I was hoping someone could shed some light on this - I was implementing CLOD w/ rottger''s paper, but when i came to the ''roughness'' calculations (d2 values) i got a little confused. It''s not really clear on how one goes about calculating max|dhi|. Are you just taking the absolute value of the mid-point of the edge, or the abs of the result of subtracting the avg height of the two endpoints from the height of the midpoint? I know there''s someone here who knows what i mean. Thanks for the help