[gdal-dev] gdaldem Roughness description

Joaquim Luis jluis at ualg.pt
Thu Oct 8 09:28:31 EDT 2009


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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