International
Tables for
Crystallography
Volume B
Reciprocal space
Edited by U. Shmueli

International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 368   | 1 | 2 |

Figure 2.5.6.4 

B. K. Vainshteinc and P. A. Penczekg
[Figure 2.5.6.4]
Figure 2.5.6.4

Discretization in two dimensions (d = 2). The assumption is that the mass is located at the centre of the voxel.