[GRASSLIST:9858] Re: GeoTiffs shifted by 360 degrees after processing in GRASS

[Markus Neteler]

On Mon, Jan 16, 2006 at 04:44:57PM +0100, Gross, Dorit (SDRN) wrote:
> Dear all,
> 
> I have a set of GeoTiffs that I import into GRASS to do some processing and
> export them afterwards as GeoTiffs again. The problem now is that GRASS
> exports the images shifted by 360 degrees to the east.
> 
> 
> Corner Coordinates (before the import into GRASS):
> Upper Left  (-180.0044643,  75.0044643) (180d 0'16.07"W, 75d 0'16.07"N)
> Lower Left  (-180.0044643, -56.0044643) (180d 0'16.07"W, 56d 0'16.07"S)
> Upper Right ( 179.9955353,  75.0044643) (179d59'43.93"E, 75d 0'16.07"N)
> Lower Right ( 179.9955353, -56.0044643) (179d59'43.93"E, 56d 0'16.07"S)
> Center      (  -0.0044645,   9.5000000) (  0d 0'16.07"W,  9d30'0.00"N)
> 
> Corner Coordinates (after the export from GRASS):
> Upper Left  ( 179.9955357,  75.0044643) (179d59'43.93"E, 75d 0'16.07"N)
> Lower Left  ( 179.9955357, -56.0044643) (179d59'43.93"E, 56d 0'16.07"S)
> Upper Right (     539.996,      75.004) (539d59'43.93"E, 75d 0'16.07"N)
> Lower Right (     539.996,     -56.004) (539d59'43.93"E, 56d 0'16.07"S)
> Center      (     359.996,       9.500) (359d59'43.93"E,  9d30'0.00"N)
> 
> 
> Has someone of you faced a similar problem? How do I receive a proper
> georeference when exporting from GRASS?
> 
> The input GeoTiffs are a set of converted Spot-Veg HDF files using GDAL.

Did you try to use the dedicated script i.in.spotvgt:

 http://grass.itc.it/grass61/manuals/html61_user/i.in.spotvgt.html

Maybe this solves the problem of the global wrap-around.
Please let us know.

Markus

> The -180.0044... degrees for the upper left X seems a bit odd, but GDAL imports
> the Spot-Veg properly with these coordinates. I checked the images in Erdas
> and they are correct. I also checked the corner coordinates of the imported
> file insight GRASS and also here the coordinates are correct. So apparently
> the shift occurs during the export from GRASS into GeoTiff. At the moment I
> solve the problem by reassigning the georeference to the GeoTiff after the
> export from GRASS, but I would be more happy with properly exported images
> right away.
> 
> Can someone help please?
> 
> Thank you,
> Dorit
> 

-- 
Markus Neteler     <neteler itc it>       http://mpa.itc.it
ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18        -       38050 Povo (Trento), Italy