[gdal-dev] mosaicking is very slow

Rahkonen Jukka (MML) jukka.rahkonen at maanmittauslaitos.fi
Mon Jan 27 04:04:33 PST 2020


If your source images are 4 GB then their size is at least 40000 by 40000 pixels, or more if they are compressed. If gdalwarp now needs 256*256 pixels worth of source data, from a striped image it must read 256*40000 (rows*pixels per row), while from tiled source it can read just from 1 to 4 tiles, 256*256 each.

Pre-processing is additional load but if you pay 10 units extra for tiling and then save 100 units in warping you are still a winner.
Make copies as
gdal_translate -of GTiff -co tiled=yes -co compress=LZW input1.tif copy1.tif

Then create a new VRT file. Absolutely do not remove -co tiled=yes from the gdalwarp command or you'll demand GDAL to write at least 400000 pixels wide stripes.

-Jukka Rahkonen-

-----Alkuperäinen viesti-----
Lähettäjä: Simon <twinbirds at protonmail.com> 
Lähetetty: maanantai 27. tammikuuta 2020 13.18
Vastaanottaja: Rahkonen Jukka (MML) <jukka.rahkonen at maanmittauslaitos.fi>
Kopio: gdal-dev at lists.osgeo.org
Aihe: Re: [gdal-dev] mosaicking is very slow

Thanks for your answer. The source images are not tiled. So, how can I tile them? Is not it additional load? I will try removing these ones:
--config GDAL_CACHEMAX 8000

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, January 27, 2020 7:48 PM, jratike80 <jukka.rahkonen at maanmittauslaitos.fi> wrote:

> Hi,
> I would suggest to remove --config GDAL_CACHEMAX 8000 first. Then I 
> would check if the source images are tiled. If they are not it could 
> be worth an extra step to make tiled copies.
> -Jukka Rahkonen-
> Simon-4 wrote
> > Hello everyone,
> > I am stiching aroung 100 geotiff images each of around 4gb. However, 
> > translating the vrt file into geotiff is going on for days.
> > gtranslate --config GDAL_CACHEMAX 8000 -co TILED=YES -co 
> > COMPRESS=LZW -co BIGTIFF=YES infile.vrt outfile.tif How can I speed 
> > up it?
> > Thank you.
> > Simon
> >
> > gdal-dev mailing list
> > gdal-dev at .osgeo
> > https://lists.osgeo.org/mailman/listinfo/gdal-dev
> --
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