[gdal-dev] gdal_merge output JPG unable to write

[Frank Warmerdam]

SriRam Prasad Bhasker wrote:
> 
> Hi
> 
> Gdal_Merge is not supporting JPEG Driver for Writing..
> 
> can anyone one know list of valid output drivers for Gdal_merge
> 
> I have 2.0 Gb sized Jpeg Files (150 odd..)need to merge them into one 
> Mosaiced Jpeg File.

Bhasker,

If you do "gdal_merge.py --formats" it will list all the formats supported
by the current build.  All those with "rw+" in brackets afterwards are
suitable output formats.  If they have "ro" then the format is read only.
If they have "rw" then the format supports writing, but only in "copy in
a single pass from another dataset" mode which is insufficient for
gdal_merge.py which needs to write the output in somewhat random chunks.

Note that you can merge into a mosaic in a format like Erdas Imagine or
BigTIFF (if you are using a new enough build) and then gdal_translate that
to JPEG.  I would however stress that JPEG is a poorly performing format
for large geospatial datasets that you want to access randomly in a
desktop viewer or web mapping situation for instance.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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