[GRASSLIST:9868] Re: GeoTiffs shifted by 360 degrees after processing in GRASS

[Gross, Dorit (SDRN)]

Markus, thanks for your reply.

I currently use Grass 6.0.0 and it seems 6.1 is still under development. Is
it possible to get the i.in.spotvgt script only and to implement it in the
old version or do we have to compile the whole source code of 6.1.

Dorit




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

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