[GRASS-user] Re: [GRASS-dev] gdal import an nodata cells

[Daniel Farnan at San Francisco]

 thnak you.

If the programming, of GRASS, is integer-centric, why not solve the null-difficulty with invisible ( ; ) c programming-style work - as, at a similar time in the computer-service world, that was the a vs 1 (text v nt) solution?
:-)

-----Original Message-----
From: grassuser-bounces at grass.itc.it [mailto:grassuser-bounces at grass.itc.it] On Behalf Of Frank Warmerdam
Sent: Thursday, July 19, 2007 8:42 AM
To: "Carlos \"Guâno\" Grohmann"
Cc: GRASS List
Subject: [GRASS-user] Re: [GRASS-dev] gdal import an nodata cells

Carlos "Guâno" Grohmann wrote:
> I just imported a DEM that was sent to to in Erdas IMG format (HFA), 
> with r.in.gdal, and after importing I had to use r.mapcalc to make the 
> NODATA cells -- which were tagged as -32768 -- became NULL.
> 
> I was just wondering if there is a way to do this automatically? can I 
> pass the -32768 value as an option to r.in.gdal so the cell will be 
> imported as null?

Carlos,

I don't see any options to provide a nodata on the r.in.gdal commandline, but r.in.gdal will set pixels to null if GDAL "knows" the nodata value for the source dataset.  Nodata support does exist now in the HFA (.img) driver but I think it was recently introduced.  It is also possible that the nodata value wasn't properly marked in the source .img file.

A commandline argument for this could be added to r.in.gdal, but given the relative ease of fixing it up with r.mapcalc, I'm not sure it would be worth the complication.

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    | President OSGeo, http://osgeo.org

_______________________________________________
grassuser mailing list
grassuser at grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser