[Qgis-user] Raster Clipping

[Khaled Ibrahimi]

Hi Rudi,
Thanks a lot. It is working now eventhough the resulting clipped raster has a poor quality compared to the origin.
Best regards,
Khaled


________________________________
 From: Rudi von Staden <rudivs at gmail.com>
To: Khaled Ibrahimi <ibrahimikhaled at yahoo.com> 
Cc: "qgis-user at lists.osgeo.org" <qgis-user at lists.osgeo.org> 
Sent: Saturday, April 6, 2013 9:46 PM
Subject: Re: [Qgis-user] Raster Clipping
 

Hi Khaled,


On Sat, Apr 6, 2013 at 9:18 PM, Khaled Ibrahimi <ibrahimikhaled at yahoo.com> wrote:

I still have the same problem. I tried the "Raster->Projections->Warp" on my Raster but I got the msg: ERROR 1: Unable to compute a transformation between pixel/line and georeferenced coordinates for".
>


It sounds like your raster may not be georeferenced. Does it display in QGIS when you load it as a raster? Does it align with the vector you are cutting it with? From the command line, you can use gdalinfo to see if there's a coordinate system defined. If you run 'gdalinfo <filename>.jpg' (from the same directory as the file), the resulting output should include something like this if it's georeferenced:

Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]

if it isn't, you'll see something like this:

Coordinate System is `'

If it's not georeferenced, you can georeference it using the Georeferencer plugin (there's a useful tutorial here: http://glaikit.org/2011/03/27/image-georeferencing-with-qgis/).

Hope this helps,
Rudi
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