A detailed description of W ψ and F O k,ν is presented in [9] . The b-scale algorithm works as follows: the ball radius k is iteratively increased starting from one, and the algorithm checks for F O k,ν (c), the fraction of the object containing c that is contained in the ball. When this fraction falls below a predefined threshold, it is considered that the ball contains an object region different from that to which c belongs [16] . This process is repeated for every voxel within the scene. Voxels are assigned their b-scale values discreetly from 1 to r max . 1 In principle, b-scale partitions the scene into several levels based on the size of local structures from 1 to r max . Computing b-scale values for every voxel leads b-scale scenes as shown in Fig. 4 (a). Note also that locally adaptive scale in regions with fine details or in the vicinity of boundaries is small, while it is large in the interior of large homogeneous objects.