Ramiro Marco Figuera <r.marcofiguera <at> jacobs-university.de> writes:
> > Hi, > > I'm re-projecting (from stereographic to gnomonic) the PDS LOLA 20m/pix > DTMS from the lunar south pole. Im using gdalwarp like this: 'gdalwarp > -t_srs '+proj=gnom +lat_0=-90 +lat_ts=-90 +lon_0=0 +k=1 +x_0=0 +y_0=0 > +a=1737400 +b=1737400 +units=m +no_defs' topo_stereo.tif topo_gnom.tif' > . After that, I'm cropping the DTM to have a smaller region (200km by > 200km) around the pole. Then, I just use gdal_translate to export it as > XYZ since I need it in this format for my software and converting it to > kilometers instead of meters using awk. As this is a gridded data, the > resolution should remain the same (20m/pixel), however when I check the > first entries of my xyz file the resolution is sometimes 21 m/pixel and > sometimes 20 m/pixel, and this happens randomly. Any clue of what may > cause this error? Has anyone faced the same issue? Hi, Gdalwarp does not try to keep resolution unchanged and I guess that the reason is to avoid extra resampling. That your output is so close to 20 m/pix is a coincident. Varying 20/21 m pixel size in xyz file may be due to rounding errors. Have you checked the pixel size of topo_gnom.tif with gdalinfo? I would try what happens when running gdalwarp with -tr 20 20 for forcing the output resolution to 20m/pix. You should be able to crop and create 20 m/pixel xyz file with one run by setting the resolution with -tr and selecting the format with -of and defining extents with -te http://www.gdal.org/gdalwarp.html -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
