Schematic example of voxel addition process. Voxel addition example taking only the stress direction and magnitude into account. When checking a specific voxel (current element), the volumetric stress that it bears (σv) and the angle (θ) that its neighbours form with the direction of maximum stress (d
, red arrow) determine the probability of appearance (p+). In the illustration, the top voxel (currently part of the ECM) would have a higher probability than the right one of becoming cell since θ1 is lower than 90 degrees whereas θ2 is higher. Note that this is a simplified 2D scheme. In 3D, 6-connectivity is used to compute the voxel addition.