[Gdal-dev] AVHRR NOAA level 1b

[Markus Neteler]

On Fri, May 19, 2006 at 09:58:50AM +0100, Juan Carlos Castaneda wrote:
> Dear list,
> 
> I'm trying to use GDAL to geocode AVHRR level 1b images. It's not giving
> me good results. I went to the archives and Google to find what's
> happening and I read that the algorithm to geocode is not the best for
> these type of image. From the documentation:
> "that GDAL simple affine georeference model completely unsuitable for
> the NOAA data. So you should not rely on it. It is recommended to use
> the thin plate spline warper (tps). Automatic image rectification can be
> done with ground control points (GCPs) from the input file. NOAA stores
> 51 GCPs per scanline both in the LAC and GAC datasets."
> 
> Any suggestions how to do the "thin plate spline warper (tps)" for these
> images? Can it be done with GDAL? I've used gdalwrap -tps but it's not 
> working neither. I used the GCPs and they don't seem to give accurate 
> positions on the image. Can anybody give me some advice?

Please use gdalwarp with -tps option:

http://www.gdal.org/gdalwarp.html
"-tps
    Enable use of thin plate spline transformer based on available
    GCPs. Use this instead of the -order switch.
"

Please let us know how it performs (I am also interested in the
AVHRR geocoding business).

Markus