I am trying to remove cloud and cloud shadows for Landsat 4-5 ASTER images in GRASS GIS.

I have knowledge that detecting cloud and cloud shadow pixels which is >(255*0.2), but I cannot figure out the appropriate syntax for r.mapcalc?

1 Answer 1


Try something like this:

r.mapcalc "cloudmask = if(lsatband > 255*0.2, null(), lsatband)"
r.mask cloudmask

However, are you sure that the formula is that simple?

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