On Fri, May 15, 2009 at 1:46 PM, Andrew Brooks <[email protected]> wrote: > On Thu, 14 May 2009 20:21:11 +0100, yehya imam <[email protected]> wrote: >> >> I've downloaded AVHRR L1b images from NOAA CLASS. I'm trying to rectify the >> images via gdalwarp -tps. The output is obviously erroneous as per gdalinfo > > The error message "There is a problem to invert the interpolation matrix" > explains why gdalinfo gave erroneous information. > > I too have had great difficulties with gdalwarp and L1B.
Me, too. I gave up so far but your answer raised my interest. I still want to process large amounts of NOAA L1b. > The way the driver reports the geolocation data is not optimal and the > methods used to process the data are also not optimal so it's no surprise > that the result is often broken. > > I submitted a patch to fix one of the issues but it was never applied; you > can download it from here: http://trac.osgeo.org/gdal/ticket/2501 (sidenote: I see you aren't in CC in that ticket) > I also submitted some code to perform proper interpolation but nobody has > made use of it. Was that submitted as ticket, too? I would like to try it. > I started a dialogue with the driver author who said he was going to rewrite > it but then he went silent and I've not heard from him since. > > One method I've used in the past to get some results is as follows: > > 1) Extract ALL of the geolocation data myself (51 points per scan line) since > the driver normally subsamples > 2) Interpolate this myself (Lagrangian method) to get 2048 points per scan > line > 3) Create two VRT files for the latitude and longitude data > 4) Create a VRT file describing the image data in the file which references > the two geolocation VRT files > 5) Use the VRT file with my patched version of gdalwarp > > This was successful for me in the past but when I tried it again recently it > failed. I can give you more details if you want though. Perhaps it is worth to document that in the trac Wiki? thanks Markus _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
