Hi,
At least in my understanding the gdaldem manual's description for the
Roughness is misleading. It states
"Roughness is the the largest inter-cell difference of a central pixel
and its surrounding cell, as defined in Wilson et al (2007, Marine
Geodesy 30:3-35)."
From that I understood that R = MAX(Zi-Zcentral) where Zi runs over all
pixels in the rectangular neighborhood.
However, what the code computes (correctly according to the paper it
refers to) is
R = Zmax - Zmin
that is also known as the range filter in image processing.
Joaquim Luis
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