[GRASS-dev] TIFF output size: r.out.gdal vs gdal_translate

[Glynn Clements]

Maciej Sieczka wrote:

> I've noticed that r.out.gdal creates GeoTIFFs significantly larger than
> gdal_translate. Could this be avoided?
> 
> 
> 
> Example, in spearfish60:
> 
> $ r.out.gdal in=landcover.30m out=landcover.30m.tif type=Byte
> $ ls -l landcover.30m.tif
> -rw-r--r-- 1 shoofi shoofi 303978 sie 20 11:49 landcover.30m.tif
> 
> $ gdal_translate landcover.30m.tif landcover.30m_gt.tif
> $ ls -l landcover.30m_gt.tif
> -rw-r--r-- 1 shoofi shoofi 300220 sie 20 11:49 landcover.30m_gt.tif
> 
> 
> 
> Applying compression makes the difference more distinct:
> 
> $ r.out.gdal in=landcover.30m out=landcover.30m.tif type=Byte 
> createopt="COMPRESS=DEFLATE"
> $ ls -l landcover.30m.tif
> -rw-r--r-- 1 shoofi shoofi 51338 sie 20 11:50 landcover.30m.tif
> 
> $ gdal_translate -co "COMPRESS=DEFLATE" landcover.30m.tif 
> landcover.30m_gt.tif
> $ ls -l landcover.30m_gt.tif
> -rw-r--r-- 1 shoofi shoofi 47567 sie 20 11:51 landcover.30m_gt.tif
> 
> 
> 
> (Probably related to [1]. Some more info in a duplicate [2].)
> 
> [1]http://trac.osgeo.org/gdal/ticket/1688
> [2]http://trac.osgeo.org/gdal/ticket/1689).

I wouldn't call 3-4KiB "significantly larger", especially as this
appears to be a fixed overhead, rather than a proportional one.

Have you compared the output from gdalinfo for the images in question?

If the extra is caused by the GRASS colour rules being added as
metadata, we could add a flag to suppress that. OTOH, if it requires
making the code significantly more complex, then it isn't likely to
happen for the sake of a few KiB.

-- 
Glynn Clements <glynn at gclements.plus.com>