[GRASSLIST:8472] converting raster value of 0 (black) to null

[Ed Davison]

I have a radar map that has a 0 value for black.  This came from a
grayscale GeoTIFF.

I need to convert the 0 value to null so that I can overlay it onto a
base map.

I have tried using mapcalc with the following:

radarnew=if(radar=0,null(),radar)

but this produces a magenta raster map with no other data in it.

r.mapcalc is very new to me and I cannot seem to make heads of tails of
how to do this from reading the man page.  Any pointers would be great.


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Ed Davison