[gdal-dev] slow translate with OVERVIEW_LEVEL=NONE when no overviews exist

[Scott]

Over the network it takes 23 seconds:

time gdal_translate -oo OVERVIEW_LEVEL=NONE -outsize 219 226 
/vsicurl/https://github.com/mdsumner/cog-example/raw/main/cog/sentinel-image.tif 
net.tif
real  0m23.909s
user  0m4.374s
sys   0m1.021s

Saving the file locally and translating it's fractional second:

time gdal_translate -oo OVERVIEW_LEVEL=NONE -outsize 219 226 sent.tif 
local.tif
real  0m0.143s
user  0m0.107s
sys   0m0.036s

My guess is there are numerous reads of the file and across a network, 
depending on server load, etc, it may take muchlonger.

On 11/24/23 15:44, Michael Sumner via gdal-dev wrote:
> When I translate this GeoTIFF to 10% original size, it's very very slow 
> if OVERVIEW_LEVEL=NONE is set.
> 
> The GeoTIFF has no overviews.
> 
> export 
> dsn="/vsicurl/https://github.com/mdsumner/cog-example/raw/main/cog/sentinel-image.tif <https://github.com/mdsumner/cog-example/raw/main/cog/sentinel-image.tif>"
> ## takes *forever*
> gdal_translate $dsn  out.tif -outsize 219 226 -oo OVERVIEW_LEVEL=NONE
> 
> ## works fast as expected
> gdal_translate $dsn  out.tif -outsize 219 226
> 
> I found this in a package that has a global open option setting for 
> overviews for subsampling with RasterIO(). There we could detect that 
> overviews are not present, or even just not set it at all ... (better to 
> use GDALwarp() for general cases IMO).
> 
> But, is there a good reason why setting that open option affects 
> translate for sources with no overviews?
> 
> I'm in master at ebac6b74a429fa6eeeb94edd074b6cb60072a35f
> 
> Cheers, Mike
> 
> 
> 
> -- 
> Michael Sumner
> Software and Database Engineer
> Australian Antarctic Division
> Hobart, Australia
> e-mail: mdsumner at gmail.com <mailto:mdsumner at gmail.com>
> 
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/gdal-dev