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

[Andrea Peri]

Hi Even,

I just notice that in the page
http://www.gdal.org/gdalinfo.html

In the sample reported is write a bloc size of 512x16:

>Band 1 Block=512x16 Type=Byte, ColorInterp=Gray

Should it be a typo error ?

A.


2015-08-23 11:40 GMT+02:00 Even Rouault <even.rouault at spatialys.com>:
> 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
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com



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Andrea Peri
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qwerty àèìòù
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