[gdal-dev] strange grid pattern when reprojecting

[Even Rouault]

Le mercredi 25 novembre 2015 16:16:17, Ramiro Marco Figuera a écrit :
> Hi all,
> 
> I noticed a curious gridded pattern when using gdalwarp to reproject. I
> am reprojecting some lunar south polar DEMs in stereographic projection
> to gnomonic projection. I am using the following command: gdalwarp
> -t_srs '+proj=gnom +lat_0=-90 +lon_0=0 +x_0=0 +y_0=0 +a=1737400
> +b=1737400 +units=m +no_defs ' topo_stereo.tif topo_gnom.tif

The default resampling of gdalwarp is nearest neighbour. Perhaps try something 
more advanced like -r bilinear or -r cubic ?

> 
> When I create a hillshaded map using gdaldem hillshade I can see a
> gridded pattern. I did a hillshaded map with the original map and the
> grid is no there. Am I making a mistake when reprojecting or is that a
> bug? I can provide images if necessary.
> 
> Cheers,
> 
> Ramiro

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