and always remember as stated in the doc-link: "Disks are the slowest
part of the process."
As fast I/O and file system as technically possible ... e.g. do not use
your laptop
Hi,
You can read considerations about memory from
https://trac.osgeo.org/gdal/wiki/UserDocs/GdalWarp#WillincreasingRAMincreasethespeedofgdalwarp
My guess it that increasing CACHEMAX might help a bit in this use case because it feels
similar to the example that is used in the user doc "This could occur, for instance,
in a scanline oriented input file which is processed in multiple chunks (horizontally) by
gdalwarp". But no documentation is as accurate as a good test. Take a stop watch and
measure timings with different settings and you will know how your system reacts.
Unfortunately it is easy to test and optimize things which are not relevant,
for example to test only different memory settings if the real issue happens to
be in the source data that requires unnecessarily much memory. But fortunately
it is also easy to run another set of tests with tiled source images and
compare the results.
-Jukka Rahkonen-
-----Alkuperäinen viesti-----
Lähettäjä: Simon <[email protected]>
Lähetetty: maanantai 27. tammikuuta 2020 15.21
Vastaanottaja: Rahkonen Jukka (MML) <[email protected]>
Kopio: [email protected]
Aihe: Re: [gdal-dev] mosaicking is very slow
Hi,
Okay, thank you.
By the way, while making copy of gtiffs, is not it good idea to increase
GDAL_CACHEMAX?
Simon
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, January 27, 2020 9:04 PM, Rahkonen Jukka (MML)
<[email protected]> wrote:
Hi,
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 256256 pixels
worth of source data, from a striped image it must read 25640000 (rowspixels
per row), while from tiled source it can read just from 1 to 4 tiles, 256256
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 [email protected]
Lähetetty: maanantai 27. tammikuuta 2020 13.18
Vastaanottaja: Rahkonen Jukka (MML)
[email protected]
Kopio: [email protected]
Aihe: Re: [gdal-dev] mosaicking is very slow
Hi,
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
-co TILED=YES
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, January 27, 2020 7:48 PM, jratike80
[email protected] 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
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