Only two of the eight hillforts in the study area have no evidence for either ramparts or towers: Turó de Montgat and Turó de Sant Miquel, both with few archaeological remains. Three hillforts have rampart remains: Puig Castellar, Castellruf and Turó de Can Gallemí. In addition to ramparts, towers have been documented in Turó de Boscà and Penjabocs, and a possible tower in Les Maleses. As detailed plans of the hillforts were unavailable when doing this exercise, the viewsheds were not calculated from specific locations of ramparts and towers.
The entire set of five viewer point viewsheds (Figures 16, 20, 24, 28, 32, 36, 40 and 44) can be compared with the respective simple binary viewsheds included in Ruestes (2006, 234, figs 6 and 7). It should be noted that the points representing Puig Castellar and Turó de Montgat hillforts have been slightly displaced in the present research towards the central and higher point of the hills.
The original height of Turó de Montgat hill, which was artificially modified during the 19th and 20th centuries, has been reconstructed in both studies by using different methods. Moreover, the binary viewsheds shown in Ruestes (2006) were carried out using a different DEM (of 25m of resolution, and interpolated from contour lines at 20m intervals as shown in digital cartography 1:25000 from the Institut Cartogràfic de Catalunya).
It should be noted that there is considerable confusion in the literature between the terms probable and fuzzy viewshed. As Fisher has pointed out (1993, 344) probable viewsheds were erroneously referred to in his previous works as fuzzy viewsheds. Both concepts were later clarified by the author (Fisher 1994). Also the papers concerning Salagassos (Nackaerts and Govers 1997; Loots et al. 1999 and Nackaerts et al. 1999), while performing probable viewsheds, refer to them as fuzzy.
It should be noted that the most probable viewsheds do not necessarily coincide with their respective more probable visible areas symbolized in green in the probable viewsheds. The most probable viewshed is the part of the probable viewshed seen from the entire set of DEMs employed (i.e. 21), whereas the more probable visible area represents those cells seen al least 21 times. However, as explained in section 3.2.2c, here a value of 21 could indicate that a cell is seen 1 time from 21 DEMs or from more than one viewer point in less than 21 DEMs..
A middle-distance Higuchi band would also have resulted in roughly 3.3km. Moreover, 3km is the maximum radius taken in a number of visibility analyses (e.g. Bell and Lock 2000, 97; García Sanjuán et al. 2006, 185).