[gdal-dev] What is the maximum '-wm' I can use with 64bit gdalwarp?

[Even Rouault]

Le mercredi 24 décembre 2014 11:19:14, Simen Langseth a écrit :
> Dear Even Rouault
> 
> Thanks for your answer.
> 
> When I used more than 1024 mb for sub-sampling an image, strangely with in
> few minutes, a completely black image is produced.

Hum, I'm just fixing a but wher putting more in -wm caused issue but it was 
very specific : http://trac.osgeo.org/gdal/ticket/5789

> Using 1024 is not sufficient because my input file is around 300GB. 

Eh, read again what I wrote : "putting more warp memory will not necessarily 
need to more performance". -wm is the size of individual chunks that will be 
warped. Working on very big chunks is actually detrimental if you want to use 
-multi since there will be less opportunity to parallelize I/O and CPU bound 
operations.
If not already done, you'll get probably much more performance by for example 
ensuring you output to a tiled GeoTIFF, by adding -co TILED=YES

> I could
> not figure out the problem. I am also using '-multi' parameter.
> There is no problem if I do not use '-wm' and '-multi' parameters or just
> use 1024 with '-wm' and '-multi' except very slowness.
> 
> I hope you can help me.
> 
> Simen
> 
> 
> 
> On Wed, Dec 24, 2014 at 6:50 PM, Even Rouault <even.rouault at spatialys.com>
> 
> wrote:
> > Le mercredi 24 décembre 2014 06:05:50, Simen Langseth a écrit :
> > > What is the maximum '-wm' I can use with 64bit gdalwarp?
> > 
> > Simen,
> > 
> > Up to 9999 for 9999 MB. And if you want more, you have to specified the
> > value
> > in bytes instead of megabytes.
> > But putting more warp memory will not necessarily need to more
> > performance, especially if you mosaic many small images into a big one.
> > 
> > See
> > 
> > https://trac.osgeo.org/gdal/wiki/UserDocs/GdalWarp#WillincreasingRAMincre
> > asethespeedofgdalwarp
> > 
> > Even
> > 
> > --
> > Spatialys - Geospatial professional services
> > http://www.spatialys.com

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