[gdal-dev] Re: The GEOS projection and gdalwarp

[Simon R. Proud]

Hi all,
Yesterday I replied to Marcel and not to the list - so I'll add a reply here in case others have a similar issue to me:
Marcel's solution works well on my Meteosat data, and the georeferencing looks perfect. The problem is solved!


Cheers,
Simon.



>>> Marcel Derrien  03/27/12 9:59 AM >>>
Hi,
First I suggest you use gdal_translate and provide -a_ullr ulx uly lrx 
lry so that your input file is georeferenced.
Assuming that your input file is the full earth disk 3712x371,  the 
corner coordinates (metre) of your image are
ulx_msg=-5570248.832537
uly_msg=5570248.832537
lrx_msg=5567248.429179
lry_msg=-5567248.429179
gdal_translate -a_srs  "+proj=geos +a=6378169 +b=6356583.8 +lon_0=0 
+h=35785831" -a_ullr $ulx_msg $uly_msg $lrx_msg $lry_msg input.tif 
input_geo.tif
Using input_geo.tif with gdalwarp should allow your desired reprojection.
Marcel
---
Marcel Derrien,
http://www.meteo-spatiale.fr

Date: Mon, 26 Mar 2012 13:31:24 +0200
From: "Simon R. Proud" 
Subject: [gdal-dev] The GEOS projection and gdalwarp
To: 
Message-ID: <4F706FAC.9690.0040.1 at geo.ku.dk>
Content-Type: text/plain; charset=US-ASCII

Hi,
I'm working with meteosat data in the GEOS projection and have been having some problems with gdalwarp.The data I'm using contains no geo-information, so I call gdalwarp with this:

gdalwarp -s_srs '+proj=geos +lon_0=0.0 +h=35785831 +x_0=0.0' -t_srs '+proj=latlong +datum=WGS84' -ts 2000 2200 -te -20.5 -40.99992 52.2272 39.0 /media/Data/ISOP.tif /home/processing/GEO.tif

This results in:
"ERROR1: Unable to compute a transformation between pixel/line and georeferenced coordinates for /media/Data/ISOP.tif.
There is no affine transformation and no GCPs."

Do you know how I could overcome this? When I convert *to* GEOS I needed to include some additional info (such as subsatellite pixel size as an argument with -tr) but I can't find how to include that info in the source projection. Any ideas/hints greatly appreciated!

Thanks,
Simon.

~~~~~~~~~~~~~~~~~~~~~~~~
Dr Simon Proud
Post-doc, Satellite Remote Sensing
University of Copenhagen

Tel: +45 35 32 25 84
~~~~~~~~~~~~~~~~~~~~~~~~