PostGIS

ST_Roughness — Returns a raster with the calculated "roughness" of a DEM.

+raster +ST_Roughness(+`raster `+rast, integer nband, raster customextent, text pixeltype="32BF" , boolean + interpolate_nodata=FALSE + );

Calculates the "roughness" of a DEM, by subtracting the maximum from the minimum for a given area.

Availability: 2.1.0

ST_MapAlgebra (callback function version), ST_TRI, ST_TPI, ST_Slope, ST_HillShade, ST_Aspect