[Gdal-dev] Re: gdal fails on vrt (virtual raster) file

[WolfgangZ]

Frank Warmerdam schrieb:
> WolfgangZ wrote:
>> Hi,
>>
>> Gdal fails on my virtual raster file that links to JPEG graphics. Map 
>> size is 17121x12100 pixel and 13.8 MB of filesize (JPEG images).
>>
>> Here the command (but also gdal_translate fails with the same error):
>>
>> D:\DOP>gdalinfo referenz.vrt
>> ERROR 1: libjpeg: Failed to create temporary file
>> gdalinfo failed - unable to open 'referenz.vrt'.
>> Open GDAL Datasets:
>>   1 N DriverIsNULL 512x512x0
>>
>> Any help is welcome.
>> Wolfgang
> 
> Wolfgang,
> 
> This is an issue in the JPEG driver.  It seems that libjpeg tries to
> create a temporary file when an operation (like processing a progressive
> jpeg) would require quite a bit of memory.  If it fails to create the file
> you get the message you see.
> 
> I recently changed the amount of memory at which this happens to be 500MB
> instead of 1MB in the builtin libjpeg for GDAL (SVN trunk)
> 
>   http://trac.osgeo.org/gdal/changeset/11706
> 
> If you are building GDAL from source, then you might want to apply the
> same change.
> 
> It might also be sufficient to copy the jpeg file to a directory where
> you have read-write access.
> 
> Best regards,

this patch is probably not jet applied in the FWTools. But I'm wondering 
why even gdalinfo needs to create a temporary file? Why is there the 
need from gdalinfo or gdal_translate to read in the full image? Do I 
understand that that limit equals the maximum file size that can be 
handled? Where is this temporary file usually generated? I'm working on W2k.

Kind regards
Wolfgang