“…The edge maps are at seven different scales (σc =4, 8,12,16,20,24,28) and a fixed set of Hough parameters are used as NumPeaks=100, Threshold=3, FillGap=40, and MinLength=450 (Reproduced with permission from [23]; based on [19]). wider range of horizontal lines detected and a fairly broad range of vertical lines, and this fits as a transition stage between the 'horizontal groupings' of identically colored tiles with the mortar lines at a focal view, and the 'zigzag vertical groupings' of the tiles [22] at a more peripheral/global view. Fig 11 (b) (center-column) shows the near vertical lines detected.…”