[gdal-dev] gdalwarp's default nodata value

Joaquim Luis jluis at ualg.pt
Tue May 11 19:37:07 EDT 2010


Before filling a ticket I would like to ask here if this gdalwarp 
behavior is the intended one.
When I convert a grid from geogs to UTM the nodatavalues are filled with 
I get the expected behaviour if I use the -dstnodata with a numeric 
value, but I found no way tom tell it use NaN.


This puts zeros on the nodata zone, but I don't find it correct as "0" 
is not exactly a natural nodata value. For my habits NaN is the natural 
no data value.

gdalwarp -s_srs "+proj=latlong" -t_srs "+proj=utm +zone=29 +datum=WGS84" 
swath_grid.grd lixo_utm.tiff

Furthermore when I load the " lixo_utm.tiff" in Mirone is does not 
recognize a nodata value, whilst if I do this instead

gdalwarp -s_srs "+proj=latlong" -t_srs "+proj=utm +zone=29 +datum=WGS84" 
-dstnodata 1 swath_grid.grd lixo_utm.tiff

than "1" is recognized as the nodata. I have not investigated the 
metadata to see why the "0" is not set to represent the nodata.


Joaquim Luis

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