Calculation of the buriedness-index of a grid point P. A: A search ray (grey plane) scans the room for atoms. Atom Q is detected, since it is located within the dimensions of the search vector. Atoms R and S are not detected, since they are not covered by the search vector. B: Distance calculations are restricted to areas controlled by neighboring centroids (encircled). Neighboring centroids are identified by scanning an extended search space (grey border).