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?
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?