks,
      I've written a python script to chop large .sid files into 10,000 x
10,000 pixel tiff , prior to conversion to .ecw format.  The sid files are
countywide mosaics of aerial photographs.  Since not a lot of the counties
in this state are square,  there can be large nodata sections in the sid
files.  This means that some of the the blocks I chop out may be composed
entirely of nodata areas.  I've been trying to figure out a quick way to
determine if a file is entirely made up of nodata pixels while it's in tiff
format, so I can delete it before wasting the cpu cycles  converting it to
ecw.

       I'm fairly sure I'm missing something obvious due to  my lack of
skill with python and lack of understanding  of how the gdal -python
interface works, so all suggestions welcome.


Doug






Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
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