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

Ramiro Marco Figuera r.marcofiguera at jacobs-university.de
Thu Jul 16 08:19:03 PDT 2015


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?



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

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