I wanted to perform a geoid offset correction to a DEM and saw this really useful post: Vertical Datum conversion of a raster with gdal
I noticed that although they use gdalwarp, they do not specify a resampling method (-r). Does gdalwarp always resample the image, making it important to specify the resampling method, or does it not resample when performing geoid correction? As the default resampling method is NN, I would like to avoid this when using elevation data but I don't want to force a resampling method if one isn't required.
