Illustration of the boundary selection process. The dashed vertical green lines correspond to the detected characteristic points, and the small bottom numbers are the associated flag. The dashed black line corresponds to the selected boundary of the structure R_select. The dashed blue line correspond to the position of the sink in the structure. The gray region corresponds to R_eq < R_min. (a) Energy of the structure as a function of the structure size. The light red curve is the sum of all the energy contributions (see Sect. 2.1). The thick red curve is the smoothed profile used for the boundary selection process. The light red area is the tolerance interval. (b) Density of the last-added cell as a function of the structure size. The light red curve corresponds to the actual density of the last-added cell. The thick red curve corresponds to the upper-limit profile. (c) Projected density map. The white contour corresponds to the projected structure boundary R_select.