[Gdal-dev] Re: ECW mosaicking
quickstuff at altern.org
Thu Apr 12 18:31:38 EDT 2007
Jose Luis Gomez Dans <josegomez <at> gmx.net> writes:
you could also give the VRT (Virtual Raster) format a try.
It can 'virtually' assemble the Geotiff files into a small text file, then
convert this VRT file to ECW with gdal_translate. Such a 'trick' avoids the
intermediary step of a huge merged file. Nevertheless it is also prone to errors
(typos etc.) ; moreover you should expect poor performance regarding disk
access, memory usage, large datasets made of thousands of files etc.
(I'm pretty sure one can improve this by fine tuning the cache options etc.)
Such a VRT file is easy to create by hand or programmatically: it is just a text
file containing references to your geotiff files and some self-explanatory
parameters. See the GDAL site for details and tutorial - or generate some dummy
vrt file with any tool, then study it.
I successfully use this trick when merging a hundred small geotiffs to one big
ecw. So it's worth a try.
Hope this helps,
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