[gdal-dev] The vrt datasource from gdalbuildvrt report a wrong block of 128x128

[Even Rouault]

Le dimanche 23 août 2015 11:28:21, Andrea Peri a écrit :
> Hi Even,
> thx for reply.
> 
> So actually a tiff born to be used with vrt datasource be better if
> you was with a tile=128x128 instead of tile=1024x1024
>  right ?

I guess that should help in most cases, but almost due to the reduced tile 
size than the matching between TIFF and VRT block size. For example, if the 
VRT is read by an algorithm that processes line by line, a reduced tile size 
will cause less data to be read.
Increasing GDAL_CACHEMAX can also be an alternative

> 
> A.
> 
> 2015-08-23 10:51 GMT+02:00 Even Rouault <even.rouault at spatialys.com>:
> > Le dimanche 23 août 2015 07:43:03, Andrea Peri a écrit :
> >> Hi,
> >> I have a tiff tiled with tile size 1024 x 1024.
> >> 
> >> When I try to build a vrt-datasource on it using the gdalbuildvrt.
> >> I see the result vrt file report a
> >> block of 128x128 instead of 1024x1024.
> >> 
> >> I dont know if this is correct by the gdalbuildvrt oint of view
> >> 
> >> Also I like to know if is preferrably to correct manually  the vrt
> >> result to report the right value 1024
> >> or is also acceptable to maintain the 128 size reported for the right
> >> work of the gdal utilities in the vrt file.
> > 
> > Andrea,
> > 
> > the 128x128 block size is currently hardcoded in the VRT driver. We could
> > imagine extending the VRT syntax to have user defined block size.
> > 
> > Even
> > 
> > --
> > Spatialys - Geospatial professional services
> > http://www.spatialys.com

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