[GRASS-user] exporting as GTiff

[Frank Warmerdam]

Stuart Edwards wrote:
> Hi
> 
> I am running into some problems exporting raster files as GTiffs.  These 
> are maps that were acquired as tiff images and georeferenced in GRASS.  
> When I export them the following dialog occurs:
> 
> "Writing format: GTiff
> Writing type:   UInt16
> Input file size is 18310, 7565
> 0Warning 1: Lost metadata writing to GeoTIFF ... too large to fit in tag.
> ...10...20...30...40...50...60...70...80...90...Warning 1: Lost metadata 
> writing to GeoTIFF ... too large to fit in tag.
> 100 - done."
>
> The metadata was created in GRASS so that message is puzzling.

Stuart,

I suspect that there is a complicated (many entries) color tables for
this raster, and when converted to "color rules" metadata by r.out.gdal
that the resulting metadata is too large to fit in a TIFF tag.  Hopefully
the only downside is loss of your color rules.

> Also, is there a man page or some guidance on selecting the file type -- 
> if it wasn't for the GIS.m output dialog I would not have known to use 
> UInt16 and that this is the only format to support a color table.  The 
> createopt and metaopt are similarly cryptic and not mentioned on the 
> help page.  If this is covered in the gdal documentation, maybe a link 
> on the GRASS help page would take care of it.

The per-format creation options are documented in the per-driver support
for GDAL format drivers.

eg.
   http://www.gdal.org/formats_list.html

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | President OSGeo, http://osgeo.org