[GRASS-user] Remove black background of GeoTiff

[Frank Warmerdam]

Craig Feuerherdt wrote:
> Have been trying to export some rectified images as GeoTiff using the 
> following command;
> 
> r.out.gdal input=s107r format=GTiff type=Byte output=s107rf.tif 
> createopt="TFW=YES" createopt="INTERLEAVE=PIXEL"
> 
> This works well and can be opened by ArcGIS however there is a black 
> background around the borders where the image has been rotated through 
> the transformation.
> Is there another creatopt tag I can use to remove this?
> I have read through the GeoTiff documentation on GDAL.org and tried a 
> few of the other tags but nothing seems to remove it.

Craig,

There is no standard tag in TIFF or GeoTIFF for describing nodata pixel
values.  The only approach you might be able to use is to somehow add an
alpha channel and mark the nodata regions as alpha=0; however, I'm not
sure how you would go about that.

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