Hi,
I made a trial with the biggest image I had on my computer and it was of size
288000 by 480000 pixels. Running gdaladdo as
gdaladdo -r average -ro --config COMPRESS_OVERVIEW JPEG --config
PHOTOMETRIC_OVERVIEW YCBCR
--config BIGTIFF_OVERVIEW YES test.jp2 2 4 8 16 32 64 128 256
It took 22 hours to create the overviews. After 9 hours the progress bar showed
75% so process was slowing down till the end.
It is a long time but it could be tolerated.
Ammar has a four times bigger image but zero progress after four days means
that it just does not work. I wonder if the original bigtiff is without tiles
and gdaladdo has to read 700000 pixel wide rows. Anyway, perhaps that image
begins to be unreasonably big.
Alternatives to gdaladdo is to create a layer group for Geoserver and try is
downsampling the image with gdal_translate is successful. Use -outsize 50% 50%
for doubling the pixel size. If nearest neighbour resampling is not good you
may have a try with gdalwarp which gives more alternatives: near, bilinear,
cubic, cubicspline, lanczos, average, and mode.
Also, once you have now a bigtiff without stripes and you do not want to do
more experiments, you can split it back to smaller pieces which are easier to
handle with gdal_translate by using -srcwin xoff yoff xsize ysize.
-Jukka Rahkonen-
Lähettäjä: Jonathan Moules [mailto:[email protected]]
Lähetetty: 21. tammikuuta 2014 14:23
Vastaanottaja: Ammar
Kopio: [email protected]
Aihe: Re: [Geoserver-users] White lines in merged GeoTIFF files after
ImageMosaicing
Hi Ammar,
The problem with this approach is that I tried to create overviews for the
image and it took 4 continuous days of gdaladdo running without any progress
until I had to cancel the gdaladdo operation.
That's a known "limitation" of Gdal. It can't handle large files well when
pyramiding/overviewing.
I'm afraid I'm not sure what the issue with the white lines is though. Maybe
someone else does?
Jonathan
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