The values of
count, mean, standard deviation of each zone were used as sub-factors under Slope. Count is
simply the total number of visible cells, mean is a measure of the average slope of the visible land
and the standard deviation suggests the diversity of visible terrain types. Only the values of count
were considered as the index of Sea since we were only concerned with the area of visible sea
(water body). Names of these sub-factors are formed by the abbreviation of the statistical type
(C for count, M for mean slope, ST for standard deviation and S for sea)