Hi Even
thanks a lot for the fast reply and the explanation! I will try your
workaround. The patience needed to wait for the completion of the
"normal" method seems to be a bit too high, I stopped the last test
after 4 days...
Best
Armin
On 19/12/16 22:26, Even Rouault wrote:
Armin,
This is a "well known" performance issue with the geotiff driver /
libtiff when switching back and forth between IFD (image file
directories). At ~ 75%, you start generating overview factor 4 and that
implies switching regularly between the one previously computed (read
operations) and the new one (write operations). Each time you switch,
you need to read and write the TileOffsets and TileByteCounts tags
(those can be 10's of megabytes large on huge file, and are the root
cause for the performance problem). With infinite patience, this would
eventually complete.
A trick you can use is :
gdaladdo -ro --config COMPRESS_OVERVIEW LZW INPUT_FILE 2
gdaladdo -ro --config COMPRESS_OVERVIEW LZW INPUT_FILE.ovr 2
gdaladdo -ro --config COMPRESS_OVERVIEW LZW INPUT_FILE.ovr.ovr 2
gdaladdo -ro --config COMPRESS_OVERVIEW LZW INPUT_FILE.ovr.ovr.ovr 2
Even
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