[Gdal-dev] Re: Angular units in GeoTiffs

Frank Warmerdam warmerdam at pobox.com
Mon Oct 18 17:13:45 EDT 2004


Brent Fraser wrote:
> Frank,
> 
>   Is there any way to create a GeoTiff with the GeogAngularUnitsGeoKey set
> using gdalwarp?  I want to create LatLong geotiffs with the tag set to
> Angular_Degree.  The GeoTiff spec doesn't say if there is any default units
> setting (maybe I missed it) and some applications don't like it when it is
> missing.

Brent,

In my not-so-humble opinion any software that doesn't assume degrees for
unstated angular units is *trying* to make life difficult for users.
Sometimes I wish I could bash software developes with a clue stick.  Of course
sometimes I could stand a good clue-whack or two.

There is currently no way to force GDAL to write out this tag except to
change the source.  You could, of course, accomplish this in an extra
translation step using geotifcp but that would be tedious.

Since you feel it would be helpful, I have modified the GDAL GeoTIFF
driver in CVS to always emit GeogAngularUnitsGeoKey (as Angular_Degree).
The change is now in CVS.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent




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