[gdal-dev] decimal rounding issue when re-projecting

[Ramiro Marco Figuera]

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?

Cheers,

Ramiro

-- 
Ramiro Marco Figuera
Department of Physics and Earth Sciences
Jacobs University Bremen
Campus Ring 1, 28759 Bremen, Germany
Office: Research III, Room 99b
Tel: +49 (0)421 200 3226